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Exj 7

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  • 1. XJ COOLING SYSTEM 7-1 COOLING SYSTEM CONTENTS page pageGENERAL INFORMATION RADIATOR COOLANT FLOW CHECK . . . . . . . 19 ACCESSORY DRIVE BELT TENSION . . . . . . . . . 3 TESTING COOLING SYSTEM FOR LEAKS . . . 19 COOLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . 20 COOLING SYSTEM COMPONENTS . . . . . . . . . . 2 SERVICE PROCEDURES COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 1 ADDING ADDITIONAL COOLANT—ROUTINE . . 22 ENGINE ACCESSORY DRIVE BELTS . . . . . . . . . 1 COOLANT LEVEL CHECK—ROUTINE . . . . . . . 22 ENGINE BLOCK HEATER . . . . . . . . . . . . . . . . . 3 COOLANT LEVEL CHECK—SERVICE . . . . . . . 22 RADIATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 COOLANT SERVICE . . . . . . . . . . . . . . . . . . . . 22 SYSTEM COOLANT ROUTING . . . . . . . . . . . . . 2 DRAINING AND FILLING COOLING SYSTEM . . 23 WATER PUMPS . . . . . . . . . . . . . . . . . . . . . . . . . 2 REVERSE FLUSHING . . . . . . . . . . . . . . . . . . . 23DESCRIPTION AND OPERATION REMOVAL AND INSTALLATION ACCESSORY DRIVE BELT TENSION . . . . . . . . . 4 AUXILIARY ELECTRIC COOLING FAN . . . . . . . 34 AUTOMATIC TRANSMISSION OIL COOLER . . . 3 COOLANT RESERVE TANK . . . . . . . . . . . . . . . 25 AUXILIARY ELECTRIC COOLING FAN . . . . . . . . 8 COOLING SYSTEM FANS . . . . . . . . . . . . . . . . 37 COOLANT PERFORMANCE . . . . . . . . . . . . . . . . 5 ENGINE ACCESSORY DRIVE BELTS . . . . . . . . 34 COOLANT RESERVE/OVERFLOW SYSTEM . . . 3 ENGINE BLOCK HEATER . . . . . . . . . . . . . . . . 34 COOLANT SELECTION-ADDITIVES . . . . . . . . . . 5 RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 COOLING SYSTEM FANS . . . . . . . . . . . . . . . . . 4 THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . 29 COOLING SYSTEM HOSES . . . . . . . . . . . . . . . . 6 TRANSMISSION OIL COOLERS . . . . . . . . . . . . 24 ENGINE BLOCK HEATER . . . . . . . . . . . . . . . . . 4 VISCOUS FAN DRIVE REMOVAL/ RADIATOR PRESSURE CAP . . . . . . . . . . . . . . . 5 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . 38 THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . 4 WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . 25 VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . 7 CLEANING AND INSPECTION WATER PUMPS . . . . . . . . . . . . . . . . . . . . . . . . . 6 COOLING SYSTEM CLEANING . . . . . . . . . . . . 38DIAGNOSIS AND TESTING COOLING SYSTEM HOSES . . . . . . . . . . . . . . . 38 AUXILIARY ELECTRIC COOLING FAN . . . . . . . 21 FAN BLADE INSPECTION . . . . . . . . . . . . . . . . 38 COOLING SYSTEM DIAGNOSIS . . . . . . . . . . . 12 RADIATOR CLEANING . . . . . . . . . . . . . . . . . . . 38 DEAERATION . . . . . . . . . . . . . . . . . . . . . . . . . 22 RADIATOR PRESSURE CAP . . . . . . . . . . . . . . 38 DRB SCAN TOOL . . . . . . . . . . . . . . . . . . . . . . . 8 SPECIFICATIONS ENGINE ACCESSORY DRIVE BELTS . . . . . . . . . 9 BELT TENSION . . . . . . . . . . . . . . . . . . . . . . . . 38 LOW COOLANT LEVEL-AERATION . . . . . . . . . 22 COOLING SYSTEM CAPACITIES . . . . . . . . . . . 38 ON-BOARD DIAGNOSTICS (OBD) . . . . . . . . . . . 8 TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . 39 PRELIMINARY CHECKS . . . . . . . . . . . . . . . . . 10 SPECIAL TOOLS PRESSURE TESTING RADIATOR CAPS . . . . . 22 COOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 RADIATOR CAP-TO-FILLER NECK SEAL— PRESSURE RELIEF CHECK . . . . . . . . . . . . . 21GENERAL INFORMATION COOLING SYSTEM The cooling system regulates engine operating tem-ENGINE ACCESSORY DRIVE BELTS perature. It allows the engine to reach normal oper- ating temperature as quickly as possible, maintainsCAUTION: When installing a serpentine accessory normal operating temperature and prevents over-drive belt, the belt MUST be routed correctly. If not, heating.the engine may overheat due to water pump rotat- The cooling system also provides a means of heat-ing in wrong direction. Refer to the appropriate ing the passenger compartment and cooling the auto-engine Belt Schematic in this group for the correct matic transmission fluid (if equipped). The coolingbelt routing. Or, refer to the Belt Routing Label system is pressurized and uses a centrifugal waterlocated in the engine compartment. pump to circulate coolant throughout the system.
  • 2. HEATER CORE RADIATOR UPPER HOSE TO WATER PUMP RADIATOR WATER PUMP TO COOLANT PULLEY RECOVERY BOTTLE RADIATOR LOWER HOSE7-2 COOLING SYSTEM XJGENERAL INFORMATION (Continued) An optional factory installed heavy duty cooling WATER PUMPSpackage is available on most models. The package A quick test to determine if the pump is working isconsists of a radiator that has an increased number to check if the heater warms properly. A defectiveof cooling fins. Vehicles equipped with a 4.0L 6- cyl- water pump will not be able to circulate heated cool-inder engine and heavy duty cooling and/or air con- ant through the long heater hose to the heater core.ditioning also have an auxiliary electric cooling fan. COOLANTCOOLING SYSTEM COMPONENTS The cooling system is designed around the coolant. The cooling system consists of: Coolant flows through the engine water jackets • A radiator absorbing heat produced during engine operation. • Cooling fan (mechanical and/or electrical) The coolant carries heat to the radiator and heater • Thermal viscous fan drive core. Here it is transferred to the ambient air pass- • Fan shroud ing through the radiator and heater core fins. The • Radiator pressure cap coolant also removes heat from the automatic trans- • Thermostat mission fluid in vehicles equipped with an automatic • Coolant reserve/overflow system transmission. • Transmission oil cooler (if equipped with anautomatic transmission) RADIATORS • Coolant 2.5L 4–cylinder engine radiators are the down flow • Water pump type, 4.0L 6-cylinder engine radiators are the cross • Hoses and hose clamps flow type. Plastic tanks are used on all radiators.SYSTEM COOLANT ROUTING CAUTION: Plastic tanks, while stronger than brass, For cooling system flow routings, refer to (Fig. 1) are subject to damage by impact, such as(Fig. 2). wrenches. Fig. 1 Coolant Flow—2.5L 4-Cylinder Engine—Typical
  • 3. TO COOLANT RADIATORWATER PUMP HEATER CORE TANK HOUSING OVERFLOW THERMOSTAT RESERVE/XJ COOLING SYSTEM 7-3GENERAL INFORMATION (Continued) ENGINE BLOCK HEATER An optional engine block heater is available for all models. The heater is equipped with a power cord. The cord is attached to an engine compartment com- ponent with tie-straps. The heater warms the engine providing easier engine starting and faster warm-up in low temperatures. The heater is mounted in a core hole of the engine cylinder block (in place of a freeze plug) with the heating element immersed in engine coolant. Connect the power cord to a grounded 110- 120 volt AC electrical outlet with a grounded, three- wire extension cord. DESCRIPTION AND OPERATION AUTOMATIC TRANSMISSION OIL COOLER WATER-TO-OIL COOLER All models equipped with an automatic transmis- sion are equipped with a transmission oil cooler mounted internally within the radiator tank. This internal cooler is supplied as standard equipment on all models equipped with an automatic transmission. Transmission oil is cooled when it passes through this separate cooler. In case of a leak in the internal radiator mounted transmission oil cooler, engine cool- ant may become mixed with transmission fluid or transmission fluid may enter engine cooling system. Fig. 2 Coolant Flow—4.0L 6-Cylinder Engine— Both cooling system and transmission should be Typical drained and inspected if the internal radiator If the plastic tank has been damaged, the plastic mounted transmission cooler is leaking.tank and/or o-rings are available for service repair.Tank replacement should be done by a qualified per- AIR-TO-OIL COOLERson with proper equipment. An auxiliary air-to-oil transmission oil cooler is available with most engine packages.ACCESSORY DRIVE BELT TENSION The auxiliary air-to-oil transmission oil cooler is Correct accessory drive belt tension is required to located in front of the radiator or A/C condenser (ifensure optimum performance of belt driven engine equipped) and behind the grill. It is mounted to theaccessories. If specified tension is not maintained, front frame crossmember.belt slippage may cause: engine overheating, lack of The auxiliary oil coolers on all models operate inpower steering assist, loss of air conditioning capac- conjunction with the internal radiator mounted mainity, reduced generator output rate, greatly reduced oil cooler. The transmission oil is routed through thebelt life and objectionable under hood noise. main cooler first, then the auxiliary cooler, before returning to the transmission.DOMESTIC LEFT HAND DRIVE VEHICLES Belt tension is adjusted at the power steering COOLANT RESERVE/OVERFLOW SYSTEMpump bracket and idler pulley assembly. The system works along with the radiator pressure cap. This is done by using thermal expansion andDOMESTIC RIGHT HAND DRIVE VEHICLES contraction of the coolant to keep the coolant free of If equipped with a 4.0L 6-cylinder engine; the ser- trapped air. It provides:pentine belt is adjusted at the generator mounting • A volume for coolant expansion and contraction.bracket. When equipped with a 2.5L 4-cylinder • A convenient and safe method for checking/ad-engine, the serpentine belt is adjusted at the power justing coolant level at atmospheric pressure. This issteering pump bracket and idler pulley assembly. done without removing the radiator pressure cap. • Some reserve coolant to the radiator to cover minor leaks and evaporation or boiling losses.
  • 4. MOUNTING CLAMP BOLTS TUBE TO RADIATOR COOLANT TANK OVERFLOW RESERVE/ LOWER BRACKET7-4 COOLING SYSTEM XJDESCRIPTION AND OPERATION (Continued) As the engine cools, a vacuum is formed in thecooling system of both the radiator and engine. Cool-ant will then be drawn from the coolant tank andreturned to a proper level in the radiator. The coolant reserve/overflow system consists of aradiator mounted pressurized cap, a plastic reserve/overflow tank (Fig. 3) (Fig. 4), a tube (hose) connect-ing the radiator and tank, and an overflow tube onthe side of the tank. Fig. 4 Reserve/Overflow Tank—With Right Hand Drive tested (between two pulleys) to check tension. Do not allow the gauge (or gauge adapter) to contact any- thing but the belt. ENGINE BLOCK HEATER An optional engine block heater is available for all models. The heater is equipped with a power cord. The cord is attached to an engine compartment com- Fig. 3 Reserve/Overflow Tank—Except Right Hand ponent with tie-straps. The heater warms the engine Drive providing easier engine starting and faster warm-up in low temperatures. The heater is mounted in a coreCOOLING SYSTEM FANS hole of the engine cylinder block (in place of a freeze Also refer to either the Viscous Fan Drive and/or plug) with the heating element immersed in enginethe Auxiliary Electric Cooling Fan. coolant. Connect the power cord to a grounded 110- All models are equipped with a mechanical temper- 120 volt AC electrical outlet with a grounded, three-ature controlled fan. This thermal viscous fan drive wire extension cord.is a torque-and-temperature-sensitive clutch unit. Itautomatically increases or decreases fan speed to WARNING: DO NOT OPERATE ENGINE UNLESSprovide proper engine cooling. Vehicles with a 4.0L BLOCK HEATER CORD HAS BEEN DISCONNECTED6-cylinder engine may also have an auxiliary electri- FROM POWER SOURCE AND SECURED IN PLACE.cal cooling fan; when equipped air conditioningand/or heavy duty cooling. BLOCK HEATER SPECIFICATIONS • 2.5L 4-Cylinder Engine: 115 Volts 400 WattsACCESSORY DRIVE BELT TENSION • 4.0L 6-Cylinder Engine: 120 Volts 600 Watts Both the 2.5l and 4.0l engines use one accessorydrive belt. Correct drive belt tension is required to THERMOSTATensure optimum performance of the belt driven A pellet-type thermostat controls the operatingengine accessories. There are different types of temperature of the engine by controlling the amountadjustment gauges for checking either a serpentine of coolant flow to the radiator. On all engines theor a conventional “V-type” belt. Refer to the instruc- thermostat is closed below 195°F (90°C). Above thistions supplied with the gauge. Make sure to use a temperature, coolant is allowed to flow to the radia-gauge designed specifically for serpentine style belts. tor. This provides quick engine warm-up and overallPlace gauge in the middle of the section of belt being temperature control.
  • 5. XJ COOLING SYSTEM 7-5DESCRIPTION AND OPERATION (Continued) An arrow plus the word UP is stamped on the and water is -32 deg. C (-26 deg. F). 5 deg. C higherfront flange next to the air bleed. The words TO than ethylene-glycol’s freeze point. The boiling pointRAD are stamped on one arm of the thermostat. (protection against summer boil-over) of propylene-They indicate the proper installed position. glycol is 125 deg. C (257 deg. F ) at 96.5 kPa (14 psi), The same thermostat is used for winter and sum- compared to 128 deg. C (263 deg. F) for ethylene-gly-mer seasons. An engine should not be operated with- col. Use of propylene-glycol can result in boil-over orout a thermostat, except for servicing or testing. freeze-up in Chrysler vehicles, which are designed forOperating without a thermostat causes other prob- ethylene-glycol. Propylene glycol also has poorer heatlems. These are: longer engine warm-up time, unre- transfer characteristics than ethylene glycol. Thisliable warm-up performance, increased exhaust can increase cylinder head temperatures under cer-emissions and crankcase condensation. This conden- tain conditions.sation can result in sludge formation. Propylene-glycol/Ethylene-glycol Mixtures—Should Not BeCAUTION: Do not operate an engine without a Used in Chrysler Vehiclesthermostat, except for servicing or testing. Propylene-glycol/ethylene-glycol Mixtures can cause the destabilization of various corrosion inhibi- tors, causing damage to the various cooling systemCOOLANT PERFORMANCE components. Also, once ethylene-glycol and propy- lene-glycol based coolants are mixed in the vehicle,ETHYLENE-GLYCOL MIXTURES conventional methods of determining freeze point will The required ethylene-glycol (antifreeze) and water not be accurate. Both the refractive index and spe-mixture depends upon the climate and vehicle oper- cific gravity differ between ethylene glycol and propy-ating conditions. The recommended mixture of 50/50 lene glycol.ethylene-glycol and water will provide protectionagainst freezing to -37 deg. C (-35 deg. F). The anti- CAUTION: Richer antifreeze mixtures cannot befreeze concentration must always be a minimum of measured with normal field equipment and can44 percent, year-round in all climates. If percentage cause problems associated with 100 percent ethyl-is lower than 44 percent, engine parts may be ene-glycol.eroded by cavitation, and cooling system com-ponents may be severely damaged by corrosion.Maximum protection against freezing is provided COOLANT SELECTION-ADDITIVESwith a 68 percent antifreeze concentration, which Coolant should be maintained at the specified levelprevents freezing down to -67.7 deg. C (-90 deg. F). A with a mixture of ethylene glycol-based antifreezehigher percentage will freeze at a warmer tempera- and low mineral content water. Only use an anti-ture. Also, a higher percentage of antifreeze can freeze containing ALUGARD 340-2 ௢.cause the engine to overheat because the specificheat of antifreeze is lower than that of water. CAUTION: Do not use coolant additives that are claimed to improve engine cooling.100 Percent Ethylene-Glycol—Should Not Be Used inChrysler Vehicles Use of 100 percent ethylene-glycol will cause for- RADIATOR PRESSURE CAPmation of additive deposits in the system, as the cor- All radiators are equipped with a pressure cap.rosion inhibitive additives in ethylene-glycol require This cap releases pressure at some point within athe presence of water to dissolve. The deposits act as range of 83-110 kPa (12-16 psi). The pressure reliefinsulation, causing temperatures to rise to as high as point (in pounds) is engraved on top of the cap (Fig.149 deg. C (300) deg. F). This temperature is hot 5).enough to melt plastic and soften solder. The The cooling system will operate at pressuresincreased temperature can result in engine detona- slightly above atmospheric pressure. This results in ation. In addition, 100 percent ethylene-glycol freezes higher coolant boiling point allowing increased radi-at 22 deg. C (-8 deg. F ). ator cooling capacity. The cap contains a spring- loaded pressure relief valve that opens when systemPropylene-glycol Formulations—Should Not Be Used in pressure reaches release range of 83-110 kPa (12-16Chrysler Vehicles psi). Propylene-glycol formulations do not meet A vent valve in the center of cap allows a smallChrysler coolant specifications. It’s overall effec- coolant flow through cap when coolant is below boil-tive temperature range is smaller than that of ethyl- ing temperature. The valve is completely closed whenene-glycol. The freeze point of 50/50 propylene-glycol boiling point is reached. As the coolant cools, it con-
  • 6. VACUUM VENT VALVE (SHOWN IN SEAL- CROSS-SECTIONAL VIEW ING POSITION) TOP VIEWPRESSURE RATING SEAL PRESSURE VALVE FILLER NECK ROTATION DIRECTIONVIEW R STAMPED INTO IMPELLER FRONT VIEWED AS ROTATION DIRECTIONVIEW BACK VIEWED AS7-6 COOLING SYSTEM XJDESCRIPTION AND OPERATION (Continued) cous fan drive assembly. REVERSE is stamped or imprinted on the cover of the viscous fan drive and inner side of the fan. The letter R is stamped into the back of the water pump impeller (Fig. 6). Fig. 6 Reverse Rotating Water Pump—Typical Engines from previous model years, depending Fig. 5 Radiator Pressure Cap and Filler Neck— upon application, may have been equipped with a for- Typical ward (clockwise) rotating water pump. Installation oftracts and creates a vacuum in the cooling system. the wrong water pump will cause engine overheating.This causes the vacuum valve to open and coolant in A quick test to determine if the pump is working isthe reserve/overflow tank to be drawn through its to check if the heater warms properly. A defectiveconnecting hose into radiator. If the vacuum valve is water pump will not be able to circulate heated cool-stuck shut, the radiator hoses will collapse on cool- ant through the long heater hose to the heater core.down. A rubber gasket seals radiator filler neck. This is COOLING SYSTEM HOSESdone to maintain vacuum during coolant cool-down Rubber hoses route coolant to and from the radia-and to prevent leakage when system is under pres- tor, intake manifold and heater core. Radiator lowersure. hoses are spring-reinforced to prevent collapse from water pump suction at moderate and high engineWATER PUMPS speeds. A centrifugal water pump circulates coolant WARNING: CONSTANT TENSION HOSE CLAMPSthrough the water jackets, passages, intake manifold, ARE USED ON MOST COOLING SYSTEM HOSES.radiator core, cooling system hoses and heater core. WHEN REMOVING OR INSTALLING, USE ONLYThe pump is driven from the engine crankshaft by a TOOLS DESIGNED FOR SERVICING THIS TYPE OFdrive belt on all engines. CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER The water pump impeller is pressed onto the rear 6094) (Fig. 7). SNAP-ON CLAMP TOOL (NUMBERof a shaft that rotates in bearings pressed into the HPC-20) MAY BE USED FOR LARGER CLAMPS.housing. The housing has a small hole to allow seep- ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-age to escape. The water pump seals are lubricated ING CONSTANT TENSION CLAMPS.by the antifreeze in the coolant mixture. No addi-tional lubrication is necessary.CAUTION: All engines are equipped with a reverse(counter-clockwise) rotating water pump and vis-
  • 7. LETTER HOSE CLAMP NUMBER/ CLAMPCONSTANT TYPICAL HOSE 6094 LOCA- TENSION TION TOOL CLAMP TYPICAL HOSE HOSECLAMP THERMOSTATIC FAN DRIVE VISCOUS SPRING MOUNTING HUBXJ COOLING SYSTEM 7-7DESCRIPTION AND OPERATION (Continued)CAUTION: A number or letter is stamped into the Ordinary worm gear type hose clamps (whentongue of constant tension clamps (Fig. 8). If equipped) can be removed with a straight screw-replacement is necessary, use only an original driver or a hex socket. To prevent damage toequipment clamp with matching number or letter. hoses or clamps, the hose clamps should be tightened to 4 N·m (34 in. lbs.) torque. Do not over tighten hose clamps. VISCOUS FAN DRIVE NOTE: Also refer to Cooling System Fans. The thermal viscous fan drive is a silicone-fluid- filled coupling used to connect the fan blades to either the engine or the water pump shaft. The cou- pling allows the fan to be driven in a normal manner. This is done at low engine speeds while limiting the top speed of the fan to a predetermined maximum level at higher engine speeds. A thermostatic bimetallic spring coil is located on the front face of the viscous fan drive unit. A typical viscous unit is shown in (Fig. 9). This spring coil Fig. 7 Hose Clamp Tool—Typical reacts to the temperature of the radiator discharge air. It engages the viscous fan drive for higher fan speed if the air temperature from the radiator rises above a certain point. Until additional engine cooling is necessary, the fan will remain at a reduced rpm regardless of engine speed. Fig. 9 Typical Viscous Fan Drive Fig. 8 Clamp Number/Letter Location Only when sufficient heat is present, will the vis- Inspect the hoses at regular intervals. Replace cous fan drive engage. This is when the air flowinghoses that are cracked, feel brittle when squeezed, or through the radiator core causes a reaction to theswell excessively when the system is pressurized. bimetallic coil. It then increases fan speed to provide For all vehicles: In areas where specific routing the necessary additional engine cooling.clamps are not provided, be sure that hoses are posi- Once the engine has cooled, the radiator dischargetioned with sufficient clearance. Check clearance temperature will drop. The bimetallic coil againfrom exhaust manifolds and pipe, fan blades, drive reacts and the fan speed is reduced to the previousbelts and sway bars. Improperly positioned hoses can disengaged speed.be damaged, resulting in coolant loss and engineoverheating.
