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  • 1. ZJ ENGINES 9-1 ENGINES CONTENTS page pageLUBRICATION SYSTEM . . . . . . . . . . . . . . . . . . . 32 5.2L ENGINE SERVICE PROCEDURES . . . . . . . 49LUBRICATION SYSTEM . . . . . . . . . . . . . . . . . . . 65 ENGINE DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . 64.0L ENGINE SERVICE PROCEDURES . . . . . . . 12 STANDARD SERVICE PROCEDURES . . . . . . . . . 1 STANDARD SERVICE PROCEDURES INDEX page pageEngine Performance . . . . . . . . . . . . . . . . . . . . . . . . 2 Measuring with Plastigage . . . . . . . . . . . . . . . . . . . . 3Form-In-Place Gaskets . . . . . . . . . . . . . . . . . . . . . . 1 Repair Damaged or Worn Threads . . . . . . . . . . . . . 4Honing Cylinder Bores . . . . . . . . . . . . . . . . . . . . . . 2 Service Engine Assembly (Short Block)—4.0LHydrostatic Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4FORM-IN-PLACE GASKETS between smooth machined metallic surfaces. It will There are several places where form-in-place gas- not cure if left in the uncovered tube. DO NOT usekets are used on the engine. DO NOT use form-in- on flexible metal flanges.place gasket material unless specified. Caremust be taken when applying form-in-place gaskets. SURFACE PREPARATIONBead size, continuity and location are of great impor- Parts assembled with form-in-place gaskets may betance. Too thin a bead can result in leakage while too disassembled without unusual effort. In some in-much can result in spill-over. A continuous bead of stances, it may be necessary to lightly tap the partthe proper width is essential to obtain a leak-free with a mallet or other suitable tool to break the sealjoint. between the mating surfaces. A flat gasket scraper Two types of form-in-place gasket materials are may also be lightly tapped into the joint but careused in the engine area (Mopar௡ Silicone Rubber Ad- must be taken not to damage the mating surfaces.hesive Sealant and Mopar௡ Gasket Maker). Each Scrape or wire brush all gasket surfaces to removehave different properties and cannot be used inter- all loose material. Inspect stamped parts to ensurechangeably. gasket rails are flat. Flatten rails with a hammer on a flat plate, if required. Gasket surfaces must be freeMOPARா SILICONE RUBBER ADHESIVE of oil and dirt. Make sure the old gasket material isSEALANT removed from blind attaching holes. Mopar௡ Silicone Rubber Adhesive Sealant, nor-mally black in color, is available in 3 ounce tubes. GASKET APPLICATIONMoisture in the air causes the sealant material to Assembling parts using a form-in-place gasket re-cure. This material is normally used on flexible metal quires care.flanges. It has a shelf life of a year and will not prop- Mopar௡ Silicone Rubber Adhesive Sealant shoulderly cure if over aged. Always inspect the package for be applied in a continuous bead approximately 3 mmthe expiration date before use. (0.12 inch) in diameter. All mounting holes must be circled. For corner sealing, a 3 or 6 mm (1/8 or 1/4MOPARா GASKET MAKER inch) drop is placed in the center of the gasket con- Mopar௡ Gasket Maker, normally red in color, is tact area. Uncured sealant may be removed with aavailable in 6 cc tubes. This anaerobic type gasket shop towel. Components should be torqued in placematerial cures in the absence of air when squeezed while the sealant is still wet to the touch (within 10
  • 2. 9-2 ENGINES ZJminutes). The use of a locating dowel is recom- (j) If cylinder(s) have abnormally low compres-mended during assembly to prevent smearing the sion pressures, repeat steps 4a through 4h.material off location. (k) If the same cylinder(s) repeat an abnormally Mopar௡ Gasket Maker should be applied sparingly low reading, it could indicate the existence of ato one gasket surface. The sealant diameter should problem in the cylinder.be 1.00 mm (0.04 inch) or less. Be certain the mate- The recommended compression pressures arerial surrounds each mounting hole. Excess material to be used only as a guide to diagnosing enginecan easily be wiped off. Components should be problems. An engine should NOT be disassem-torqued in place within 15 minutes. The use of a lo- bled to determine the cause of low compressioncating dowel is recommended during assembly to pre- unless some malfunction is present.vent smearing the material off location. (5) Clean or replace spark plugs as necessary. Ad- just gap (refer to Group 8D, Ignition System for gapENGINE PERFORMANCE adjustment and torque). To provide best vehicle performance and lowest ve- (6) Test resistance of spark plug cables (refer tohicle emissions, it is most important that the tune-up Group 8D, Ignition System).be done accurately. Use the specifications listed on (7) Inspect the primary wire. Test coil output volt-the Vehicle Emission Control Information label found age, primary and secondary resistance. Replace partson the engine compartment hood. as necessary (refer to Group 8D, Ignition System and (1) Test battery specific gravity. Add water, if nec- make necessary adjustment).essary. Clean and tighten battery connections. (2) Test cranking amperage draw (refer to Group (8) Set ignition timing to specifications (refer to8B, Battery/Starter Service for the proper proce- Specification Label on engine compartment hood).dures). (9) Perform a combustion analysis. (3) Tighten the intake manifold bolts (refer to (10) Test fuel pump for pressure (refer to GroupGroup 11, Exhaust System and Intake Manifold for 14, Fuel System for the proper specifications).the proper specifications). (11) Inspect air filter element (refer to Group 0, (4) Perform cylinder compression test: Lubrication and Maintenance for the proper proce- (a) Check engine oil level and add oil, if neces- dure). sary. (12) Inspect crankcase ventilation system (refer to (b) Drive the vehicle until engine reaches normal Group 0, Lubrication and Maintenance for the proper operating temperature. procedure). (c) Select a route free from traffic and other (13) For emission controls refer to Group 25, Emis- forms of congestion, observe all traffic laws and sion Controls System for service procedures. briskly accelerate through the gears several times. (14) Inspect and adjust accessory belt drives (refer The higher engine speed may help clean out valve to Group 7, Cooling System for the proper adjust- seat deposits which can prevent accurate compres- ments). sion readings. (15) Road test vehicle as a final test.CAUTION: DO NOT overspeed the engine. HONING CYLINDER BORES Before honing, stuff plenty of clean shop towels un- (d) Remove all spark plugs from engine. As spark der the bores and over the crankshaft to keep abra- plugs are being removed, check electrodes for ab- sive materials from entering the crankshaft area. normal firing indicators - fouled, hot, oily, etc. (1) Used carefully, the Cylinder Bore Sizing Hone Record cylinder number of spark plug for future C-823 equipped with 220 grit stones, is the best tool reference. for this job. In addition to deglazing, it will reduce (e) Disconnect coil wire from distributor and se- taper and out-of-round as well as removing light cure to good ground to prevent a spark from start- scuffing, scoring or scratches. Usually a few strokes ing a fire. will clean up a bore and maintain the required lim- (f) Be sure throttle blades are fully open during its. the compression check. (g) Insert compression gage adaptor into the CAUTION: DO NOT use rigid type hones to remove No.1 spark plug hole. Crank engine until maximum cylinder wall glaze. pressure is reached on gauge. Record this pressure as No.1 cylinder pressure. (2) Deglazing of the cylinder walls may be done if (h) Repeat Step 4 g for all remaining cylinders. the cylinder bore is straight and round. Use a cylin- (i) Compression should not be less than 689 kPa der surfacing hone, Honing Tool C-3501, equipped (100 psi) and not vary more than 172 kPa (25 psi) with 280 grit stones (C-3501-3810). 20-60 strokes, de- from cylinder to cylinder. pending on the bore condition, will be sufficient to
  • 3. ZJ ENGINES 9-3provide a satisfactory surface. Using honing oil and the crankshaft. Place a minimum of 0.254 mmC-3501-3880 or a light honing oil available from ma- (0.010 inch) shim between the bearing shell and thejor oil distributors. adjacent bearing cap. Tighten the bolts to 18 N⅐m (13 ft. lbs.) torque.CAUTION: DO NOT use engine or transmission oil, • CHECK NO.1 BEARING: Shim No.2 main bear-mineral spirits or kerosene. ing. • CHECK NO.2 BEARING: Shim No.1 and No.3 (3) Honing should be done by moving the hone up main bearing.and down fast enough to get a crosshatch pattern. • CHECK NO.3 BEARING: Shim No.2 and No.4The hone marks should INTERSECT at 50° to 60° main bearing.for proper seating of rings (Fig. 1). • CHECK NO.4 BEARING: Shim No.3 and No.5 main bearing. • CHECK NO.5 BEARING: Shim No.4 main bear- ing (5.2L). Shim No.4 and No.6 main bearing (4.0L). • CHECK NO.6 BEARING: Shim No.5 and No.7 main bearing (4.0L). • CHECK NO.7 BEARING: Shim No.6 main bear- ing (4.0L). Remove all shims before assembling engine. METHOD - 2 (ALTERNATIVE)—The weight of the crankshaft is supported by a jack under the coun- terweight adjacent to the bearing being checked. (3) Place a piece of Plastigage across the entire width of the bearing cap shell (Fig. 2). Position the Plastigage approximately 6.35 mm (1/4 inch) off cen- ter and away from the oil holes. In addition, suspect Fig. 1 Cylinder Bore Crosshatch Pattern areas can be checked by placing the Plastigage in that area. Tighten the bearing cap bolts of the bear- (4) A controlled hone motor speed between 200 and ing being checked to 108 N⅐m (80 ft. lbs.) torque300 RPM is necessary to obtain the proper cross- (4.0L Engine). Tighten the bearing cap bolts of thehatch angle. The number of up and down strokes per bearing being checked to 115 N⅐m (85 ft. lbs.) torqueminute can be regulated to get the desired 50° to 60° (5.2L Engine). DO NOT rotate the crankshaft orangle. Faster up and down strokes increase the cross- the Plastigage may be smeared, giving inaccu-hatch angle. rate results. (5) After honing, it is necessary that the block becleaned to remove all traces of abrasive. Use a brushto wash parts with a solution of hot water and deter-gent. Dry parts thoroughly. Use a clean, white, lint-free cloth to check that the bore is clean. Oil thebores after cleaning to prevent rusting.MEASURING WITH PLASTIGAGECRANKSHAFT MAIN BEARING CLEARANCE Engine crankshaft bearing clearances can be deter-mined by use of Plastigage, or equivalent. The follow-ing is the recommended procedures for the use ofPlastigage: Fig. 2 Placement of Plastigage in Bearing Shell (1) Remove oil film from surface to be checked. (4) Remove the bearing cap and compare the widthPlastigage is soluble in oil. of the flattened Plastigage with the scale provided on (2) The total clearance of the main bearings can the package (Fig. 3). Plastigage generally comes in 2only be determined by removing the weight of the scales (one scale is in inches and the other is a met-crankshaft. This can be accomplished by either of two ric scale). Locate the band closest to the same width.methods: This band shows the amount of clearance. Differ- METHOD - 1 (PREFERRED)—Shim the bear- ences in readings between the ends indicate theings adjacent to the bearing to be checked. This will amount of taper present. Record all readings takenremove the clearance between upper bearing shell (refer to Engine Specifications).
  • 4. 9-4 ENGINES ZJ • Tapping the hole with a special Heli-Coil Tap, or equivalent. • Installing an insert into the tapped hole. This brings the hole back to its original thread size. CAUTION: Be sure that the tapped holes maintain the original center line. Heli-Coil tools and inserts are readily available from automotive parts jobbers. Fig. 3 Clearance Measurement SERVICE ENGINE ASSEMBLY (SHORT BLOCK)— (5) Plastigage is available in a variety of clearance 4.0L ENGINEranges. The 0.025-0.076 mm (0.001-0.003 inch) range A service replacement engine assembly (shortis usually the most appropriate for checking engine block) may be installed whenever the original cylin-bearing clearances. der block is defective or damaged beyond repair. It consists of the cylinder block, crankshaft, piston andCONNECTING ROD BEARING CLEARANCE rod assemblies. If needed, the camshaft must be pro- Engine connecting rod bearing clearances can be cured separately and installed before the engine isdetermined by use of Plastigage, or equivalent. The installed in the vehicle.following is the recommended procedures for the use A short block is identified with the letter Sof Plastigage: stamped on the same machined surface where the (1) Remove oil film from surface to be checked. build date code is stamped for complete engine as-Plastigage is soluble in oil. semblies. (2) Place a piece of Plastigage across the entire Installation includes the transfer of componentswidth of the bearing cap shell (Fig. 2). Position the from the defective or damaged original engine. Fol-Plastigage approximately 6.35 mm (1/4 inch) off cen- low the appropriate procedures for cleaning, inspec-ter and away from the oil holes. In addition, suspect tion and torque tightening.areas can be checked by placing the Plastigage in thesuspect area. HYDROSTATIC LOCK (3) The crankshaft must be turned until the con- When an engine is suspected of hydrostatic locknecting rod to be checked starts moving toward the (regardless of what caused the problem), follow thetop of the engine. Only then should the rod cap with steps below.Plastigage in place be assembled. Tighten the 4.0L (1) Preform the Fuel Pressure Release Procedurerod cap nut to 45 N⅐m (33 ft. lbs.) torque. Tighten the (refer to Group 14, Fuel System).5.2L rod cap nut to 61 N⅐m (45 ft. lbs.) torque. DO (2) Disconnect the negative cable from the battery.NOT rotate the crankshaft or the Plastigage (3) Inspect air cleaner, induction system and in-may be smeared, giving inaccurate results. take manifold to ensure system is dry and clear of foreign material. (4) Remove the bearing cap and compare the width (4) Place a shop towel around the spark plugs toof the flattened Plastigage with the scale provided on catch any fluid that may possibly be under pressurethe package (Fig. 3). Plastigage generally comes in 2 in the cylinder head. Remove the plugs from the en-scales (one scale is in inches and the other is a met- gine.ric scale). Locate the band closest to the same width.This band shows the amount of clearance. Differ- CAUTION: DO NOT use the starter motor to rotateences in readings between the ends indicate the the crankshaft. Severe damage could occur.amount of taper present. Record all readings taken(refer to Engine Specifications). (5) With all spark plugs removed, rotate the crank- (5) Plastigage is available in a variety of clearance shaft using a breaker bar and socket.ranges. The 0.025-0.076 mm (0.001-0.003 inch) range (6) Identify the fluid in the cylinders (coolant, fuel,is usually the most appropriate for checking engine oil, etc.).bearing clearances. (7) Make sure all fluid has been removed from the cylinders.REPAIR DAMAGED OR WORN THREADS (8) Repair engine or components as necessary to Damaged or worn threads can be repaired. Essen- prevent this problem from occurring again.tially, this repair consists of: (9) Squirt engine oil into the cylinders to lubricate• Drilling out worn or damaged threads. the walls. This will prevent damage on restart.
  • 5. ZJ ENGINES 9-5 (10) Install new spark plugs. Tighten the 4.0L en- (13) Install a new oil filter.gine spark plugs to 37 N⅐m (27 ft. lbs.) torque. (14) Fill engine crankcase with the specifiedTighten the 5.2L engine spark plugs to 41 N⅐m (30 ft. amount and grade of oil (refer to Group 0, Lubrica-lbs.) torque. tion and Maintenance). (11) Drain engine oil. Remove and discard the oil (15) Connect the negative cable to the battery.filter. (16) Start the engine and check for any leaks. (12) Install the drain plug. Tighten the drain plugto 34 N⅐m (25 ft. lbs.) torque.
  • 6. 9-6 ENGINES ZJ ENGINE DIAGNOSIS Engine diagnosis is helpful in determining the (5) Insert a compression pressure gauge and rotatecauses of malfunctions not detected and remedied by the engine with the engine starter motor for threeroutine tune-ups. revolutions. These malfunctions may be classified as either per- (6) Record the compression pressure on the 3rdformance (engine idles rough and stalls) or mechani- revolution. Continue the test for the remaining cylin-cal (a strange noise). ders. Refer to the Service Diagnosis—Performance chart Refer to Engine Specifications for the correct en-and the Service Diagnosis—Mechanical chart for pos- gine compression pressures.sible causes and corrections of malfunctions. Refer toGroup 14, Fuel System for the fuel system diagnosis. ENGINE CYLINDER HEAD GASKET FAILURE DIAGNOSISGENERAL INFORMATION A leaking engine cylinder head gasket usually re- Additional tests and diagnostic procedures may be sults in loss of power, loss of coolant and engine mis-necessary for specific engine malfunctions that can firing.not be isolated with the Service Diagnosis charts. In- An engine cylinder head gasket leak can be locatedformation concerning additional tests and diagnosis between adjacent cylinders or between a cylinder andis provided within the following diagnosis: the adjacent water jacket.• Cylinder Compression Pressure Test. • An engine cylinder head gasket leaking between• Cylinder Combustion Pressure Leakage Test. adjacent cylinders is indicated by a loss of power or• Engine Cylinder Head Gasket Failure Diagnosis. engine misfire.• Intake Manifold Leakage Diagnosis. • An engine cylinder head gasket leaking between a cylinder and an adjacent water jacket is indicated byINTAKE MANIFOLD LEAKAGE DIAGNOSIS coolant foaming or overheating and loss of coolant. An intake manifold air leak is characterized bylower than normal manifold vacuum. Also, one or CYLINDER-TO-CYLINDER LEAKAGE TESTmore cylinders may not be functioning. To determine if an engine cylinder head gasket is leaking between adjacent cylinders; follow the proce-WARNING: USE EXTREME CAUTION WHEN THE dures outlined in Cylinder Compression PressureENGINE IS OPERATING. DO NOT STAND IN A DI- Test. An engine cylinder head gasket leaking betweenRECT LINE WITH THE FAN. DO NOT PUT YOUR adjacent cylinders will result in approximately a 50-HANDS NEAR THE PULLEYS, BELTS OR THE FAN. 70% reduction in compression pressure.DO NOT WEAR LOOSE CLOTHING. CYLINDER-TO-WATER JACKET LEAKAGE (1) Start the engine. TEST (2) Spray a small stream of water at the suspectedleak area. WARNING: USE EXTREME CAUTION WHEN THE (3) If a change in RPM’S, the area of the suspected ENGINE IS OPERATING. DO NOT STAND IN A DI-leak has been found. RECT LINE WITH THE FAN. DO NOT PUT YOUR (4) Repair as required. HANDS NEAR THE PULLEYS, BELTS OR THE FAN. DO NOT WEAR LOOSE CLOTHING.CYLINDER COMPRESSION PRESSURE TEST The results of a cylinder compression pressure test Remove the radiator cap.can be utilized to diagnose several engine malfunc- Start the engine and allow it to warm up until thetions. engine thermostat opens. Ensure the battery is completely charged and the If a large combustion/compression pressure leak ex-engine starter motor is in good operating condition. ists, bubbles will be visible in the coolant.Otherwise the indicated compression pressures may If bubbles are not visible, install a radiator pres-not be valid for diagnosis purposes. sure tester and pressurize the coolant system. (1) Clean the spark plug recesses with compressed If a cylinder is leaking combustion pressure intoair. the water jacket, the tester pointer will pulsate with (2) Remove the spark plugs. every combustion stroke of the cylinder. (3) Secure the throttle in the wide-open position. (4) Disconnect the ignition coil.
  • 7. ZJ ENGINES 9-7CYLINDER COMBUSTION PRESSURE LEAKAGE (3) Using a black light, inspect the entire engineTEST for fluorescent dye, particularly at the suspected area The combustion pressure leakage test provides an of oil leak. If the oil leak is found and identified, re-accurate means for determining engine condition. pair per service manual instructions. Combustion pressure leakage testing will detect: (4) If dye is not observed, drive the vehicle at var-• Exhaust and intake valve leaks (improper seat- ious speeds for approximately 24km (15 miles), anding). repeat step (3).• Leaks between adjacent cylinders or into water If the oil leak source is not positively identi-jacket. fied at this time, proceed with the air leak detec-• Any causes for combustion/compression pressure tion test method as follows:loss. (1) Disconnect the breather cap to air cleaner hose at the breather cap end. Cap or plug breather capWARNING: DO NOT REMOVE THE RADIATOR CAP nipple.WITH THE SYSTEM HOT AND UNDER PRESSURE (2) Remove the PCV valve from the cylinder headBECAUSE SERIOUS BURNS FROM COOLANT CAN cover. Cap or plug the PCV valve grommet.OCCUR. (3) Attach an air hose with pressure gauge and regulator to the dipstick tube. Check the coolant level and fill as required. DO CAUTION: Do not subject the engine assembly toNOT install the radiator cap. more than 20.6 kpa (3 PSI) of test pressure. Start and operate the engine until it attains nor-mal operating temperature, then turn the engine (4) Gradually apply air pressure from 1 psi to 2.5OFF. psi maximum while applying soapy water at the sus- Remove the spark plugs. pected source. Adjust the regulator to the suitable Remove the oil filler cap. test pressure that provide the best bubbles which Remove the air cleaner. will pinpoint the leak source. If the oil leak is de- Calibrate the tester according to the manufactur- tected and identified, repair per service manual pro-er’s instructions. The shop air source for testing cedures.should maintain 483 kPa (70 psi) minimum, 1 379 (5) If the leakage occurs at the rear oil seal area,kPa (200 psi) maximum and 552 kPa (80 psi) recom- refer to the section, Inspection for Rear Seal Areamended. Leak. Perform the test procedures on each cylinder ac- (6) If no leaks are detected, turn off the air supplycording to the tester manufacturer’s instructions. and remove the air hose and all plugs and caps. In-While testing, listen for pressurized air escaping stall the PCV valve and breather cap hose. Proceedthrough the throttle body, tailpipe and oil filler cap to step 7.opening. Check for bubbles in the radiator coolant. (7) Clean the oil off the suspect oil leak area using All gauge pressure indications should be equal, a suitable solvent. Drive the vehicle at variouswith no more than 25% leakage. speeds approximately 24 km (15 miles). Inspect the engine for signs of an oil leak by using a black light. FOR EXAMPLE: At 552 kPa (80 psi) input pres-sure, a minimum of 414 kPa (60 psi) should be main- INSPECTION FOR REAR SEAL AREA LEAKStained in the cylinder. Since it is sometimes difficult to determine the Refer to the Cylinder Combustion Pressure Leak- source of an oil leak in the rear seal area of the en-age Test Diagnosis chart. gine, a more involved inspection is necessary. The fol- lowing steps should be followed to help pinpoint theINSPECTION (ENGINE OIL LEAKS IN GENERAL) source of the leak. Begin with a through visual inspection of the en- If the leakage occurs at the crankshaft rear oil sealgine, particularly at the area of the suspected leak. If area:an oil leak source is not readily identifiable, the fol- (1) Disconnect the battery.lowing steps should be followed: (2) Raise the vehicle. (1) Do not clean or degrease the engine at this (3) Remove torque converter or clutch housingtime because some solvents may cause rubber to cover and inspect rear of block for evidence of oil.swell, temporarily stopping the leak. Use a black light to check for the oil leak: (2) Add an oil soluble dye (use as recommended by (a) Circular spray pattern generally indicatesmanufacturer). Start the engine and let idle for ap- seal leakage or crankshaft damage.proximately 15 minutes. Check the oil dipstick to (b) Where leakage tends to run straight down,make sure the dye is thoroughly mixed as indicated possible causes are a porous block, distributor seal,with a bright yellow color under a black light. camshaft bore cup plugs oil galley pipe plugs, oil
  • 8. 9-8 ENGINES ZJ filter runoff, and main bearing cap to cylinder (6) For bubbles that remain steady with shaft ro- block mating surfaces. See Group 9, Engines for tation, no further inspection can be done until disas- proper repair procedures of these items. sembled. Refer to the service Diagnosis—Mechanical, (4) If no leaks are detected, pressurized the crank- under the Oil Leak row for components inspectionscase as outlined in the, Inspection (Engine oil Leaks on possible causes and corrections.in general) (7) After the oil leak root cause and appropriate corrective action have been identified, Refer to GroupCAUTION: Do not exceed 20.6 kPa (3 psi). 9, Engines—Crankshaft Rear Oil Seals, for proper re- (5) If the leak is not detected, very slowly turn the placement procedures.crankshaft and watch for leakage. If a leak is de-tected between the crankshaft and seal while slowly ENGINE OIL PRESSUREturning the crankshaft, it is possible the crankshaft (1) Remove oil pressure sending unit.seal surface is damaged. The seal area on the crank- (2) Install Oil Pressure Line and Gauge Toolshaft could have minor nicks or scratches that can be C-3292. Start engine and record pressure. Refer topolished out with emery cloth. Oil Pressure in Engine Specifications for the proper pressures.CAUTION: Use extreme caution when crankshaftpolishing is necessary to remove minor nicks andscratches. The crankshaft seal flange is especiallymachined to complement the function of the rear oilseal.