  • 8. POWER RIGHT FENDER DISTRIBUTION CENTER BATTERY7-8 COOLING SYSTEM XJDESCRIPTION AND OPERATION (Continued)CAUTION: Engines equipped with serpentine drivebelts have reverse rotating fans and viscous fandrives. They are marked with the word REVERSE todesignate their usage. Installation of the wrong fanor viscous fan drive can result in engine overheat-ing.CAUTION: If the viscous fan drive is replacedbecause of mechanical damage, the cooling fanblades should also be inspected. Inspect for fatiguecracks, loose blades, or loose rivets that couldhave resulted from excessive vibration. Replace fanblade assembly if any of these conditions arefound. Also inspect water pump bearing and shaftassembly for any related damage due to a viscousfan drive malfunction.NOISE It is normal for fan noise to be louder (roar-ing) when: • The underhood temperature is above the engage-ment point for the viscous drive coupling. This may Fig. 10 Power Distribution Center (PDC)occur when ambient (outside air temperature) is very DIAGNOSIS AND TESTINGhigh. • Engine loads and temperatures are high such as ON-BOARD DIAGNOSTICS (OBD)when towing a trailer. • Cool silicone fluid within the fan drive unit is COOLING SYSTEM RELATED DIAGNOSTICSbeing redistributed back to its normal disengaged The Powertrain Control Module (PCM) has been(warm) position. This can occur during the first 15 programmed to monitor the certain following coolingseconds to one minute after engine start-up on a cold system components:engine. • If the engine has remained cool for too long a period, such as with a stuck open thermostat, a Diag-AUXILIARY ELECTRIC COOLING FAN nostic Trouble Code (DTC) can be set. Models equipped with a 4.0L 6-cylinder engine may • If an open or shorted condition has developed inalso have an auxiliary electrical cooling fan. This is the relay circuit controlling the electric radiator fan,with models that have air conditioning and/or heavy a Diagnostic Trouble Code (DTC) can be set.duty cooling. The fan is controlled by the cooling fan If the problem is sensed in a monitored circuitrelay, which is located in the power distribution cen- often enough to indicate an actual problem, a DTC ister (PDC) (Fig. 10). For the location of relay within stored. The DTC will be stored in the PCM memorythe PDC, refer to the label on PDC cover. for eventual display to the service technician. (Refer When coolant temperature reaches approximately to Group 25, Emission Control Systems for proper103°C (218°F), or when air conditioning is requested, procedures)the powertrain control module (PCM) provides aground path for the fan relay. This ground is pro- ACCESSING DIAGNOSTIC TROUBLE CODESvided to the cooling fan relay through pin C2 of PCM To read DTC’s and to obtain cooling system data,connector C3. Battery voltage is then applied to the refer to Group 25, Emission Control Systems forfan through the relay. When coolant temperature proper procedures.drops below approximately 98°C (209°F), the PCMopens the ground path to the relay. This will prevent DRB SCAN TOOLthe cooling fan from being energized. For operation of the DRB scan tool, refer to the appropriate Powertrain Diagnostic Procedures ser- vice manual.
  • 9. XJ COOLING SYSTEM 7-9DIAGNOSIS AND TESTING (Continued)ENGINE ACCESSORY DRIVE BELTSBELT DIAGNOSIS When diagnosing serpentine accessory drive belts,small cracks that run across the ribbed surface of thebelt from rib to rib (Fig. 11), are considered normal.These are not a reason to replace the belt. However,cracks running along a rib (not across) are not nor-mal. Any belt with cracks running along a rib mustbe replaced (Fig. 11). Also replace the belt if it hasexcessive wear, frayed cords or severe glazing. Refer to the Serpentine Drive Belt Diagnosischarts for further belt diagnosis. Fig. 11 Serpentine Belt Wear Patterns SERPENTINE BELT DIAGNOSIS CHART CONDITION POSSIBLE CAUSES CORRECTIONRIB CHUNKING (One or more ribs has 1. Foreign objects imbedded in pulley 1. Remove foreign objects from pulleyseparated from belt body) grooves. grooves. Replace belt. 2. Installation damage 2. Replace beltRIB OR BELT WEAR 1. Pulley misaligned 1. Align pulley(s) 2. Abrasive environment 2. Clean pulley(s). Replace belt if necessary 3. Rusted pulley(s) 3. Clean rust from pulley(s) 4. Sharp or jagged pulley groove tips 4. Replace pulley. Inspect belt. 5. Belt rubber deteriorated 5. Replace beltBELT SLIPS 1. Belt slipping because of insufficient 1. Adjust tension tension 2. Belt or pulley exposed to substance 2. Replace belt and clean pulleys that has reduced friction (belt dressing, oil, ethylene glycol) 3. Driven component bearing failure 3. Replace faulty component or bearing (seizure) 4. Belt glazed or hardened from heat 4. Replace belt. and excessive slippageLONGITUDAL BELT CRACKING 1. Belt has mistracked from pulley 1. Replace belt groove 2. Pulley groove tip has worn away 2. Replace belt rubber to tensile member
  • 10. 7 - 10 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONЉGROOVE JUMPING” 1. Belt tension either too low or too 1. Adjust belt tension(Belt does not maintain correct highposition on pulley) 2. Pulley(s) not within design 2. Replace pulley(s) tolerance 3. Foreign object(s) in grooves 3. Remove foreign objects from grooves 4. Pulley misalignment 4. Align component 5. Belt cordline is broken 5. Replace beltBELT BROKEN 1. Excessive tension 1. Replace belt and adjust tension to(Note: Identify and correct problem specificationbefore new belt is installed) 2. Tensile member damaged during 2. Replace belt belt installation 3. Severe misalignment 3. Align pulley(s) 4. Bracket, pulley, or bearing failure 4. Replace defective component and beltNOISE 1. Belt slippage 1. Adjust belt(Objectional squeal, squeak, or 2. Bearing noise 2. Locate and repairrumble is heard or felt while drive belt 3. Belt misalignment 3. Align belt/pulley(s)is in operation) 4. Belt to pulley mismatch 4. Install correct belt 5. Driven component induced 5. Locate defective driven component vibration and repair 6. System resonant frequency 6. Vary belt tension within induced vibration specifications.TENSION SHEETING FABRIC 1. Tension sheeting contacting 1. Correct rubbing conditionFAILURE stationary object(Woven fabric on outside, 2. Excessive heat causing woven 2. Replace beltcircumference of belt has cracked or fabric to ageseparated from body of belt) 3. Tension sheeting splice has 3. Replace belt fracturedCORD EDGE FAILURE 1. Excessive tension 1. Adjust belt tension(Tensile member exposed at edges of 2. Belt contacting stationary object 2. Replace beltbelt or separated from belt body) 3. Pulley(s) out of tolerance 3. Replace pulley 4. Insufficient adhesion between 4. Replace belt and adjust tension to tensile member and rubber matrix specificationsPRELIMINARY CHECKS TRAILER TOWING: Consult Trailer Towing section of owners manual.ENGINE COOLING SYSTEM OVERHEATING Do not exceed limits. Establish what driving conditions caused the com-plaint. Abnormal loads on the cooling system such as AIR CONDITIONING; ADD-ON OR AFTER MARKET:the following may be the cause: A maximum cooling package should have been ordered with vehicle if add-on or after market A/C isPROLONGED IDLE, VERY HIGH AMBIENT TEMPERATURE, installed. If not, maximum cooling system compo-SLIGHT TAIL WIND AT IDLE, SLOW TRAFFIC, TRAFFIC nents should be installed for model involved perJAMS, HIGH SPEED OR STEEP GRADES. manufacturer’s specifications. Driving techniques that avoid overheating are: • Idle with A/C off when temperature gauge is at RECENT SERVICE OR ACCIDENT REPAIR:end of normal range. Determine if any recent service has been per- • Increasing engine speed for more air flow is rec- formed on vehicle that may effect cooling system.ommended. This may be:
  • 11. XJ COOLING SYSTEM 7 - 11DIAGNOSIS AND TESTING (Continued) • Engine adjustments (incorrect timing) NOTE: If investigation reveals none of the previous • Slipping engine accessory drive belt(s) items as a cause for an engine overheating com- • Brakes (possibly dragging) plaint, refer to following Cooling System Diagnosis • Changed parts. Incorrect water pump or pump charts.rotating in wrong direction due to belt not correctlyrouted These charts are to be used as a quick-reference • Reconditioned radiator or cooling system refill- only. Refer to the group text for information.ing (possibly under filled or air trapped in system).