  • 9. ZJ ENGINES 9-9 SERVICE DIAGNOSIS—PERFORMANCE
  • 10. 9 - 10 ENGINES ZJ SERVICE DIAGNOSIS—MECHANICAL
  • 11. ZJ ENGINES 9 - 11 SERVICE DIAGNOSIS—LUBRICATION
  • 12. 9 - 12 4.0L ENGINE ZJ 4.0L ENGINE SERVICE PROCEDURES INDEX page pageCamshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Rocker Arms and Push Rods . . . . . . . . . .... . . . 18Camshaft Pin Replacement . . . . . . . . . . . . . . . . . . 29 Timing Case Cover . . . . . . . . . . . . . . . . . .... . . . 25Engine Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 14 Timing Case Cover Oil Seal Replacement .... . . . 26Engine Cylinder Head . . . . . . . . . . . . . . . . . . . . . . 20 Timing Chain and Sprockets . . . . . . . . . . .... . . . 26Engine Cylinder Head Cover . . . . . . . . . . . . . . . . . 17 Valve Component Replace—Cylinder Head NotEngine Mount—Rear . . . . . . . . . . . . . . . . . . . . . . . 14 Removed . . . . . . . . . . . . . . . . . . . . . . . .... . . . 18Engine Mounts—Front . . . . . . . . . . . . . . . . . . . . . 13 Valve Stem Seal and Spring Replacement .... . . . 18General Information . . . . . . . . . . . . . . . . . . . . . . . 12 Valve Timing . . . . . . . . . . . . . . . . . . . . . . .... . . . 24Hydraulic Tappets . . . . . . . . . . . . . . . . . . . . . . . . . 19 Valves and Valve Springs . . . . . . . . . . . . .... . . . 22Oil Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Vibration Damper . . . . . . . . . . . . . . . . . . .... . . . 25GENERAL INFORMATION The 4.0 Liter (242 CID) six-cylinder engine is anIn-line, lightweight, overhead valve engine (Fig. 1). Fig. 2 Engine Firing Order BUILD DATE CODE The engine Build Date Code is located on a ma- chined surface on the right side of the cylinder block between the No.2 and No.3 cylinders (Fig. 3). Fig. 1 Engine Description This engine is designed for unleaded fuel. The engine cylinder head has dual quench-typecombustion chambers that create turbulence and fastburning of the air/fuel mixture. This results in goodfuel economy. The cylinders are numbered 1 through 6 from frontto rear. The firing order is 1-5-3-6-2-4 (Fig. 2). The crankshaft rotation is clockwise, when viewedfrom the front of the engine. The crankshaft rotateswithin seven main bearings. The camshaft rotateswithin four bearings. Fig. 3 Build Date Code Location The digits of the code identify:
  • 13. ZJ 4.0L ENGINE 9 - 13 (1) 1st Digit—The year (4 = 1994). (2) 2nd & 3rd Digits—The month (01 - 12). (3) 4th & 5th Digits—The engine type/fuel system/compression ratio (MX = A 4.0 Liter (242 CID) 8.8:1compression ratio engine with a multi-point fuel in-jection system). (4) 6th & 7th Digits—The day of engine build (01 -31). FOR EXAMPLE: Code * 401MX12 * Identifies a4.0 Liter (242 CID) engine with a multi-point fuel in-jection system, 8.7:1 compression ratio and built onJanuary 12, 1994.OVERSIZE AND UNDERSIZE COMPONENTCODES Some engines may be built with oversize or under-size components such as:• Oversize cylinder bores.• Oversize camshaft bearing bores.• Undersize crankshaft main bearing journals.• Undersize connecting rod journals. These engines are identified by a letter code (Fig. Fig. 5 Oversize and Undersize Component Code4) stamped on a boss between the ignition coil and Locationthe distributor (Fig. 5). REMOVAL (1) Disconnect the negative cable from the battery. (2) Support the engine. (3) Raise the vehicle. (4) Remove the insulator assembly-to-lower front sill bolts (Fig. 6 or 7). (5) Raise the engine slightly. (6) Remove the thru-bolt nut and thru-bolt (Fig. 6 or 7). Remove the insulator. Fig. 4 Oversize and Undersize Component CodesENGINE MOUNTS—FRONT The front mounts support the engine at each side. Fig. 6 Front Engine Mount—Right SideThese insulators are made of resilient rubber.
  • 14. 9 - 14 4.0L ENGINE ZJ Fig. 8 Engine Mount—Rear Fig. 7 Front Engine Mount—Left Side (6) Remove the bolts holding the rear mount (7) If required, remove the engine bracket from the bracket to the transmission (Fig. 8). Remove theblock (Fig. 6 or 7). bracket from the exhaust pipe hanger. Remove theINSTALLATION bracket. (1) If removed, install the engine bracket to the INSTALLATIONblock (Fig. 6 or 7). Tighten the bolts to 61 N⅐m (45 ft. (1) Position the rear mount bracket onto the ex-lbs.) torque. haust hanger. Position the rear mount bracket as- (2) Install the insulator assembly to the lower sembly onto the transmission and install the boltsfront sill. Tighten the bolts to 65 N⅐m (48 ft. lbs.) (Fig. 8). Tighten the bolts to the proper torque:torque. • MANUAL TRANSMISSION—Tighten to 46 N⅐m (3) With the engine insulator assembly and engine (34 ft. lbs.) torque.bracket in position, install the thru-bolt and nut (Fig. • AUTOMATIC TRANSMISSION—Tighten to 756 or 7). Tighten the thru-bolt nut to 121 N⅐m (89 ft. N⅐m (55 ft. lbs.) torque.lbs.) torque. (2) Install the thru-bolt into the rear mount (4) Lower the vehicle. bracket and clevis (Fig. 8). Finger tighten the nut at (5) Remove the engine support. this time. (6) Connect the negative cable to the battery. (3) Lower the transmission until the clevis bracket studs are in position on the crossmember (Fig. 8). In-ENGINE MOUNT—REAR stall the clevis bracket stud nuts. Tighten the nuts to A resilient rubber cushion bracket assembly sup- 41 N⅐m (30 ft. lbs) torque.ports the transmission at the rear. This bracket is at- (4) Tighten the thru-bolt nut to 121 N⅐m (89 ft.tached to the crossmember (Fig. 8). lbs.) torque.REMOVAL (5) Remove the transmission support. (1) Disconnect the negative cable from the battery. (6) Lower the vehicle. (2) Raise the vehicle and support the transmission. (7) Connect the negative cable to the battery. (3) Remove the nuts holding the clevis bracket tothe crossmember (Fig. 8). ENGINE ASSEMBLY (4) Raise the transmission SLIGHTLY. REMOVAL (5) Remove the thru-bolt and nut (Fig. 8). Remove (1) Disconnect the battery cables. Remove the bat-the rear mount bracket clevis. tery.
  • 15. ZJ 4.0L ENGINE 9 - 15 (2) Mark the hinge locations on the hood panel for (14) Disconnect the vehicle speed control cable (ifalignment reference during installation. Remove the equipped)—(Fig. 10).engine compartment lamp. Remove the hood. (15) Disconnect the line pressure cable (if equipped with automatic transmission).WARNING: THE COOLANT IN A RECENTLY OPER- (16) Disconnect injection system wire harness con-ATED ENGINE IS HOT AND PRESSURIZED. USE nector at each injector. Mark the wires for proper in-CARE TO PREVENT SCALDING BY HOT COOLANT. stallation.CAREFULLY RELEASE THE PRESSURE BEFORE (17) Disconnect the distributor electrical connec-REMOVING THE RADIATOR DRAIN COCK AND CAP. tion and the oil pressure switch connector. (3) Remove the radiator drain cock and radiator (18) Disconnect the quick-connect fuel lines at thecap to drain the coolant. DO NOT waste usable cool- fuel rail and return line by squeezing the two retain-ant. If the solution is clean, drain the coolant into a ing tabs against the fuel tube (Fig. 10). Pull the fuelclean container for reuse. tube and retainer from the quick-connect fitting (re- (4) Remove the upper radiator hose and coolant re- fer to Group 14, Fuel System for the proper proce-covery hose (Fig. 9). dure). (5) Remove the lower radiator hose. (6) Remove upper radiator support retaining boltsand remove radiator support. (7) Remove the fan assembly from the water pump. (8) Remove the fan shroud (Fig. 9). (9) Disconnect the transmission fluid cooler tubing(automatic transmission). (10) Vehicles with Air Conditioning: (a) Discharge the A/C system (refer to Group 24, Heating and Air Conditioning). (b) Remove the service valves and cap the com- pressor ports. (11) Remove the radiator or radiator/condenser (ifequipped with A/C). (12) Disconnect the heater hoses at the enginethermostat housing and water pump (Fig. 9). Fig. 10 Accelerator Cable, Vehicle Speed Control Cable, Automatic Transmission Control Cable & Quick-Connect Fuel Lines (19) Remove the fuel line bracket from the intake manifold. (20) Remove the air cleaner assembly (Fig. 11). (21) Remove the power brake vacuum check valve from the booster, if equipped. (22) Vehicles with Power Steering (Fig. 11): (a) Disconnect the hoses from the fittings at the steering gear. (b) Drain the pump reservoir. (c) Cap the fittings on the hoses and steering gear to prevent foreign objects from entering the system. (23) Identify, tag and disconnect all necessary wire connectors and vacuum hoses. Fig. 9 Upper Radiator Hose, Coolant Recovery (24) Raise and support the vehicle. Hose, Fan Shroud & Heater hoses (25) Disconnect the wires from the engine starter (13) Disconnect the throttle linkages (Fig. 10). motor solenoid.
  • 16. 9 - 16 4.0L ENGINE ZJ (1) Attach a lifting device to the engine and lower the engine into the engine compartment. For easier installation, it may be necessary to remove the en- gine mount bracket as an aid in alignment of the en- gine to the transmission. (2) Vehicles with Manual Transmission: (a) Insert the transmission shaft into the clutch spline. (b) Align the engine flywheel housing with the engine. (c) Install and tighten the engine flywheel hous- ing lower bolts finger tight. (3) Vehicles with Automatic Transmission: (a) Align the transmission torque converter hous- ing with the engine. (b) Loosely install the converter housing lower bolts and install the next higher bolt and nut on each side. (c) Tighten all 4 bolts finger tight. (4) Install the engine mount brackets (if removed). (5) Lower the engine and engine mount brackets Fig. 11 Air Cleaner Assembly & Power Steering onto the engine compartment cushions. Install the Pump bolts and finger tighten the nuts. (26) Remove the engine starter motor. (6) Remove the engine lifting device. (27) Disconnect the oxygen sensor from the ex- (7) Raise and support the vehicle.haust pipe. (8) Install the remaining engine flywheel/converter (28) Disconnect the exhaust pipe from the mani- housing bolts. Tighten all bolts to 38 N⅐m (28 ft. lbs.)fold. torque. (29) Disconnect the vehicle speed sensor wire con- (9) Vehicles with Automatic Transmission:nection. (a) Install the converter-to-drive plate bolts. (30) Remove the exhaust pipe support. (b) Ensure the installation reference marks are (31) Remove the engine flywheel/converter housing aligned.access cover. (10) Install the engine flywheel/converter housing (32) Vehicles with Automatic Transmission: access cover. (a) Mark the converter and drive plate location. (11) Install the exhaust pipe support and tighten (b) Remove the converter-to-drive plate bolts. the screw. (33) Remove the upper engine flywheel/converter (12) Tighten the engine mount-to-bracket bolts.housing bolts and loosen the bottom bolts. (13) Connect the vehicle speed sensor wire connec- (34) Remove the engine mount cushion-to-engine tions and tighten the screws.compartment bracket bolts. (14) Connect the exhaust pipe to the manifold. (35) Lower the vehicle. (15) Install the engine starter motor and connect (36) Attach a lifting device to the engine. the cable. (37) Raise the engine off the front supports. (16) Connect the wires to the engine starter motor (38) Place a support or floor jack under the con- solenoid.verter (or engine flywheel) housing. (17) Lower the vehicle. (39) Remove the remaining converter (or engine (18) Connect all the vacuum hoses and wire con-flywheel) housing bolts. nectors identified during engine removal. (40) Lift the engine out of the engine compart- (19) Vehicles equipped with Power Steering:ment. (a) Remove the protective caps (b) Connect the hoses to the fittings at the steer-INSTALLATION ing gear. Tighten the nut to 52 N⅐m (38 ft. lbs.) torque.CAUTION: When installing the engine into a vehicle (c) Fill the pump reservoir with fluid.equipped with an automatic transmission, be care- (20) Install the power brake vacuum check valveful not to damage the trigger wheel on the engine from the booster, if equipped.flywheel.
  • 17. ZJ 4.0L ENGINE 9 - 17 (21) Connect the fuel inlet and return hoses at the ENGINE CYLINDER HEAD COVERfuel rail. Verify that the quick-connect fitting assem- A cured gasket is part of the engine cylinder headbly fits securely over the fuel lines by giving the fuel cover.lines a firm tug. (22) Install the fuel line bracket to the intake man- REMOVALifold. (1) Disconnect negative cable from battery. (23) Connect the distributor electrical connector (2) Disconnect the Crankcase Ventilation (CCV)and oil pressure switch connector. vacuum hose from engine cylinder head cover (Fig. (24) Connect the injection system wires to the in- 1).jectors. (3) Disconnect the fresh air inlet hose from the en- gine cylinder head cover (Fig. 1). (25) Connect the line pressure cable (if equipped (4) Remove the engine cylinder head cover mount-with automatic transmission). ing bolts. (26) Connect the vehicle speed control cable, if (5) Remove the engine cylinder head cover.equipped. (27) Connect the throttle cable linkages. (28) Connect the heater hoses at the engine ther-mostat housing and water pump. (29) Install the fan assembly to the water pump. (30) Place the fan shroud in position over the fan. (31) Install the radiator or radiator/condenser (ifequipped with A/C). (32) Connect the service valves to the A/C compres-sor ports, if equipped with A/C. (33) Charge the air conditioner system (refer toGroup 24, Heating and Air Conditioning). (34) Connect the radiator hoses and automatictransmission fluid cooler pipes, if equipped. (35) Install the fan shroud to the radiator or radi-ator/condenser (if equipped with A/C). (36) Install upper radiator support. (37) Connect the upper radiator hose and tighten Fig. 1 Engine Cylinder Head Coverthe clamp. CLEANING (38) Connect the lower radiator hose and tighten Remove any original sealer from the cover sealingthe clamp. surface of the engine cylinder head and clean the (39) Fill the cooling system with reusable coolant surface using a fabric cleaner.or new coolant (refer to Group 7, Cooling System). Remove all residue from the sealing surface using (40) Align the hood to the scribe marks. Install the a clean, dry cloth.hood. INSPECTION (41) Connect the vacuum harness connector. Inspect the engine cylinder head cover for cracks. (a) Firmly push the connectors together ensuring Replace the cover, if cracked. that the retaining tabs are engaged. The original dark grey gasket material should NOT (b) Insert the vacuum connector assembly into be removed. If sections of the gasket material are the retaining bracket on the intake manifold. missing or are compressed, replace the engine cylin- (42) Install the air cleaner assembly. der head cover. However, sections with minor damage (43) Install the battery and connect the battery ca- such as small cracks, cuts or chips may be repairedble. with a hand held applicator. The new material must be smoothed over to maintain gasket height. AllowWARNING: USE EXTREME CAUTION WHEN THE the gasket material to cure prior to engine cylinderENGINE IS OPERATING. DO NOT STAND IN A DI- head cover installation.RECT LINE WITH THE FAN. DO NOT PUT YOURHANDS NEAR THE PULLEYS, BELTS OR FAN. DO INSTALLATIONNOT WEAR LOOSE CLOTHING. (1) If a replacement cover is installed, transfer the CCV valve grommet and oil filler cap from the origi- (44) Start the engine, inspect for leaks and correct nal cover to the replacement cover.the fluid levels, as necessary. (2) Install engine cylinder head cover. Tighten the mounting bolts to 10 N⅐m (85 in. lbs.) torque.
  • 18. 9 - 18 4.0L ENGINE ZJ (3) Connect the CCV hoses (Fig. 1). Inspect each push rod end for excessive wear and (4) Connect negative cable to battery. replace as required. If any push rod is excessively worn because of lack of oil, replace it and inspect theVALVE COMPONENT REPLACE—CYLINDER HEAD corresponding hydraulic tappet for excessive wear.NOT REMOVED Inspect the push rods for straightness by rolling them on a flat surface or by shining a light betweenROCKER ARMS AND PUSH RODS the push rod and the flat surface. This procedure can be done with the engine in or A wear pattern along the length of the push rod isout of the vehicle. not normal. Inspect the engine cylinder head for ob- struction if this condition exists.REMOVAL (1) Remove the engine cylinder head cover. INSTALLATION (2) Remove the capscrews at each bridge and pivot (1) Lubricate the ball ends of the push rods withassembly (Fig. 2). Alternately loosen the capscrews Mopar௡ Engine Oil Supplement, or equivalent and install push rods in their original locations. Ensureone turn at a time to avoid damaging the bridges. that the bottom end of each push rod is centered in (3) Check for rocker arm bridges which are causing the tappet plunger cap seat.misalignment of the rocker arm to valve tip area. (2) Using Mopar௡ Engine Oil Supplement, or (4) Remove the bridges, pivots and corresponding equivalent, lubricate the area of the rocker arm thatpairs of rocker arms (Fig. 2). Place them on a bench the pivot contacts. Install rocker arms, pivots andin the same order as removed. bridge above each cylinder in their original position. (5) Remove the push rods and place them on a (3) Loosely install the capscrews through eachbench in the same order as removed. bridge. (4) At each bridge, tighten the capscrews alter- nately, one turn at a time, to avoid damaging the bridge. Tighten the capscrews to 28 N⅐m (21 ft. lbs.) torque. (5) Install the engine cylinder head cover. VALVE STEM SEAL AND SPRING REPLACEMENT This procedure can be done with the engine cylin- der head installed on the block. REMOVAL Each valve spring is held in place by a retainer and a set of conical valve locks. The locks can be removed only by compressing the valve spring. (1) Remove the engine cylinder head cover. (2) Remove capscrews, bridge and pivot assemblies and rocker arms for access to each valve spring to be removed. (3) Remove push rods. Retain the push rods, bridges, pivots and rocker arms in the same order and position as removed. (4) Inspect the springs and retainer for cracks and Fig. 2 Rocker Arm Assembly possible signs of weakening.CLEANING (5) Remove the spark plug(s) adjacent to the cylin- Clean all the components with cleaning solvent. der(s) below the valve springs to be removed. Use compressed air to blow out the oil passages in (6) Install a 14 mm (1/2 inch) (thread size) air hosethe rocker arms and push rods. adaptor in the spark plug hole. An adaptor can be constructed by welding an air hose connection to theINSPECTION body of a spark plug with the porcelain removed. Inspect the pivot surface area of each rocker arm. (7) Connect an air hose to the adapter and applyReplace any that are scuffed, pitted, cracked or ex- air pressure slowly. Maintain at least 621 kPa (90cessively worn. psi) of air pressure in the cylinder to hold the valves Inspect the valve stem tip contact surface of each against their seats. For vehicles equipped with an airrocker arm and replace any rocker arm that is deeply conditioner, use a flexible air adaptor when servicingpitted. the No.1 cylinder.
  • 19. ZJ 4.0L ENGINE 9 - 19 (8) Tap the retainer or tip with a rawhide hammer (6) Install the push rods. Ensure the bottom end ofto loosen the lock from the retainer. Use Valve Spring each rod is centered in the plunger cap seat of theCompressor Tool MD-998772A to compress the spring hydraulic valve tappet.and remove the locks (Fig. 3). (7) Install the rocker arms, pivots and bridge at (9) Remove valve spring and retainer (Fig. 3). their original location. (10) Remove valve stem oil seals (Fig. 3). Note the (8) Tighten the bridge capscrews alternately, onevalve seals are different for intake and exhaust at a time, to avoid damaging the bridge. Tighten thevalves. The top of each seal is marked either INT (In- capscrews to 28 N⅐m (21 ft. lbs.) torque.take) or EXH (Exhaust). DO NOT mix the seals. (9) Install the engine cylinder head cover. HYDRAULIC TAPPETS Retain all the components in the same order as re- moved. REMOVAL (1) Remove the engine cylinder head cover. (2) Remove the bridge and pivot assemblies and rocker arms by removing the capscrews at each bridge. Alternately loosen each capscrew, one turn at a time, to avoid damaging the bridges. (3) Remove the push rods. (4) Remove the intake and engine exhaust mani- folds (refer to Group 11, Exhaust System and Intake Manifold for the proper procedure). (5) Remove the engine cylinder head and gasket. (6) Remove the tappets through the push rod open- ings in the cylinder block with Hydraulic Valve Tap- pet Removal/Installation Tool C-4129-A (Fig. 4). Fig. 3 Valve and Valve ComponentsINSPECTION Inspect the valve stems, especially the grooves. AnArkansas smooth stone should be used to removenicks and high spots.INSTALLATIONCAUTION: Install oil seals carefully to prevent dam-age from the sharp edges of the valve spring lockgrove. (1) Lightly push the valve seal over the valve stemand valve guide boss. Be sure the seal is completelyseated on the valve guide boss. (2) Install valve spring and retainer. (3) Compress the valve spring with Valve SpringCompressor Tool MD-988772A and insert the valvelocks. Release the spring tension and remove thetool. Tap the spring from side-to-side to ensure that Fig. 4 Hydraulic Valve Tappet Removal/Installationthe spring is seated properly on the engine cylinder Tool C-4129-Ahead. CLEANING (4) Disconnect the air hose. Remove the adaptor Clean each tappet assembly in cleaning solvent tofrom the spark plug hole and install the spark plug. remove all varnish, gum and sludge deposits. (5) Repeat the procedures for each remaining valvespring to be removed.
  • 20. 9 - 20 4.0L ENGINE ZJINSPECTION Inspect for indications of scuffing on the side andbase of each tappet body. Inspect each tappet base for concave wear with astraightedge positioned across the base. If the base isconcave, the corresponding lobe on the camshaft isalso worn. Replace the camshaft and defective tap-pets.LEAK-DOWN TEST After cleaning and inspection, test each tappet forspecified leak-down rate tolerance to ensure zero-lashoperation (Fig. 5). Swing the weighted arm of the hydraulic valve tap-pet tester away from the ram of the Leak-DownTester 7980. (1) Place a 7.925-7.950 mm (0.312-0.313 inch) di- Fig. 5 Leak-Down Tester 7980ameter ball bearing on the plunger cap of the tappet. (2) Lift the ram and position the tappet (with the (5) Install the push rods in their original locations.ball bearing) inside the tester cup. (6) Install the rocker arms and bridge and pivot (3) Lower the ram, then adjust the nose of the ram assemblies at their original locations. Loosely installuntil it contacts the ball bearing. DO NOT tighten the capscrews at each bridge.the hex nut on the ram. (7) Tighten the capscrews alternately, one turn at (4) Fill the tester cup with hydraulic valve tappet a time, to avoid damaging the bridges. Tighten thetest oil until the tappet is completely submerged. capscrews to 28 N⅐m (21 ft. lbs.) torque. (5) Swing the weighted arm onto the push rod and (8) Pour the remaining Mopar௡ Engine Oil Supple-pump the tappet plunger up and down to remove air. ment, or equivalent over the entire valve actuatingWhen the air bubbles cease, swing the weighted arm assembly. The Mopar௡ Engine Oil Supplement, oraway and allow the plunger to rise to the normal po- equivalent must remain with the engine oil for atsition. least 1 609 km (1,000 miles). The oil supplement (6) Adjust the nose of the ram to align the pointer need not be drained until the next scheduled oilwith the SET mark on the scale of the tester and change.tighten the hex nut. (9) Install the engine cylinder head cover. (7) Slowly swing the weighted arm onto the pushrod. ENGINE CYLINDER HEAD (8) Rotate the cup by turning the handle at the This procedure can be done with the engine in orbase of the tester clockwise one revolution every 2 out of the vehicle.seconds. (9) Observe the leak-down time interval from the REMOVALinstant the pointer aligns with the START mark on (1) Disconnect negative cable from battery.the scale until the pointer aligns with the 0.125mark. A normally functioning tappet will require 20- WARNING: DO NOT REMOVE THE CYLINDER110 seconds to leak-down. Discard tappets with leak- BLOCK DRAIN PLUGS OR LOOSEN THE RADIATORdown time interval not within this specification. DRAIN COCK WITH THE SYSTEM HOT AND PRES- SURIZED BECAUSE SERIOUS BURNS FROM THEINSTALLATION COOLANT CAN OCCUR. It is not necessary to charge the tappets with en-gine oil. They will charge themselves within a very (2) Drain the coolant and disconnect the hoses atshort period of engine operation. the engine thermostat housing. DO NOT waste reus- (1) Dip each tappet in Mopar௡ Engine Oil Supple- able coolant. If the solution is clean and is beingment, or equivalent. drained only to service the engine or cooling system, (2) Use Hydraulic Valve Tappet Removal/Installa- drain the coolant into a clean container for reuse.tion Tool C-4129-A to install each tappet in the same (3) Remove the air cleaner assembly.bore from where it was originally removed. (4) Remove the engine cylinder head cover. (3) Install the exhaust and intake manifolds (referto Group 11, Exhaust System and Intake Manifold (5) Remove the capscrews, bridge and pivot assem-for the proper procedure). blies and rocker arms (Fig. 2). (4) Install the engine cylinder head and gasket.
  • 21. ZJ 4.0L ENGINE 9 - 21 (6) Remove the push rods (Fig. 2). Retain thepush rods, bridges, pivots and rocker arms inthe same order as removed. (7) Loosen the serpentine drive belt at the powersteering pump, if equipped or at the idler pulley (re-fer to Group 7, Cooling System for the proper proce-dure). (8) If equipped with air conditioning, perform thefollowing: (a) Remove the bolts from the A/C compressor mounting bracket and set the compressor aside. (b) Remove the air conditioner compressor bracket bolts from the engine cylinder head. (c) Loosen the thru-bolt at the bottom of the bracket. (9) If equipped, disconnect the power steeringpump bracket. Set the pump and bracket aside. DO Fig. 6 Engine Cylinder Head AssemblyNOT disconnect the hoses. INSPECTION (10) Perform the Fuel System Pressure Release Use a straightedge and feeler gauge to check theprocedure (refer to Group 14, Fuel System). Remove flatness of the engine cylinder head and block matingthe fuel lines and vacuum advance hose. surfaces. (11) Remove the intake and engine exhaust mani-folds from the engine cylinder head (refer to Group INSTALLATION11, Exhaust System and Intake Manifold for the The engine cylinder head gasket is a compositionproper procedures). gasket. The gasket is to be installed DRY. DO NOT (12) Disconnect the ignition wires and remove the use a gasket sealing compound on the gasket.spark plugs. If the engine cylinder head is to be replaced and (13) Disconnect the temperature sending unit wire the original valves used, measure the valve stem di-connector. ameter. Only standard size valves can be used with a (14) Remove the ignition coil and bracket assem- service replacement engine cylinder head unless thebly. replacement head valve stem guide bores are reamed (15) Remove the engine cylinder head bolts. Bolt to accommodate oversize valve stems. Remove allNo.14 cannot be removed until the head is moved for- carbon buildup and reface the valves.ward. Pull bolt No.14 out as far as it will go and then (1) Remove the shop towels from the cylindersuspend the bolt in this position (tape around the bores. Coat the bores with clean engine oil.bolt). (2) Position the engine cylinder head gasket (with (16) Remove the engine cylinder head and gasket the numbers facing up) onto the cylinder block.(Fig. 6). CAUTION: Engine cylinder head bolts should be re- (17) If this was the first time the bolts were re- used only once. Replace the head bolts if they weremoved, put a paint dab on the top of the bolt. If the used before or if they have a paint dab on the topbolts have a paint dab on the top of the bolt or it of the bolt.isn’t known if they were used before, discard thebolts. (3) With bolt No.14 held in place (tape around (18) Stuff clean lint free shop towels into the cylin- bolt), install the engine cylinder head. Remove theder bores. tape from bolt No.14. (4) Coat the threads of stud bolt No.11 with LoctiteCLEANING 592 sealant, or equivalent. Thoroughly clean the engine cylinder head and cyl- (5) Tighten the engine cylinder head bolts in se-inder block mating surfaces. Clean the intake and quence according to the following procedure (Fig. 7):engine exhaust manifold and engine cylinder head (a) Tighten all bolts in sequence (1 through 14)mating surfaces. Remove all gasket material and car- to 30 N⅐m (22 ft. lbs.) torque.bon. (b) Tighten all bolts in sequence (1 through 14) Check to ensure that no coolant or foreign material to 61 N⅐m (45 ft. lbs.) torque.has fallen into the tappet bore area. (c) Check all bolts to verify they are set to 61 Remove the carbon deposits from the combustion N⅐m (45 ft. lbs.) torque.chambers and top of the pistons. (d) Tighten bolts (in sequence):
  • 22. 9 - 22 4.0L ENGINE ZJ• Bolts 1 through 10 to 149 N⅐m (110 ft. lbs.) torque. (16) Install the serpentine drive belt and correctly• Bolt 11 to 136 N⅐m (100 ft. lbs.) torque. tension the belt (refer to Group 7, Cooling System for• Bolts 12 through 14 to 149 N⅐m (110 ft. lbs.) the proper procedure).torque. (17) Install the air cleaner and ducting. (18) Install the engine cylinder head cover.CAUTION: During the final tightening sequence, (19) Connect the hoses to the engine thermostatbolt No.11 will be tightened to a lower torque than housing and fill the cooling system to the specifiedthe rest of the bolts. DO NOT overtighten bolt level (refer to Group 7, Cooling Systems for theNo.11. proper procedure). (20) The automatic transmission throttle linkage (e) Check all bolts in sequence to verify the cor- and cable must be adjusted after completing the en- rect torque. gine cylinder head installation (refer to Group 21, (f) If not already done, clean and mark each bolt Transmissions for the proper procedures). with a dab of paint after tightening. Should you en- (21) Install the temperature sending unit and con- counter bolts which were painted in an earlier ser- nect the wire connector. vice operation, replace them. (22) Connect the fuel pipe and vacuum advance hose. (23) Connect negative cable to battery. (24) Connect the upper radiator hose and heater hose at the engine thermostat housing. (25) Fill the cooling system. Check for leaks. WARNING: USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT STAND IN DIRECT LINE WITH THE FAN. DO NOT PUT HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING. Fig. 7 Engine Cylinder Head Bolt Tightening Sequence (26) Operate the engine with the radiator cap off. (6) Install the ignition coil and bracket assembly. Inspect for leaks and continue operating the engine (7) Connect the temperature sending unit wire until the engine thermostat opens. Add coolant, if re-connector. quired. (8) Install the spark plugs and tighten to 37 N⅐m(27 ft. lbs.) torque. Connect the ignition wires. VALVES AND VALVE SPRINGS (9) Install the intake and engine exhaust mani- This procedure is done with the engine cylinderfolds (refer to Group 11, Exhaust System and Intake head removed from the block.Manifold for the proper procedures). REMOVAL (10) Install the fuel lines and the vacuum advance (1) Remove the engine cylinder head from the cyl-hose. inder block. (11) If equipped, attach the power steering pump (2) Use Valve Spring Compressor Tooland bracket. MD-998772A and compress each valve spring. (12) Install the push rods, rocker arms, pivots and (3) Remove the valve locks, retainers, springs andbridges in the order they were removed. valve stem oil seals. Discard the oil seals. (13) Install the engine cylinder head cover. (4) Use an Arkansas smooth stone or a jewelers (14) Attach the air conditioner compressor mount- file to remove any burrs on the top of the valve stem,ing bracket to the engine cylinder head and block. especially around the groove for the locks.Tighten the bolts to 40 N⅐m (30 ft. lbs.) torque. (5) Remove the valves, and place them in a rack in (15) Attach the air conditioning compressor to the the same order as removed.bracket. Tighten the bolts to 27 N⅐m (20 ft. lbs.)torque. VALVE CLEANING Clean all carbon deposits from the combustionCAUTION: The serpentine drive belt must be routed chambers, valve ports, valve stems, valve stemcorrectly. Incorrect routing can cause the water guides and head.pump to turn in the opposite direction causing the Clean all grime and gasket material from the en-engine to overheat. gine cylinder head machined gasket surface.
  • 23. ZJ 4.0L ENGINE 9 - 23INSPECTION Inspect for cracks in the combustion chambers andvalve ports. Inspect for cracks on the exhaust seat. Inspect for cracks in the gasket surface at eachcoolant passage. Inspect valves for burned, cracked or warpedheads. Inspect for scuffed or bent valve stems. Replace valves displaying any damage.VALVE REFACING (1) Use a valve refacing machine to reface the in-take and exhaust valves to the specified angle. (2) After refacing, a margin of at least 0.787 mm(0.031 inch) must remain (Fig. 8). If the margin isless than 0.787 mm (0.031 inch), the valve must be Fig. 9 Measurement of Valve Seat Runoutreplaced. When the valve stem guide clearance is excessive, the valve guide bores must be reamed oversize. Ser- vice valves with oversize stems are available in 0.076 mm (0.003 inch) and 0.381 mm (0.015 inch) incre- ments. Corresponding oversize valve stem seals are also available and must be used with valves having 0.381 mm (0.015 inch) oversize stems, 0.076mm (.003in.) oversize stems do not require oversize seals. If the valve guides are reamed oversize, the valve seats must be ground to ensure that the valve seat is concentric to the valve guide. VALVE STEM-TO-GUIDE CLEARANCE MEASUREMENT Valve stem-to-guide clearance may be measured by either of the following two methods. Fig. 8 Valve Facing MarginVALVE SEAT REFACING PREFERRED METHOD: (1) Install a pilot of the correct size in the valve (1) Remove the valve from the head.guide bore. Reface the valve seat to the specified an- (2) Clean the valve stem guide bore with solventgle with a good dressing stone. Remove only enough and a bristle brush.metal to provide a smooth finish. (3) Insert a telescoping gauge into the valve stem (2) Use tapered stones to obtain the specified seat guide bore approximately 9.525 mm (.375 inch) fromwidth when required. the valve spring side of the head (Fig. 10). (3) Control valve seat runout to a maximum of (4) Remove and measure telescoping gauge with a0.0635 mm (0.0025 in.)—(Fig. 9). micrometer.VALVE STEM OIL SEAL REPLACEMENT (5) Repeat the measurement with contacts length- Valve stem oil seals are installed on each valve wise to engine cylinder head.stem to prevent rocker arm lubricating oil from en- (6) Compare the crosswise to lengthwise measure-tering the combustion chamber through the valve ments to determine out-of-roundness. If the measure-guide bores. One seal is marked INT (intake valve) ments differ by more than 0.0635 mm (0.0025 in.),and the other is marked EXH (exhaust valve). ream the guide bore to accommodate an oversize Replace the oil seals whenever valve service is per- valve stem.formed or if the seals have deteriorated. (7) Compare the measured valve guide bore diam- eter with specifications (7.95-7.97 mm or 0.313-0.314VALVE GUIDES inch). If the measurement differs from specification The valve guides are an integral part of the engine by more than 0.076 mm (0.003 inch), ream the guidecylinder head and are not replaceable. bore to accommodate an oversize valve stem.
  • 24. 9 - 24 4.0L ENGINE ZJ VALVE SPRING TENSION TEST Use Universal Valve Spring Tester and a torque wrench to test each valve spring for the specified ten- sion value (Fig. 12). Replace valve springs that are not within specifica- tions.Fig. 10 Measurement of Valve Guide Bore Diameter Fig. 12 Valve Spring TesterALTERNATIVE METHOD: INSTALLATION (1) Use a dial indicator to measure the lateral (1) Thoroughly clean the valve stems and the valvemovement of the valve stem (stem-to-guide clear- guide bores.ance). This must be done with the valve installed in (2) Lightly lubricate the stem.its guide and just off the valve seat (Fig. 11). (3) Install the valve in the original valve guide (2) Correct clearance is 0.025-0.0762 mm (0.001- bore.0.003 inch). If indicated movement exceeds the spec- (4) Install the replacement valve stem oil seals onification ream the valve guide to accommodate an the valve stems. If the 0.381 mm (0.015 inch) over-oversize valve stem. size valve stems are used, oversize oil seals are re- Valve seats must be ground after reaming the quired.valve guides to ensure that the valve seat is (5) Position the valve spring and retainer on theconcentric to the valve guide. engine cylinder head and compress the valve spring with Valve Spring Compressor Tool MD-998772A. (6) Install the valve locks and release the tool. (7) Tap the valve spring from side to side with a hammer to ensure that the spring is properly seated at the engine cylinder head. Also tap the top of the retainer to seat the valve locks. (8) Install the engine cylinder head. VALVE TIMING Disconnect the spark plug wires and remove the spark plugs. Remove the engine cylinder head cover. Remove the capscrews, bridge and pivot assembly, and rocker arms from above the No.1 cylinder. Alternately loosen each capscrew, one turn at aFig. 11 Measurement of Lateral Movement of Valve time, to avoid damaging the bridge. Stem Rotate the crankshaft until the No.6 piston is at top dead center (TDC) on the compression stroke. Rotate the crankshaft counterclockwise (viewed from the front of the engine) 90°.
  • 25. ZJ 4.0L ENGINE 9 - 25 Install a dial indicator on the end of the No.1 cyl- tems for the proper specifications and procedures).inder intake valve push rod. Use rubber tubing to se- (5) Connect negative cable to battery.cure the indicator stem on the push rod. Set the dial indicator pointer at zero. TIMING CASE COVER Rotate the crankshaft clockwise (viewed from thefront of the engine) until the dial indicator pointer REMOVALindicates 0.305 mm (0.012 inch) travel distance (lift). (1) Disconnect negative cable from battery. The timing notch index on the vibration damper (2) Remove the vibration damper (Fig. 2).should be aligned with the TDC mark on the timing (3) Remove the fan and hub assembly and removedegree scale. the fan shroud. If the timing notch is more than 13 mm (1/2 inch) (4) Remove the accessory drive brackets that areaway from the TDC mark in either direction, the attached to the timing case cover.valve timing is incorrect. (5) Remove the A/C compressor (if equipped) and If the valve timing is incorrect, the cause may be a generator bracket assembly from the engine cylinderbroken camshaft pin. It is not necessary to replace head and move to one side.the camshaft because of pin failure. A spring pin is (6) Remove the oil pan-to-timing case cover boltsavailable for service replacement. and timing case cover-to-cylinder block bolts. (7) Remove the timing case cover and gasket fromVIBRATION DAMPER the engine. Make sure the tension spring and thrust pin do not fall out of the preload bolt.REMOVAL (8) Pry the crankshaft oil seal from the front of the (1) Disconnect negative cable from battery. timing case cover (Fig. 2). (2) Remove the serpentine drive belt and fanshroud. (3) Remove the vibration damper retaining boltand washer. (4) Use Vibration Damper Removal Tool 8068 to re-move the damper from the crankshaft (Fig. 1). Fig. 2 Timing Case Cover Components CLEANING Clean the timing case cover, oil pan and cylinder block gasket surfaces. INSTALLATION Fig. 1 Vibration Damper Removal Tool 8068 (1) Install a new crankshaft oil seal in the timingINSTALLATION case cover. The open end of the seal should be toward (1) Apply Mopar௡ Silicone Rubber Adhesive Seal- the inside of the cover. Support the cover at the sealant to the keyway in the crankshaft and insert the area while installing the seal. Force it into positionkey. With the key in position, align the keyway of the with Seal Installation Tool 6139.vibration damper hub with the crankshaft key and (2) Position the gasket on the cylinder block.tap the damper onto the crankshaft. (3) Position the timing case cover on the oil pan (2) Install the vibration damper retaining bolt and gasket and the cylinder block. Make sure the tensionwasher. spring and thrust pin are in place in the camshaft (3) Tighten the damper retaining bolt to 108 N⅐m preload bolt.(80 ft. lbs.) torque. (4) Insert Timing Case Cover Alignment and Seal (4) Install the serpentine drive belt and tighten to Installation Tool 6139 in the crankshaft opening inthe specified tension (refer to Group 7, Cooling Sys- the cover (Fig. 3).
  • 26. 9 - 26 4.0L ENGINE ZJ film of Perfect Seal, or equivalent, on the outside di- ameter of the seal. Lightly coat the crankshaft with engine oil. (7) Position the tool and seal over the end of the crankshaft and insert a draw screw tool into Seal In- stallation Tool 6139 (Fig. 4). Tighten the nut against the tool until it contacts the cover. Fig. 3 Timing Case Cover Alignment and Seal Installation Tool 6139 (5) Install the timing case cover-to-cylinder blockand the oil pan-to-timing case cover bolts. (6) Tighten the 1/4 inch front cover-to-block boltsto 7 N⅐m (60 in. lbs.) torque. Tighten the 5/16 inchfront cover-to-block bolts to 22 N⅐m (192 in. lbs.)torque. Tighten the oil pan-to-cover 1/4 inch bolts to Fig. 4 Timing Case Cover Oil Seal Installation14 N⅐m (120 in. lbs.) torque. Tighten the oil pan-to-cover 5/16 inch bolts to 18 N⅐m (156 in. lbs.) torque. (8) Remove the tools. Apply a light film of engine (7) Remove the cover alignment tool. oil on the vibration damper hub contact surface of (8) Apply a light film of engine oil on the vibration the seal.damper hub contact surface of the seal. (9) Apply Mopar௡ Silicone Rubber Adhesive Seal- (9) Apply Mopar௡ Silicone Rubber Adhesive Seal- ant to the keyway in the crankshaft and insert theant to the keyway in the crankshaft and insert the key. With the key inserted in the keyway in thekey. With the key inserted in the keyway in the crankshaft, install the vibration damper, washer andcrankshaft, install the vibration damper, washer and bolt. Lubricate and tighten the bolt to 108 N⅐m (80 ft.bolt. Lubricate and tighten the bolt to 108 N⅐m (80 ft. lbs.) torque.lbs.) torque. (10) Install the serpentine belt and tighten to the (10) Install the A/C compressor (if equipped) and specified tension (refer to Group 7, Cooling Systemsgenerator bracket assembly. for the proper specifications and procedures). (11) Install the engine fan and hub assembly and (11) Install the radiator shroud.shroud. (12) Connect negative cable to battery. (12) Install the serpentine drive belt and tighten toobtain the specified tension. TIMING CHAIN AND SPROCKETS (13) Connect negative cable to battery. REMOVAL (1) Disconnect negative cable from battery.TIMING CASE COVER OIL SEAL REPLACEMENT (2) Remove the fan and shroud. This procedure is done with the timing case cover (3) Remove the serpentine drive belt.installed. (4) Remove the crankshaft vibration damper. (1) Disconnect negative cable from battery. (5) Remove the timing case cover. (2) Remove the serpentine drive belt. (6) Rotate crankshaft until the 0 timing mark is (3) Remove the vibration damper. closest to and on the center line with camshaft (4) Remove the radiator shroud. sprocket timing mark (Fig. 5). (5) Carefully remove the oil seal. Make sure seal (7) Remove the oil slinger from the crankshaft.bore is clean. (8) Remove the tension spring and thrust pin from (6) Position the replacement oil seal on Timing the preload bolt (Fig. 6). Remove the camshaftCase Cover Alignment and Seal Installation Tool sprocket retaining preload bolt and washer.6139 with seal open end facing inward. Apply a light (9) Remove the crankshaft sprocket, camshaft sprocket and timing chain as an assembly.