  • 12. 7 - 12 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)COOLING SYSTEM DIAGNOSIS CONDITION POSSIBLE CAUSES CORRECTIONTEMPERATURE GAUGE READS 1. Has a Diagnostic Trouble Code 1. Refer to On-Board Diagnostics inLOW (DTC) number 17 been set indicating the service manual text. Replace a stuck open engine thermostat? thermostat if necessary. If a Diagnostic Trouble Code (DTC) number 17 has not been set, the problem may be with the temperature gauge. 2. Is the temperature gauge (if 2. Check the engine temperature equipped) connected to the sensor connector in the engine temperature gauge coolant sensor on compartment. Refer to Group 8E. the engine? Repair as necessary. 3. Is the temperature gauge (if 3. Check gauge operation. Refer to equipped) operating OK? Group 8E. Repair as necessary. 4. Coolant level low in cold ambient 4. Check coolant level in the coolant temperatures accompanied with poor reserve/overflow tank and the heater performance. radiator. Inspect system for leaks. Repair leaks as necessary. Refer to the Coolant section of the manual text for WARNINGS and precautions before removing the radiator cap. 5. Improper operation of internal 5. Inspect heater and repair as heater doors or heater controls. necessary. Refer to Group 24, Heating and Air Conditioning for procedures.TEMPERATURE GAUGE READS 1. Trailer is being towed, a steep hill is1. This may be a temporary conditionHIGH OR ENGINE COOLANT being climbed, vehicle is operated in and repair is not necessary. Turn offWARNING LAMP ILLUMINATES. slow moving traffic, or engine is being the air conditioning and attempt toCOOLANT MAY OR MAY NOT BE idled with very high ambient (outside) drive the vehicle without any of theLOST OR LEAKING FROM temperatures and the air conditioning previous conditions. Observe theCOOLING SYSTEM is on. Higher altitudes could aggravate temperature gauge. The gauge these conditions. should return to the normal range. If the gauge does not return to normal range, determine the cause for overheating and repair. Refer to POSSIBLE CAUSES (numbers 2 through 20). 2. Is temperature gauge (if equipped) 2. Check gauge. Refer to Group 8E. reading correctly? Repair as necessary. 3. Is temperature warning lamp (if 3. Check warning lamp operation. equipped) illuminating unnecessarily? Refer to Group 8E. Repair as necessary. 4. Coolant low in coolant reserve/ 4. Check for coolant leaks and repair overflow tank and radiator. as necessary. Refer to Testing Cooling System For Leaks in this group. 5. Pressure cap not installed tightly. If 5. Tighten cap. cap is loose, boiling point of coolant will be lowered. Also refer to the following step 6. 6. Poor seals at radiator cap. 6. (a) Check condition of cap and cap seals. Refer to Radiator Cap. Replace cap if necessary. (b) Check condition of radiator filler neck. If neck is bent or damaged, replace radiator. COOLING SYSTEM DIAGNOSIS
  • 13. XJ COOLING SYSTEM 7 - 13DIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONTEMPERATURE GAUGE READS 7. Coolant level low in radiator but not 7. (a) Check condition of radiator capHIGH OR ENGINE COOLANT in coolant reserve/overflow tank. This and cap seals. Refer to Radiator CapWARNING LAMP ILLUMINATES. means the radiator is not drawing in this group. Replace cap if necessary.COOLANT MAY OR MAY NOT BE coolant from the coolant reserve/ (b) Check condition of radiator fillerLOST OR LEAKING FROM COOLING overflow tank as the engine cools. neck. If neck is bent or damaged,SYTEM (Continued) As the engine cools, a vacuum is replace radiator. formed in the cooling system of the (c) Check the condition of the hose engine and radiator. If radiator cap from the radiator to the coolant tank. It seals are defective, or cooling system should fit tight at both ends without any has leaks, a vacuum can not be kinks or tears. Replace hose if formed. necessary. (d) Check coolant reserve/overflow tank and tank hose for blockage. Repair as necessary. 8. Freeze point of antifreeze not 8. Check antifreeze. Refer to Coolant correct. Mixture may be too rich. section of this group. Adjust antifreeze- to-water ratio as required. 9. Coolant not flowing through system. 9. Check for coolant flow at radiator filler neck with some coolant removed, engine warm and thermostat open. Coolant should be observed flowing through radiator. If flow is not observed, determine reason for lack of flow and repair as necessary. 10. Radiator or A/C condenser fins are 10. Clean insects or debris. Refer to dirty or clogged. Radiator Cleaning in this group. 11. Radiator core is corroded or 11. Have radiator re-cored or replaced. plugged. 12. Aftermarket A/C installed without 12. Install proper radiator. proper radiator. 13. Fuel or ignition system problems. 13. Refer to Fuel and Ignition System groups for diagnosis. Also refer to the appropriate Powertrain Diagnostic Procedures service manual for operation of the DRB scan tool. 14. Dragging brakes. 14. Check and correct as necessary. Refer to Group 5, Brakes in this manual text. 15. Bug screen is being used reducing 15. Remove bug screen. airflow. 16. Thermostat partially or completely 16. Check thermostat operation and shut. This is more prevalent on high replace as necessary. Refer to mileage vehicles. Thermostats in this group. 17. Thermal viscous fan drive not 17. Check fan drive operation and operating properly. replace if necessary. Refer to Viscous Fan Drive in this group. 18. Electric cooling fan not operating 18. Check electric fan operation and properly (XJ models with 4.0L engine repair as necessary. Refer to Auxiliary equipped with heavy duty cooling Electric Cooling Fan-XJ Models with and/or air conditioning). 4.0L 6-cylinder engine in the manual text. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 14. 7 - 14 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONTEMPERATURE GAUGE READS 19. Cylinder head gasket leaking 19. Check for cylinder head gasketHIGH OR ENGINE COOLANT leaks. Refer to Testing Cooling SystemWARNING LAMP ILLUMINATES. for Leaks in this group. For repair referCOOLANT MAY OR MAY NOT BE to Group 9, Engines.LOST OR LEAKING FROM COOLINGSYSTEM (Continued) 20. Heater core leaking. 20. Check heater core for leaks. Refer to Group 24, Heating and Air Conditioning. Repair as necessary.TEMPERATURE GUAGE READING IS 1. On XJ models equipped with a 4.0L 1. A normal condition. No correction isINCONSISTENT (FLUCTUATES, 6-cylinder engine, heavy duty cooling necessary. If gauge cycling is goingCCLES OR IS ERRACTIC) and/or air conditioning, the gauge may into the hot zone, check electric fan cycle up and down. This is due to the operation and repair as necessary. cycling of the electric radiator fan. Refer to Auxiliary Electric Cooling Fan-XJ Models with 4.0L 6-cylinder engine in the manual text. 2. During cold weather operation, with 2. A normal condition. No correction is the heater blower in the high position, necessary. the gauge reading may drop slightly. 3. Temperature gauge or engine 3. Check operation of gauge and repair mounted gauge sensor defective or if necessary. Refer to Group 8E, shorted. Also, corroded or loose wiring Instrument Panel and Gauges. in this circuit. 4. Gauge reading rises when vehicle is 4. A normal condition. No correction is brought to a stop after heavy use necessary. Gauge reading should (engine still running). return to normal range after vehicle is driven. 5. Gauge reading high after restarting a 5. A normal condition. No correction is warmed-up (hot) engine. necessary. The gauge should return to normal range after a few minutes of engine operation. 6. Coolant level low in radiator (air will 6. Check and correct coolant leaks. build up in the cooling system causing Refer to Testing Cooling Sytem for the thermostat to open late). Leaks in this group. 7. Cylinder head gasket leaking 7. (a) Check for cylinder head gasket allowing exhaust gas to enter cooling leaks with a commercially available system causing thermostat to open late. Block Leak Tester. Repair as necessary. (b) Check for coolant in the engine oil. Inspect for white steam emitting from exhaust system. Repair as necessary. 8. Water pump impeller loose on shaft. 8. Check water pump and replace as necessary. Refer to Water Pumps in this group. 9. Loose accessory drive belt (water 9. Refer to Engine Accessory Drive pump slipping). Belts in this group. Check and correct as necessary. 10. Air leak on the suction side of water 10. Locate leak and repair as pump allows air to build up in cooling necessary. system causing thermostat to open late. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 15. XJ COOLING SYSTEM 7 - 15DIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONPRESSURE CAP IS BLOWING OFF 1. Pressure relief valve in radiator cap 1. Check condition of radiator cap andSTEAM AND/OR COOLANT TO is defective. cap seals. Refer to Radiator Caps inCOOLANT TANK. TEMPERATURE this group. Replace cap as necessary.GAUGE READING MAY BE ABOVENORMAL BUT NOT HIGH. COOLANTLEVEL MAY BE HIGH IN COOLANTRESERVE/OVERFLOW TANKCOOLANT LOSS TO THE GROUND 1. Coolant leaks in radiator, cooling 1. Pressure test and repair asWITHOUT PRESSURE CAP system hoses, water pump or engine. necessary. Refer to Testing CoolingBLOWOFF. GAUGE IS READING System for Leaks in this group.HIGH OR HOTDETONATION OR PREIGNITION 1. Engine overheating. 1. Check reason for overheating and(NOT CAUSED BY IGNITION repair as necessary.SYSTEM). GAUGE MAY OR MAYNOT BE READING HIGH 2. Freeze point of antifreeze not 2. Check antifreeze. Refer to the correct. Mixture is too rich or too lean. Coolant section in this group. Adjust antifreeze-to-water ratio as required.HOSE OR HOSES COLLAPSE WHEN 1. Vacuum created in cooling system on 1. (a) Radiator cap relief valve stuck.ENGINE IS COOLING engine cool-down is not being relieved Refer to Radiator Cap in this group. through coolant reserve/overflow Replace if necessary. system. (b) Hose between coolant reserve/ overflow tank and radiator is kinked. Repair as necessary. (c) Vent at coolant reserve/overflow tank is plugged. Clean vent and repair as necessary. (d) Reserve/overflow tank is internally blocked or plugged. Check for blockage and repair as necessary.ELECTRIC RADIATOR FAN RUNS 1. Fan relay, powertrain control module 1. Refer to Auxiliary Electric CoolingALL THE TIME (XJ MODELS WITH (PCM) or engine coolant temperature Fan-XJ Models with 4.0L 6-Cylinder4.0L ENGINE EQUIPPED WITH sensor defective. engine in the manual text. Repair asHEAVY DUTY COOLING AND/OR AIR necessary. Also refer to appropriateCONDITIONING ONLY) Powertrain Diagnostic Procedures service manual for operation of the DRB scan tool.ELECTRIC RADIATOR FAN WILL NOT 1. Fan motor defective. 1. Refer to Auxiliary Electric CoolingRUN (XJ MODELS WITH 4.0L Fan-XJ Models with 4.0L 6-CylinderENGINE EQUIPPED WITH HEAVY engine in the manual text. Repair asDUTY COOLING AND/OR AIR necessary.CONDITIONING ONLY) GAUGE 2. Fan relay, powertrain control module 2. Refer to Auxiliary Electric CoolingREADING HIGH OR HOT (PCM) or engine coolant temperature Fan-XJ Models with 4.0L 6-Cylinder sensor defective. engine in the manual text. Repair as necessary. Also refer to the appropriate Powertrain Diagnostic Procedures service manual for operation of the DRB scan tool 3. Blown fuse in power distribution 3. Determine reason for blown fuse center (PDC). and repair as necessary. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 16. 7 - 16 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONNOISY FAN 1. Fan blades loose. Replace fan blade assembly. Refer to Cooling System Fans in this group. 2. Fan blades striking a surrounding 2. Locate point of fan blade contact object. and repair as necessary. 3. Air obstructions at radiator or air 3. Remove obstructions and/or clean conditioning condenser. debris or insects from radiator or A/C condenser. 4. Electric fan motor defective (if 4. Replace electric fan motor. Refer to equipped). Auxiliary Electric Cooling Fan-XJ Models with 4.0L 6-Cylinder engine in the manual text. 5. Thermal viscous fan drive has 5. Replace fan drive. Bearing is not defective bearing. serviceable. Refer to Viscous Fan Drive in this group. 6. A certain amount of fan noise 6. Refer to Viscous Fan Drive in this (roaring) may be evident on models group for an explanation of normal fan equipped with a thermal viscous fan noise. drive. Some of this noise is normal.INADEQUATE AIR CONDITIONER 1. Radiator and/or A/C condenser is 1. Remove restriction and/or clean asPERFORMANCE (COOLING SYSTEM restricted, obstructed or dirty (insects, necessary. Refer to Radiator CleaningSUSPECTED) leaves etc.). in this group. 2. Electric radiator fan not operating 2. Refer to Auxiliary Electric Cooling when A/C is operated (if equipped with Fan-XJ Models with 4.0L 6-Cylinder electric fan). engine in the manual text. Repair as necessary. 3. Thermal viscous fan drive is 3. Refer to Viscous Fan Drive for freewheeling. diagnosis. Repair as necessary. 4. Engine is overheating (heat may be 4. Correct overheating condition. Refer transferred from radiator to A/C to text in Group 7, Cooling. condenser. High underhood temperatures due to engine overheating may also transfer heat to A/C components). 5. Some models with certain engines 5. Check for missing or damaged air are equipped with air seals at the seals and repair as necessary. radiator and/or A/C condenser. If these seals are missing or damaged, not enough air flow will be pulled through the radiator and A/C condenser.INADEQUATE HEATER 1. Has a diagnostic trouble code (DTC) 1. Refer to On-Board Diagnostics inPERFORMANCE. THERMOSTAT number 17 been set? the manual text and replace thermostatFAILED IN OPEN POSITION if necessary. 2. Coolant level low. 2. Refer to Testing Cooling System for Leaks in the manual text. Repair as necessary. 3. Obstructions in heater hose fittings at 3. Remove heater hoses at both ends engine. and check for obstructions. Repair as necessary. 4. Heater hose kinked. 4. Locate kinked area and repair as necessary. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 17. XJ COOLING SYSTEM 7 - 17DIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONINADEQUATE HEATER 5. Some models with certain engines 5. Refer to Group 24, Heating andPERFORMANCE. THERMOSTAT are equipped with a water control Air Conditioning for diagnosis. RepairFAILED IN OPEN POSITION valve located on one of the heater as necessary.(Continued) hoses. This valve may be defective. 6. Water pump is not pumping water 6. Refer to Water Pumps in this to heater core. When the engine is group. Repair as necessary. If a fully warmed up, both heater hoses slipping belt is detected, refer to should be hot to the touch. If only Engine Accessory Drive Belts in this one of the hoses is hot, the water group. Repair as necessary. pump may not be operating correctly. The accessory drive belt may also be slipping causing poor water pump operation.HEAT ODOR 1. Various heat shields are used at 1. Locate missing shields and certain drive line components. One or replace or repair as necessary. more of these shields may be missing. 2. Is temperature gauge reading 2. Refer to the previous Temperature above the normal range? Gauge Reads High in these Diagnosis Charts. Repair as necessary. 3. Is cooling fan operating correctly? 3. Refer to Cooling System Fan in this group for diagnosis. Repair as necessary. 4. Has undercoating been applied to 4. Clean undercoating as necessary. any unnecessary component? 5. Engine may be running rich 5. Refer to the DRB scan tool and causing the catalytic convertor to the appropriate Powertrain overheat. Diagnostic Procedures service manual. Repair as necessary.POOR DRIVEABILITY 1. For proper driveability, good 1. Refer to On-Board Diagnostics in(THERMOSTAT POSSIBLY STUCK vehicle emissions and for preventing this group. DTC’s may also beOPEN) GAUGE READING MAY BE build-up of engine oil sludge, the checked using the DRB scan tool.LOW thermostat must be operating Refer to the proper Powertrain properly. Has a diagnostic trouble Diagnostics Procedures service code (DTC) number 17 been set? manual for checking the thermostat using the DRB scan tool. Replace thermostat if necessary.STEAM IS COMING FROM FRONT 1. During wet weather, moisture 1. Occasional steam emitting fromOF VEHICLE NEAR GRILL AREA (snow, ice or rain condensation) on this area is normal. No repair isWHEN WEATHER IS WET, ENGINE the radiator will evaporate when the necessary.IS WARMED UP AND RUNNING, thermostat opens. This openingAND VEHICLE IS STATIONARY. allows heated water into the radiator.TEMPERATURE GAUGE IS IN When the moisture contacts the hotNORMAL RANGE radiator, steam may be emitted. This usually occurs in cold weather with no fan or airflow to blow it away. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 18. 7 - 18 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued) CONDITION POSSIBLE CAUSES CORRECTIONCOOLANT COLOR 1. Coolant color is not necessarily an 1. Refer to Coolant in this group for indication of adequate corrosion or antifreeze tests. Adjust antifreeze-to- temperature protection. Do not rely water ratio as necessary. on coolant color for determining condition of coolant.COOLANT LEVEL CHANGES IN 1. Level changes are to be expected 1. A normal condition. No repair isCOOLANT RESERVE/OVERFLOW as coolant volume fluctuates with necessary.TANK. TEMPERATURE GAUGE IS engine temperature. If the level in theIN NORMAL RANGE tank was between the FULL and ADD marks at normal engine operating temperature, the level should return to within that range after operation at elevated temperatures. COOLING SYSTEM DIAGNOSIS (CONT.)
  • 19. TYPICAL COOLINGTESTER PRESSURE SYTEM TYPICAL BLACK LIGHT TOOLXJ COOLING SYSTEM 7 - 19DIAGNOSIS AND TESTING (Continued)RADIATOR COOLANT FLOW CHECK WARNING: HOT, PRESSURIZED COOLANT CAN The following procedure will determine if coolant is CAUSE INJURY BY SCALDING.flowing through the cooling system. If engine is cold, idle engine until normal operating Carefully remove the radiator pressure cap fromtemperature is reached. Then feel the upper radiator the filler neck and check the coolant level. Pushhose. If hose is hot, the thermostat is open and water down on the cap to disengage it from the stop tabs.is circulating through cooling system. Wipe the inner part of the filler neck and examine the lower inside sealing seat for nicks, cracks, paint,TESTING COOLING SYSTEM FOR LEAKS dirt and solder residue. Inspect the reserve/overflow tank tube for internal obstructions. Insert a wireULTRAVIOLET LIGHT METHOD through the tube to be sure it is not obstructed. All Jeep models have a leak detection additive Inspect the cams on the outside part of the filleradded to the cooling system before they leave the fac- neck. If the cams are bent, seating of pressure captory. The additive is highly visible under ultraviolet valve and tester seal will be affected. Replace cap iflight (black light). If the factory original coolant has cams are bent.been drained, pour one ounce of additive into the Attach pressure tester 7700 (or an equivalent) tocooling system. The additive is available through the the radiator filler neck (Fig. 13).part’s department. Place the heater control unit inHEAT position. Start and operate the engine untilthe radiator upper hose is warm to the touch. Aimthe commercially available black light tool at thecomponents to be checked. If leaks are present, theblack light will cause the additive to glow a brightgreen color. The black light can be used along with a pressuretester to determine if any external leaks exist (Fig.12). Fig. 13 Pressurizing System—Typical Operate the tester pump to apply 124 kPa (18 psi) pressure to the system. If the hoses enlarge exces- sively or bulge while testing, replace as necessary. Observe the gauge pointer and determine the condi- tion of the cooling system according to the following criteria: • Holds Steady: If the pointer remains steady for two minutes, there are no serious coolant leaks in the system. However, there could be an internal leak that does not appear with normal system test pres- sure. Inspect for interior leakage or do the Internal Leakage Test. Do this if it is certain that coolant is being lost and no leaks can be detected. • Drops Slowly: Shows a small leak or seepage is occurring. Examine all connections for seepage or Fig. 12 Leak Detection Using Black Light—Typical slight leakage with a flashlight. Inspect the radiator,PRESSURE TESTER METHOD hoses, gasket edges and heater. Seal any small leak The engine should be at the normal operating tem- holes with a Sealer Lubricant or equivalent. Repairperature. Recheck the system cold if the cause of leak holes and reinspect the system with pressurecoolant loss is not located during warm engine exam- applied.ination. • Drops Quickly: Shows that a serious leakage is occurring. Examine the system for serious external
  • 20. 7 - 20 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)leakage. If no leaks are visible, inspect for internal Drain sufficient coolant to allow for thermostatleakage. Large radiator leak holes should be repaired removal. Refer to Thermostat Replacement. Discon-by a reputable radiator repair shop. nect the water pump drive belt. Disconnect the upper radiator hose from the ther-INTERNAL LEAKAGE INSPECTION mostat housing. Remove the housing and thermostat. Remove the engine oil pan drain plug and drain a Install the thermostat housing.small amount of engine oil. Coolant, being heavier Add coolant to the radiator to bring the level tothan engine oil, will drain first. Another way of test- within 6.3 mm (1/4 in) of the top of the thermostating is to operate the engine and check for water glob- housing.ules on the engine oil dipstick. Also inspect theautomatic transmission oil dipstick for water glob- CAUTION: Avoid overheating. Do not operate theules. Inspect the automatic transmission fluid cooler engine for an excessive period of time. Open thefor leakage. Operate the engine without the pressure draincock immediately after the test to eliminatecap on the radiator until thermostat opens. boil over of coolant. Attach a pressure tester to the filler neck. If pres-sure builds up quickly, a leak exists as a result of a Start the engine and accelerate rapidly three timesfaulty cylinder head gasket or crack in the engine. (to approximately 3000 rpm) while observing theRepair as necessary. coolant. If internal engine combustion gases are leak- ing into the cooling system, bubbles will appear inWARNING: DO NOT ALLOW PRESSURE TO the coolant. If bubbles do not appear, there is noEXCEED 124 KPA (18 PSI). TURN THE ENGINE OFF. internal combustion gas leakage.TO RELEASE THE PRESSURE, ROCK THE TESTERFROM SIDE TO SIDE. WHEN REMOVING THE VISCOUS FAN DRIVETESTER, DO NOT TURN THE TESTER MORE THAN1/2 TURN IF THE SYSTEM IS UNDER PRESSURE. LEAKS Viscous fan drive operation is not affected by small If there is no immediate pressure increase, pump oil stains near the drive bearing. If leakage appearsthe pressure tester until the indicated pressure is excessive, replace the fan drive unit.within the system range. Vibration of the gaugepointer indicates compression or combustion leakage TESTINGinto the cooling system. If the fan assembly free-wheels without drag (the fan blades will revolve more than five turns whenWARNING: DO NOT DISCONNECT THE SPARK spun by hand), replace the fan drive. This spin testPLUG WIRES WHILE THE ENGINE IS OPERATING. must be performed when the engine is cool. For the following test, the cooling system must be in good condition. It also will ensure against exces-CAUTION: Do not operate the engine with a spark sively high coolant temperature.plug shorted for more than a minute. The catalyticconverter may be damaged. WARNING: BE SURE THAT THERE IS ADEQUATE FAN BLADE CLEARANCE BEFORE DRILLING. Isolate the compression leak by shorting eachspark plug to the cylinder block. The gauge pointer (1) Drill a 3.18-mm (1/8-in) diameter hole in theshould stop or decrease vibration when spark plug top center of the fan shroud.for leaking cylinder is shorted. This happens because (2) Obtain a dial thermometer with an 8 inch stemof the absence of combustion pressure. (or equivalent). It should have a range of -18°-to- 105°C (0°-to-220° F). Insert thermometer through theCOMBUSTION LEAKAGE TEST (WITHOUT hole in the shroud. Be sure that there is adequatePRESSURE TESTER) clearance from the fan blades. DO NOT WASTE reusable coolant. If the solution (3) Connect a tachometer and an engine ignitionis clean, drain the coolant into a clean container for timing light (timing light is to be used as a strobereuse. light). (4) Block the air flow through the radiator. SecureWARNING: DO NOT REMOVE THE CYLINDER a sheet of plastic in front of the radiator (or air con-BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR ditioner condenser). Use tape at the top to secure theDRAINCOCK WITH THE SYSTEM HOT AND UNDER plastic and be sure that the air flow is blocked.PRESSURE. SERIOUS BURNS FROM COOLANT (5) Be sure that the air conditioner (if equipped) isCAN OCCUR. turned off.
  • 21. VACUUM VENT VALVE (SHOWN IN SEAL- ING POSITION) PRESSURE RATING SEAL PRESSURE VALVE FILLER NECKXJ COOLING SYSTEM 7 - 21DIAGNOSIS AND TESTING (Continued)WARNING: USE EXTREME CAUTION WHEN THE SHOULD NOT BE REMOVED WHILE THE SYSTEMENGINE IS OPERATING. DO NOT STAND IN A IS HOT AND/OR UNDER PRESSURE.DIRECT LINE WITH THE FAN. DO NOT PUT YOURHANDS NEAR THE PULLEYS, BELTS OR FAN. DONOT WEAR LOOSE CLOTHING. (6) Start the engine and operate at 2400 rpm.Within ten minutes the air temperature (indicated onthe dial thermometer) should be up to 88° C (190° F).Fan drive engagement should have started to occurat between 74° to 82° C (165° to 180° F). Engage-ment is distinguishable by a definite increase in fanflow noise (roaring). The timing light also will indi-cate an increase in the speed of the fan. (7) When the air temperature reaches 88° C (190°F), remove the plastic sheet. Fan drive disengage-ment should have started to occur at between 57° to79° C (135° to 175° F). A definite decrease of fanflow noise (roaring) should be noticed. If not, replacethe defective viscous fan drive unit.AUXILIARY ELECTRIC COOLING FANELECTRIC COOLING FAN AND RELAYDIAGNOSISNOTE: Refer to Electrical Group 8W for electriccooling fan and relay circuit schematic. The powertrain control module (PCM) will enter adiagnostic trouble code (DTC) in memory if it detectsa problem in the auxiliary cooling fan relay or circuit. Fig. 14 Radiator Pressure CapRefer to Group 25, Emission Control Systems for cor- There is no need to remove the radiator caprect DTC retrieval procedures. except for the following purposes: If the electric cooling fan is inoperative, check fuse (1) To check and adjust antifreeze freeze point.#11 (20A) in junction block and fuse #5 (40A maxi- (2) To refill system with new antifreeze.fuse) in the Power Distribution Center (PDC) with a (3) For conducting service procedures.12 volt test lamp or DVOM. If fuses are o.k., refer to (4) When checking for vacuum leaks.Group 8W for electric cooling fan and relay circuitschematic. WARNING: IF VEHICLE HAS BEEN RUN RECENTLY, WAIT AT LEAST 15 MINUTES BEFORERADIATOR CAP-TO-FILLER NECK SEAL— REMOVING RADIATOR CAP. WITH A RAG,PRESSURE RELIEF CHECK SQUEEZE RADIATOR UPPER HOSE TO CHECK IF With radiator cap installed on filler neck, remove SYSTEM IS UNDER PRESSURE. PLACE A RAGcoolant reserve/ overflow tank hose from nipple on OVER THE CAP AND WITHOUT PUSHING DOWN,filler neck. Connect a hand operated vacuum pump ROTATE CAP COUNTER-CLOCKWISE TO THEto nipple. Operate pump until a reading of 47-to-61 FIRST STOP. ALLOW FLUID TO ESCAPE THROUGHkPa (14- to-18 in. Hg) appears on gauge. If the read- OVERFLOW HOSE INTO COOLANT RESERVE/ing stays steady, or drops slightly and then remains OVERFLOW TANK. SQUEEZE RADIATOR UPPERsteady, the pressure valve seal is good. Replace radi- HOSE TO DETERMINE WHEN PRESSURE HASator cap if reading does not hold. BEEN RELEASED. WHEN COOLANT AND STEAM STOP BEING PUSHED INTO TANK AND SYSTEMWARNING: THE WARNING WORDS -DO NOT OPEN PRESSURE DROPS, REMOVE RADIATOR CAPHOT- ON THE RADIATOR PRESSURE CAP (Fig. 14) COMPLETELY.ARE A SAFETY PRECAUTION. WHEN HOT, PRES-SURE BUILDS UP IN COOLING SYSTEM. TO PRE-VENT SCALDING OR INJURY, THE RADIATOR CAP
  • 22. 7 - 22 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)PRESSURE TESTING RADIATOR CAPS Low coolant level can cause thermostat pellet to be Remove cap from radiator. Be sure that sealing suspended in air instead of coolant. This will causesurfaces are clean. Moisten rubber gasket with water thermostat to open later, which in turn causes higherand install the cap on pressure tester (tool 7700 or coolant temperature. Air trapped in cooling systeman equivalent) (Fig. 15). also reduces amount of coolant circulating in heater core resulting in low heat output. DEAERATION As the engine operates, any air trapped in cooling system gathers under the radiator cap. The next time the engine is operated, thermal expansion of coolant will push any trapped air past radiator cap into the coolant reserve/overflow tank. Here it escapes to the atmosphere into the tank. When the engine cools down the coolant, it will be drawn from the reserve/ overflow tank into the radiator to replace any removed air. SERVICE PROCEDURES COOLANT LEVEL CHECK—ROUTINE NOTE: Do not remove radiator cap for routine coolant level inspections. The coolant level can be checked at coolant reserve/overflow tank. The coolant reserve/overflow system provides a Fig. 15 Pressure Testing Radiator Pressure quick visual method for determining coolant level Cap—Typical without removing radiator pressure cap. With engine Operate the tester pump and observe the gauge cold and not running, observe coolant level inpointer at its highest point. The cap release pressure reserve/overflow tank. The coolant level should beshould be 83-to-110 kPa (12-to-16 psi). The cap is sat- between ADD and FULL marks.isfactory when the pressure holds steady. It is alsogood if it holds pressure within the 83-to-110 kPa COOLANT SERVICE(12-to-16 psi) range for 30 seconds or more. If the It is recommended that the cooling system bepointer drops quickly, replace the cap. drained and flushed at 84,000 kilometers (52,500 miles), or 3 years, whichever occurs first. Then everyCAUTION: Radiator pressure testing tools are very two years, or 48,000 kilometers (30,000 miles),sensitive to small air leaks, which will not cause whichever occurs first.cooling system problems. A pressure cap that doesnot have a history of coolant loss should not be ADDING ADDITIONAL COOLANT—ROUTINEreplaced just because it leaks slowly when tested Do not remove radiator cap to add coolant towith this tool. Add water to tool. Turn tool upside system. When adding coolant to maintain correctdown and recheck pressure cap to confirm that cap level, do so at coolant reserve/overflow tank. Use aneeds replacement. 50/50 mixture of ethylene-glycol antifreeze containing Alugard 340-2 ௢ and low mineral content water. CAP INSPECTION Remove radiator cap only for testing or when refill- Visually inspect the pressure valve gasket on the ing system after service. Removing cap unnecessarilycap. Replace cap if the gasket is swollen, torn or can cause loss of coolant and allow air to enter sys-worn. Inspect the area around radiator filler neck for tem, which produces corrosion.white deposits that indicate a leaking cap. COOLANT LEVEL CHECK—SERVICELOW COOLANT LEVEL-AERATION The cooling system is closed and designed to main- If the coolant level in radiator drops below top of tain coolant level to top of radiator.radiator core tubes, air will enter cooling system.
  • 23. RADIATOR PETCOCKXJ COOLING SYSTEM 7 - 23SERVICE PROCEDURES (Continued)WARNING: DO NOT OPEN RADIATOR DRAINCOCKWITH ENGINE RUNNING OR WHILE ENGINE IS HOTAND COOLING SYSTEM IS UNDER PRESSURE. When vehicle servicing requires a coolant levelcheck in radiator, drain several ounces of coolantfrom radiator drain cock. Do this while observingcoolant reserve/overflow system tank. The coolantlevel in reserve/overflow tank should drop slightly. Ifnot, inspect for a leak between radiator and coolantreserve/overflow system connection. Remove radiatorcap. The coolant level should be to top of radiator. Ifnot and if coolant level in reserve/overflow tank is atADD mark, check for: • An air leak in coolant reserve/overflow tank orits hose • An air leak in radiator filler neck • Leak in pressure cap seal to radiator filler neckDRAINING AND FILLING COOLING SYSTEM Fig. 16 Radiator Petcock—4.0L (LHD/RHD)DRAINING 2.5L 4-CYLINDER ENGINE a clean container. Open draincock and drain coolant from radiator.WARNING: DO NOT REMOVE THE CYLINDER BLOCK (4) Drain coolant from engine by removing theDRAIN PLUGS OR LOOSEN THE RADIATOR DRAIN- drain plug and coolant temperature sensor on leftCOCK WITH SYSTEM HOT AND UNDER PRESSURE. side of block.SERIOUS BURNS FROM COOLANT CAN OCCUR. REFILLING COOLING SYSTEM DO NOT WASTE reusable coolant. If the solution (1) Tighten the radiator petcock and the cylinderis clean, drain the coolant into a clean container for block drain plug(s). If removed, install coolant tem-reuse. perature sensor (4.0L 6-cylinder engine). DO NOT remove the radiator cap when draining (2) Fill system using a 50/50 mixture of water andthe coolant from the reserve/overflow tank. Open the antifreeze as described in the Coolant section of thisradiator draincock and when the tank is empty, group. Fill radiator to top and install radiator cap.remove the radiator cap. The coolant does not have Add sufficient coolant to reserve/overflow tank toto be removed from the tank unless the system is raise level to FULL mark.being refilled with a fresh mixture. (3) With heater control unit in the HEAT position, (1) Drain the coolant from the radiator by loosen- operate engine with radiator cap in place.ing the petcock. (4) After engine has reached normal operating (2) Drain coolant from engine by removing drain temperature, shut engine off and allow it to cool.plug at left rear side of block. (5) Add coolant to reserve/overflow tank as neces- sary. Only add coolant when the engine is cold.DRAINING 4.0L 6-CYLINDER ENGINE Coolant level in a warm engine will be higher due to thermal expansion.WARNING: DO NOT REMOVE THE CYLINDER BLOCKDRAIN PLUGS OR LOOSEN THE RADIATOR DRAIN- REVERSE FLUSHINGCOCK WITH SYSTEM HOT AND UNDER PRESSURE.SERIOUS BURNS FROM COOLANT CAN OCCUR. CAUTION: The cooling system normally operates at 97-to-124 kPa (14- to-18 psi) pressure. Exceeding DO NOT WASTE reusable coolant. If the solution this pressure may damage the radiator or hoses.is clean, drain the coolant into a clean container forreuse. Reverse flushing of the cooling system is the forc- (1) Remove radiator pressure cap. ing of water through the cooling system. This is done (2) For access to radiator draincock (Fig. 16), using air pressure in the opposite direction of normalremove radiator grille mounting screws and remove coolant flow. It is usually only necessary with verygrill. Refer to Group 23, Body for correct procedure. dirty systems with evidence of partial plugging. (3) Attach one end of a 24 inch long X 1/4 inch IDhose to the radiator draincock. Put the other end into
  • 24. AIR CONDENSER ING CONDITION- HOSEMOUNTING BOLT CLAMPS (2) MOUNTING BOLT AUXILIARY AUTOMATIC TRANSMIS- SION OIL COOLER7 - 24 COOLING SYSTEM XJSERVICE PROCEDURES (Continued)CHEMICAL CLEANING REMOVAL AND INSTALLATION If visual inspection indicates the formation of sludge orscaly deposits, use a radiator cleaner (Mopar Radiator TRANSMISSION OIL COOLERSKleen or equivalent) before flushing. This will softenscale and other deposits and aid the flushing operation. WATER-TO-OIL COOLER The internal transmission oil cooler located withinCAUTION: Be sure instructions on the container the radiator is not serviceable. If it requires service,are followed. the radiator must be replaced. Once the repaired or replacement radiator has been installed, fill the cooling system and inspect for leaks.REVERSE FLUSHING RADIATOR Refer to the Refilling Cooling System and Testing Cool- Disconnect the radiator hoses from the radiator fit- ing System For Leaks sections in this group. If thetings. Attach a section of radiator hose to the radia- transmission operates properly after repairing the leak,tor bottom outlet fitting and insert the flushing gun. drain the transmission and remove the transmission oilConnect a water supply hose and air supply hose to pan. Inspect for sludge and/or rust. Inspect for a dirtythe flushing gun. or plugged inlet filter. If none of these conditions areCAUTION: The cooling system normally operates found, the transmission and torque convertor may notat 97-to-124 kPa (14- to-18 psi) pressure. Exceeding require reconditioning. Refer to Group 21 for automaticthis pressure may damage the radiator or hoses. transmission servicing. Allow the radiator to fill with water. When radiator AIR-TO-OIL COOLERis filled, apply air in short blasts allowing radiator to REMOVALrefill between blasts. Continue this reverse flushinguntil clean water flows out through rear of radiator (1) Remove the grill mounting screws and removecooling tube passages. For more information, refer to the grill. Refer to Group 23, Body for procedures.operating instructions supplied with flushing equip- (2) Place a drain pan below the transmission oilment. Have radiator cleaned more extensively by a cooler.radiator repair shop. (3) Remove the two hose clamps at oil cooler inlet and outlet tubes.REVERSE FLUSHING ENGINE (4) Remove the two oil cooler mounting bolts (Fig. Drain the cooling system. Remove the thermostat 17) (Fig. 18).housing and thermostat. Install the thermostat hous- (5) Remove the oil cooler from vehicle.ing. Disconnect the radiator upper hose from theradiator and attach the flushing gun to the hose. Dis-connect the radiator lower hose from the waterpump. Attach a lead away hose to the water pumpinlet fitting.CAUTION: Be sure that the heater control valve isclosed (heat off). This is done to prevent coolantflow with scale and other deposits from enteringthe heater core. Connect the water supply hose and air supply hoseto the flushing gun. Allow the engine to fill withwater. When the engine is filled, apply air in shortblasts, allowing the system to fill between air blasts.Continue until clean water flows through the leadaway hose. For more information, refer to operatinginstructions supplied with flushing equipment. Remove the lead away hose, flushing gun, water sup-ply hose and air supply hose. Remove the thermostathousing and install thermostat. Install the thermostathousing with a replacement gasket. Refer to ThermostatReplacement. Connect the radiator hoses. Refill the Fig. 17 Auxiliary Air-To-Oil Cooler—4.0L Enginecooling system with the correct antifreeze/water mix-ture.
  • 25. AUTO. TRANS. OIL COOLER HOSECLAMPS MOUNTING BOLTS FRONT TUBECLAMP TO RADI- MOUNTING BOLTS ATOR LOWER BRACKET RESERVE/OVER- TO COOLANTTUBETANK OVERFLOW CLAMP RESERVE/RADI- TOR MOUNTING A FLOW BOLTS TANKXJ COOLING SYSTEM 7 - 25REMOVAL AND INSTALLATION (Continued) Fig. 18 Auxiliary Air-To-Oil Cooler2.5L Engine Fig. 19 Reserve/Overflow Tank—Except Right HandINSTALLATION Drive (1) Position and secure oil cooler to vehicle.Tighten mounting bolts to 8 N·m (72 in. lbs.) torque. (2) Secure inlet and outlet tubes with hose clamps.Tighten the two clamps to 2 N·m (15 in. lbs.) torque.COOLANT RESERVE TANKREMOVAL (1) Remove the tube clamp at the tank and removetube. (2) Remove the tank mounting bolts and removetank (Fig. 19) (Fig. 20).INSTALLATION (1) Position tank and tighten to 2 N·m (17 in. lbs.)torque. (2) Position tube and secure clamp.WATER PUMPCAUTION: If the water pump is replaced becauseof mechanical damage, the fan blades and viscousfan drive should also be inspected. These compo- Fig. 20 Reserve/Overflow Tank—With Right Handnents could have been damaged due to excessive Drivevibration. years, depending upon application, may be The water pump can be removed without discharg- equipped with a forward (clockwise) rotating watering the air conditioning system (if equipped). pump. Installation of the wrong water pump will cause engine over heating.CAUTION: All engines have a reverse (counter-clockwise) rotating water pump. The letter R is The water pump impeller is pressed on the rear ofstamped into the back of the water pump impeller the pump shaft and bearing assembly. The water(Fig. 21) to identify. Engines from previous model pump is serviced only as a complete assembly.