  • 27. ZJ 4.0L ENGINE 9 - 27 number of chain pins between the timing marks of both sprockets. There must be 15 pins. Fig. 5 Crankshaft/Camshaft Alignment—Typical Fig. 7 Verify Sprocket/Chain Installation—Typical (4) Install the crankshaft oil slinger. (5) Replace the oil seal in the timing case cover. (6) Lubricate the tension spring, thrust pin and pin bore in the preload bolt with Mopar௡ Engine Oil Supplement, or equivalent. Install the spring and thrust pin in the preload bolt head (Fig. 6). (7) Install the timing case cover and gasket. Fig. 6 Camshaft Sprocket Preload Bolt (8) With the key installed in the crankshaft key- way, install the vibration damper, washer and bolt. Installation of the timing chain with the timing Lubricate and tighten the bolt to 108 N⅐m (80 ft. lbs.)marks on the crankshaft and camshaft sprockets torque.properly aligned ensures correct valve timing. A worn (9) Install the serpentine drive belt and tighten toor stretched timing chain will adversely affect valve the specified tension (refer to Group 7, Cooling Sys-timing. If the timing chain deflects more than 12.7 tem for the proper procedure).mm (1/2 inch) replace it. The correct timing chain (10) Install the fan and hub (or Tempatrol fan) as-has 48 pins. A chain with more than 48 pins will sembly. Install the shroud.cause excessive slack. (11) Connect negative cable to battery.INSTALLATION Assemble the timing chain, crankshaft sprocket CAMSHAFTand camshaft sprocket with the timing marks REMOVALaligned (Fig. 5). (1) Apply Mopar௡ Silicone Rubber Adhesive Seal- WARNING: THE COOLANT IN A RECENTLY OPER-ant to the keyway in the crankshaft and insert the ATED ENGINE IS HOT AND PRESSURIZED. RE-key. With the key in the keyway on the crankshaft, LEASE THE PRESSURE BEFORE REMOVING THEinstall the assembly on the crankshaft and camshaft. DRAIN COCK, CAP AND DRAIN PLUGS. (2) Install the camshaft sprocket retaining preloadbolt and washer (Fig. 6). Tighten the preload bolt to (1) Disconnect negative cable from battery.108 N⅐m (80 ft. lbs.) torque. (2) Drain the cooling system. DO NOT waste reus- (3) To verify correct installation of the timing able coolant. If the solution is clean, drain it into achain, turn the crankshaft to position the camshaft clean container for reuse.sprocket timing mark as shown in Fig. 7. Count the
  • 28. 9 - 28 4.0L ENGINE ZJ (3) Remove the radiator or radiator/condenser, if (4) Install the camshaft sprocket retaining preloadequipped with A/C (refer to Group 7, Cooling System bolt. Tighten the bolt to 108 N⅐m (80 ft. lbs.) torque.for the proper procedure). (5) Lubricate the tension spring, the thrust pin (4) Remove the air conditioner condenser and re- and the pin bore in the preload bolt with Mopar௡ En-ceiver/drier assembly as a charged unit, if equipped gine Oil Supplement, or equivalent. Install the spring(refer to Group 24, Heating and Air Conditioning). and thrust pin in the preload bolt head. (5) Remove the distributor cap and mark the posi- (6) Install the timing case cover with a replace-tion of the rotor. ment oil seal (Fig. 9). Refer to Timing Case Cover In- (6) Remove the distributor and ignition wires. stallation. (7) Remove the engine cylinder head cover. (7) Install the vibration damper (Fig. 9). (8) Remove the rocker arms, bridges and pivots. (9) Remove the push rods. (10) Remove the engine cylinder head and gasket. (11) Remove the hydraulic valve tappets from theengine cylinder head. (12) Remove the vibration damper. (13) Remove the timing case cover. (14) Remove the timing chain and sprockets. (15) Remove the front bumper and grille, as re-quired. (16) Remove the camshaft (Fig. 8). Fig. 9 Timing Case Cover Components (8) Install the hydraulic valve tappets. (9) Install the engine cylinder head. (10) Install the push rods. (11) Install the rocker arms and pivot and bridge assemblies. Tighten each of the capscrews for each bridge alternately, one turn at a time, to avoid dam- aging the bridge. (12) Install the engine cylinder head cover. (13) Install the serpentine drive belt and tighten to Fig. 8 Camshaft the specified tension (refer to Group 7, Cooling Sys-INSPECTION tem for the proper procedure). Inspect the cam lobes for wear. (14) Rotate the crankshaft until the No.1 piston is Inspect the bearing journals for uneven wear pat- at the TDC position on the compression stroke.tern or finish. (15) Install the distributor, cap and ignition wires. Inspect the bearings for wear. Install the distributor so that the rotor is aligned Inspect the distributor drive gear for wear. with the mark made during removal. The rotor If the camshaft appears to have been rubbing should be aligned with the No.1 cylinder spark plugagainst the timing case cover, examine the oil pres- terminal on the cap when the distributor housing issure relief holes in the rear cam journal. The oil fully seated on the cylinder block.pressure relief holes must be free of debris. During installation, lubricate the hydraulic valve tappets and all valve components withINSTALLATION Mopar௡ Engine Oil Supplement, or equivalent. (1) Lubricate the camshaft with Mopar௡ Engine The Mopar௡ Engine Oil Supplement, or equiva-Oil Supplement, or equivalent. lent must remain with the engine oil for at (2) Carefully install the camshaft to prevent dam- least 1 609 km (1,000 miles). The oil supplementage to the camshaft bearings (Fig. 8). need not be drained until the next scheduled (3) Install the timing chain, crankshaft sprocketand camshaft sprocket with the timing marks oil change.aligned.
  • 29. ZJ 4.0L ENGINE 9 - 29 (16) Install the A/C condenser and receiver/drierassembly, if equipped (refer to Group 24, Heating andAir Conditioning).CAUTION: Both service valves must be opened be-fore the air conditioning system is operated. (17) Install the radiator, connect the hoses and fillthe cooling system to the specified level (refer toGroup 7, Cooling System for the proper procedure). (18) Check the ignition timing and adjust as neces-sary. (19) Install the grille and bumper, if removed. (20) Connect negative cable to battery.CAMSHAFT PIN REPLACEMENT Fig. 10 Timing Chain Alignment—TypicalREMOVAL CAUTION: The following procedural step must beWARNING: DO NOT LOOSEN THE RADIATOR accomplished to prevent the camshaft from damag-DRAIN COCK WITH THE SYSTEM HOT AND PRES- ing the rear camshaft plug during pin installation.SURIZED BECAUSE SERIOUS BURNS FROM COOL-ANT CAN OCCUR. (15) Inspect the damaged camshaft pin. (16) If the pin is a spring-type pin, remove the bro- (1) Disconnect negative cable from battery. ken pin by inserting a self-tapping screw into the pin (2) Drain the radiator. DO NOT waste reusable and carefully pulling the pin from the camshaft.coolant. Drain the coolant into a clean container. (17) If the pin is a dowel-type pin, center-punch it. (3) Remove the fan and shroud. Ensure the exact center is located when center- (4) Disconnect the radiator overflow tube, radiator punching the pin.hoses, automatic transmission fluid cooler pipes (ifequipped). CAUTION: Cover the opened oil pan area to prevent (5) Remove the radiator. metal chips from entering the pan. (6) If equipped with air conditioning: (18) Drill into the pin center with a 4 mm (5/32CAUTION: DO NOT loosen or disconnect any air inch) drill bit.conditioner system fittings. Move the condenser (19) Insert a self-tapping screw into the drilled pinand receiver/drier aside as a complete assembly. and carefully pull the pin from the camshaft. (a) Remove the A/C compressor serpentine drive CAMSHAFT BEARINGS belt idler pulley. The camshaft rotates within four steel-shelled, bab- (b) Disconnect and remove the generator. bitt-lined bearings that are pressed into the cylinder (c) Remove the A/C condenser attaching bolts block and then line reamed. The camshaft bearing and move the condenser and receiver/drier assem- bores and bearing diameters are not the same size. bly up and out of the way. They are stepped down in 0.254 mm (0.010 inch) in- (7) Remove the serpentine drive belt. crements from the front bearing (largest) to the rear (8) Remove the crankshaft vibration damper. bearing (smallest). This permits easier removal and (9) Remove the timing case cover. Clean the gasket installation of the camshaft. The camshaft bearingsmaterial from the cover. are pressure lubricated. (10) Remove the thrust pin and tension spring It is not advisable to attempt to replace cam-from the preload bolt head. shaft bearings unless special removal and in- (11) Rotate crankshaft until the crankshaft stallation tools are available.sprocket timing mark is closest to and on the center Camshaft end play is maintained by the loadline with the camshaft sprocket timing mark (Fig. placed on the camshaft by the sprocket preload bolt10). tension spring and thrust pin. (12) Remove the camshaft sprocket preload retain-ing bolt and washer. INSTALLATION (13) Remove the crankshaft oil slinger. (1) Clean the camshaft pin hole. (14) Remove the sprockets and chain as an assem- (2) Compress the center of the replacement springbly. pin with vise grips.
  • 30. 9 - 30 4.0L ENGINE ZJ (3) Carefully drive the pin into the camshaft pinhole until it is seated. (4) Install the camshaft sprocket, crankshaftsprocket and timing chain with the timing marksaligned (Fig. 10). (5) To verify correct installation of the timingchain, turn the crankshaft to position the camshaftsprocket timing mark as shown in Fig. 11. Count thenumber of chain pins between the timing marks ofboth sprockets. There must be 15 pins. Fig. 12 Timing Case Cover Alignment and Seal Installation Tool 6139 Tighten the oil pan-to-cover 1/4 inch bolts to 14 N⅐m (120 in. lbs.) torque. Tighten the oil pan-to-cover 5/16 inch bolts to 18 N⅐m (156 in. lbs.) torque. (15) Remove the cover alignment tool and install a replacement oil seal into the cover. (16) Install the vibration damper on the crank- shaft. (17) Lubricate and tighten the damper bolt to 108 N⅐m (80 ft. lbs.) torque. (18) If equipped with air conditioning: (a) Install the A/C compressor serpentine drive belt idler pulley. (b) Install the generator. (c) Install the A/C condenser and receiver/drier Fig. 11 Verify Crankshaft/Camshaft Installation— assembly. Typical (19) Install the serpentine drive belt on the pulleys (6) Install the crankshaft oil slinger. and tighten (refer to Group 7, Cooling System for the (7) Tighten the camshaft sprocket preload bolt to specifications and procedures).108 N⅐m (80 ft. lbs.) torque. (20) Install the radiator. Connect the radiator (8) Check the valve timing. hoses and automatic transmission fluid cooler pipes, (9) Lubricate the tension spring, the thrust pin if equipped. Fill the cooling system.and the pin bore in the preload bolt with Mopar௡ En- (21) Install the fan and shroud.gine Oil Supplement, or equivalent. Install the spring (22) Connect negative cable to battery.and thrust pin in the preload bolt head. (10) Coat both sides of the replacement timing case OIL PANcover gasket with gasket sealer. Apply a 3 mm (1/8inch) bead of Mopar௡ Silicone Rubber Adhesive Seal- REMOVALant, or equivalent to the joint formed at the oil pan (1) Disconnect negative cable from battery.and cylinder block. (2) Raise the vehicle. (11) Position the timing case cover on the oil pan (3) Remove the oil pan drain plug and drain thegasket and the cylinder block. engine oil. (12) Place Timing Case Cover Alignment and Seal (4) Disconnect the exhaust pipe at the engine ex-Installation Tool 6139 in the crankshaft opening in haust manifold.the cover (Fig. 12). (13) Install the timing case cover-to-cylinder block (5) Disconnect the exhaust hanger at the catalyticbolts. Install the oil pan-to-timing case cover bolts. converter and lower the pipe. (14) Tighten the 1/4 inch cover-to-block bolts to 7 (6) Remove the starter motor.N⅐m (60 in. lbs.) torque. Tighten the 5/16 inch front (7) Remove the engine flywheel/transmissioncover-to-block bolts to 22 N⅐m (192 in. lbs.) torque. torque converter housing access cover.
  • 31. ZJ 4.0L ENGINE 9 - 31 (8) If equipped with an oil level sensor, disconnectthe sensor. (9) Position a jack stand directly under the enginevibration damper. (10) Place a piece of wood (2 x 2) between the jackstand and the engine vibration damper. (11) Remove the engine mount thru-bolts. (12) Using the jack stand, raise the engine untiladequate clearance is obtained to remove the oil pan. (13) Remove the oil pan bolts. Carefully slide theoil pan and gasket to the rear. If equipped with an oillevel sensor, take care not to damage the sensor.CLEANING Clean the block and pan gasket surfaces. Fig. 2 Position of Dowels in Cylinder BlockINSTALLATION (1) Fabricate 4 alignment dowels from 1/4 x 1 1/2inch bolts. Cut the head off the bolts and cut a slotinto the top of the dowel. This will allow easier in-stallation and removal with a screwdriver (Fig. 1). Fig. 3 Position of 5/16 inch Oil Pan Bolts (9) Lower the jack stand and remove the piece of wood. (10) If equipped with an oil level sensor, connect Fig. 1 Fabrication of Alignment Dowels the sensor. (11) Install the engine flywheel/transmission (2) Install two dowels in the timing case cover. In- torque converter housing access cover.stall the other two dowels in the cylinder block (Fig. (12) Install the engine starter motor.2). (13) Connect the exhaust pipe to the hanger and to (3) Slide the one-piece gasket over the dowels and the engine exhaust manifold.onto the block and timing case cover. (14) Install the oil pan drain plug (Fig. 3). Tighten (4) Position the oil pan over the dowels and onto the plug to 34 N⅐m (25 ft. lbs.) torque.the gasket. If equipped with an oil level sensor, take (15) Lower the vehicle.care not to damage the sensor. (16) Connect negative cable to battery. (5) Install the 1/4 inch oil pan bolts. Tighten these (17) Fill the oil pan with engine oil to the specifiedbolts to 14 N⅐m (120 in. lbs.) torque. Install the 5/16 level.inch oil pan bolts (Fig. 3). Tighten these bolts to 18N⅐m (156 in. lbs.) torque. WARNING: USE EXTREME CAUTION WHEN THE (6) Remove the dowels. Install the remaining 1/4 ENGINE IS OPERATING. DO NOT STAND IN A DI-inch oil pan bolts. Tighten these bolts to 14 N⅐m (120 RECT LINE WITH THE FAN. DO NOT PUT YOURin. lbs.) torque. HANDS NEAR THE PULLEYS, BELTS OR FAN. DO (7) Lower the engine until it is properly located on NOT WEAR LOOSE CLOTHING.the engine mounts. (8) Install the thru-bolts and tighten the nuts. (18) Start the engine and inspect for leaks.
  • 32. 9 - 32 4.0L ENGINE ZJ LUBRICATION SYSTEM A gear—type positive displacement pump is passes through the squirt hole and is thrown off asmounted at the underside of the block opposite the the rod rotates. This oil throwoff lubricates the cam-No. 4 main bearing. The pump draws oil through the shaft lobes, distributor drive gear, cylinder walls, andscreen and inlet tube from the sump at the rear of piston pins.the oil pan. The oil is driven between the drive and The hydraulic valve tappets receive oil directlyidler gears and pump body, then forced through the from the main oil gallery. Oil is provided to the cam-outlet to the block. An oil gallery in the block chan- shaft bearing through galleries. The front camshaftnels the oil to the inlet side of the full flow oil filter. bearing journal passes oil through the camshaftAfter passing through the filter element, the oil sprocket to the timing chain. Oil drains back to thepasses from the center outlet of the filter through an oil pan under the number one main bearing cap.oil gallery that channels the oil up to the main gal- The oil supply for the rocker arms and bridgedlery which extends the entire length of the block. pivot assemblies is provided by the hydraulic valve Galleries extend downward from the main oil gal- tappets which pass oil through hollow push rods to alery to the upper shell of each main bearing. The hole in the corresponding rocker arm. Oil from thecrankshaft is drilled internally to pass oil from the rocker arm lubricates the valve train components,main bearing journals (except number 4 main bear- then passes down through the push rod guide holesing journal) to the connecting rod journals. Each con- in the cylinder head past the valve tappet area, andnecting rod bearing cap has a small squirt hole, oil returns to the oil pan.
  • 33. ZJ 4.0L ENGINE 9 - 33 Fig. 4 Oil Lubrication System
  • 34. 9 - 34 4.0L ENGINE ZJOIL PUMP (3) Fill the oil pan with oil to the specified level. A gear-type oil pump is mounted at the undersideof the cylinder block opposite the No.4 main bearing. PISTONS AND CONNECTING RODS The pump incorporates a nonadjustable pressurerelief valve to limit maximum pressure to 517 kPa REMOVAL (1) Remove the engine cylinder head cover.(75 psi). In the relief position, the valve permits oil to (2) Remove the rocker arms, bridges and pivots.bypass through a passage in the pump body to the (3) Remove the push rods.inlet side of the pump. (4) Remove the engine cylinder head. Oil pump removal or replacement will not affect (5) Position the pistons one at a time near the bot-the distributor timing because the distributor drive tom of the stroke. Use a ridge reamer to remove thegear remains in mesh with the camshaft gear. ridge from the top end of the cylinder walls. Use aOIL PUMP PRESSURE protective cloth to collect the cuttings. The MINIMUM oil pump pressure is 89.6 kPa (13 (6) Raise the vehicle.psi) at 600 RPM. The MAXIMUM oil pump pressure (7) Drain the engine oil.is 255-517 kPa (37-75 psi) at 1,600 RPM or more. (8) Remove the oil pan and gasket. (9) Remove the connecting rod bearing caps and in-REMOVAL serts. Mark the caps and rods with the cylinder bore (1) Drain the engine oil. location. The connecting rods and caps are stamped (2) Remove the oil pan. with a two letter combination (Fig. 1). (3) Remove the pump-to-cylinder block attachingbolts. Remove the pump assembly with gasket (Fig.5).CAUTION: If the oil pump is not to be serviced, DONOT disturb position of oil inlet tube and strainerassembly in pump body. If the tube is moved withinthe pump body, a replacement tube and strainer as-sembly must be installed to assure an airtight seal. Fig. 1 Stamped Connecting Rods and Caps (10) Lower the vehicle until it is about 2 feet from the floor. CAUTION: Ensure that the connecting rod bolts DO NOT scratch the crankshaft journals or cylinder walls. Short pieces of rubber hose, slipped over the rod bolts will provide protection during removal. (11) Have an assistant push the piston/connecting rod assemblies up and through the top of the cylinder bores (Fig. 2). INSPECTION—CONNECTING ROD Fig. 5 Oil Pump Assembly CONNECTING ROD BEARINGSINSTALLATION Inspect the connecting rod bearings for scoring and (1) Install the oil pump on the cylinder block using bent alignment tabs (Figs. 3 and 4). Check the bear-a replacement gasket. Tighten the bolts to 23 N⅐m ings for normal wear patterns, scoring, grooving, fa-(17 ft. lbs.) torque. tigue and pitting (Fig. 5). Replace any bearing that (2) Install the oil pan. shows abnormal wear.
  • 35. ZJ 4.0L ENGINE 9 - 35 Fig. 4 Locking Tab Inspection Fig. 2 Removal of Connecting Rod and Piston Assembly Inspect the connecting rod journals for signs ofscoring, nicks and burrs. Fig. 5 Scoring Caused by Insufficient Lubrication or by Damaged Crankshaft Pin Journal (3) Lubricate the upper bearing insert and install in connecting rod. (4) Use piston ring compressor to install the rod and piston assemblies. The oil squirt holes in the rods must face the camshaft. The arrow on the piston crown should point to the front of the engine (Fig. 6). Verify that the oil squirt holes in the rods face the camshaft and that the arrows on the pistons face the front of the engine. Fig. 3 Connecting Rod Bearing InspectionCONNECTING RODS Misaligned or bent connecting rods can cause ab-normal wear on pistons, piston rings, cylinder walls,connecting rod bearings and crankshaft connectingrod journals. If wear patterns or damage to any ofthese components indicate the probability of a mis-aligned connecting rod, inspect it for correct rodalignment. Replace misaligned, bent or twisted con-necting rods. Fig. 6 Rod and Piston Assembly InstallationBEARING-TO-JOURNAL CLEARANCE (5) Install the lower bearing insert in the bearing (1) Wipe the oil from the connecting rod journal. cap. The lower insert must be dry. Place strip of Plas- (2) Use short rubber hose sections over rod bolts tigage across full width of the lower insert at the cen-during installation.
  • 36. 9 - 36 4.0L ENGINE ZJter of bearing cap. Plastigage must not crumble inuse. If brittle, obtain fresh stock. (6) Install bearing cap and connecting rod on thejournal and tighten nuts to 45 N⅐m (33 ft. lbs.)torque. DO NOT rotate crankshaft. Plastigage willsmear, resulting in inaccurate indication. (7) Remove the bearing cap and determine amountof bearing-to-journal clearance by measuring thewidth of compressed Plastigage (Fig. 7). Refer to En-gine Specifications for the proper clearance. Plasti-gage should indicate the same clearance acrossthe entire width of the insert. If the clearancevaries, it may be caused by either a taperedjournal, bent connecting rod or foreign mate-rial trapped between the insert and cap or rod. (8) If the correct clearance is indicated, replace-ment of the bearing inserts is not necessary. Remove Fig. 7 Measuring Bearing Clearance with Plastigagethe Plastigage from crankshaft journal and bearing dersize inserts would reduce the clearance by 0.025insert. Proceed with installation. mm (0.001 inch). The clearance would be 0.002 inch (9) If bearing-to-journal clearance exceeds the spec- and within specification. A 0.051 mm (0.002 inch) un-ification, install a pair of 0.0254 mm (0.001 inch) un- dersize insert would reduce the initial clearance andersize bearing inserts. All the odd size inserts must additional 0.013 mm (0.0005 inch). The clearancebe on the bottom. The sizes of the service replace-ment bearing inserts are stamped on the backs of the would then be 0.038 mm (0.0015 inch).inserts. Measure the clearance as described in the (11) Repeat the Plastigage measurement to verifyprevious steps. your bearing selection prior to final assembly. (10) The clearance is measured with a pair of (12) Once you have selected the proper insert, in-0.0254 mm (0.001 inch) undersize bearing inserts in- stall the insert and cap. Tighten the connecting rodstalled. This will determine if two 0.0254 mm (0.001 bolts to 45 N⅐m (33 ft. lbs.) torque.inch) undersize inserts or another combination isneeded to provide the correct clearance (refer to Con- SIDE CLEARANCE MEASUREMENTnecting Rod Bearing Fitting Chart). Slide snug-fitting feeler gauge between the connect- FOR EXAMPLE: If the initial clearance was ing rod and crankshaft journal flange. Refer to En-0.0762 mm (0.003 inch), 0.025 mm (0.001 inch) un- CONNECTING ROD BEARING FITTING CHART
  • 37. ZJ 4.0L ENGINE 9 - 37gine Specifications for the proper clearance. Replacethe connecting rod if the side clearance is not withinspecification.PISTON FITTINGBORE GAGE METHOD (1) To correctly select the proper size piston, a cyl-inder bore gauge, Special Tool 6879 or equivalent, ca-pable of reading in .0001Љ INCREMENTS with gaugering Special Tool 6884 is required. If a bore gauge isnot available, do not use an inside micrometer. (2) Set the bore gauge, Special Tool 6879 or equiv-alent, to the gauge ring, Special Tool 6884, and zerogauge. (3) Remove gauge from ring and check cylinder asshown in (Fig. 8) bore and record reading. (4) Measure the inside diameter of the cylinderbore at a point 58.725 mm (2-5/16 inches) below topof bore. Start perpendicular (across or at 90 degrees)to the axis of the crankshaft at point B and then takean additional bore reading 90 degrees to that at point Fig. 8 Bore GaugeA. (5) Recheck bore gauge, Special Tool 6879 or equiv-alent, in gauge ring, Special Tool 6884, bore gaugeshould read zero. If gauge does not read zero, resetgauge and start over with procedure. The coated pistons will be serviced with the pistonpin and connecting rod pre-assembled. The coatedpiston connecting rod assembly can be used toservice previous built engines and MUST be re- Fig. 9 Piston Size Chartplaced as complete sets. Tin coated pistons shouldnot be used as replacements for the new coated pis-tons. The coating material is applied to the piston afterthe final piston machining process. Measuring theoutside diameter of a coated piston will not provideaccurate results. Therefore measuring the inside di-ameter of the cylinder bore with a dial Bore Gauge isMANDATORY.. To correctly select the proper sizepiston, a cylinder bore gauge capable of reading in.0001Љ increments is required. Piston installation into the cylinder bore requireslightly more pressure than that required for non-coated pistons. The bonded coating on the piston willgive the appearance of a line-to-line fit with the cyl-inder bore.PISTON PIN Piston pins are press-fitted into the connecting rodsand require no locking device. The piston, piston pin Fig. 10 Piston Dimensionsand connecting rod are replaced as an assembly. the grooves or lands. This will change ring-to-groovePISTON RING FITTING clearances and will damage the ring-to-land seating. (1) Carefully clean the carbon from all ring (2) Be sure the piston ring grooves are free of nicksgrooves. Oil drain openings in the oil ring groove and and burrs.pin boss must be clear. DO NOT remove metal from
  • 38. 9 - 38 4.0L ENGINE ZJ (3) Measure the ring side clearance with a feeler (6) The two compression rings are different andgauge fitted snugly between the ring land and ring cannot be interchanged. The top ring (Fig. 13) is a(Fig. 11). Rotate the ring in the groove. It must move moly ring (the scraping edge is gray in color). Thefreely around circumference of the groove. second ring (Fig. 14) is a black cast iron ring (the scraping edge is black in color when new). The com- pression rings may also be identified by 1 or 2 dots on the top surface of the ring (Figs. 13 and 14). Fig. 13 Top Compression Ring Identification Fig. 11 Ring Side Clearance Measurement (4) Place ring in the cylinder bore and push downwith inverted piston to position near lower end of thering travel. Measure ring gap with a feeler gauge fit-ting snugly between ring ends (Fig. 12). The correctcompression ring end gap is 0.25-0.51 mm (0.010-0.020 inch). The correct oil control ring end gap is0.381-1.397 mm (0.015-0.055 inch). Fig. 14 Second Compression Ring Identification (7) The second compression ring (black cast iron) has a chamfer on the BOTTOM of the inside edge (Fig. 15). This ring may also have 2 dots located on the top surface. Fig. 12 Ring Gap Measurement (5) Install the oil control rings according to instruc- Fig. 15 Compression Ring Chamfer Locationtions in the package. It is not necessary to use a tool (8) Using a ring installer, install the second com-to install the upper and lower rails. Insert oil rail pression ring with the chamfer facing down (Fig. 15).spacer first, then side rails. The 2 dots will be facing up.
  • 39. ZJ 4.0L ENGINE 9 - 39 Fig. 16 Compression Ring Installation (9) The top compression ring (the scraping edge isgray in color) has a chamfer on the TOP of the insideedge (Fig. 15). This ring may also have 1 dot locatedon the top surface. (10) Using a ring installer, install the top ring withthe chamfer facing up (Fig. 15). The dot will be fac-ing up. (11) Position the ring end gaps on the piston (Fig.17):• Oil spacer—Gap on center line of piston pin bore.• Oil rails—Gap 180° apart on center line of piston Fig. 17 Ring Gap Positionskirt.• No.2 Compression ring—Gap 180° from top oil railgap.• No.1 Compression ring—Gap 180° from No.2 com-pression ring gap.CLEANING Clean the cylinder bores thoroughly. Apply a lightfilm of clean engine oil to the bores with a clean lint-free cloth.INSTALLATION (1) Install the piston rings on the pistons if re-moved. (2) Lubricate the piston and rings with clean en- Fig. 18 Rod and Piston Assembly Installationgine oil. Each bearing insert is fitted to its respective jour-CAUTION: Ensure that connecting rod bolts DO nal to obtain the specified clearance between theNOT scratch the crankshaft journals or cylinder bearing and the journal. In production, the select fitwalls. Short pieces of rubber hose slipped over the is obtained by using various-sized, color-coded bear-connecting rod bolts will provide protection during ing inserts as listed in the Connecting Rod Bearinginstallation. Fitting Chart. The color code appears on the edge of the bearing insert. The size is not stamped on inserts (3) Use a piston ring compressor to install the con- used for production of engines.necting rod and piston assemblies through the top of The rod journal is identified during the engine pro-the cylinder bores (Fig. 18). duction by a color-coded paint mark on the adjacent (4) Ensure the arrow on the piston top points to cheek or counterweight toward the flange (rear) endthe front of the engine (Fig. 18). (5) Raise the vehicle.
  • 40. 9 - 40 4.0L ENGINE ZJof the crankshaft. The color codes used to indicatejournal sizes are listed in the Connecting Rod Bear-ing Fitting Chart. When required, upper and lower bearing inserts ofdifferent sizes may be used as a pair (refer to Con-necting Rod Bearing Fitting Chart). A standard sizeinsert is sometimes used in combination with a 0.025mm (0.001 inch) undersize insert to reduce clearance0.013 mm (0.0005 inch).CAUTION: DO NOT intermix bearing caps. Eachconnecting rod and bearing cap are stamped withthe cylinder number. The stamp is located on a ma-chined surface adjacent to the oil squirt hole thatfaces the camshaft side of the cylinder block. (6) Install the connecting rod bearing caps and in-serts in the same positions as removed.CAUTION: Verify that the oil squirt holes in the rodsface the camshaft and that the arrows on the pis-tons face the front of the engine. Fig. 1 Removing Main Bearing Caps and Lower (7) Install the oil pan and gaskets as outlined in Insertsthe installation procedure. (8) Lower the vehicle. (9) Install the engine cylinder head, push rods,rocker arms, bridges, pivots and engine cylinder headcover. (10) Fill the crankcase with engine oil.CRANKSHAFT MAIN BEARINGSREMOVAL (1) Disconnect negative cable from battery. (2) Remove the spark plugs. (3) Raise the vehicle. (4) Remove the oil pan and oil pump. (5) Remove only one main bearing cap and lowerinsert at a time (Fig. 1). (6) Remove the lower insert from the bearing cap. (7) Remove the upper insert by LOOSENING (DONOT REMOVE) all of the other bearing caps. Nowinsert a small cotter pin tool in the crankshaft jour-nal oil hole. Bend the cotter pin as illustrated to fab-ricate the tool (Fig. 2). With the cotter pin tool in Fig. 2 Removing Upper Insertsplace, rotate the crankshaft so that the upper bear-ing insert will rotate in the direction of its locking INSPECTIONtab. Because there is no hole in the No.3 main jour- Wipe the inserts clean and inspect for abnormalnal, use a tongue depressor or similar soft-faced tool wear patterns and for metal or other foreign materialto remove the bearing insert (Fig. 2). After moving imbedded in the lining. Normal main bearing insertthe insert approximately 25 mm (1 inch), it can be wear patterns are illustrated (Fig. 3).removed by applying pressure under the tab. If any of the crankshaft journals are scored, (8) Using the same procedure described above, re- remove the engine for crankshaft repair.move the remaining bearing inserts one at a time for Inspect the back of the inserts for fractures, scrap-inspection. ings or irregular wear patterns. Inspect the upper insert locking tabs for damage.
  • 41. ZJ 4.0L ENGINE 9 - 41 When replacing inserts, the odd size inserts must be either all on the top (in cylinder block) or all on the bottom (in main bearing cap). Once the bearings have been properly fitted, pro- ceed to Crankshaft Main Bearing—Installation. BEARING-TO-JOURNAL CLEARANCE—CRANKSHAFT INSTALLED When using Plastigage, check only one bearing clearance at a time. Install the grooved main bearings into the cylinder block and the non-grooved bearings into the bearing caps. Install the crankshaft into the upper bearings dry. Place a strip of Plastigage across full width of the crankshaft journal to be checked. Fig. 3 Main Bearing Wear Patterns Install the bearing cap and tighten the bolts to 108 N⅐m (80 ft. lbs.) torque. Replace all damaged or worn bearing inserts. DO NOT rotate the crankshaft. This will cause the Plastigage to shift, resulting in an in-FITTING—CRANKSHAFT INSTALLED accurate reading. Plastigage must not be per- The main bearing caps, numbered (front to rear) mitted to crumble. If brittle, obtain fresh stock.from 1 through 7 have an arrow to indicate the for- Remove the bearing cap. Determine the amount ofward position. The upper main bearing inserts are clearance by measuring the width of the compressedgrooved to provide oil channels while the lower in- Plastigage with the scale on the Plastigage envelopeserts are smooth. (Fig. 5). Refer to Engine Specifications for the proper Each bearing insert pair is selectively fitted to its clearance.respective journal to obtain the specified operatingclearance. In production, the select fit is obtained byusing various-sized color-coded bearing insert pairsas listed in the Main Bearing Fitting Chart. Thebearing color code appears on the edge of the insert.The size is not stamped on bearing inserts usedfor engine production. The main bearing journal size (diameter) is identi-fied by a color-coded paint mark on the adjacentcheek. The rear main journal, is identified by a color-coded paint mark on the crankshaft rear flange. When required, upper and lower bearing inserts ofdifferent sizes may be used as a pair. A standard sizeinsert is sometimes used in combination with a 0.025mm (0.001 inch) undersize insert to reduce the clear-ance by 0.013 mm (0.0005 inch). Never use a pairof bearing inserts with greater than a 0.025 mm(0.001 inch) difference in size (Fig. 4). Fig. 5 Measuring Bearing Clearance with Plastigage Plastigage should indicate the same clearance across the entire width of the insert. If clearance var- ies, it may indicate a tapered journal or foreign ma- terial trapped behind the insert. If the specified clearance is indicated and there are no abnormal wear patterns, replacement of the bear- ing inserts is not necessary. Remove the Plastigage from the crankshaft journal and bearing insert. Pro- ceed to Crankshaft Main Bearing—Installation. If the clearance exceeds specification, install a pair of 0.025 mm (0.001 inch) undersize bearing inserts and measure the clearance as described in the previ- Fig. 4 Bearing Insert Pairs ous steps.
  • 42. 9 - 42 4.0L ENGINE ZJ The clearance indicated with the 0.025 mm (0.001 (2) Loosen all the main bearing caps. Install theinch) undersize insert pair installed will determine if main bearing upper inserts.this insert size or some other combination will pro- (3) Install the lower bearing inserts into the mainvide the specified clearance. bearing caps. FOR EXAMPLE: If the clearance was 0.0762 mm (4) Install the main bearing cap(s) and lower in-(0.003 inch) originally, a pair of 0.0254 mm (0.001 sert(s).inch) undersize inserts would reduce the clearance by (5) Tighten the bolts of caps 1, 2, 4, 5, 6, and 7 to0.0254 mm (0.001 inch). The clearance would then be 54 N⅐m (40 ft. lbs.) torque. Now tighten these bolts to0.0508 mm (0.002 inch) and within the specification. 95 N⅐m (70 ft. lbs.) torque. Finally, tighten theseA 0.051 mm (0.002 inch) undersize bearing insert bolts to 108 N⅐m (80 ft. lbs.) torque.and a 0.0254 mm (0.001 inch) undersize insert would (6) Push the crankshaft forward and backward.reduce the original clearance an additional 0.0127 Load the crankshaft front or rear and tighten capmm (0.0005 inch). The clearance would then be bolt No.3 to 54 N⅐m (40 ft. lbs.) torque. Then tighten0.0381 mm (0.0015 inch). to 95 N⅐m (70 ft. lbs.) torque and finally tighten to 108 N⅐m (80 ft. lbs.) torque.CAUTION: Never use a pair of inserts that differ (7) Rotate the crankshaft after tightening eachmore than one bearing size as a pair. main bearing cap to ensure the crankshaft rotates freely. FOR EXAMPLE: DO NOT use a standard size up- (8) Check crankshaft end play. Crankshaft endper insert and a 0.051 mm (0.002 inch) undersize play is controlled by the thrust bearing which islower insert. flange and installed at the No.2 main bearing posi- If the clearance exceeds specification using a pair tion.of 0.051 mm (0.002 inch) undersize bearing inserts, (a) Attach a magnetic base dial indicator to themeasure crankshaft journal diameter with a mi- cylinder block at either the front or rear of the en-crometer. If the journal diameter is correct, the gine.crankshaft bore in the cylinder block may be mis- (b) Position the dial indicator rod so that it isaligned, which requires cylinder block replacement or parallel to the center line of the crankshaft.machining to true bore. (c) Pry the crankshaft forward, position the dial Replace the crankshaft or grind to accept the ap- indicator to zero.propriate undersize bearing inserts if: (d) Pry the crankshaft forward and backward.• Journal diameters 1 through 6 are less than Note the dial indicator readings. End play is the63.4517 mm (2.4981 inches). difference between the high and low measurements• Journal 7 diameter is less than 63.4365 mm (Fig. 6). Correct end play is 0.038-0.165 mm(2.4975 inches). (0.0015-0.0065 inch). The desired specifications are Once the proper clearances have been obtained, 0.051-0.064 mm (0.002-0.0025 inch).proceed to Crankshaft Main Bearing—Installation. (e) If end play is not within specification, inspect crankshaft thrust faces for wear. If no wear is ap-MAIN BEARING JOURNAL DIAMETER—CRANKSHAFTREMOVED parent, replace the thrust bearing and measure Remove the crankshaft from the cylinder block (re- end play. If end play is still not within specifica-fer to Cylinder Block - Disassemble). tion, replace the crankshaft. Clean the oil off the main bearing journal. If the crankshaft was removed, install the crank- Determine the maximum diameter of the journal shaft into the cylinder block (refer to Cylinder Block -with a micrometer. Measure at two locations 90° Assemble).apart at each end of the journal. (9) Install the oil pan. The maximum allowable taper and out of round is (10) Install the drain plug. Tighten the plug to 340.013 mm (0.0005 inch). Compare the measured di- N⅐m (25 ft. lbs.) torque.ameter with the journal diameter specification (Main (11) Lower the vehicle.Bearing Fitting Chart). Select inserts required to ob- (12) Install the spark plugs. Tighten the plugs totain the specified bearing-to-journal clearance. 37 N⅐m (27 ft. lbs.) torque. Install the crankshaft into the cylinder block (refer (13) Fill the oil pan with engine oil to the fullto Cylinder Block - Assemble and Crankshaft Main mark on the dipstick level.Bearings - Installation). (14) Connect negative cable to battery.INSTALLATION REAR MAIN OIL SEALS (1) Lubricate the bearing surface of each insert The crankshaft rear main bearing oil seal consistswith engine oil. of two half pieces of viton with a single lip that ef-
  • 43. ZJ 4.0L ENGINE 9 - 43 MAIN BEARING FITTING CHART
  • 44. 9 - 44 4.0L ENGINE ZJ Fig. 6 Crankshaft End Play Measurementfectively seals the rear of the crankshaft. Replace theupper and lower seal halves as a unit to ensure leak-free operation.REMOVAL Fig. 7 Rear Main Bearing Oil Seal (1) Remove the engine flywheel or converter driveplate. (2) Remove the oil pan. (3) Remove the rear main bearing cap (No.7). (4) Push the upper seal out of the groove. Ensurethat the crankshaft and seal groove are not damaged. (5) Remove the lower half of the seal from thebearing cap.INSTALLATION (1) Wipe the seal surface area of the crankshaftuntil it is clean. (2) Apply a thin coat of engine oil. (3) Coat the lip of the seal with engine oil. (4) Carefully position the upper seal into thegroove in the cylinder block. The lip of the seal facestoward the front of the engine. (5) Place the lower half of the seal into bearing capNo.7 (Fig. 7). (6) Coat the outer curved surface of the lower sealwith soap and the lip of the seal with engine oil (Fig.7). (7) Position the lower seal into the bearing cap re- Fig. 8 Location of Loctite 518 (or equivalent)cess and seat it firmly. Be sure the seal is flush with (12) Install the engine flywheel or converter drivethe cylinder block pan rail. plate. (8) Apply Loctite 518, or equivalent on the rearbearing cap (Fig. 8). The bead should be 3 mm (0.125 CYLINDER BLOCKin) thick. DO NOT apply Loctite 518, or equivalent to Remove the Engine Assembly from the vehicle.the lip of the seal. (9) Install the rear main bearing cap. DO NOT DISASSEMBLYstrike the cap more than twice for proper engage- Refer to the applicable sections for detailed instruc-ment. tions. (10) Tighten all main bearing bolts to 108 N⅐m (80 (1) Drain the engine oil. Remove and discard theft. lbs.) torque. oil filter. (11) Install the oil pan gasket and oil pan.
  • 45. ZJ 4.0L ENGINE 9 - 45 (2) Remove the water pump from the cylinderblock. (3) Remove the vibration damper. (4) Remove the timing case cover and lay the coverupside down. (5) Position a drift punch into the slot in the backof the cover and tap the old seal out. (6) Remove the oil slinger from crankshaft. (7) Remove the camshaft retaining bolt and re-move the sprockets and chain as an assembly. (8) Remove the camshaft. (9) Remove the oil pan and gasket. (10) Remove the front and rear oil galley plugs. (11) Remove the oil pump. (12) Remove the connecting rods and the pistons.Remove the connecting rod and piston assembliesthrough the top of the cylinder bores. (13) Remove the crankshaft.CLEANING Thoroughly clean the oil pan and engine block gas-ket surfaces. Fig. 9 Cylinder Bore Measurement Use compressed air to clean out:• The galley at the oil filter adaptor hole, the filter HONING—CYLINDER BORE The honing operation should be closely coordinatedbypass hole. with the fitting of pistons and rings. This will ensure• The front and rear oil galley holes. specified clearances are maintained.• The feed holes for the crankshaft main bearings. Refer to Standard Service Procedures in the begin- Once the block has been completely cleaned, apply ning of this Group for the proper honing of cylinderLoctite PST pipe sealant with Teflon 592 to the bores.threads of the front and rear oil galley plugs. Tightenthe plugs to 41 N⅐m (30 ft. lbs.) torque. ASSEMBLY Refer to the applicable sections for detailed instruc-INSPECTION—CYLINDER BORE tions. (1) Use a bore gauge to measure each cylinder bore (1) Install the crankshaft.diameter (Fig. 9). If a bore gauge is not available, use (2) Install the connecting rods and the pistonsan inside micrometer. through the top of the cylinder bores. (2) Measure the cylinder bore diameter crosswise (3) Install the oil pump.to the cylinder block near the top of the bore. Repeat (4) Install the oil pan and gasket.the measurement near the bottom of the bore. (5) Install the camshaft. (3) Determine taper by subtracting the smaller di- (6) Install the sprockets and chain as an assembly.ameter from the larger diameter. (7) Install the oil slinger from the crankshaft. (4) Rotate measuring device 120° and repeat steps (8) Install the timing case cover seal.above. Finally, rotate the device another 120° and re- (9) Install the timing case cover.peat measurements. (10) Install the vibration damper. (5) Determine out-of-roundness by comparing the (11) Install the water pump. Tighten the mountingdifference between each 120° measurement. bolts to 31 N⅐m (270 in. lbs.) torque. (6) If cylinder bore taper does not exceed 0.025 mm (12) Lubricate the oil filter seal with clean engine(0.001 inch) and out-of-roundness does not exceed oil. Tighten oil filter to 18 N⅐m (13 ft. lbs.) torque.0.025 mm (0.001 inch), the cylinder bore can be (13) Install the engine into the vehicle. (14) Fill the engine with clean lubrication oil (referhoned. If the cylinder bore taper or out-of-round con- to Group 0, Lubrication and Maintenance).dition exceeds these maximum limits, the cylinder (15) Fill the cooling system (refer to Group 7, Cool-must be bored and then honed to accept an oversize ing System for the proper procedures).piston. A slight amount of taper always exists in thecylinder bore after the engine has been in use for aperiod of time.
  • 46. 9 - 46 4.0L ENGINE ZJ ENGINE SPECIFICATIONSSPECIFICATIONS
  • 47. ZJ 4.0L ENGINE 9 - 47 ENGINE SPECIFICATIONS—CONT.
  • 48. 9 - 48 4.0L ENGINE ZJ ENGINE SPECIFICATIONS—CONT. TORQUE SPECIFICATIONS
  • 49. ZJ 5.2L ENGINE 9 - 49 5.2L ENGINE SERVICE PROCEDURES INDEX page pageCamshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Oil Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Cylinder Head Cover . . . . . . . . . . . . . . . . . . . . . . . 52 Rocker Arms and Push Rods . . . . . . . . . . . . . . . . 52Cylinder Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Timing Chain Cover . . . . . . . . . . . . . . . . . . . . . . . 58Distributor Bushing . . . . . . . . . . . . . . . . . . . . . . . . 62 Valve Components Replace—Cylinder Head NotEngine Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 51 Removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Engine Mounts—Front . . . . . . . . . . . . . . . . . . . . . 49 Valve Stem Seal and Spring Replacement . . . . . . . 52Engine Mounts—Rear . . . . . . . . . . . . . . . . . . . . . . 50 Valve Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Front Crankshaft Oil Seal Replacement . . . . . . . . . 60 Valves and Valve Springs . . . . . . . . . . . . . . . . . . . 54General Information . . . . . . . . . . . . . . . . . . . . . . . 49 Vibration Damper . . . . . . . . . . . . . . . . . . . . . . . . . 58Hydraulic Tappets . . . . . . . . . . . . . . . . . . . . . . . . . 56GENERAL INFORMATION The 5.2 Liter (318 CID) eight-cylinder engine is aV-Type lightweight, single cam, overhead valve en-gine with hydraulic roller tappets (Fig. 1). Fig. 2 Firing Order Fig. 1 Engine Description This engine is designed for unleaded fuel. Engine lubrication system consists of a rotor typeoil pump and a full flow oil filter. The cylinders are numbered from front to rear; 1,3, 5, 7 on the left bank and 2, 4, 6, 8 on the right Fig. 3 Engine Identification Numberbank. The firing order is 1-8-4-3-6-5-7-2 (Fig. 2). The engine serial number is stamped into a ma- ENGINE MOUNTS—FRONTchined pad located on the left, front corner of the cyl- REMOVALinder block. When component part replacement is (1) Disconnect the negative cable from the battery.necessary, use the engine type and serial number for (2) Position fan to assure clearance for radiator topreference (Fig. 3). tank and hose.