  • 26. R STAMPED INTO IMPELLER COUS THERMAL DRIVE (4) FAN BLADE-TO-VISCOUS (4) FAN HUB-TO-PUMP LEY PUMP FAN VIS- (4) PUMP PULLEY BOLTS FAN INTAKEBRACKET WATER PUMP ASSEMBLY 2.5L DRIVE NUTS PUMP MANIFOLD BLADEPUMP WATER HUB-TO- FAB PUL- PULLEY STUDS7 - 26 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) Fig. 21 Reverse Rotating Water Pump—Typical Fig. 22 Fan Mounting NutsWARNING: DO NOT REMOVE THE BLOCK DRAINPLUG(S) OR LOOSEN RADIATOR DRAINCOCKWITH THE SYSTEM HOT AND UNDER PRESSURE.SERIOUS BURNS FROM COOLANT CAN OCCUR. DO NOT WASTE reusable coolant. If the solutionis clean, drain coolant into a clean container forreuse.REMOVAL-2.5L ENGINE (LHD/RHD) (1) Disconnect negative battery cable at battery. (2) Drain the cooling system. (3) Remove upper radiator hose. (4) Loosen (but do not remove at this time) thefour fan hub-to-water pump pulley mounting nuts(Fig. 22). (5) Remove accessory drive belt (refer to AccessoryDrive Belt, Removal and Installation in this section) Fig. 23 Power Steering Pump Attachment-2.5L (6) Unbolt fan shroud (7) Remove the four fan hub-to-water pump pulley ket. Note that one of the four bolts is longer than thenuts and remove fan and shroud together other bolts. (11) If pump is to be replaced, the heater hose fit-CAUTION: After removing fan blade/viscous fan ting must be removed. Note position of fitting beforedrive assembly, do not place thermal viscous fan removal.drive in horizontal position. If stored horizontally,silicone fluid in viscous fan drive could drain into INSTALLATION-2.5L ENGINE (LHD/RHD)its bearing assembly and contaminate lubricant. (1) If pump is being replaced, install the heater hose fitting to the pump. Use a sealant on the fitting (8) Remove power steering pump and bracket (Fig. such as Mopar௢ Thread Sealant With Teflon. Refer23), refer to Group 19 Steering for correct procedure. to the directions on the package. (9) Remove lower radiator hose from water pump. (2) Clean the gasket mating surfaces. If the origi-Remove heater hose from water pump fitting. nal pump is used, remove any deposits or other for- (10) Remove the four pump mounting bolts (Fig. eign material. Inspect the cylinder block and water24) and remove pump from vehicle. Discard old gas- pump mating surfaces for erosion or damage from cavitation.
  • 27. BOLTS PULLEY (4) LONG BOLT MOUNTING SHORT (3) LOWER VENT HOLE STUDS HEATER WATERFITTING UPPER VENT GAS- PUMP PUMP HOSE HOLE KET PUMP PULLEY WATER PUMP HUB BOLTS (4)XJ COOLING SYSTEM 7 - 27REMOVAL AND INSTALLATION (Continued) (10) Install upper radiator hose. (11) Fill cooling system with coolant and check for leaks. Refer to Refilling Cooling System in this group. (12) Connect battery cable to battery. (13) Start and warm the engine. Check for leaks. REMOVAL-4.0L ENGINE (LHD/RHD) (1) Disconnect negative battery cable at battery. (2) Drain the cooling system. (3) Disconnect electric cooling fan connector. (4) Remove electric cooling fan/shroud assembly (if equipped). (5) Unbolt viscous fan shroud. (6) Loosen (but do not remove at this time) the four water pump pulley-to-water pump hub mounting bolts (Fig. 25) and the four viscous fan to idler pulley nuts. Fig. 24 Water Pump Remove/Install—Typical (3) Install the gasket and water pump. The sili-cone bead on the gasket should be facing the waterpump. Also, the gasket is installed dry. Tightenmounting bolts to 30 N·m (22 ft. lbs.) torque. Rotatethe shaft by hand to be sure it turns freely. (4) Connect the radiator and heater hoses to the Fig. 25 Water Pump Pulley Boltswater pump. NOTE: The engine accessory drive belt must be (5) Install power steering pump and bracket. Refer removed prior to removing the fan (if installed atto Group 19, Steering. pump) or fan pulley. (6) Position water pump pulley to water pumphub. (7) Remove accessory drive belt (refer to Accessory (7) Install shroud and fan together and install four Drive Belt, Removal and Installation in this section)nuts to water pump hub studs. Tighten nuts to 27 (8) Remove the four viscous fan to idler pulleyN·m (20 ft. lbs.) torque. nuts and remove the fan and shroud together. (8) Install and tighten upper fan shroud nuts. CAUTION: After removing fan blade/viscous fanCAUTION: When installing the serpentine engine drive assembly, do not place thermal viscous fanaccessory drive belt, the belt MUST be routed cor- drive in horizontal position. If stored horizontally,rectly. If not, the engine may overheat due to the silicone fluid in viscous fan drive could drain intowater pump rotating in the wrong direction. Refer to its bearing assembly and contaminate lubricant.the Belt Removal and Installation in this group forappropriate belt routing. You may also refer to the (9) Remove the four water pump pulley bolts andBelt Routing Label in the vehicle engine compart- remove the pulley.ment. (10) Remove power steering pump and bracket (Fig. 26), refer to Group 19 Steering. (9) Install and tension accessory drive belt, refer to (11) Remove lower radiator hose from water pump.Accessory Drive Belt removal and installation in this Remove heater hose from water pump fitting.group.
  • 28. BOLTS PULLEY (4) LONG BOLT MOUNTING SHORT (3) LOWER VENT HOLE STUDS HEATER WATERFITTING UPPER VENT GAS- PUMP PUMP HOSE HOLE KET7 - 28 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) Fig. 26 Power Steering Pump Attachment-4.0L (12) Remove the four pump mounting bolts (Fig. (13) If pump is to be replaced, the heater hose fit-27) and remove pump from vehicle. Discard old gas- ting must be removed. Note position of fitting beforeket. Note that one of the four bolts is longer than the removal.other bolts. INSTALLATION-4.0L ENGINE (LHD/RHD) (1) If pump is being replaced, install the heater hose fitting to the pump. Use a sealant on the fitting such as Mopar௢ Thread Sealant With Teflon. Refer to the directions on the package. (2) Clean the gasket mating surfaces. If the origi- nal pump is used, remove any deposits or other for- eign material. Inspect the cylinder block and water pump mating surfaces for erosion or damage from cavitation. (3) Install the gasket and water pump. The sili- cone bead on the gasket should be facing the water pump. Also, the gasket is installed dry. Tighten mounting bolts to 30 N·m (22 ft. lbs.) torque. Rotate the shaft by hand to be sure it turns freely. (4) Connect the radiator and heater hoses to the water pump. (5) Position water pump pulley to water pump hub. (6) Install four pump pulley bolts. Tighten bolts (or nuts) to 27 N·m (20 ft. lbs.) torque. (7) Install power steering pump. Refer to Group 19, Steering for proper procedure and torque values. (8) Install the viscous fan and shroud together. Install the four fan to idler pulley nuts and tighten to 27 N·m (20 ft. lbs.). Fig. 27 Water Pump Remove/Install—Typical
  • 29. LONG SHORT BOLT BOLT GASKET THERMOSTAT HOUSING THERMOSTATXJ COOLING SYSTEM 7 - 29REMOVAL AND INSTALLATION (Continued)CAUTION: When installing the serpentine engine (4) Remove thermostat housing mounting bolts,accessory drive belt, the belt MUST be routed cor- thermostat housing, gasket and thermostat (Fig. 28).rectly. If not, the engine may overheat due to the Discard old gasket.water pump rotating in the wrong direction. Refer tothe Belt Removal and Installation in this group forappropriate belt routing. You may also refer to theBelt Routing Label in the vehicle engine compart-ment. (9) Install and tighten viscous fan shroud bolts. (10) Install and tension the accessory drive belt,refer to Accessory Drive Belt removal and installa-tion in this group. (11) Install the electric cooling fan/shroud assy. (12) Install and tighten fan shroud bolts and con-nect electrical fan connector. (13) Fill cooling system with coolant and check forleaks. Refer to Refilling Cooling System in thisgroup. (14) Connect battery cable to battery. (15) Start and warm the engine. Check for leaks.THERMOSTATREMOVALWARNING: DO NOT LOOSEN THE RADIATOR Fig. 28 Thermostat Removal/InstallationDRAINCOCK WITH THE SYSTEM HOT AND PRES- (5) Clean the gasket mating surfaces.SURIZED. SERIOUS BURNS FROM THE COOLANTCAN OCCUR. INSTALLATION (1) Install the replacement thermostat so that the DO NOT WASTE reusable coolant. If the solution pellet, which is encircled by a coil spring, faces theis clean, drain the coolant into a clean container for engine. All thermostats are marked on the outerreuse. flange to indicate the proper installed position. (1) Drain the coolant from the radiator until the (a) Observe the recess groove in the engine cyl-level is below the thermostat housing. inder head (Fig. 29). (b) Position thermostat into this groove withWARNING: CONSTANT TENSION HOSE CLAMPS arrow and air bleed hole on outer flange pointingARE USED ON MOST COOLING SYSTEM HOSES. up.WHEN REMOVING OR INSTALLING, USE ONLY (2) Install replacement gasket and thermostatTOOLS DESIGNED FOR SERVICING THIS TYPE OF housing.CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER6094) (Fig. 7). SNAP-ON CLAMP TOOL (NUMBER CAUTION: Tightening the thermostat housingHPC-20) MAY BE USED FOR LARGER CLAMPS. unevenly or with the thermostat out of its recessALWAYS WEAR SAFETY GLASSES WHEN SERVIC- may result in a cracked housing.ING CONSTANT TENSION CLAMPS. (3) Tighten the housing bolts to 20 N·m (15 ft. lbs.) torque.CAUTION: A number or letter is stamped into the (4) Install hoses to thermostat housing.tongue of constant tension clamps (Fig. 8). If (5) Install electrical connector to coolant tempera-replacement is necessary, use only an original ture sensor.equipment clamp with matching number or letter. (6) Be sure that the radiator draincock is tightly closed. Fill the cooling system to the correct level (2) Remove radiator upper hose and heater hose at with the required coolant mixture. Refer to Refillingthermostat housing. Cooling System in this group. (3) Disconnect wiring connector at engine coolant (7) Start and warm the engine. Check for leaks.temperature sensor.
  • 30. GROOVE7 - 30 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) (3) Position drain pan under draincock. Open radi- ator draincock. Drain radiator. (4) Remove radiator upper and lower hose clamps (Fig. 7) (Fig. 8). Remove hoses. (5) Remove E-clip from alignment dowel at radia- tor lower mounting bracket (Fig. 30). (6) Disconnect coolant reserve/overflow tank hose from radiator. (7) Remove four radiator fan shroud mounting bolts (Fig. 30). Push shroud back against front of engine. (8) If equipped, disconnect and plug automatic transmission fluid cooler lines. Refer to Group 21, Transmission for procedures. (9) Remove two radiator top mounting bolts (Fig. 30). (10) Air conditioning equipped (a) Remove the radiator grille mounting screws and remove grill. Refer to Group 23, Body for pro- cedures. (b) Remove the air conditioning condenser-to- radiator mounting bolt. Use an open end wrench to Fig. 29 Thermostat Recess remove bottom bolts (Fig. 31). (11) Lift radiator straight up and out of vehicle.RADIATOR Take care not to damage radiator fins. When remov-WARNING: DO NOT REMOVE THE CYLINDER ing radiator, note position of the rubber seals locatedBLOCK DRAIN PLUGS, RADIATOR CAP, OR on the top, bottom and sides of radiator (Fig. 30). ToLOOSEN THE RADIATOR DRAINCOCK WITH THE prevent possible overheating, these seals must beSYSTEM HOT AND PRESSURIZED. SERIOUS installed to their original positions.BURNS FROM THE COOLANT CAN OCCUR. INSTALLATION DO NOT WASTE reusable coolant. If solution is (1) Install radiator behind air conditioning con-clean, drain coolant into a clean container for reuse. denser with bottom alignment dowel inserted into radiator lower mounting bracket (Fig. 30).WARNING: CONSTANT TENSION HOSE CLAMPS (2) Install E-clip to radiator alignment dowel (Fig.ARE USED ON MOST COOLING SYSTEM HOSES. 30).WHEN REMOVING OR INSTALLING, USE ONLY (3) Tighten the four condenser-to-radiator mount-TOOLS DESIGNED FOR SERVICING THIS TYPE OF ing bolts to 6.2 N·m (55 in. lbs.) torque.CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER (4) If removed, install radiator grille.6094) (Fig. 7). SNAP-ON CLAMP TOOL (NUMBER (5) Tighten radiator top mounting bolts to 6 N·mHPC-20) MAY BE USED FOR LARGER CLAMPS. (55 in. lbs.) torque.ALWAYS WEAR SAFETY GLASSES WHEN SERVIC- (6) If equipped, connect automatic transmissionING CONSTANT TENSION CLAMPS. fluid cooler lines to radiator. Refer to Group 21, Transmission for procedures. (7) Install the radiator fan shroud.CAUTION: A number or letter is stamped into the (8) Connect the coolant reserve/overflow tank hose.tongue of constant tension clamps (Fig. 8). If (9) Connect radiator hoses and install hose clamps.replacement is necessary, use only an original (10) Connect negative battery cable.equipment clamp with matching number or letter. (11) Close the draincock. (12) Fill cooling system with correct coolant.2.5L 4-CYLINDER ENGINE (13) Install radiator cap. (14) Check and adjust automatic transmissionREMOVAL fluid level (if equipped). (1) Disconnect negative battery cable at battery. (2) Observe the previous WARNINGS. Removeradiator cap.
  • 31. RIGHT SIDE RUBBER SEAL CONDENSER CONDENSER A/C 6 N·m (55 IN. LBS.) UPPER RADIATORLOWERBOLTS LOWER CROSSMEMBER MOUNTINGBRACKET RADIATOR SEAL RECEIVER/DRIER RUBBER (2) E-CLIP TOP MOUNTING BOLTS (2)UPPER RADIATOR SHROUD LEFT SIDE RUBBER SEAL SHROUD MOUNTING RUBBER PORT WELLBOLTS(2) FAN FAN SEAL SUP- NUTS(4) ALIGN DOWELXJ COOLING SYSTEM 7 - 31REMOVAL AND INSTALLATION (Continued) Fig. 30 Radiator Remove/Install—2.5L 4-Cylinder Engine 4.0L 6-CYLINDER ENGINE WARNING: DO NOT REMOVE THE CYLINDER BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR DRAINCOCK WITH THE SYSTEM HOT AND PRES- SURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR. DO NOT WASTE reusable coolant. If solution is clean, drain coolant into a clean container for reuse. WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES. WHEN REMOVING OR INSTALLING, USE ONLY TOOLS DESIGNED FOR SERVICING THIS TYPE OF CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER 6094) (Fig. 7). SNAP-ON CLAMP TOOL (NUMBER HPC-20) MAY BE USED FOR LARGER CLAMPS. ALWAYS WEAR SAFETY GLASSES WHEN SERVIC- ING CONSTANT TENSION CLAMPS. CAUTION: A number or letter is stamped into theFig. 31 Condenser Mounting Bolts—2.5L 4-Cylinder tongue of constant tension clamps (Fig. 8). If Engine—Typical replacement is necessary, use only an original equipment clamp with matching number or letter.
  • 32. MOUNTING ELECTRIC COOLING FAN BOLT ELECTRIC COOLING FAN CONNECTOR MOUNTINGBOLT7 - 32 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued)REMOVAL (11) Mark the position of the hood latch striker on (1) Disconnect negative battery cable at battery. the radiator crossmember and remove hood latch (2) Observe the previous WARNINGS. striker. (3) Remove pressure cap. (12) Remove two radiator upper crossmember-to- (4) For access to radiator draincock, remove radia- isolator nuts (Fig. 33).tor grille mounting screws and remove grill. Refer to (13) Remove four radiator upper crossmemberGroup 23, Body for procedures. bolts (Fig. 33) and remove upper crossmember. (5) Attach one end of a 24 inch long X 1/4 inch ID (14) If equipped with air conditioning, separatehose to the radiator draincock. Put the other end into radiator from condenser by removing condenser-to-ra-a clean container. Open draincock and drain radiator. diator mounting brackets (Fig. 34). (6) If equipped, disconnect auxiliary electric cool- (15) Lift radiator straight up and out of engineing fan electrical connector (Fig. 32). compartment taking care not to damage fins. INSTALLATION The radiator is supplied with two alignment dowels (Fig. 33) xxxxxxx (Fig. 35). They are located on the bottom tank and fit into rubber grommets in the radiator lower crossmember. (1) Lower radiator into engine compartment. Posi- tion alignment dowels into rubber grommets in radi- ator lower crossmember (Fig. 33) xxxxxxxx (Fig. 35) (2) If equipped with air conditioning, attach con- denser to radiator with mounting brackets (Fig. 34). (3) Install radiator upper crossmember and four mounting bolts. (4) Install radiator upper crossmember-to-isolator nuts. Tighten nuts to 10 N·m (86 in. lbs.) torque. If isolator-to-radiator nuts had been removed, tighten them to 5 N·m (47 in. lbs.) torque. (5) Install hood latch striker. Note previously marked position. (6) Connect radiator upper and lower hoses. (7) If equipped, connect automatic transmission fluid cooler lines. Refer to Group 21, Transmissions for procedures. If equipped with remote cooler, attach Fig. 32 Auxiliary Electric Cooling Fan Wiring cooler line to bracket at bottom of radiator. Connector—Typical (8) Install electric cooling fan (if equipped). Insert (7) If equipped, remove two electric cooling fan alignment tabs at bottom of fan shroud into slots inmounting bolts. Lift cooling fan straight up until bracket at bottom of radiator. Tighten mounting boltsalignment tabs at the bottom are clear of slots in to 3 N·m (31 in. lbs.) torque.bracket at bottom of radiator (Fig. 33). (9) Connect electric cooling fan electrical connec- (8) Remove the two mechanical (non-electrical) fan tor.shroud mounting bolts. Lift shroud straight up until (10) Install mechanical cooling fan shroud. Insertalignment tabs at the bottom are clear of slots in alignment tabs at bottom of shroud into slots inbracket at bottom of radiator (Fig. 33). Place shroud bracket at bottom of radiator. Tighten mounting boltsover mechanical fan. to 3 N·m (31 in. lbs.) torque. (9) If equipped, disconnect and plug automatic (11) Close radiator draincock.transmission fluid cooler lines. Refer to Group 21, (12) Install grille.Transmissions for procedures. If equipped with (13) Connect negative battery cable.remote transmission cooler, remove line to cooler (14) Fill cooling system with correct coolant. Referfrom bracket at bottom of radiator. to the Coolant section of this group. (10) Disconnect radiator upper and lower hoses (15) Install pressure cap.clamps (Fig. 7) (Fig. 8). Disconnect radiator upper (16) Check and adjust automatic transmissionand lower hoses. fluid level (if equipped).