  • 50. 9 - 50 5.2L ENGINE ZJCAUTION: DO NOT lift the engine by the intake (a) RIGHT SIDE—Install the sill bracket assem-manifold. bly onto the sill assembly (Fig. 4). Install and tighten the bolts to 65 N⅐m (48 ft. lbs.) torque. (3) Install engine lifting fixture. (b) LEFT SIDE—Install the sill bracket assem- (4) Raise vehicle on hoist. bly onto the sill assembly (Fig. 5). Install and (5) Remove the engine support insulator thru-bolts tighten the 2 top bolts to 65 N⅐m (48 ft. lbs.)and nuts (Figs. 4 and 5). torque. Install and tighten the 2 side bolts to 95 (6) Raise engine SLIGHTLY. Remove the engine N⅐m (70 ft. lbs.) torque. Install and tighten the 2support insulator bolts. Remove the engine support bottom bolts to 121 N⅐m (89 ft. lbs.) torque.insulator assembly. (2) With the engine raised SLIGHTLY, position en- gine support insulator assembly onto the engine block (Figs. 4 and 5). Install bolts and tighten to 88 N⅐m (65 ft. lbs.) torque. (3) Lower engine with lifting fixture while aligning engine support insulator assembly into sill bracket assembly. (4) Install the thru-bolt and nut. Tighten the RIGHT SIDE nut to 65 N⅐m (48 ft. lbs.) torque. Tighten the LEFT SIDE nut to 121 N⅐m (89 ft. lbs.) torque. (5) Lower the vehicle. (6) Remove lifting fixture. (7) Connect the negative cable to the battery. ENGINE MOUNTS—REAR Fig. 4 Front Engine Mount—Right Side REMOVAL (1) Disconnect the negative cable from the battery. (2) Raise the vehicle on a hoist. (3) Support the transmission with a jack. (4) Remove engine mount bracket thru-bolt (Fig. 6). (5) Raise the transmission and engine SLIGHTLY. (6) Remove stud nuts attaching engine mount cle- vis bracket to crossmember (Fig. 6). Remove bracket. Fig. 5 Front Engine Mount—Left Side (7) If required, remove the sill bracket assembly.INSTALLATION (1) If the sill bracket assembly was removed, in-stall the bracket to the sill assembly. Fig. 6 Engine Rear Support Assembly
  • 51. ZJ 5.2L ENGINE 9 - 51 (7) Remove the engine mount bracket assembly (21) Support automatic transmission with a trans-from the adaptor (Fig. 6). mission stand. This will assure that the torque con- (8) If required, remove the transmission support verter will remain in proper position in thebracket adaptor. transmission housing. (22) Remove bell housing bolts and inspectionINSTALLATION plate. Attach C-clamp on front bottom of transmis- (1) If the transmission support bracket adaptor sion torque converter housing to prevent torque con-was removed, position the adaptor to the transmis- verter from coming out.sion (Fig. 6). Tighten the bolts to 60 N⅐m (44 ft. lbs.) (23) Remove torque converter drive plate boltstorque. from torque converter drive plate. Mark converter (2) Install the engine mount clevis bracket onto and drive plate to aid in assembly.crossmember. Tighten the stud nuts to 41 N⅐m (30 ft. (24) Disconnect the engine from the torque con-lbs) torque. verter drive plate. (3) Install the engine mount bracket assembly tothe adaptor. Install the bolts and tighten to 75 N⅐m CAUTION: DO NOT lift the engine by the intake(55 ft. lbs.) torque. manifold. (4) Lower the transmission and engine while align- (25) Install an engine lifting fixture.ing the engine mount bracket assembly to the engine (26) Remove the engine front mount thru-bolts.mount clevis bracket. (27) Lower the vehicle. (5) Install thru-bolt and tighten the nut to 65 N⅐m (28) Remove engine from engine compartment.(48 ft. lbs.) torque. (29) Install on engine repair stand. (6) Remove transmission jack. (7) Lower the vehicle. INSTALLATION (8) Connect the negative cable to the battery. (1) Remove engine from the repair stand and posi- tion in the engine compartment.ENGINE ASSEMBLY (2) Install engine support fixture. (3) Raise and support the vehicle on a hoist.REMOVAL (4) Position the torque converter and drive plate. (1) Scribe hood hinge outlines on hood and remove Install torque converter drive plate bolts. Tighten thethe hood. bolts to 31 N⅐m (270 in. lbs.) torque. (2) Remove the battery. (5) Install the engine front mount thru-bolts. (3) Drain cooling system. (6) Install bell housing bolts. Tighten the bolts to (4) Remove the air cleaner and tube. 41 N⅐m (30 ft. lbs.) torque. (5) Set fan shroud aside. (7) Remove C-clamp and install inspection plate. (6) Remove radiator and heater hoses. Remove the (8) Remove stand from transmission.radiator (refer to Group 7, Cooling System). (9) Install exhaust pipe to manifold. (7) Remove the vacuum lines. (10) Lower the vehicle. (8) Remove the distributor cap and wiring. (11) Remove engine lifting fixture. (9) Disconnect the accelerator linkage. (12) Install the generator (refer to Group 8C, Gen- (10) Perform the Fuel System Pressure Release erator Service).procedure (refer to Group 14, Fuel System). (13) Install starter motor (refer to Group 8B, Bat- (11) Remove throttle body. tery/Starter Service). (12) Remove the starter wires. (14) Install power steering hoses, if equipped. (15) Install air conditioning hoses. (13) Remove the oil pressure wire. (16) Charge the air conditioner, if equipped (refer (14) Discharge the air conditioning system, if to Group 24, Heater and Air Conditioning for serviceequipped (refer to Group 24, Heating and Air Condi- procedures).tioning for service procedures). (17) Using a new gasket, install throttle body. (15) Remove air conditioning hoses. Tighten the throttle body bolts to 23 N⅐m (200 in. (16) Disconnect the power steering hoses, if lbs.) torque.equipped. (18) Connect the accelerator linkage. (17) Remove starter motor (refer to Group 8B, Bat- (19) Connect the starter wires.tery/Starter Service). (20) Connect the oil pressure wire. (18) Remove the generator (refer to Group 8C, (21) Install the distributor cap and wiring.Generator Service). (22) Install vacuum lines. (19) Raise and support the vehicle on a hoist. (23) Install radiator, radiator hoses and heater (20) Disconnect exhaust pipe at manifold. hoses (refer to Group 7, Cooling System).
  • 52. 9 - 52 5.2L ENGINE ZJ (24) Install fan shroud in position. VALVE COMPONENTS REPLACE—CYLINDER HEAD (25) Install the battery NOT REMOVED (26) Fill cooling system (refer to Group 7, CoolingSystem for the proper procedure). ROCKER ARMS AND PUSH RODS (27) Install the air cleaner. (28) Warm engine and adjust. REMOVAL (29) Install hood and line up. (1) Disconnect spark plug wires by pulling on the (30) Road test vehicle. boot straight out in line with plug. (2) Remove cylinder head cover and gasket.CYLINDER HEAD COVER (3) Remove the rocker arm bolts and pivots (Fig. A steel backed silicon gasket is used with the cyl- 2). Place them on a bench in the same order as re-inder head cover (Fig. 1). This gasket can be used moved.again. (4) Remove the push rods and place them on a bench in the same order as removed. Fig. 1 Cylinder Head Cover Gasket Fig. 2 Rocker ArmsREMOVAL (1) Disconnect the negative cable from the battery. INSTALLATION (2) Disconnect closed ventilation system and evap- (1) Rotate the crankshaft until the V8 mark linesoration control system from cylinder head cover. up with the TDC mark on the timing chain case (3) On the left cover, remove the coolant tube cover (located 17.5° ATDC from the No.1 firingbracket. mark). (2) Install the push rods in the same order as re- (4) Remove the ignition wires from the holders. moved. (5) Remove cylinder head cover and gasket. The (3) Install rocker arm and pivot assemblies in thegasket may be used again. same order as removed. Tighten the rocker arm boltsCLEANING to 28 N⅐m (21 ft. lbs.) torque. Clean cylinder head cover gasket surface. CAUTION: DO NOT rotate or crank the engine dur- Clean head rail, if necessary. ing or immediately after rocker arm installation. Al- low the hydraulic roller tappets adequate time toINSPECTION bleed down (about 5 minutes). Inspect cover for distortion and straighten, if nec-essary. (4) Install cylinder head cover. Check the gasket for use in head cover installation. (5) Connect spark plug wires.If damaged, use a new gasket. VALVE STEM SEAL AND SPRING REPLACEMENTINSTALLATION This procedure is done with the cylinder head in- (1) The cylinder head cover gasket can be used stalled.again. Install the gasket onto the head rail. (1) Set engine basic timing to TDC and remove Air (2) Position the cylinder head cover onto the gas- Cleaner.ket. On the left cover, install the coolant tube bracket (2) Remove cylinder head covers and spark plugs.(refer to Group 7, Cooling System). Tighten the bolts (3) Remove coil wire from distributor and secure toto 11 N⅐m (95 in. lbs.) torque. good ground to prevent engine from starting. (3) Install the ignition wires onto the holders. (4) Using suitable socket and flex handle at crank- (4) Install closed crankcase ventilation system and shaft retaining bolt, turn engine so the No.1 piston isevaporation control system. at Top Dead Center on the compression stroke. (5) Connect the negative cable to the battery. (5) Remove rocker arms.
  • 53. ZJ 5.2L ENGINE 9 - 53 (6) With air hose attached to an adapter installed (7) Perform the Fuel System Pressure Release pro-in No.1 spark plug hole, apply 620-689 kPa (90-100 cedure (refer to Group 14, Fuel System). Disconnectpsi) air pressure. the fuel lines. (7) Using Valve Spring Compressor Tool (8) Disconnect accelerator linkage and if soMD-988772A, compress valve spring and remove re- equipped, the speed control and transmission kick-tainer valve locks and valve spring. down cables. (8) Install seals on the exhaust valve stem and po- (9) Remove the return spring.sition down against valve guides. (10) Remove distributor cap and wires. (9) The intake valve stem seals should be pushed (11) Disconnect the coil wires.firmly and squarely over the valve guide using the (12) Disconnect heat indicator sending unit wire.valve stem as a guide. DO NOT force seal against top (13) Disconnect heater hoses and bypass hose.of guide. When installing the valve retainer locks, (14) Remove cylinder head covers and gaskets.compress the spring only enough to install the locks. (15) Remove intake manifold and throttle body as (10) Follow the same procedure on the remaining 7 an assembly. Discard the flange side gaskets and thecylinders using the firing sequence 1-8-4-3-6-5-7-2. front and rear cross-over gaskets.Make sure piston in cylinder is at TDC on the valve (16) Remove exhaust manifolds.spring that is being removed. (17) Remove rocker arm assemblies and push rods. (11) Remove adapter from the No.1 spark plug Identify to ensure installation in original locations.hole. (18) Remove the head bolts from each cylinder (12) Install rocker arms. head and remove cylinder heads. Discard the cylin- (13) Install covers and coil wire to distributor. der head gasket. (14) Install air cleaner. (19) Remove spark plugs. (15) Road test vehicle. CLEANINGCYLINDER HEADS Clean all surfaces of cylinder block and cylinder The alloy cast iron cylinder heads (Fig. 3) are held heads.in place by 10 bolts. The spark plugs are located in Clean cylinder block front and rear gasket surfacesthe peak of the wedge between the valves. using a suitable solvent. The 5.2L cylinder head is identified by the foundrymark NH. INSPECTION Inspect all surfaces with a straightedge if there is any reason to suspect leakage. If out-of-flatness ex- ceeds 0.00075 mm (0.00075 inch/inch) times the span length in inches in any direction, either replace head or lightly machine the head surface. FOR EXAMPLE: A 305 mm (12 inch) span is 0.102 mm (0.004 inch) out-of-flat. The allowable out- of-flat is 305 X 0.00075 (12 X 0.00075) equals 0.23 mm (0.009 inch). This amount of out-of-flat is accept- able. The cylinder head surface finish should be 1.78-3.00 microns (70-125 microinches). Inspect push rods. Replace worn or bent rods. INSTALLATION (1) Position the new cylinder head gaskets onto the Fig. 3 Cylinder Head Assembly cylinder block.REMOVAL (2) Position the cylinder heads onto head gaskets (1) Disconnect the negative cable from the battery. and cylinder block. (2) Drain cooling system (refer to Group 7, Cooling (3) Starting at top center, tighten all cylinder headSystem for the proper procedures). bolts, in sequence, to 68 N⅐m (50 ft. lbs.) torque (Fig. (3) Remove the generator. 4). Repeat procedure, tighten all cylinder head bolts (4) Remove closed crankcase ventilation system. to 143 N⅐m (105 ft. lbs.) torque. Repeat procedure to (5) Disconnect the evaporation control system. confirm that all bolts are at 143 N⅐m (105 ft. lbs.) (6) Remove the air cleaner. torque.
  • 54. 9 - 54 5.2L ENGINE ZJ (22) Connect the negative cable to the battery. VALVES AND VALVE SPRINGS The valves are arranged in-line and inclined 18°. The rocker pivot support and the valve guides are cast integral with the heads. This procedure requires the removal of the cylinder head. REMOVAL (1) Remove the cylinder head. (2) Compress valve springs using Valve Spring Compressor Tool MD-998772A. (3) Remove valve retaining locks, valve spring re- tainers, valve stem seals and valve springs. (4) Before removing valves, remove any burrs from Fig. 4 Cylinder Head Bolt Tightening Sequence valve stem lock grooves to prevent damage to theCAUTION: When tightening the rocker arm bolts, valve guides. Identify valves to ensure installation inmake sure the piston in that cylinder is NOT at original location.TDC. Contact between the valves and piston couldoccur. VALVE CLEANING Clean valves thoroughly. Discard burned, warped (4) Install push rods and rocker arm assemblies in and cracked valves.their original position. Tighten the bolts to 28 N⅐m Remove carbon and varnish deposits from inside of(21 ft. lbs.) torque. valve guides with a reliable guide cleaner. (5) Install the intake manifold and throttle bodyassembly (refer to Group 11, Exhaust System and In- VALVE INSPECTIONtake Manifold). Measure valve stems for wear. If wear exceeds (6) Install exhaust manifolds. Tighten the bolts 0.051 mm (0.002 inch), replace the valve.and nuts to 34 N⅐m (25 ft. lbs.) torque. (7) Adjust spark plugs to specifications (refer to VALVE GUIDESGroup 8D, Ignition System). Install the plugs and Measure valve stem guide clearance as follows:tighten to 41 N⅐m (30 ft. lbs.) torque. (a) Install Valve Guide Sleeve Tool C-3973 over valve stem and install valve (Fig. 5). The special (8) Install coil wires. sleeve places the valve at the correct height for (9) Connect heat indicator sending unit wire. checking with a dial indicator. (10) Connect the heater hoses and bypass hose. (11) Install distributor cap and wires. (12) Hook up the return spring. (13) Connect the accelerator linkage and if soequipped, the speed control and transmission kick-down cables. (14) Install the fuel lines. (15) Install the generator and drive belt. Tightengenerator mounting bolt to 41 N⅐m (30 ft. lbs.)torque. Tighten the adjusting strap bolt to 23 N⅐m(200 in. lbs.) torque. Refer to Group 7, Cooling Sys-tem for adjusting the belt tension. (16) Install the intake manifold-to-generatorbracket support rod. Tighten the bolts. Fig. 5 Positioning Valve with Tool C-3973 (17) Place the cylinder head cover gaskets in posi- (b) Attach Dial Indicator Tool C-3339 to cylindertion and install cylinder head covers. Tighten the head and set it at right angle of valve stem beingbolts to 11 N⅐m (95 in. lbs.) torque. measured (Fig. 6). (18) Install closed crankcase ventilation system. (c) Move valve to and from the indicator. The to- (19) Connect the evaporation control system. tal dial indicator reading should not exceed 0.432 (20) Install the air cleaner. mm (0.017 inch). Ream the guides for valves with (21) Fill cooling system (refer to Group 7, Cooling oversize stems if dial indicator reading is excessiveSystem for proper procedure). or if the stems are scuffed or scored.