  • 33. UPPER RADIATOR MEMBER RUBBER LOWERMEMBER ALIGNMENT GROM- (4) METS (2) SLOTS CROSS- CROSS- UPPER ISOLATOR UTS DOWELS (2) RADIATOR N BOLTS (4) CROSSMEMBER ALIGNMENT TABS ALIGNMENT RADIATOR MECHANICAL(2)BOLTS FAN SHROUD MOUNTINGFAN SHROUD AIR ELECTRIC COOLING FAN (2) ALIGNMENT GROMMET RUBBER TORS DOWEL ISOLA- (2) TIONING CONDENSER FAN WIRING COOLING CONDI- ALIGNMENT TABS MOUNTING BOLTS HARNESS RADIATOR CLIPSXJ COOLING SYSTEM 7 - 33REMOVAL AND INSTALLATION (Continued) Fig. 33 Auxiliary Electric Cooling Fan and Fan Shroud—TypicalFig. 34 Condenser-to-Radiator Mounting Brackets— Fig. 35 Radiator Installation 4.0L 6-Cylinder Engine 4.0L 6- Cylinder Engine
  • 34. MOUNTING ELECTRIC COOLING FAN BOLT ELECTRIC COOLING FAN CONNECTOR MOUNTINGBOLT BLOCK HEATER POWER CORD LOCATION7 - 34 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued)AUXILIARY ELECTRIC COOLING FAN DO NOT WASTE reusable coolant. If solution is clean, drain coolant into a clean container for reuse.REMOVAL (1) Drain coolant from radiator and engine cylin- The auxiliary cooling fan is attached to the radia- der block.tor upper crossmember behind the radiator. (2) Unplug power cord from block heater. (1) Remove the two fan mounting bolts from radi- (3) Loosen screw in center of block heater (Fig. 37)ator upper crossmember (Fig. 36). (Fig. 38). (2) Disconnect the electric fan connector. (4) Remove block heater from cylinder block. INSTALLATION (1) Thoroughly clean the engine core hole and the block heater seat. (2) Insert block heater assembly into core hole with element loop pointing Up. (3) Seat block heater flush against block face. Tighten mounting screw to 3.6 N·m (32 in. lbs.) torque. (4) Fill cooling system with coolant. Pressurize system and inspect for leaks. (5) Plug power cord into block heater. Route cord away from moving parts, linkages and exhaust sys- tem components. Secure cord in place with tie-straps. Fig. 36 Auxiliary Cooling Fan—Remove/Install— Typical (3) Lift fan straight up and out of vehicle.INSTALLATION (1) Align lower retaining tabs of fan shroud withslots in bracket at bottom of radiator. Push fan downinto position. (2) Tighten the mounting bolts to 4 N·m (31 in. Fig. 37 Heater and Cord— 2.5L 4-Cylinder Enginelbs.) torque. ENGINE ACCESSORY DRIVE BELTS (3) Connect auxiliary cooling fan electrical connec- Correct drive belt tension is required to ensuretor. optimum performance of the belt driven engine acces- sories. There are different types of adjustmentENGINE BLOCK HEATER gauges for checking either a serpentine or a V-type belt. Refer to the instructions supplied with theREMOVAL gauge. Use the correct gauge when checking belt ten- Refer to correct illustration (Fig. 37) (Fig. 38)when sion. Place gauge in the middle of the section of beltservicing block heater. being tested (between two pulleys) to check tension. Do not allow the gauge (or gauge adapter) to contactWARNING: DO NOT REMOVE THE CYLINDER anything but the belt.BLOCK DRAIN PLUGS OR LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND PRES- BELT SCHEMATICSSURIZED. SERIOUS BURNS FROM THE COOLANT The belt routing schematics are published from theCAN OCCUR. latest information available at the time of publica- tion. If anything differs between these schemat- ics and the Belt Routing Label, use the
  • 35. BLOCK LOCA- CORD POWER HEATER TION AC + IDL + + ALT WP & + + PSFAN ALT ALT IDL + FAN + IDL + CRANK + WP & + CRANK+ FAN IDL + PS+ PS + CRANK IDL + WP & FAN IDL + + + + +XJ COOLING SYSTEM 7 - 35REMOVAL AND INSTALLATION (Continued) Fig. 38 Heater and Cord—4.0L 6-Cylinder Engineschematics on Belt Routing Label. This label islocated in the engine compartment. Refer to (Fig. 39) xxxxx (Fig. 40) xxxxxx (Fig. 41) Fig. 40 Models with 2.5L Engine—Without A/Cxxxxx (Fig. 42) for proper belt routing on vehicleswith conventional left hand drive. Refer to (Fig. 43)xxxxx (Fig. 44) for proper belt routing on vehicleswith right hand drive (RHD). Or, refer to the BeltRouting Label located in the vehicle engine compart-ment. Fig. 41 Models with 4.0L Engine—Without A/C— Except RHD (4) Remove belt. INSTALLATION (1) Check condition of all pulleys. Fig. 39 Models with 2.5L Engine—With A/C CAUTION: When installing the serpentine acces-BELT REPLACEMENT OR ADJUSTMENT— sory drive belt, the belt MUST be routed correctly. IfLEFT HAND DRIVE not, the engine may overheat due to the water Belt tension is adjusted at the power steering pump rotating in the wrong direction. Refer to (Fig.pump bracket and idler pulley assembly. 39) xxxxx (Fig. 40) xxxx (Fig. 41) xxxxx (Fig. 42) (1) Disconnect negative battery cable from battery. xxxx for correct belt routing. (2) Loosen idler pulley bolt at the power steeringbracket (Fig. 45). (2) Install new belt. (3) Loosen adjusting bolt until belt can be removed (3) Using serpentine belt tension gauge, tightenfrom pulleys. adjusting bolt until belt reaches proper tension. Refer
  • 36. FAN ALT IDLAC+IDL +ALT + + CRANK WP CRANK + + PS + WP + + IDL AC FAN FAN+ + PS + & ALT PULLEY IDL IDLERBOLT + IDL + ADJUSTING BOLT CRANK+ WP + FAN+ PS + IDL + + + +7 - 36 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued)Fig. 42 Models With 4.0L Engine—With A/C—Except Fig. 44 Models With 4.0L Engine—Without A/C— RHD With RHD Fig. 43 Models With 4.0L Engine—With A/C—With Fig. 45 Power Steering Pump Bracket and Idler RHD Pulleyto Belt Tension at the rear of this section for proper (4) Loosen adjusting bolt at upper alternatorbelt tension. bracket (Fig. 46) until belt can be removed from pul- (4) After belt is tensioned correctly, tighten idler leys.pulley bolt to 47 N·m (35 ft. lbs.) (5) Remove belt. (5) After idler pulley has been tightened into posi-tion, recheck belt tension. Adjust if necessary. INSTALLATION (1) Check condition of all pulleys.BELT REPLACEMENT OR ADJUSTMENT—RIGHT HAND DRIVE (4.0L) CAUTION: When installing the serpentine acces- (1) Disconnect negative battery cable from battery. sory drive belt, the belt MUST be routed correctly. If (2) Loosen lower alternator mounting bolt and nut. not, the engine may overheat due to the water (3) Loosen upper alternator mounting nut. pump rotating in the wrong direction. Refer to (Fig. 43) xxxxx (Fig. 44) for correct belt routing.
  • 37. TENSION UPPER ALTERNATOR NUT ADJUSTMENT BOLT COUS THERMAL DRIVE (4) FAN BLADE-TO-VISCOUS BRACKETFAN VIS- (4) PULLEY HUB-TO- PUMP PULLEY BOLTS FAN DRIVE NUTS NUTS (4) FAN HUB-TO-PUMP LEY PUMP HUB/BEARINGPUMPWATER PUMP FAB BLADE WATER WATER PUL- PULLEY STUDS PULLEYXJ COOLING SYSTEM 7 - 37REMOVAL AND INSTALLATION (Continued) Fig. 46 Generator Belt Tension Adjust Bracket (2) Install new belt. (3) Using serpentine belt tension gauge, tightenadjusting bolt until belt reaches proper tension. Refer Fig. 47 Water Pump Mounted Cooling Fanto Belt Tension at the rear of this section for properbelt tension. (4) Tighten alternator upper and lower mountingbolts. (5) After generator and adjust bracket have beentightened into position, recheck belt tension. Adjust ifnecessary.COOLING SYSTEM FANSREMOVAL Some engines have the mechanical fan/viscous fandrive assembly mounted directly to the water pumphub (Fig. 47). It may also be mounted to a hub/bear-ing attached to an aluminum bracket on the rightfront side of engine (Fig. 48). (1) Loosen but do not remove at this time, the fourfan hub mounting nuts (Fig. 47) xxxxxx (Fig. 48). (2) Remove accessory serpentine drive belt. Referto Belt Service in the Engine Accessory Drive Beltsection of this group. (3) Some models with certain engines may requirethe removal of the fan shroud to remove the viscous Fig. 48 Bracket Mounted Cooling Fanfan drive. The fan shroud and fan blade/viscous fan fluid in viscous fan drive could drain into its bearingdrive should be removed from the vehicle as one assembly and contaminate lubricant.assembly. (4) Remove four fan hub mounting nuts (Fig. 47) INSTALLATIONxxxxxxxxxx (Fig. 48) and remove fan/viscous fan (1) Assemble fan blade to viscous fan drive.drive assembly from vehicle. Tighten mounting bolts to 27 N·m (20 ft. lbs.) torque. (5) After removing fan blade/viscous fan drive (2) Position mounting flange of fan blade/viscousassembly, do not place thermal viscous fan drive in fan drive assembly onto hub. Install four nuts andhorizontal position. If stored horizontally, silicone tighten to 24 N·m (18 ft. lbs.) torque. Tighten the
  • 38. 7 - 38 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued)first two nuts 180 degrees apart. Then tighten last (1) Remove fan blade and viscous fan drive as antwo nuts. assembly from the engine. Refer to preceding Removal procedure.CAUTION: When installing a serpentine accessory (2) Remove fan blade assembly from viscous fandrive belt, the belt MUST be routed correctly. If not, drive unit (four bolts).the engine may overheat due to the water pump (3) Lay fan on a flat surface with leading edge fac-rotating in the wrong direction. Refer to appropriate ing down. With tip of blade touching flat surface,Engine Accessory Drive Belt Schematic in this replace fan if clearance between opposite blade andgroup for correct belt routing. surface is greater than 2.0 mm (.090 inch). Rocking motion of opposite blades should not exceed 2.0 mm (3) Install accessory drive belts. Tension belts to (.090 inch). Test all blades in this manner.specifications. Refer to the Specifications section atthe end of this group. WARNING: DO NOT ATTEMPT TO BEND OR STRAIGHTEN FAN BLADES IF NOT WITHIN SPECI-VISCOUS FAN DRIVE REMOVAL/INSTALLATION FICATIONS. Refer to Cooling System Fan for removal andinstallation procedures of the viscous drive unit. (4) Inspect fan assembly for cracks, bends, loose rivets or broken welds. Replace fan if any damage isViscous Fan Drive Fluid Pump Out found.Requirement: After installing a new viscous fan drive, bring the CAUTION: If fan blade assembly is replacedengine speed up to approximately 2000 rpm and hold because of mechanical damage, water pump andfor approximately two minutes. This will ensure viscous fan drive should also be inspected. Theseproper fluid distribution within the drive. components could have been damaged due to excessive vibration.CLEANING AND INSPECTION COOLING SYSTEM HOSESRADIATOR PRESSURE CAP INSPECTIONINSPECTION Inspect the hoses at regular intervals. Replace Visually inspect the pressure valve gasket on the hoses that are cracked, feel brittle when squeezed orcap. Replace cap if the gasket is swollen, torn or swell excessively when the system is pressurized.worn. Inspect the area around radiator filler neck for The use of molded replacement hoses is recom-white deposits that indicate a leaking cap. mended. When performing a hose inspection, inspect the radiator lower hose for proper position and con-RADIATOR CLEANING dition of the spring. The radiator and air conditioning fins should becleaned when an accumulation of bugs, leaves etc.has occurred. Clean radiator fins are necessary for SPECIFICATIONSgood heat transfer. With the engine cold, apply coldwater and compressed air to the back (engine side) of COOLING SYSTEM CAPACITIESthe radiator to flush the radiator and/or A/C con-denser of debris. BELT TENSION Belt tension must be adjusted. Refer to the follow-COOLING SYSTEM CLEANING ing Belt Tension chart for specifications. Drain cooling system and refill with water. Runengine with radiator cap installed until upper radia-tor hose is hot. Stop engine and drain water fromsystem. If water is dirty, fill system with water, runengine and drain system. Repeat until water drainsclean.FAN BLADE INSPECTION The fan blades cannot be repaired. If fan is dam-aged, it must be replaced. Inspect fan as follows:
  • 39. XJ COOLING SYSTEM 7 - 39SPECIFICATIONS (Continued) MECHANICAL COOLING COOLING AUXILIARY* MODEL ENGINE RADIATOR A/C FAN CAPACITY PACKAGE ELECTRIC FAN (VISCOUS DRIVE) 2.5L 4.0L QTS. LITERS STD. HD. ROWS FINS DIA NO. BLADE DIA. NO. BLADE OF PER (INCH) OF PITCH (INCH) OF PITCH TUBES INCH BLADE (INCH) BLADES (INCH) • 10.0 9.5 • 1 15 16.0 5 2.5 • 10.0 9.5 • 1 20 • 16.05 5 2.5 XJ • 12.0 11.4 • 1 19 15.0 7 1.88 • 12.0 11.4 • 1 19 • 15.0 7 1.88 11.0 6 1.75 • 12.0 11.4 • 2 19 15.0 7 1.88 11.0 6 1.75 • 12.0 11.4 • 2 19 • 15.0 7 1.88 11.0 6 1.75*4.0L ENGINE WITH HEAVY DUTY COOLING AND /OR AIR CONDITIONING COOLING SYSTEM CAPACITIES*800-900 N (180-200 lbs. force) DESCRIPTION TORQUE(With ** new serpentine belt) Radiator (2.5L Engine)*623-712 N (140-160 lbs. force) Mounting Bolts . . . . . . . . . . . . . 6 N·m (55 in. lbs.)(With ** used serpentine belt) Thermostat Housing**Belt is considered new if it has been used 15 Bolts . . . . . . . . . . . . . . . . . . . . 20 N·m (15 ft. lbs.)minutes or less. Viscous Fan Drive Assy.-to-Water Pump*Specifications for use with a belt tension gauge. Nuts . . . . . . . . . . . . . . . . . . . . 27 N·m (20 ft. lbs.)Refer to operating instructions supplied with gauge. Water Pump Bolts . . . . . . . . . . . . . . . . . . . . 30 N·m (22 ft. lbs.)TORQUE SPECIFICATIONS SPECIAL TOOLSDESCRIPTION TORQUEAuto. Trans. Auxiliary Oil Cooler COOLING Mtg. Screws . . . . . . . . . . . . . . . . 2 N·m (18in. lbs.)Auxiliary Electric Cooling Fan Mtg. Screws . . . . . . . . . . . . . . . 4 N·m (36 in. lbs.)Block Heater Mounting Screw . . . . . . . . . . . . 4 N·m (20 in. lbs.)Condenser-to-Radiator Screws . . . . . . . . . . . . . . . . . . . 6 N·m (55 in. lbs.)Fan Blade Assy.-to-Viscous Fan Drive Bolts . . . . . . . . . . . . . . . . . . . . 24 N·m (18 ft. lbs.)Fan Shroud (2.5L Engine) Mounting Bolts . . . . . . . . . . . . . 2 N·m (20 in. lbs.) Hose Clamp Tool—6094Fan Shroud (4.0L Engine) Cooling System Pressure Tester—7700–A Screws . . . . . . . . . . . . . . . . . . . 4 N·m (20 in. lbs.)Generator Pivot Bolt . . . . . . . . . . . . . . . . . . . . . 38 N·m (28 ft. lbs.)Generator Rear Adj. Bolt . . . . . . . . . . . . . . . . . . . . . 27 N·m (20 ft. lbs.)Isolator-to-Crossmember Nuts . . . . . . . . . . . . . . . . . . . . 10 N·m (86 in. lbs.)Isolator-to-Radiator Nuts . . . . . . . . . . . . . . . . . . . . . 5 N·m (47 in. lbs.)Radiator (4.0L Engine) Mounting Bolts . . . . . . . . . . . . . . 8 N·m (6 ft. lbs.)
  • 40. XJ COOLING SYSTEM 7-1 COOLING SYSTEM CONTENTS page pageGENERAL INFORMATION SERVICE PROCEDURES COOLANT TANK . . . . . . . . . . . . . . . . . . . . . . . . 2 COOLANT LEVEL CHECK . . . . . . . . . . . . . . . . 17 COOLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 COOLANT REPLACEMENT . . . . . . . . . . . . . . . 18 COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 1 DRAINING COOLING SYSTEM . . . . . . . . . . . . 17 ENGINE ACCESSORY DRIVE BELTS . . . . . . . . . 2 REFILLING COOLING SYSTEM . . . . . . . . . . . . 17 LOW COOLANT LEVEL SENSOR . . . . . . . . . . . 4 REMOVAL AND INSTALLATION RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 AUTOMATIC BELT TENSIONER . . . . . . . . . . . . 22 WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . 3 DRIVE BELT . . . . . . . . . . . . . . . . . . . . . . . . . . . 22DESCRIPTION AND OPERATION FAN BLADE REMOVAL . . . . . . . . . . . . . . . . . . 20 AUTOMATIC BELT TENSIONER . . . . . . . . . . . . . 7 RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 BELT TENSION . . . . . . . . . . . . . . . . . . . . . . . . . 7 THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . 21 COOLANT PERFORMANCE . . . . . . . . . . . . . . . . 4 VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . 20 COOLING SYSTEM HOSES . . . . . . . . . . . . . . . . 5 WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . 22 PRESSURE/VENT CAP . . . . . . . . . . . . . . . . . . . 4 CLEANING AND INSPECTION THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . 4 COOLING SYSTEM CLEANING/REVERSE VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . 6 FLUSHING . . . . . . . . . . . . . . . . . . . . . . . . . . 25DIAGNOSIS AND TESTING FAN BLADE . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 BELT DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . 15 PRESSURE/VENT CAP . . . . . . . . . . . . . . . . . . 25 LOW COOLANT LEVEL- AERATION . . . . . . . . . 15 RADIATOR CLEANING . . . . . . . . . . . . . . . . . . . 24 PRELIMINARY CHECKS . . . . . . . . . . . . . . . . . . 7 WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . 24 PRESSURE/VENT CAP . . . . . . . . . . . . . . . . . . 15 ADJUSTMENTS RADIATOR COOLANT FLOW CHECK . . . . . . . 13 DRIVE BELT TENSION . . . . . . . . . . . . . . . . . . . 26 TESTING COOLING SYSTEM FOR LEAKS . . . 14 SPECIFICATIONS THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . 13 COOLING SYSTEM CAPACITY . . . . . . . . . . . . 26 VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . 13 THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . 26 TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . 26GENERAL INFORMATION • A threaded-on, pressure/vent cap mounted to the coolant tankCOOLING SYSTEM • Cooling fan (mechanical) The cooling system regulates engine operating tem- • Thermal viscous fan driveperature. It allows the engine to reach normal oper- • Fan shroudating temperature as quickly as possible, maintains • Thermostatnormal operating temperature and prevents over- • Coolantheating. • Low coolant level sensor The cooling system also provides a means of heat- • Low coolant warning lamping the passenger compartment. The cooling system • Coolant temperature gaugeis pressurized and uses a centrifugal water pump to • Water pumpcirculate coolant throughout the system. A water • Hoses and hose clampsmanifold collects coolant from the cylinder heads. Aseparate and remotely mounted, pressurized coolant COOLANT ROUTINGtank using a pressure/vent cap is used. For cooling system flow routing, refer to (Fig. 1)COOLING SYSTEM COMPONENTS RADIATOR The cooling system consists of: The radiator used with the 2.5L diesel is con- • A brass-core radiator with plastic side tanks structed of a horizontal cross-flow brass core with • A radiator mounted fill vent valve plastic side tanks. • A separate pressurized coolant tank
  • 41. 7-2 COOLING SYSTEM XJGENERAL INFORMATION (Continued) Fig. 1 Coolant Flow—2.5L Diesel Engine—TypicalCAUTION: Plastic tanks, while stronger than brass, CAUTION: When installing a serpentine accessoryare subject to damage by impact, such as drive belt, the belt MUST be routed correctly. If not,wrenches. the engine may overheat due to water pump rotat- ing in wrong direction. Refer to the engine Belt If the plastic tank has been damaged, the tank Schematic in Specification section at the end of thisand/or gaskets are available for service repair. Tank group for the correct belt routing.replacement should be done by qualified personalwith proper equipment. COOLANT TANKENGINE ACCESSORY DRIVE BELTS A pressurized, plastic coolant tank is used with the The accessory drive components are operated by a cooling system. This separate tank should be consid-single, crankshaft driven, serpentine drive belt. Ini- ered part of the radiator. The tank is located at thetial belt adjustment is done with an adjustable ten- right-rear side of the engine compartment and issioner pulley. After the initial adjustment is mounted as the highest point of the cooling system.performed, an automatic belt tensioner is used to This will allow any air or vapor exceeding the pres-maintain correct belt tension at all times. sure/vent cap rating to escape through the cap. Cool- ant will flow through the tank at all times during engine operation whether the engine is cold or at
  • 42. XJ COOLING SYSTEM 7-3GENERAL INFORMATION (Continued) Fig. 2 Coolant Tank and Radiator Hosesnormal operating temperature. The coolant tank isequipped with a threaded pressure/vent cap. Refer toPressure/Vent Cap for additional information. A separate coolant reserve/overflow tank is notused with this system. The low coolant level sensor is located on the bot-tom of the tank (Fig. 2).WATER PUMP A centrifugal water pump circulates coolantthrough the water jackets, passages, water manifold,radiator core, pressurized coolant tank, cooling sys-tem hoses and heater core. The pump is driven fromthe engine crankshaft by a drive belt. The waterpump is bolted to the water pump adapter (Fig. 3).The water pump adapter is bolted to the engine. The water pump impeller is pressed onto the rearof a shaft that rotates in bearings pressed into thehousing. The bottom of the housing is equipped witha small vent tube (Fig. 3) to allow seepage to escape.A drain hose is attached to this tube. The waterpump seals are lubricated by the antifreeze in thecoolant mixture. No additional lubrication is neces-sary. A rubber o-ring (instead of a gasket) is used as aseal between the water pump and the water pumpadapter (Fig. 3). Fig. 3 Water Pump— Typical
  • 43. 7-4 COOLING SYSTEM XJGENERAL INFORMATION (Continued) A quick test to determine if the pump is working is Operating without a thermostat causes other prob-to check if the heater warms properly. A defective lems. These are: longer engine warmup time, unreli-water pump will not be able to circulate heated cool- able warmup performance, increased exhaustant through the long heater hose to the heater core. emissions and crankcase condensation. This conden- sation can result in sludge formation.COOLANT The cooling system is designed around the coolant. CAUTION: Do not operate an engine without aCoolant flows through the engine water jackets and thermostat, except for servicing or testing.water manifold absorbing heat produced duringengine operation. The coolant carries heat to theradiator and heater core. Here it is transferred to the PRESSURE/VENT CAPambient air passing through the radiator and heater The pressure/vent cap is threaded-on to the coolantcore fins. tank. This cap releases excess pressure at some point within a range of 90-117 kPa (13- 17 psi). The actualLOW COOLANT LEVEL SENSOR pressure relief point (in pounds) is labeled on top of The low coolant level sensor checks for low coolant the cap (Fig. 5).level in the coolant tank. A signal will be sent from The cooling system will operate at pressuresthis sensor to the powertrain control module (PCM). slightly above atmospheric pressure. This results in aWhen the PCM determines low coolant level, the higher coolant boiling point allowing increased radi-instrument panel mounted low coolant level warning ator cooling capacity. The cap (Fig. 5) contains alamp will be illuminated. The sensor is located on the spring-loaded pressure relief valve. This valve opensfront side of the coolant tank (Fig. 4). For information, when system pressure reaches approximately 103refer to Group 8E, Instrument Panel and Gauges. kPa (15 psi). When the engine is cooling down, vacuum is formed within the cooling system. To prevent collapse of the radiator and coolant hoses from this vacuum, a vac- uum valve is used within the cap. This valve prevents excessive pressure differences from occurring between the closed cooling system and the atmosphere. If the vacuum valve is stuck shut, the radiator and/or cooling system hoses will collapse on cool-down. NOTE: Do not use any type of tool when tighten- ing the cap. Hand tighten only (approximately 5 N·m or 44 in. lbs.) torque. COOLANT PERFORMANCE ETHYLENE-GLYCOL MIXTURES Fig. 4 Low Coolant Level Sensor The required ethylene-glycol (antifreeze) and water mixture depends upon the climate and vehicle oper- If this lamp is illuminated, it indicates the need for ating conditions. The recommended mixture of 50/50service. ethylene-glycol and water will provide protection against freezing to -37 deg. C (-35 deg. F). The anti-DESCRIPTION AND OPERATION freeze concentration must always be a minimum of 44 percent, year-round in all climates. If percentageTHERMOSTAT is lower than 44 percent, engine parts may be A pellet-type thermostat controls the operating tem- eroded by cavitation, and cooling system com-perature of the engine by controlling the amount of ponents may be severely damaged by corrosion.coolant flow to the radiator. The thermostat starts to Maximum protection against freezing is providedopen at 80°C (176°F). Above this temperature, coolant with a 68 percent antifreeze concentration, whichis allowed to flow to the radiator. This provides quick prevents freezing down to -67.7 deg. C (-90 deg. F). Aengine warmup and overall temperature control. higher percentage will freeze at a warmer tempera- The same thermostat is used for winter and sum- ture. Also, a higher percentage of antifreeze canmer seasons. An engine should not be operated with- cause the engine to overheat because the specificout a thermostat, except for servicing or testing. heat of antifreeze is lower than that of water.
  • 44. XJ COOLING SYSTEM 7-5DESCRIPTION AND OPERATION (Continued) transfer characteristics than ethylene glycol. This can increase cylinder head temperatures under cer- tain conditions. Propylene-glycol/Ethylene-glycol Mixtures—Should Not Be Used in Chrysler Vehicles Propylene-glycol/ethylene-glycol Mixtures can cause the destabilization of various corrosion inhibi- tors, causing damage to the various cooling system components. Also, once ethylene-glycol and propy- lene-glycol based coolants are mixed in the vehicle, conventional methods of determining freeze point will not be accurate. Both the refractive index and spe- cific gravity differ between ethylene glycol and propy- lene glycol. CAUTION: Richer antifreeze mixtures cannot be measured with normal field equipment and can cause problems associated with 100 percent ethyl- ene-glycol. COOLING SYSTEM HOSES Rubber hoses route coolant to and from the radia- tor, water manifold and heater core. Models equipped with air conditioning have a heater water control (shut-off) valve. This is located in-line with the heater core inlet and outlet hoses. It controls coolant flow to the heater core when the air conditioning sys- Fig. 5 Coolant Tank Pressure/Vent Cap tem is in operation.100 Percent Ethylene-Glycol—Should Not Be Used in Radiator lower hoses are spring-reinforced to pre-Chrysler Vehicles vent collapse from water pump suction at moderate Use of 100 percent ethylene-glycol will cause for- and high engine speeds.mation of additive deposits in the system, as the cor-rosion inhibitive additives in ethylene-glycol require WARNING: CONSTANT TENSION HOSE CLAMPSthe presence of water to dissolve. The deposits act as ARE USED ON MOST COOLING SYSTEM HOSES.insulation, causing temperatures to rise to as high as WHEN REMOVING OR INSTALLING, USE ONLY149 deg. C (300) deg. F). This temperature is hot TOOLS DESIGNED FOR SERVICING THIS TYPE OFenough to melt plastic and soften solder. The CLAMP (Fig. 6). ALWAYS WEAR SAFETY GLASSESincreased temperature can result in engine detona- WHEN SERVICING CONSTANT TENSION CLAMPS.tion. In addition, 100 percent ethylene-glycol freezesat 22 deg. C (-8 deg. F ).Propylene-glycol Formulations—Should Not Be Used inChrysler Vehicles Propylene-glycol formulations do not meetChrysler coolant specifications. It’s overall effec-tive temperature range is smaller than that of ethyl-ene-glycol. The freeze point of 50/50 propylene-glycoland water is -32 deg. C (-26 deg. F). 5 deg. C higherthan ethylene-glycol’s freeze point. The boiling point(protection against summer boil-over) of propylene-glycol is 125 deg. C (257 deg. F ) at 96.5 kPa (14 psi),compared to 128 deg. C (263 deg. F) for ethylene-gly-col. Use of propylene-glycol can result in boil-over orfreeze-up in Chrysler vehicles, which are designed forethylene-glycol. Propylene glycol also has poorer heat Fig. 6 Hose Clamp Tool
  • 45. 7-6 COOLING SYSTEM XJDESCRIPTION AND OPERATION (Continued)CAUTION: A number or letter is stamped into the radiator discharge air. It engages the viscous fantongue of constant tension clamps (Fig. 7). If drive for higher fan speed if the air temperature fromreplacement is necessary, use only an original the radiator rises above a certain point. Until addi-equipment clamp with matching number or letter. tional engine cooling is necessary, the fan will remain at a reduced rpm regardless of engine speed. Fig. 8 Viscous Fan Drive The viscous fan drive will only engage when suffi- cient heat is present. This is when the air flowing through the radiator core causes a reaction from the bimetallic coil. It then increases fan speed to provide the necessary additional engine cooling. Once the engine has cooled, the radiator discharge temperature will drop. The bimetallic coil again Fig. 7 Clamp Number/Letter Location reacts and the fan speed is reduced to the previous Inspect the hoses at regular intervals. Replace disengaged speed.hoses that are cracked, feel brittle when squeezed, or CAUTION: Some engines equipped with serpentineswell excessively when the system is pressurized. drive belts have reverse rotating fans and viscous For all vehicles: In areas where specific routing fan drives. They are marked with the word REVERSEclamps are not provided, be sure that hoses are posi- to designate their usage. Installation of the wrong fantioned with sufficient clearance. Check clearance or viscous fan drive can result in engine overheating.from exhaust manifolds and pipe, fan blades, drivebelts and sway bars. Improperly positioned hoses can NOISEbe damaged, resulting in coolant loss and engineoverheating. NOTE: It is normal for fan noise to be louder (roar- Ordinary worm gear type hose clamps (when ing) when:equipped) can be removed with a straight screw-driver or a hex socket. To prevent damage to • The underhood temperature is above the engage-hoses or clamps, the hose clamps should be ment point for the viscous drive coupling. This maytightened to 4 N·m (34 in. lbs.) torque. Do not occur when ambient (outside air temperature) is veryover tighten hose clamps. high. When performing a hose inspection, inspect the • Engine loads and temperatures are high such asradiator lower hose for proper position and condition when towing a trailer.of the internal spring. • Cool silicone fluid within the fan drive unit is being redistributed back to its normal disengagedVISCOUS FAN DRIVE (warm) position. This can occur during the first 15 The thermal viscous fan drive (Fig. 8) is a silicone- seconds to one minute after engine start-up on a coldfluid-filled coupling. It connects the fan blade assem- engine.bly to the fan pulley. The coupling allows the fan tobe driven in a normal manner. This is done at low LEAKSengine speeds while limiting the top speed of the fan Viscous fan drive operation is not affected by smallto a predetermined maximum level at higher engine oil stains near the drive bearing. If leakage appearsspeeds. A bimetallic spring coil is located on the front excessive, replace the fan drive unit.face. This spring coil reacts to the temperature of the
  • 46. XJ COOLING SYSTEM 7-7DESCRIPTION AND OPERATION (Continued)BELT TENSION WARNING: BECAUSE OF HIGH SPRING PRES- Correct accessory drive belt tension is required to SURE, DO NOT ATTEMPT TO DISASSEMBLE THEbe sure of optimum performance of belt driven engine AUTOMATIC BELT TENSIONER. UNIT IS SERVICEDaccessories. If specified tension is not maintained, AS AN ASSEMBLY.belt slippage may cause; engine overheating, lack ofpower steering assist, loss of air conditioning capac-ity, reduced generator output rate and greatly DIAGNOSIS AND TESTINGreduced belt life. Initial belt adjustment is done with a adjustable PRELIMINARY CHECKStensioner pulley. After the initial adjustment is per-formed, an automatic belt tensioner is used to main- ENGINE COOLING SYSTEM OVERHEATINGtain correct belt tension at all times. Do not attempt Establish what driving conditions caused the com-to check belt tension with a belt tension gauge on plaint. Abnormal loads on the cooling system such asvehicles equipped with an automatic belt tensioner. the following may be the cause:Refer to Automatic Belt Tensioner in this group. (1) PROLONGED IDLE, VERY HIGH AMBIENT TEMPERATURE, SLIGHT TAIL WIND AT IDLE,AUTOMATIC BELT TENSIONER SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED Drive belt tension is controlled by a spring loaded OR STEEP GRADES.automatic belt tensioner located below and to the Driving techniques that avoid overheating are:front of the engine oil filter (Fig. 9). This tensioner is • Idle with A/C off when temperature gauge is atconnected to a pivot bracket and a pulley (Fig. 9). end of normal range.The pivot bracket rotates on a pivot pin attached to • Increasing engine speed for more air flow is rec-the engine. Special machined washers with rubber ommended.o-rings (Fig. 9) are used at each side of the pivot (2) TRAILER TOWING:bracket to help keep dirt and water away from the Consult Trailer Towing section of owners manual.pivot pin. Do not exceed limits. (3) RECENT SERVICE OR ACCIDENT REPAIR: Determine if any recent service has been per- formed on vehicle that may effect cooling system. This may be: • Engine adjustments (incorrect timing) • Slipping engine accessory drive belt • Brakes (possibly dragging) • Changed parts (incorrect water pump) • Reconditioned radiator or cooling system refill- ing (possibly under filled or air trapped in system). NOTE: If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to following Cooling System Diagnosis charts. These charts are to be used as a quick-reference only. Refer to the group text for information. Fig. 9 Automatic Belt Tensioner Assembly If a defective belt tensioner is suspected, a check ofthis pivot bracket and pivot pin should be made. Cor-rosion may have formed at the pin and may causethe pivot bracket to stick. Belt slippage will result.