  • 55. ZJ 5.2L ENGINE 9 - 55 Fig. 6 Measuring Valve Guide Wear Service valves with oversize stems are available(Fig. 7): Fig. 8 Valve Face and Seat Angles Fig. 7 Reamer Sizes Slowly turn reamer by hand and clean guide thor-oughly before installing new valve. Ream the valveguides from standard to 0.381 mm (0.015 inch).Use a 2 step procedure so the valve guides arereamed true in relation to the valve seat:• Step 1—Ream to 0.0763 mm (0.003 inch).• Step 2—Ream to 0.381 mm (0.015 inch).REFACING VALVES—VALVE SEATS Fig. 9 Intake and Exhaust Valves The intake and exhaust valves have a 43-1/4° to (1) When refacing valve seats, it is important that43-3/4° face angle and a 44-1/4° to 44-3/4° seat angle the correct size valve guide pilot be used for reseat-(Fig. 8). ing stones. A true and complete surface must be ob-VALVES tained. Inspect the remaining margin after the valves are (2) Measure the concentricity of valve seat using arefaced (Fig. 9). Valves with less than 1.190 mm dial indicator. Total runout should not exceed 0.051(0.047 inch) margin should be discarded. mm (0.002 inch) total indicator reading. (3) Inspect the valve seat with Prussian blue to de-VALVE SEATS termine where the valve contacts the seat. To do this, coat valve seat LIGHTLY with Prussian blue then setCAUTION: DO NOT un-shroud valves during valve valve in place. Rotate the valve with light pressure.seat refacing (Fig. 10). If the blue is transferred to the center of valve face, contact is satisfactory. If the blue is transferred to the top edge of valve face, lower valve seat with a 15°
  • 56. 9 - 56 5.2L ENGINE ZJ Fig. 10 Refacing Valve Seats Fig. 11 Testing Valve Spring for Compressed Lengthstone. If the blue is transferred to bottom edge of If height is greater than 42.86 mm (1-11/16 inches),valve face raise valve seat with a 60° stone. install a 1.587 mm (1/16 inch) spacer in head coun- (4) When seat is properly positioned the width of terbore. This should bring spring height back to nor-intake seats should be 1.016-1.524 mm (0.040-0.060 mal 41.27 to 42.86 mm (1-5/8 to 1-11/16 inch).inch). The width of the exhaust seats should be1.524-2.032 mm (0.060-0.080 inch). HYDRAULIC TAPPETS Before disassembling any part of the engine to cor-VALVE SPRING INSPECTION rect tappet noise, check the oil pressure. If vehicle Whenever valves have been removed for inspection, has no oil pressure gauge, install a reliable gauge atreconditioning or replacement, valve springs should the pressure sending unit. The pressure should bebe tested. As an example the compression length of between 207-552 kPa (30-80 psi) at 3,000 RPM.the spring to be tested is 1-5/16 inch. Turn table of Check the oil level after the engine reaches normalUniversal Valve Spring Tester Tool (Fig. 11) until operating temperature. Allow 5 minutes to stabilizesurface is in line with the 1-5/16 inch mark on the oil level, check dipstick.threaded stud. Be sure the zero mark is to the front. The oil level in the pan should never be above thePlace spring over stud on the table and lift compress- FULL mark or below the ADD OIL mark on dipstick.ing lever to set tone device. Pull on torque wrench Either of these 2 conditions could be responsible foruntil ping is heard. Take reading on torque wrench noisy tappets.at this instant. Multiply this reading by 2. This willgive the spring load at test length. Fractional mea- OIL LEVELsurements are indicated on the table for finer adjust-ments. Refer to specifications to obtain specified HIGHheight and allowable tensions. Discard the springs If oil level is above the FULL mark, it is possiblethat do not meet specifications. for the connecting rods to dip into the oil. With the engine running this condition could create foam inINSTALLATION the oil pan. Foam in oil pan would be fed to the hy- (1) Coat valve stems with lubrication oil and insert draulic tappets by the oil pump causing them to losethem in cylinder head. length and allow valves to seat noisily. (2) If valves or seats are reground, check valvestem height. If valve is too long, replace cylinder LOWhead. Low oil level may allow oil pump to take in air. (3) Install new seals on all valve guides. Install When air is fed to the tappets, they lose length whichvalve springs and valve retainers. allows valves to seat noisily. Any leaks on intake side (4) Compress valve springs with Valve Spring of oil pump through which air can be drawn will cre-Compressor Tool MD-998772A, install locks and re- ate the same tappet action. Check the lubricationlease tool. If valves and/or seats are ground, measure system from the intake strainer to the pump cover,the installed height of springs. Make sure the mea- including the relief valve retainer cap. When tappetsurement is taken from bottom of spring seat in cyl- noise is due to aeration, it may be intermittent orinder head to the bottom surface of spring retainer. If constant, and usually more than 1 tappet will bespacers are installed, measure from the top of spacer. noisy. When oil level and leaks have been corrected,
  • 57. ZJ 5.2L ENGINE 9 - 57operate the engine at fast idle. Run engine for a suf- work on one tappet at a time to avoid mixing officient time to allow all of the air inside the tappets parts. Mixed parts are not compatible. DO NOT dis-to be bled out. assemble a tappet on a dirty work bench.TAPPET NOISE DIAGNOSIS (1) To determine source of tappet noise, operate en- DISASSEMBLEgine at idle with cylinder head covers removed. (1) Pry out plunger retainer spring clip (Fig. 12). (2) Feel each valve spring or rocker arm to detect (2) Clean varnish deposits from inside of tappet body above plunger cap.noisy tappet. The noisy tappet will cause the affected (3) Invert tappet body and remove plunger cap,spring and/or rocker arm to vibrate or feel rough in plunger, check valve, check valve spring, check valveoperation. retainer and plunger spring (Fig. 12). Check valve Worn valve guides or cocked springs are could be flat or ball.sometimes mistaken for noisy tappets. If such isthe case, noise may be dampened by applying ASSEMBLEside thrust on the valve spring. If noise is not (1) Clean all tappet parts in a solvent that will re-appreciably reduced, it can be assumed the move all varnish and carbon.noise is in the tappet. Inspect the rocker arm (2) Replace tappets that are unfit for further ser-push rod sockets and push rod ends for wear. vice with new assemblies. (3) Valve tappet noise ranges from light noise to a (3) If plunger shows signs of scoring or wear, in-heavy click. A light noise is usually caused by exces- stall a new tappet assembly. If valve is pitted, orsive leak-down around the unit plunger or by the valve seat on end of plunger is prevented from seat-plunger partially sticking in the tappet body cylinder. ing, install a new tappet assembly.The tappet should be replaced. A heavy click is (4) Assemble tappets (Fig. 12).caused by a tappet check valve not seating or by for-eign particles becoming wedged between the plungerand the tappet body. This will cause the plunger tostick in the down position. This heavy click will beaccompanied by excessive clearance between thevalve stem and rocker arm as valve closes. In eithercase, tappet assembly should be removed for inspec-tion and cleaning. The valve train generates a noise very much like alight tappet noise during normal operation. Caremust be taken to ensure that tappets are making thenoise. In general, if more than one tappet seems to Fig. 12 Hydraulic Tappet Assemblybe noisy, its probably not the tappets. INSTALLATION (1) Lubricate tappets.REMOVAL (2) Install tappets and push rods in their original (1) Remove the air cleaner. positions. Ensure that the oil feed hole in the side of (2) Remove cylinder head cover, rocker assembly the tappet body faces up (away from the crankshaft).and push rods. Identify push rods to ensure installa- (3) Install aligning yokes with ARROW towardtion in original location. camshaft. (3) Remove intake manifold, yoke retainer and (4) Install yoke retainer. Tighten the bolts to 23aligning yokes. N⅐m (200 in. lbs.) torque. Install intake manifold. (4) Slide Hydraulic Tappet Remover/Installer Tool (5) Install push rods in original positions.C-4129-A through opening in cylinder head and seat (6) Install rocker arm.tool firmly in the head of tappet. (7) Install cylinder head cover. (5) Pull tappet out of bore with a twisting motion. (8) Start and operate engine. Warm up to normalIf all tappets are to be removed, identify tappets to operating temperature.ensure installation in original location. CAUTION: To prevent damage to valve mechanism, (6) If the tappet or bore in cylinder block is scored, engine must not be run above fast idle until all hy-scuffed, or shows signs of sticking, ream the bore to draulic tappets have filled with oil and have becomenext oversize. Replace with oversize tappet. quiet.CAUTION: The plunger and tappet bodies are notinterchangeable. The plunger and valve must al- VALVE TIMINGways be fitted to the original body. It is advisable to (1) Turn crankshaft until the No.6 exhaust valve is
  • 58. 9 - 58 5.2L ENGINE ZJclosing and No.6 intake valve is opening. (2) Place installing tool, part of Puller Tool Set (2) Insert a 6.350 mm (1/4 inch) spacer between C-3688 in position and press the vibration damperrocker arm pad and stem tip of No.1 intake valve. Al- onto the crankshaft (Fig. 2).low spring load to bleed tappet down giving in effecta solid tappet. (3) Install a dial indicator so plunger contactsvalve spring retainer as nearly perpendicular as pos-sible. Zero the indicator. (4) Rotate the crankshaft clockwise (normal run-ning direction) until the valve has lifted 0.254 mm(0.010 inch). The timing of the crankshaft shouldnow read from 10° before top dead center to 2° aftertop dead center. Remove spacer.CAUTION: DO NOT turn crankshaft any furtherclockwise as valve spring might bottom and result Fig. 2 Installing Vibration Damperin serious damage. (3) Install the crankshaft bolt and washer. Tighten the bolt to 183 N⅐m (135 ft. lbs.) torque. (5) If reading is not within specified limits: (4) Install the crankshaft pulley. Tighten the pul- (a) Check sprocket index marks. ley bolts to 23 N⅐m (200 in. lbs.) torque. (b) Inspect timing chain for wear. (5) Install the serpentine belt (refer to Group 7, (c) Check accuracy of DC mark on timing indica- Cooling System). tor. (6) Install the cooling system fan. Tighten the bolts to 23 N⅐m (17 ft. lbs.) torque.VIBRATION DAMPER (7) Position the fan shroud and install the bolts. Tighten the retainer bolts to 11 N⅐m (95 in. lbs.)REMOVAL torque. (1) Disconnect the negative cable from the battery. (8) Connect the negative cable to the battery. (2) Remove fan shroud retainer bolts and setshroud back over engine. TIMING CHAIN COVER (3) Remove the cooling system fan. (4) Remove the serpentine belt (refer to Group 7, REMOVALCooling System). (1) Disconnect the negative cable from the battery. (5) Remove the vibration damper pulley. (2) Drain cooling system (refer to Group 7, Cooling (6) Remove vibration damper bolt and washer from System).end of crankshaft. (3) Remove the serpentine belt (refer to Group 7, (7) Install bar and screw from Puller Tool Set Cooling System).C-3688. Install 2 bolts with washers through the (4) Remove water pump (refer to Group 7, Coolingpuller tool and into the vibration damper (Fig. 1). System). (5) Remove power steering pump (refer to Group 19, Steering). (6) Remove vibration damper. (7) Loosen oil pan bolts and remove the front bolt at each side. (8) Remove the cover bolts. (9) Remove chain case cover and gasket using ex- treme caution to avoid damaging oil pan gasket. (10) Place a suitable tool behind the lips of the oil seal to pry the oil seal outward. Be careful not to damage the crankshaft seal surface of cover (Fig. 3). Fig. 1 Vibration Damper Assembly TIMING CHAIN STRETCH (8) Pull vibration damper off of the crankshaft. (1) Place a scale next to the timing chain so that any movement of the chain may be measured.INSTALLATION (2) Place a torque wrench and socket over cam- (1) Position the vibration damper onto the crank- shaft sprocket attaching bolt. Apply torque in the di-shaft. rection of crankshaft rotation to take up slack; 41
  • 59. ZJ 5.2L ENGINE 9 - 59 Fig. 3 Removal of Front Crankshaft Oil Seal Fig. 5 Alignment of Timing MarksN⅐m (30 ft. lbs.) torque with cylinder head installed (11) Install the camshaft bolt. Tighten the bolt toor 20 N⅐m (15 ft. lbs.) torque with cylinder head re- 68 N⅐m (50 ft. lbs.) torque.moved. With a torque applied to the camshaft (12) Check camshaft end play. The end play shouldsprocket bolt, crankshaft should not be permitted to be 0.051-0.152 mm (0.002-0.006 inch) with a newmove. It may be necessary to block the crankshaft to thrust plate and up to 0.254 mm (0.010 inch) with aprevent rotation. used thrust plate. If not within these limits install a (3) Hold a scale with dimensional reading even new thrust plate.with the edge of a chain link. With cylinder heads in-stalled, apply 14 N⅐m (30 ft. lbs.) torque in the re- CLEANINGverse direction. With the cylinder heads removed, Be sure mating surfaces of chain case cover andapply 20 N⅐m (15 ft. lbs.) torque in the reverse direc- cylinder block are clean and free from burrs.tion. Note the amount of chain movement (Fig. 4). The water pump mounting surface must be cleaned. INSTALLATION (1) Using a new cover gasket, carefully install chain case cover to avoid damaging oil pan gasket. Use a small amount of Mopar௡ Silicone Rubber Ad- hesive Sealant, or equivalent, at the joint between timing chain cover gasket and the oil pan gasket. Finger tighten the timing chain cover bolts at this time. (2) Place the smaller diameter of the oil seal over Front Oil Seal Installation Tool 6635 (Fig. 6). Seat Fig. 4 Measuring Timing Chain Wear and Stretch the oil seal in the groove of the tool. (4) Install a new timing chain, if its movement ex-ceeds 3.175 mm (1/8 inch). (5) If chain is not satisfactory, remove camshaftsprocket attaching bolt and remove timing chain withcrankshaft and camshaft sprockets. (6) Place both camshaft sprocket and crankshaftsprocket on the bench with timing marks on exactimaginary center line through both camshaft andcrankshaft bores. (7) Place timing chain around both sprockets. (8) Turn crankshaft and camshaft to line up withkeyway location in crankshaft sprocket and in cam-shaft sprocket. (9) Lift sprockets and chain (keep sprockets tightagainst the chain in position as described). (10) Slide both sprockets evenly over their respec- Fig. 6 Placing Oil Seal on Installation Tool 6635tive shafts and use a straightedge to check alignment (3) Position the seal and tool onto the crankshaftof timing marks (Fig. 5). (Fig. 7).
  • 60. 9 - 60 5.2L ENGINE ZJ (8) Remove the vibration damper bolt and seal in- stallation tool. (9) Install vibration damper. (10) Install water pump and housing assembly us- ing new gaskets (refer to Group 7, Cooling System). Tighten bolts to 41 N⅐m (30 ft. lbs.) torque. (11) Install power steering pump (refer to Group 19, Steering). (12) Install the serpentine belt (refer to Group 7, Cooling System). (13) Install the cooling system fan. Tighten the bolts to 23 N⅐m (17 ft. lbs.) torque. (14) Position the fan shroud and install the bolts. Tighten the bolts to 11 N⅐m (95 in. lbs.) torque. (15) Fill cooling system (refer to Group 7, Cooling System for the proper procedure). (16) Connect the negative cable to the battery. FRONT CRANKSHAFT OIL SEAL REPLACEMENT The oil seal can be replaced without removing the timing chain cover provided the cover is not mis- Fig. 7 Position Tool and Seal onto Crankshaft aligned. (4) Tighten the 4 lower chain case cover bolts to (1) Disconnect the negative cable from the battery.13N⅐m (10 ft.lbs.) to prevent the cover from tipping (2) Remove vibration damper.during seal installation. (3) If front seal is suspected of leaking, check front (5) Using the vibration damper bolt, tighten the oil seal alignment to crankshaft. The seal installa-bolt to draw the seal into position on the crankshaft tion/alignment tool 6635, should fit with minimum(Fig. 8). interference. If tool does not fit, the cover must be re- moved and installed properly. (4) Place a suitable tool behind the lips of the oil seal to pry the oil seal outward. Be careful not to damage the crankshaft bore surface of cover. (5) Place the smaller diameter of the oil seal over Front Oil Seal Installation Tool 6635 (Fig. 6). Seat the oil seal in the groove of the tool. (6) Position the seal and tool onto the crankshaft (Fig. 7). (7) Using the vibration damper bolt, tighten the bolt to draw the seal into position on the crankshaft (Fig. 8). (8) Remove the vibration damper bolt and seal in- stallation tool. (9) Install the vibration damper. (10) Connect the negative cable to the battery. CAMSHAFT The camshaft has an integral oil pump and distrib- utor drive gear (Fig. 9). REMOVAL Fig. 8 Installing Oil Seal (1) Remove intake manifold. (6) Loosen the 4 bolts tightened in step 4 to allow (2) Remove cylinder head covers.realignment of front cover assembly. (3) Remove timing case cover and timing chain. (7) Tighten chain case cover bolts to 41 N⅐m (30 ft. (4) Remove rocker arms.lbs.) torque. Tighten oil pan bolts to 24 N⅐m (215 in. (5) Remove push rods and tappets. Identify eachlbs.) torque. part so it can be installed in its original location.
  • 61. ZJ 5.2L ENGINE 9 - 61 Fig. 9 Camshaft and Sprocket Assembly (6) Remove distributor and lift out the oil pump Fig. 11 Camshaft Bearings Removal and Installationand distributor drive shaft. with Tool C-3132-A (7) Remove camshaft thrust plate; note location of INSTALLATION—BEARINGoil tab (Fig. 10). (1) Install new camshaft bearings with Camshaft Bearing Remover/Installer Tool C-3132-A by sliding the new camshaft bearing shell over proper adapter. (2) Position rear bearing in the tool. Install horse- shoe lock and by reversing removal procedure, care- fully drive bearing shell into place. (3) Install remaining bearings in the same manner. Bearings must be carefully aligned to bring oil holes into full register with oil passages from the main bearing. If the camshaft bearing shell oil holes are not in exact alignment, remove and install them cor- rectly. Install a new core hole plug at the rear of camshaft. Be sure this plug does not leak. INSTALLATION (1) Lubricate camshaft lobes and camshaft bearing journals and insert the camshaft to within 51 mm (2 inches) of its final position in cylinder block. Whenever an engine has been rebuilt, a new camshaft and/or new tappets installed, add 1 pint of Mopar௡ Crankcase Conditioner, or equivalent. The oil mixture should be left in en- gine for a minimum of 805 km (500 miles). Fig. 10 Timing Chain Oil Tab Installation Drain at the next normal oil change. (8) Install a long bolt into front of camshaft to fa- (2) Install Camshaft Gear Installer Tool C-3509cilitate removal of the camshaft. Remove camshaft, with tongue back of distributor drive gear (Fig. 12).being careful not to damage cam bearings with thecam lobes.REMOVAL—BEARING This procedure requires that the engine is removedfrom the vehicle. (1) With engine completely disassembled, drive outrear cam bearing core hole plug. (2) Install proper size adapters and horseshoewashers (part of Camshaft Bearing Remover/InstallerTool C-3132-A) at back of each bearing shell. Driveout bearing shells (Fig. 11). Fig. 12 Camshaft Holding Tool C-3509 (Installed Position) (3) Hold tool in position with a distributor lock- plate bolt. This tool will restrict camshaft from being
  • 62. 9 - 62 5.2L ENGINE ZJpushed in too far and prevent knocking out the welch (3) Hold puller screw and tighten puller nut untilplug in rear of cylinder block. Tool should remain bushing is removed.installed until the camshaft and crankshaftsprockets and timing chain have been installed. (4) Install camshaft thrust plate and chain oil tab.Make sure tang enters lower right hole inthrust plate. Tighten bolts to 24 N⅐m (210 in. lbs.)torque. Top edge of tab should be flat against thrustplate in order to catch oil for chain lubrication. (5) Place both camshaft sprocket and crankshaftsprocket on the bench with timing marks on exactimaginary center line through both camshaft andcrankshaft bores. (6) Place timing chain around both sprockets. Fig. 14 Distributor Driveshaft Bushing Removal (7) Turn crankshaft and camshaft to line up withkeyway location in crankshaft sprocket and in cam- INSTALLATION—DRIVE SHAFT BUSHINGshaft sprocket. (1) Slide new bushing over burnishing end of Dis- (8) Lift sprockets and chain (keep sprockets tight tributor Drive Shaft Bushing Driver/Burnisher Toolagainst the chain in position as described). C-3053. Insert the tool and bushing into the bore. (9) Slide both sprockets evenly over their respec- (2) Drive bushing and tool into position, using ative shafts and use a straightedge to check alignment hammer (Fig. 15).of timing marks (Fig. 13). Fig. 15 Distributor Driveshaft Bushing Installation Fig. 13 Alignment of Timing Marks (3) As the burnisher is pulled through the bushing, the bushing is expanded tight in the block and bur- (10) Install the camshaft bolt/cup washer. Tighten nished to correct size (Fig. 16). DO NOT ream thisbolt to 68 N⅐m (50 ft. lbs.) torque. bushing. (11) Measure camshaft end play. Refer to Specifica-tions for proper clearance. If not within limits install CAUTION: This procedure MUST be followed whena new thrust plate. installing a new bushing or seizure to shaft may oc- (12) Each tappet reused must be installed in the cur.same position from which it was removed. Whencamshaft is replaced, all of the tappets must bereplaced.DISTRIBUTOR BUSHINGDISTRIBUTOR REMOVAL Refer to Group 8D, Ignition Systems for the properprocedure.REMOVAL—DRIVE SHAFT BUSHING (1) Remove the intake manifold (refer to Group 11,Exhaust System and Intake Manifold). (2) Insert Distributor Drive Shaft Bushing Puller Fig. 16 Burnishing Distributor Driveshaft BushingTool C-3052 into old bushing and thread down until a (4) Install the intake manifold (refer to Group 11,tight fit is obtained (Fig. 14). Exhaust System and Intake Manifold).
  • 63. ZJ 5.2L ENGINE 9 - 63DISTRIBUTOR INSTALLATION CLEANING Refer to the Component Removal/Installation sec- Clean the block and pan gasket surfaces.tion of Group 8D, Ignition Systems for the proper Trim or remove excess sealant film in the rearprocedure. See Distributor. After the distributor has main cap oil pan gasket groove. DO NOT removebeen installed, its rotational position must be set us- the sealant inside the rear main cap slots.ing the SET SYNC mode of the DRB scan tool. Refer If present, trim excess sealant from inside the en-to Checking Distributor Position following the Dis- gine.tributor Installation section in Group 8D, Ignition Clean oil pan in solvent and wipe dry with a cleansystem. Do not attempt to adjust ignition timing cloth.by rotating the distributor. It has no effect on Clean oil screen and pipe thoroughly in clean sol-ignition timing. Adjusting distributor position vent. Inspect condition of screen.will effect fuel synchronization only. Before installing the distributor, the oil pump drive INSPECTIONshaft must be aligned to number one cylinder. Inspect oil drain plug and plug hole for stripped or (1) Rotate crankshaft until No.1 cylinder is at top damaged threads. Repair as necessary.dead center on the firing stroke. Inspect oil pan mounting flange for bends or distor- (2) When in this position, the timing mark on vi- tion. Straighten flange, if necessary.bration damper should be under 0 on the timing in-dicator. INSTALLATION (1) Fabricate 4 alignment dowels from 5/16 x 1 1/2 (3) Install the shaft so that after the gear spirals inch bolts. Cut the head off the bolts and cut a slotinto place, it will index with the oil pump shaft. The into the top of the dowel. This will allow easier in-slot on top of oil pump shaft should be aligned to- stallation and removal with a screwdriver (Fig. 1).wards left front intake manifold attaching bolt hole(Fig. 17). Fig. 1 Fabrication of Alignment Dowels (2) Install the dowels in the cylinder block (Fig. 2). Fig. 17 Position of Oil Pump Shaft Slot (3) Apply small amount of Mopar௡ Silicone RubberOIL PAN Adhesive Sealant, or equivalent in the corner of the cap and the cylinder block.REMOVAL (4) Slide the one-piece gasket over the dowels and (1) Disconnect the negative cable from the battery. onto the block. (2) Raise the vehicle. (5) Position the oil pan over the dowels and onto (3) Remove the oil pan drain plug and drain the the gasket. If equipped with an oil level sensor, takeengine oil. care not to damage the sensor. (4) Remove the oil filter. (6) Install the oil pan bolts. Tighten the bolts to 24 (5) Remove the starter (refer to Group 8B, Battery/ N⅐m (215 in. lbs.) torque.Starter/Generator Service). (7) Remove the dowels. Install the remaining oil (6) If equipped with an oil level sensor, disconnect pan bolts. Tighten these bolts to 24 N⅐m (215 in. lbs.)the sensor. torque. (7) Position the cooler lines out of the way. (8) Install the drain plug. Tighten drain plug to 34 (8) Disconnect the oxygen sensor. N⅐m (25 ft. lbs.) torque. (9) Remove exhaust pipe. (9) Install exhaust pipe. (10) Remove the oil pan bolts. Carefully slide the (10) Connect the oxygen sensor.oil pan and gasket to the rear. If equipped with an oil (11) Install the oil filter.level sensor, take care not to damage the sensor. (12) If equipped with an oil level sensor, connect the sensor.
  • 64. 9 - 64 5.2L ENGINE ZJ (14) Move the cooler lines back into position. (15) Lower vehicle. (16) Connect the negative cable to the battery. (17) Fill the oil pan with engine oil to the specified level. WARNING: USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT STAND IN A DI- RECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING. (18) Start the engine and inspect for leaks. Fig. 2 Position of Dowels in Cylinder Block (13) Install the starter (refer to Group 8B, Battery/Starter/Generator Service). LUBRICATION SYSTEM A gear—type positive displacement pump is passes through the hole when the rods rotate and themounted at the underside of the rear main bearing hole lines up, oil is then thrown off as the rod ro-cap. The pump draws oil through the screen and in- tates. This oil throwoff lubricates the camshaft lobes,let tube from the sump at the rear of the oil pan. The distributor drive gear, cylinder walls, and pistonoil is driven between the drive and idler gears and pins.pump body, then forced through the outlet to the The hydraulic valve tappets receive oil directlyblock. An oil gallery in the block channels the oil to from the main oil gallery. The camshaft bearings re-the inlet side of the full flow oil filter. After passing ceive oil from the main bearing galleries. The frontthrough the filter element, the oil passes from the camshaft bearing journal passes oil through the cam-center outlet of the filter through an oil gallery that shaft sprocket to the timing chain. Oil drains back tochannels the oil up to the main gallery which ex- the oil pan under the number one main bearing cap.tends the entire length on the right side of the block. The oil supply for the rocker arms and bridgedThe oil then goes down to the No. 1 main bearing, pivot assemblies is provided by the hydraulic valveback up to the left side of the block and into the oil tappets which pass oil through hollow push rods to agallery on the left side of the engine. hole in the corresponding rocker arm. Oil from the Galleries extend downward from the main oil gal- rocker arm lubricates the valve train components.lery to the upper shell of each main bearing. The The oil then passes down through the push rod guidecrankshaft is drilled internally to pass oil from the holes, and the oil drain back passages in the cylindermain bearing journals to the connecting rod journals. head past the valve tappet area, and returns to theEach connecting rod bearing has half a hole in it, oil oil pan.
  • 65. ZJ 5.2L ENGINEFig. 3 Oil Lubrication System 9 - 65
  • 66. 9 - 66 5.2L ENGINE ZJOIL PUMPOIL PUMP PRESSURE The MINIMUM oil pump pressure is 41.4 kPa (6psi) at curb idle. The MAXIMUM oil pump pressureis 207-552 kPa (30-80 psi) at 3000 RPM or more.CAUTION: If oil pressure is ZERO at curb idle, DONOT run engine at 3000 RPM.REMOVAL (1) Remove the oil pan. (2) Remove the oil pump from rear main bearing Fig. 5 Oil Pumpcap.DISASSEMBLE (1) Remove the relief valve as follows: (a) Remove cotter pin. Drill a 3.175 mm (1/8 inch) hole into the relief valve retainer cap and in- sert a self-threading sheet metal screw into cap. (b) Clamp screw into a vise and while supporting oil pump, remove cap by tapping pump body using a soft hammer. Discard retainer cap and remove spring and relief valve (Fig. 4). Fig. 6 Checking Oil Pump Cover Flatness Measure thickness and diameter of outer rotor. If outer rotor thickness measures 20.9 mm (0.825 inch) or less or if the diameter is 62.7 mm (2.469 inches) or less, replace outer rotor (Fig. 7). Fig. 4 Oil Pressure Relief Valve (2) Remove oil pump cover (Fig. 5). (3) Remove pump outer rotor and inner rotor withshaft (Fig. 5). (4) Wash all parts in a suitable solvent and inspectcarefully for damage or wear. Fig. 7 Measuring Outer Rotor ThicknessINSPECTION If inner rotor measures 20.9 mm (0.825 inch) or Mating surface of the oil pump cover should be less, replace inner rotor and shaft assembly (Fig. 8).smooth. Replace pump assembly if cover is scratched Slide outer rotor into pump body. Press rotor to theor grooved. side with your fingers and measure clearance be- Lay a straightedge across the pump cover surface tween rotor and pump body (Fig. 9). If clearance is(Fig. 6). If a 0.038 mm (0.0015 inch) feeler gauge can 0.356 mm (0.014 inch) or more, replace oil pump as-be inserted between cover and straightedge, pump sembly.assembly should be replaced.
  • 67. ZJ 5.2L ENGINE 9 - 67 Fig. 11 Measuring Clearance Over Rotors Fig. 8 Measuring Inner Rotor Thickness Inspect oil pressure relief valve plunger for scoring and free operation in its bore. Small marks may be removed with 400-grit wet or dry sandpaper. The relief valve spring has a free length of approx- imately 49.5 mm (1.95 inches). The spring should test between 19.5 and 20.5 pounds when compressed to 34 mm (1-11/32 inches). Replace spring that fails to meet these specifications (Fig. 12). If oil pressure was low and pump is within specifi- cations, inspect for worn engine bearings or other reasons for oil pressure loss.Fig. 9 Measuring Outer Rotor Clearance in Housing Install inner rotor and shaft into pump body. Ifclearance between inner and outer rotors is 0.203mm (0.008 inch) or more, replace shaft and both ro-tors (Fig. 10). Fig. 12 Proper Installation of Retainer Cap ASSEMBLE (1) Install pump rotors and shaft, using new parts as required. (2) Position the oil pump cover onto the pump body. Tighten cover bolts to 11 N⅐m (95 in. lbs.) torque. (3) Install the relief valve and spring. Insert the cotter pin. Fig. 10 Measuring Clearance Between Rotors (4) Tap on a new retainer cap. Place a straightedge across the face of the pump, (5) Prime oil pump before installation by filling ro-between bolt holes. If a feeler gauge of 0.102 mm tor cavity with engine oil.(0.004 inch) or more can be inserted between rotorsand the straightedge, replace pump assembly (Fig. INSTALLATION11). (1) Install oil pump. During installation slowly ro- tate pump body to ensure driveshaft-to-pump rotor shaft engagement.
  • 68. 9 - 68 5.2L ENGINE ZJ (2) Hold the oil pump base flush against matingsurface on No.4 main bearing cap. Finger tightenpump attaching bolts. Tighten attaching bolts to 41N⅐m (30 ft. lbs.) torque. (3) Install the oil pan.PISTON AND CONNECTING ROD ASSEMBLY The pistons are elliptically turned so that the di-ameter at the pin boss is less than its diameteracross the thrust face. This allows for expansion un-der normal operating conditions. Under operatingtemperatures, expansion forces the pin bosses awayfrom each other, causing the piston to assume a morenearly round shape. All pistons are machined to the same weight, re-gardless of size, to maintain piston balance. The piston pin rotates in the piston only and is re-tained by the press interference fit of the piston pinin the connecting rod.REMOVAL (1) Remove the engine from the vehicle. (2) Remove the cylinder head. (3) Remove the oil pan. (4) Remove top ridge of cylinder bores with a reli-able ridge reamer before removing pistons from cyl-inder block. Be sure to keep tops of pistons coveredduring this operation. (5) Be sure the connecting rod and connecting rod Fig. 1 Piston Measurementscap are identified with the cylinder number. Remove FITTING RINGSconnecting rod cap. Install connecting rod bolt guide (1) Measurement of end gaps:set on connecting rod bolts. (a) Measure piston ring gap 2 inches from bot- (6) Pistons and connecting rods must be removed tom of cylinder bore. An inverted piston can befrom top of cylinder block. When removing piston and used to push the rings down to ensure positioningconnecting rod assemblies, rotate crankshaft so that rings squarely in the cylinder bore before measur-the connecting rod is centered in cylinder bore and at ing.BDC. Be careful not to nick crankshaft journals. (b) Insert feeler gauge in the gap. The top com- (7) After removal, install bearing cap on the mat- pression ring gap should be between 0.254-0.508ing rod. mm (0.010-0.020 inch). The second compressionINSPECTION ring gap should be between 0.508-0.762 mm (0.020- Check the crankshaft connecting rod journal for ex- 0.030 inch). The oil ring gap should be 0.254-1.270cessive wear, taper and scoring. mm (0.010-0.050 inch). Check the cylinder block bore for out-of-round, (c) Rings with insufficient end gap may be filedtaper, scoring and scuffing. to the correct dimension. Rings with excess gaps Check the pistons for taper and elliptical shape be- should not be used.fore they are fitted into the cylinder bore (Fig. 1). (2) Install rings and confirm ring side clearance: (a) Install oil rings being careful not to nick orFITTING PISTONS scratch the piston. Piston and cylinder wall must be clean and dry. (b) Install the compression rings using Installa-Specified clearance between the piston and the cylin- tion Tool C-4184. The top compression may be in-der wall is 0.013-0.038 mm (0.0005-0.0015 inch). stalled with either side up. The second compression Piston diameter should be measured at the top of ring must be installed with the identification markskirt, 90° to piston pin axis. Cylinder bores should be face up (toward top of piston) and the chamfermeasured halfway down the cylinder bore and trans- should face down. An identification mark on theverse to the engine crankshaft center line. ring is a drill point, a stamped letter O, an oval de- Pistons and cylinder bores should be measured at pression or the word TOP.normal room temperature, 21°C (70°F).
  • 69. ZJ 5.2L ENGINE 9 - 69 (c) Measure side clearance between piston ring The bearing shells must be installed so that the and ring land (Fig. 2). Clearance should be 0.038- tangs are in the machined grooves in the rods and 0.076 mm (0.0015-0.0030 inch) for the compression caps. rings. The steel rail oil ring should be free in Limits of taper or out-of-round on any crankshaft groove, but should not exceed 0.203 mm (0.0080 journals should be held to 0.025 mm (0.001 inch). inch) side clearance. Bearings are available in 0.025 mm (0.001 inch), 0.051 mm (0.002 inch), 0.076 mm (0.003 inch), 0.254 mm (0.010 inch) and 0.305 mm (0.012 inch) under- size. Install the bearings in pairs. DO NOT use a new bearing half with an old bearing half. DO NOT file the rods or bearing caps. INSTALLATION (1) Be sure that compression ring gaps are stag- gered so that neither is in-line with oil ring rail gap. (2) Before installing the ring compressor, make sure the oil ring expander ends are butted and the rail gaps located properly (Fig. 3). (3) Immerse the piston head and rings in clean en- gine oil. Slide Piston Ring Compressor Tool C-385 over the piston and tighten with the special wrench Fig. 2 Measuring Piston Ring Side Clearance (part of Tool C-385). Be sure position of rings does not change during this operation. (d) Pistons with insufficient or excessive side (4) Install connecting rod bolt protectors on rod clearance should be replaced. (3) Arrange ring gaps 90° apart as shown in Fig. 3. bolts, the long protector should be installed on the numbered side of the connecting rod.CONNECTING ROD BEARINGS (5) Rotate crankshaft so that the connecting rod journal is on the center of the cylinder bore. Be sure connecting rod and cylinder bore number are the same. Insert rod and piston into cylinder bore and guide rod over the crankshaft journal. (6) Tap the piston down in cylinder bore, using a hammer handle. At the same time, guide connecting rod into position on crankshaft journal. (7) The notch or groove on top of piston must be pointing toward front of engine. The larger chamfer of the connecting rod bore must be installed toward crankshaft journal fillet. (8) Install rod caps. Be sure connecting rod, con- necting rod cap and cylinder bore number are the same. Install nuts on cleaned and oiled rod bolts and tighten nuts to 61 N⅐m (45 ft. lbs.) torque. (9) Install the oil pan. (10) Install the cylinder head. Fig. 3 Proper Ring Installation (11) Install the engine into the vehicle. Fit all rods on a bank until completed. DO NOT al-ternate from one bank to another, because connecting CRANKSHAFTrods and pistons are not interchangeable from one A crankshaft which has undersize journals will bebank to another. stamped with 1/4 inch letters on the milled flat on The bearing caps are not interchangeable and the No.8 crankshaft counterweight (Fig. 4).should be marked at removal to ensure correct as- FOR EXAMPLE: R2 stamped on the No.6 crank-sembly. shaft counterweight indicates that the No.2 rod jour- Each bearing cap has a small V-groove across the nal is 0.025 mm (0.001 in) undersize. M4 indicatesparting face. When installing the lower bearing shell, that the No.4 main journal is 0.025 mm (0.001 in)make certain that the V-groove in the shell is in line undersize. R3 M2 indicates that the No.3 rod journalwith the V-groove in the cap. This provides lubrica- and the No.2 main journal are 0.025 mm (0.001 in)tion of the cylinder wall in the opposite bank. undersize.
  • 70. 9 - 70 5.2L ENGINE ZJ INSTALLATION (1) Lightly oil the new upper seal lips with engine oil. (2) Install the new upper rear bearing oil seal with the white paint facing towards the rear of the engine. (3) Position the crankshaft into the cylinder block. (4) Lightly oil the new lower seal lips with engine oil. (5) Install the new lower rear bearing oil seal into the bearing cap with the white paint facing towards the rear of the engine. (6) Apply 5 mm (0.20 in) drop of Loctite 515, or equivalent, on each side of the rear main bearing cap (Fig. 5). DO NOT over apply sealant or allow the sealant to contact the rubber seal. Assemble bearing Fig. 4 Location of Crankshaft Identification cap to cylinder block immediately after sealant appli- When a crankshaft is replaced, all main and con- cation.necting rod bearings should be replaced with newbearings. Therefore, selective fitting of the bearingsis not required when a crankshaft and bearings arereplaced.REMOVAL (1) Remove the oil pan. (2) Remove the oil pump from the rear main bear-ing cap. (3) Identify bearing caps before removal. Removebearing caps and bearings one at a time. (4) Lift the crankshaft out of the block. (5) Remove and discard the crankshaft rear oilseals. (6) Remove and discard the front crankshaft oilseal. Fig. 5 Sealant Application to Bearing CapINSPECTION OF JOURNALS (7) To align the bearing cap, use cap slot, align- The crankshaft connecting rod and main journals ment dowel and cap bolts. DO NOT remove excessshould be checked for excessive wear, taper and scor- material after assembly. DO NOT strike rear caping. The maximum taper or out-of-round on any more than 2 times for proper engagement.crankshaft journal is 0.025 mm (0.001 inch). (8) Clean and oil all cap bolts. Install all main Journal grinding should not exceed 0.305 mm bearing caps. Install all cap bolts and alternately(0.012 inch) under the standard journal diameter. DO tighten to 115 N⅐m (85 ft. lbs.) torque.NOT grind thrust faces of No.3 main bearing. DO (9) Install oil pump.NOT nick crank pin or bearing fillets. After grinding, (10) Install the timing chain cover.remove rough edges from crankshaft oil holes and (11) Install the vibration damper.clean out all oil passages. (12) Apply Mopar௡ Silicone Rubber Adhesive Seal- ant, or equivalent, at bearing cap to block joint toCAUTION: After any journal grind, it is important provide cap to block and oil pan sealing (Fig. 6). Ap-that the final paper or cloth polish be in the same ply enough sealant until a small amount is squeezeddirection as the engine rotates. out. Withdraw nozzle and wipe excess sealant off the oil pan seal groove. Clean Loctite 515 residue and sealant from the cyl- (13) Install new front crankshaft oil seal.inder block and rear cap mating surface. Do this be- (14) Immediately install the oil pan.fore applying the Loctite drop and the installation ofrear cap. CRANKSHAFT MAIN BEARINGS Bearing caps are not interchangeable and should be marked at removal to ensure correct assembly.
  • 71. ZJ 5.2L ENGINE 9 - 71 Fig. 6 Apply Sealant to Bearing Cap to Block JointUpper and lower bearing halves are NOT inter- Fig. 8 Upper Main Bearing Removal and Installationchangeable. Lower main bearing halves of No.2 and 4 with Tool C-3059are interchangeable. INSTALLATION Upper and lower No.3 bearing halves are flanged Only one main bearing should be selectively fittedto carry the crankshaft thrust loads. They are NOT while all other main bearing caps are properly tight-interchangeable with any other bearing halves in the ened. All bearing capbolts removed during serviceengine (Fig. 7). Bearing shells are available in stan- procedures are to be cleaned and oiled before instal-dard and the following undersizes: 0.25 mm (0.001 lation.inch), 0.051 mm (0.002 inch), 0.076 mm (0.003 inch), When installing a new upper bearing shell, slightly0.254 mm (0.010 inch) and 0.305 mm (0.012 inch). chamfer the sharp edges from the plain side.Never install an undersize bearing that will reduce (1) Start bearing in place, and insert Crankshaftclearance below specifications. Main Bearing Remover/Installer Tool C-3059 into oil hole of crankshaft (Fig. 8). (2) Slowly rotate crankshaft counterclockwise slid- ing the bearing into position. Remove Tool C-3059. (3) Install the bearing caps. Clean and oil the bolts. Tighten the capbolts to 115 N⅐m (85 ft. lbs.) torque. (4) Install the oil pump. (5) Install the oil pan. CRANKSHAFT REAR OIL SEALS The service seal is a 2 piece, viton seal. The upper seal half can be installed with crankshaft removed from engine or with crankshaft installed. When a new upper seal is installed, install a new lower seal. The lower seal half can only be installed with the rear main bearing cap removed. Fig. 7 Main Bearing Identification UPPER SEAL REPLACEMENT—CRANKSHAFTREMOVAL REMOVED (1) Remove the oil pan. (1) Remove the crankshaft. (2) Remove the oil pump from the rear main bear- (2) Clean the cylinder block rear cap mating sur-ing cap. face. Make sure the seal groove is free of debris. (3) Identify bearing caps before removal. Remove Check for burr at the oil hole on the cylinder blockbearing caps one at a time. mating surface to rear cap. (4) Remove upper half of bearing by inserting (3) Lightly oil the new upper seal lips with engineCrankshaft Main Bearing Remover/Installer Tool oil.C-3059 into the oil hole of crankshaft (Fig. 8). (4) Install the new upper rear bearing oil seal with (5) Slowly rotate crankshaft clockwise, forcing out the white paint facing towards the rear of the engine.upper half of bearing shell. (5) Position the crankshaft into the cylinder block.
  • 72. 9 - 72 5.2L ENGINE ZJ (6) Lightly oil the new lower seal lips with engine cap to cylinder block immediately after sealant appli-oil. cation. Be sure the white paint faces toward the rear (7) Install the new lower rear bearing oil seal into of the engine.the bearing cap with the white paint facing towards (10) To align the bearing cap, use cap slot, align-the rear of the engine. ment dowel and cap bolts. DO NOT remove excess (8) Apply 5 mm (0.20 in) drop of Loctite 515, or material after assembly. DO NOT strike rear capequivalent, on each side of the rear main bearing cap more than 2 times for proper engagement.(Fig. 5). DO NOT over apply sealant or allow the (11) Install the rear main bearing cap with cleanedsealant to contact the rubber seal. Assemble bearing and oiled cap bolts. Alternately tighten ALL cap boltscap to cylinder block immediately after sealant appli- to 115 N⅐m (85 ft. lbs.) torque.cation. (12) Install oil pump. (9) To align the bearing cap, use cap slot, align- (13) Apply Mopar௡ Silicone Rubber Adhesive Seal-ment dowel and cap bolts. DO NOT remove excess ant, or equivalent, at bearing cap to block joint tomaterial after assembly. DO NOT strike rear cap provide cap to block and oil pan sealing (Fig. 6). Ap-more than 2 times for proper engagement. ply enough sealant until a small amount is squeezed (10) Clean and oil all cap bolts. Install all main out. Withdraw nozzle and wipe excess sealant off thebearing caps. Install all cap bolts and alternately oil pan seal groove.tighten to 115 N⅐m (85 ft. lbs.) torque. (14) Immediately install the oil pan. (11) Install oil pump. (12) Apply Mopar௡ Silicone Rubber Adhesive Seal- LOWER SEAL REPLACEMENTant, or equivalent, at bearing cap to block joint to (1) Remove the oil pan.provide cap to block and oil pan sealing (Fig. 6). Ap- (2) Remove the oil pump from the rear main bear-ply enough sealant until a small amount is squeezed ing cap.out. Withdraw nozzle and wipe excess sealant off the (3) Remove the rear main bearing cap and discardoil pan seal groove. the old lower seal. (13) Install new front crankshaft oil seal. (4) Clean the rear main cap mating surfaces in- (14) Immediately install the oil pan. cluding the oil pan gasket groove. (5) Carefully install a new upper seal (refer to Up-UPPER SEAL REPLACEMENT—CRANKSHAFT per Seal Replacement - Crankshaft Installed proce-INSTALLED dure above). (1) Remove the oil pan. (6) Lightly oil the new lower seal lips with engine (2) Remove the oil pump from the rear main bear- oil.ing cap. (7) Install a new lower seal in bearing cap with the (3) Remove the rear main bearing cap. Remove white paint facing the rear of engine.and discard the old lower oil seal. (8) Apply 5 mm (0.20 in) drop of Loctite 515, or (4) Carefully remove and discard the old upper oil equivalent, on each side of the rear main bearing capseal. (Fig. 5). DO NOT over apply sealant or allow the (5) Clean the cylinder block mating surfaces before sealant to contact the rubber seal. Assemble bearingoil seal installation. cap to cylinder block immediately after sealant appli- Check for burr at the oil hole on the cylinder block cation.mating surface to rear cap. (9) To align the bearing cap, use cap slot, align- (6) Lightly oil the new upper seal lips with engine ment dowel and cap bolts. DO NOT remove excessoil. To allow ease of installation of the seal, loosen at material after assembly. DO NOT strike rear capleast the 2 main bearing caps forward of the rear more than 2 times for proper engagement.bearing cap. (10) Install the rear main bearing cap with cleaned (7) Rotate the new upper seal into the cylinder and oiled cap bolts. Alternately tighten the cap boltsblock being careful not to shave or cut the outer sur- to 115 N⅐m (85 ft. lbs.) torque.face of the seal. To assure proper installation, use the (11) Install oil pump.installation tool provided with the kit. Install the (12) Apply Mopar௡ Silicone Rubber Adhesive Seal-new seal with the white paint facing towards the ant, or equivalent, at bearing cap to block joint torear of the engine. provide cap to block and oil pan sealing (Fig. 6). Ap- (8) Install the new lower rear bearing oil seal into ply enough sealant until a small amount is squeezedthe bearing cap with the white paint facing towards out. Withdraw nozzle and wipe excess sealant off thethe rear of the engine. oil pan seal groove. (9) Apply 5 mm (0.20 in) drop of Loctite 515, or (13) Immediately install the oil pan.equivalent, on each side of the rear main bearing cap(Fig. 5). DO NOT over apply sealant or allow the CYLINDER BLOCKsealant to contact the rubber seal. Assemble bearing Remove the engine assembly from the vehicle.
  • 73. ZJ 5.2L ENGINE 9 - 73DISASSEMBLE (1) Remove the cylinder head. (2) Remove the oil pan. (3) Remove the piston/connecting rod assembly.CLEANING Clean cylinder block thoroughly and check all corehole plugs for evidence of leaking.INSPECTION Examine block for cracks or fractures. The cylinder walls should be checked for out-of-round and taper with Cylinder Bore Indicator Tool6879. The cylinder block should be bored and honedwith new pistons and rings fitted if:• The cylinder bores show more than 0.127 mm(0.005 inch) out-of-round.• The cylinder bores show a taper of more than0.254 mm (0.010 inch).• The cylinder walls are badly scuffed or scored. Boring and honing operation should be closely co-ordinated with the fitting of pistons and rings so Fig. 9 Oil Line Plugspecified clearances may be maintained. Refer to Standard Service Procedures in the begin-ning of this Group for the proper honing of cylinderbores.OIL LINE PLUG The oil line plug is located in the vertical passageat the rear of the block between the Oil-To-Filter andOil-From-Filter passages (Fig. 9). Improper installa-tion or plug missing could cause erratic, low or no oilpressure. (1) Remove oil pressure sending unit from back ofblock. (2) Insert a 3.175 mm (1/8 inch) finish wire orequivalent into passage. (3) Plug should be 190.0 to 195.2 mm (7-1/2 to7-11/16 inches) from machined surface of block (Fig.9). If plug is too high, use a suitable flat dowel to po-sition properly. (4) If plug is to low, remove oil pan and rear main Fig. 10 Location of Cup Plugs in Oil Galleriesbearing cap. Use suitable flat dowel to position prop- REMOVALerly. Coat outside diameter of new plug with Mopar௡ (1) Using a blunt tool such as a drift or a screw-(Stud and Bearing Mount Adhesive), or equivalent. driver and a hammer, strike the bottom edge of thePlug should be 54.0 to 57.7 mm (2-1/8 to 2-5/16 cup plug (Fig. 11).inches) from bottom of the block. (2) With the cup plug rotated, grasp firmly with (5) Assemble engine and check oil pressure. pliers or other suitable tool and remove plug (Fig. 11).ENGINE CORE, OIL AND CAMSHAFT PLUGS Engine core plugs have been pressed into the oil CLEANINGgalleries behind the camshaft thrust plate (Fig. 10). Thoroughly clean inside of cup plug hole in cylinderThis will reduce internal leakage and help maintain block or head. Be sure to remove old sealer.higher oil pressure at idle. Make certain the new plug is cleaned of all oil or grease.
  • 74. 9 - 74 5.2L ENGINE ZJ CAUTION: DO NOT drive cup plug into the casting as restricted coolant flow can result and cause se- rious engine problems. (2) Using proper plug driver, drive cup plug into hole. The sharp edge of the plug should be at least 0.50 mm (0.020 inch) inside the lead-in chamfer. It is not necessary to wait for curing of the sealant. The cooling system can be filled and the vehicle placed in service immediately. ASSEMBLE (1) Install the piston/connecting rod assembly. (2) Install the oil pan. (3) Install the cylinder head. (4) Install the engine into the vehicle. Fig. 11 Core Hole Plug RemovalINSTALLATION (1) Coat edges of plug and core hole with Mopar௡Gasket Maker, or equivalent.
  • 75. ZJ 5.2L ENGINE 9 - 75SPECIFICATIONS—5.2L ENGINE ENGINE SPECIFICATIONS
  • 76. 9 - 76 5.2L ENGINE ZJ ENGINE SPECIFICATIONS—CONT.
  • 77. ZJ 5.2L ENGINE 9 - 77 ENGINE SPECIFICATIONS—CONT. OVERSIZE AND UNDERSIZE ENGINE COMPONENT MARKINGS
  • 78. 9 - 78 5.2L ENGINE ZJ TORQUE SPECIFICATIONS