  • 47. 7-8 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)COOLING SYSTEM DIAGNOSIS–DIESEL ENGINE
  • 48. XJ COOLING SYSTEM 7-9DIAGNOSIS AND TESTING (Continued)
  • 49. 7 - 10 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)
  • 50. XJ COOLING SYSTEM 7 - 11DIAGNOSIS AND TESTING (Continued)
  • 51. 7 - 12 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)
  • 52. XJ COOLING SYSTEM 7 - 13DIAGNOSIS AND TESTING (Continued)THERMOSTAT VISCOUS FAN DRIVEDIAGNOSIS TESTING Diesel engines, due to their inherent efficiency are If the fan assembly free-wheels without drag (theslower to warm up than gasoline powered engines, fan blades will revolve more than five turns whenand will operate at lower temperatures when the spun by hand), replace the fan drive. This spin testvehicle is unloaded. Because of this, lower tempera- must be performed when the engine is cool.ture gauge readings for diesel versus gasoline The cooling system must be in good condition. Thisengines may, at times be normal. is checked prior to performing the following test. It Typically, complaints of low engine coolant temper- also will ensure against excessively high coolant tem-ature are observed as low heater output when com- perature.bined with cool or cold outside temperatures. To help promote faster engine warm-up, an electric WARNING: BE SURE OF ADEQUATE FAN BLADEengine block heater must be used with cool or cold CLEARANCE BEFORE DRILLING.outside temperatures. This will help keep the enginecoolant warm when the vehicle is parked. Use the (1) Drill a 3.12-mm (1/8-in) diameter hole in theblock heater if the outside temperature is below 4°C top center of the fan shroud.(40°F). Do not use the block heater if the out- (2) Obtain a dial thermometer with an 8 inch stemside temperature is above 4°C (40°F). (or equivalent). It should have a range of -18°-to- 105°C (0°-to-220° F). Insert thermometer through theTESTING hole in the shroud. Be sure that there is adequate clearance from the fan blades.NOTE: The DRB scan tool cannot be used to monitor (3) Block the air flow through the radiator. Secureengine coolant temperature on the diesel engine. a sheet of plastic in front of the radiator (or air con- ditioner condenser). Use tape at the top to secure the (1) To determine if the thermostat is defective, it plastic and be sure that the air flow is blocked.must be removed from the vehicle. Refer to Thermo- (4) Be sure that the air conditioner (if equipped) isstats for removal and installation procedures. turned off. (2) After the thermostat has been removed, exam-ine the thermostat and inside of thermostat housing WARNING: USE EXTREME CAUTION WHEN THEfor contaminants. If contaminants are found, the ENGINE IS OPERATING. DO NOT STAND IN Athermostat may already be in a “stuck open” position. DIRECT LINE WITH THE FAN. DO NOT PUT YOURFlush the cooling system before replacing thermostat. HANDS NEAR THE PULLEYS, BELTS OR FAN. DORefer to Cooling System Cleaning/Reverse Flushing NOT WEAR LOOSE CLOTHING.in this group for additional information. (3) Place the thermostat into a container filled (5) Start the engine and operate at 2400 rpm.with water. Within ten minutes the air temperature (indicated on (4) Place the container on a hot plate or other suit- the dial thermometer) should be up to 93° C (200° F).able heating device. Fan drive engagement should have started to occur (5) Place a commercially available radiator ther- at between 82° to 91° C (180° to 195° F). Engage-mometer into the water. ment is distinguishable by a definite increase in fan (6) Apply heat to the water while observing the flow noise (roaring).thermostat and thermometer. (6) When the air temperature reaches 93° C (200° (7) When the water temperature reaches 80°C F), remove the plastic sheet. Fan drive disengage-(176°F) the thermostat should start to open (valve ment should have started to occur at between 57° towill start to move). If the valve starts to move before 79° C (135° to 175° F). A definite decrease of fanthis temperature is reached, it is opening too early. flow noise (roaring) should be noticed. If not, replaceReplace thermostat. The thermostat should be fully the defective viscous fan drive unit.open (valve will stop moving) at approximately 89°C(192°F). If the valve is still moving after the water RADIATOR COOLANT FLOW CHECKtemperature reaches this temperature, it is opening There is coolant flow through the coolant tank (bot-too late. Replace thermostat. tle) before and after the thermostat opens. (8) If the valve refuses to move at any time,replace thermostat.
  • 53. 7 - 14 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued)CAUTION: Do not remove the vent valve to insert a the pressure/vent cap from the filler neck. Warm thetemperature gauge thought the opening, coolant will engine with the pressure/vent cap off to normal oper-spill out of the system and the engine will not be ating temperature. With the engine turned off attachfilled with coolant up to the heads. Major damage the cooling system pressure tester and test the sys-could happen if you run the engine in this condition. tem as described below. Recheck the system cold if the cause of coolant lossTESTING COOLING SYSTEM FOR LEAKS is not located during warm engine examination. A two-piece, threaded adapter set (Fig. 11) must beULTRAVIOLET LIGHT METHOD used to adapt a standard pressure-type tester (Fig. All Jeep௢ models have a leak detection additive 12) when testing either the coolant tank or pressureadded to the cooling system before they leave the fac- cap. Use Kent-Moore௡ adapter set numbertory. The additive is highly visible under ultraviolet J-24460-92 or Snap-On௡ numbers TA-32 and TA-33.light (black light). If the factory original coolant has Attach one of the adapters to the coolant pressurebeen drained, pour one ounce of additive into the cool- tank neck. Adapter must first be threaded to tank.ing system. The additive is available through the parts Attach pressure tester to adapter.department. Place the heater control unit in HEATposition. Start and operate the engine until the radia-tor upper hose is warm to the touch. Aim the commer-cially available black light tool at the components to bechecked. If leaks are present, the black light will causethe additive to glow a bright green color. The black light can be used along with a radiatorpressure tester to determine if any external leaksexist (Fig. 10). Fig. 11 Typical Pressure Tester Adapters Fig. 10 Leak Detection Using Black Light—TypicalPRESSURE TESTER METHODWARNING: HOT, PRESSURIZED COOLANT CANCAUSE SERIOUS INJURY BY SCALDING. NEVERREMOVE THE PRESSURE/VENT CAP OR PRES-SURE TESTER WHEN THE COOLING SYSTEM ISHOT OR UNDER PRESSURE! Fig. 12 Typical Cooling System Pressure Tester Operate the tester pump to apply 103 kPa (15 psi) Allow the engine to cool sufficiently so that the pressure to the system. If the hoses enlarge excessivelysystem is not under pressure and carefully remove
  • 54. XJ COOLING SYSTEM 7 - 15DIAGNOSIS AND TESTING (Continued)or bulge while testing, replace as necessary. Observe cap. Use Kent-Moore௡ adapter set numberthe gauge pointer and determine the condition of the J-24460-92 or Snap-On௡ numbers TA-32 and TA-33.cooling system according to the following criteria: Attach the adapter to the cap. Adapter must first be • Holds Steady: If the pointer remains steady for threaded to cap. Attach pressure tester to adapter.two minutes, there are no serious coolant leaks in Operate the tester pump and observe the gaugethe system. However, there could be an internal leak pointer at its highest point. The cap release pressurethat does not appear with normal system test pres- should be 90-to-117 kPa (13-to-17 psi). The cap is sat-sure. Inspect for interior leakage or do the Internal isfactory when the pressure holds steady. It is alsoLeakage Test. Do this if it is certain that coolant is good if it holds pressure within the 90-to-117 kPabeing lost and no leaks can be detected. (13-to-17 psi) range for 30 seconds or more. If the • Drops Slowly: Shows a small leak or seepage is pointer drops quickly, replace the cap.occurring. Examine all connections for seepage orslight leakage with a flashlight. Inspect the radiator, CAUTION: Radiator pressure testing tools are veryhoses, gasket edges and heater. Seal any small leak sensitive to small air leaks, which will not causeholes with a Sealer Lubricant or equivalent. Repair cooling system problems. A pressure cap that doesleak holes and reinspect the system with pressure not have a history of coolant loss should not beapplied. replaced just because it leaks slowly when tested • Drops Quickly: Shows that a serious leakage is with this tool. Add water to tool. Turn tool upsideoccurring. Examine the system for serious external down and recheck pressure/vent cap to confirmleakage. If no leaks are visible, inspect for internal that cap needs replacement.leakage. Large radiator leak holes should be repairedby a reputable radiator repair shop. LOW COOLANT LEVEL- AERATIONINTERNAL LEAKAGE INSPECTION Remove the oil pan drain-plug and drain a small CAUTION: Engine damage could occur if the cool-amount of engine oil. Coolant, being heavier will ant level is allowed to get this low. Always ensuredrain first, or operate engine to churn oil, then exam- that the coolant level is not below the add coolantine dipstick for water globules. Operate the engine mark. The baffles in the pressurized coolant tankwithout the pressure/vent cap on the coolant tank (degasser bottle) will not allow you to see the fluiduntil thermostat opens. level. Check the coolant level through the pressur- Attach a radiator pressure tester to the tank filler ized coolant tank. For better visibility of the coolantneck. If pressure builds up quickly, a leak exists as level use a shop lamp to light the pressurized cool-result of a faulty cylinder head gasket or crack in the ant tank and look through the pressurized coolantengine. Repair as necessary. tank.WARNING: DO NOT ALLOW PRESSURE TO If the coolant level in the radiator drops below theEXCEED 117 KPA (17 PSI). TURN THE ENGINE OFF. top of radiator core tubes, air will enter the coolingTO RELEASE THE PRESSURE, ROCK THE TESTER system.FROM SIDE TO SIDE. WHEN REMOVING THE Low coolant level can cause the thermostat pelletTESTER, DO NOT TURN THE TESTER MORE THAN to be suspended in air instead of coolant. This will1/2 TURN IF THE SYSTEM IS UNDER PRESSURE. cause the thermostat to open later, which in turn causes higher coolant temperature. Air trapped in If there is no immediate pressure increase, pump the cooling system also reduces the amount of coolantthe pressure tester until the indicated pressure is circulating in the heater core resulting in low heatwithin the system range. Vibration of the gauge output.pointer indicates compression or combustion leakageinto the cooling system. BELT DIAGNOSIS When diagnosing serpentine accessory drive belts,PRESSURE/VENT CAP small cracks that run across the ribbed surface of the belt from rib to rib (Fig. 13), are considered normal.PRESSURE TESTING These are not a reason to replace the belt. However, Remove the cap from the coolant tank. Be sure cracks running along a rib (not across) are not nor-that sealing surfaces are clean. Moisten rubber gas- mal. Any belt with cracks running along a rib mustket with water. be replaced (Fig. 13). Also replace the belt if it has A two-piece, threaded adapter set (Fig. 11) must be excessive wear, frayed cords or severe glazing.used to adapt a standard pressure-type tester (Fig. Refer to the Serpentine Drive Belt Diagnosis chart12) when testing either the coolant tank or pressure for further belt diagnosis
  • 55. 7 - 16 COOLING SYSTEM XJDIAGNOSIS AND TESTING (Continued) . SERPENTINE DRIVE BELT DIAGNOSIS
  • 56. XJ COOLING SYSTEM 7 - 17DIAGNOSIS AND TESTING (Continued) the engine is cold. Coolant level in a warm engine will be higher in the tank due to ther- mal expansion. (2) After the engine has been operated through a few heat-up and cool-down cycles, recheck the coolant level in the tank. DRAINING COOLING SYSTEM The cooling system is equipped with a pressurized coolant tank using a pressure/vent cap. WARNING: DO NOT REMOVE THE CYLINDER BLOCK DRAIN-PLUG, THE COOLANT TANK CAP, THE RADIATOR FILL VENT VALVE, OR LOOSEN THE RADIATOR DRAINCOCK WITH THE SYSTEM HOT AND PRESSURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR. WARNING: IF VEHICLE HAS BEEN RUN RECENTLY, WAIT AT LEAST 15 MINUTES BEFORE Fig. 13 Serpentine Belt Wear Patterns REMOVING COOLANT TANK CAP. WITH A RAG, SQUEEZE THE UPPER RADIATOR HOSE TO CHECK IF SYSTEM IS UNDER PRESSURE. PLACE A RAGSERVICE PROCEDURES OVER THE CAP. VERY SLOWLY ROTATE THE CAP COUNTERCLOCKWISE ALLOWING PRESSURE TOCOOLANT LEVEL CHECK SLOWLY RELEASE. AFTER ALL PRESSURE HAS The coolant level is checked and adjusted at the BEEN RELEASED, REMOVE THE COOLANT TANKpressurized coolant tank (Fig. 14). The tank is CAP COMPLETELY.located at the right-rear side of the engine compart-ment and is mounted as the highest point of the cool- DO NOT WASTE reusable coolant. If the solutioning system. This will allow any air or vapor is clean, drain the coolant into a clean container forexceeding the pressure/vent cap rating to escape reuse.through the cap. The coolant tank is equipped with a (1) Observe the previous WARNINGS and removethreaded-on pressure/vent cap. Refer to Pressure/ the coolant tank pressure/vent cap.Vent Cap for additional information. (2) The plastic radiator draincock is located on the A coolant reserve/overflow system with a separate bottom of the left radiator tank. It can be accessedtank is not used with the 2.5L diesel engine. from the bottom of vehicle. (a) Attach one end of a 24 inch long X 1/4 inch ID drain-hose to the nipple below the radiator draincock. (b) Put the other end of drain-hose into a clean container. (c) Open the draincock (counterclockwise as viewed from left side of vehicle) and drain coolant from radiator. (3) If the complete cooling system must be drained, raise the vehicle and remove the cylinder block drain-plug (Fig. 15). This hex- headed plug is located on the right/rear side of the engine above the starter motor. REFILLING COOLING SYSTEM Fig. 14 Coolant Tank and Pressure/Vent Cap The cooling system is equipped with a pressurized coolant tank using a pressure/vent cap. Refilling of (1) Add coolant into the coolant tank up to the the system is done through this tank.COLD mark. If possible, only add coolant when
  • 57. 7 - 18 COOLING SYSTEMSERVICE PROCEDURES (Continued) XJ freeze as described in the Coolant section of this group. (4) Continue to fill the cooling system until coolant is observed escaping from the fill vent opening. When this occurs, install the fill vent valve. The plastic fill vent valve is equipped with a rubber o- ring. Do not over tighten the fill vent valve. (5) Continue to fill the system until the coolant tank is full. (6) Install and tighten the coolant tank pressure/ vent cap. Do not use any type of tool when tight- ening the cap. Hand tighten only. (7) With the heater control unit in the HEAT posi- tion, operate engine with coolant tank cap tightened. (8) After engine has reached normal operating temperature, shut engine off and allow it to cool. (9) Remove coolant tank cap. (10) Add coolant into the coolant tank up to the COLD mark. If possible, only add coolant when the engine is cold. Coolant level in a warm engine will be higher in the tank due to ther- mal expansion. Fig. 15 Cylinder Block Drain-Plug (11) After the engine has been operated through aNOTE: The radiator draincock is equipped with a few heat-up and cool-down cycles, recheck the coolantrubber o-ring. Do not over tighten draincock. level in the tank. (1) Tighten the radiator draincock and (if COOLANT REPLACEMENTremoved), the cylinder block drain-plug. It is recommended that the cooling system be (2) Remove the plastic radiator fill vent valve drained and flushed at 84,000 kilometers (52,500(unscrews counter- clockwise) from the radiator. The miles), or 3 years, whichever occurs first. Then everyfill vent valve is located on the top of the right radi- two years, or 48,000 kilometers (30,000 miles),ator tank (Fig. 16). whichever occurs first. REMOVAL AND INSTALLATION RADIATOR WARNING: DO NOT REMOVE THE CYLINDER BLOCK DRAIN-PLUG, THE COOLANT TANK CAP, THE RADIATOR FILL VENT VALVE, OR LOOSEN THE RADIATOR DRAINCOCK WITH THE SYSTEM HOT AND PRESSURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR. DO NOT WASTE reusable coolant. If solution is clean, drain coolant into a clean container for reuse. WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES. WHEN REMOVING OR INSTALLING, USE ONLY TOOLS DESIGNED FOR SERVICING THIS TYPE OF CLAMP (Fig. 17). ALWAYS WEAR SAFETY Fig. 16 Radiator Fill Vent Valve GLASSES WHEN SERVICING CONSTANT TENSION (3) With the fill vent valve removed, proceed to fill CLAMPS.the system using a 50/50 mixture of water and anti-
  • 58. XJ COOLING SYSTEM 7 - 19REMOVAL AND INSTALLATION (Continued)CAUTION: A number or letter is stamped into the radiator. Slip the fan shroud rearward and position ittongue of constant tension clamps (Fig. 18). If over the fan blades.replacement is necessary, use only an original (6) Remove radiator hose clamps and remove radi-equipment clamp with matching number or letter. ator hoses. (7) Mark the position of the hood latch striker on the radiator crossmember and remove hood latch striker. (8) Remove radiator upper crossmember. (9) If equipped with air conditioning, separate the radiator from the A/C condenser by removing the condenser-to-radiator mounting brackets. (10) Lift radiator straight up and out of engine compartment taking care not to damage radiator or A/C condenser fins. INSTALLATION The radiator is equipped with two alignment dow- els (Fig. 19). They are located on the bottom of the plastic side tanks and fit into rubber grommets located in the front lower crossmember. (1) Carefully lower the radiator into engine com- Fig. 17 Hose Clamp Tool partment. Position the alignment dowels on the bot- tom of radiator into the rubber grommets in front lower crossmember (Fig. 19). Fig. 18 Clamp Number/Letter LocationREMOVAL (1) Disconnect negative battery cable at battery. Fig. 19 Radiator Alignment Dowels—Typical (2) Observe the previous WARNINGS. (3) Drain cooling system. Refer to Draining Cool- (2) If equipped with air conditioning, attach con-ing System in this group. denser to radiator with mounting brackets. (4) Remove the upper fan shroud-to-upper cross- (3) Install radiator upper crossmember.member mounting bolts. One of the bolts is mounted (4) Install hood latch striker.vertically at the bottom of the fan shroud. (5) Connect radiator upper and lower hoses. (5) Lift the fan shroud up until alignment tabs at (6) Insert alignment tabs at bottom of fan shroudthe bottom are clear of slots in bracket at bottom of into slots in bracket at bottom of radiator. Install and tighten fan shroud bolts to 3 N·m (31 in. lbs.) torque. (7) Connect negative battery cable.
  • 59. 7 - 20 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) (8) Fill cooling system with correct coolant. Refer (7) After removing fan blade/viscous fan driveto Refilling Cooling System in this group. assembly, do not place viscous fan drive in horizon- (9) Start and warm the engine. Check for coolant tal position. If stored horizontally, silicone fluid inleaks. the viscous fan drive could drain into its bearing assembly and contaminate lubricant.FAN BLADE REMOVAL CAUTION: Do not attempt to remove the fan pulleyFAN BLADE REMOVAL bolts. The fan pulley is under tension from the drive Accessory drive belt removal is not necessary for belt.fan blade or viscous fan drive removal. (1) Disconnect negative battery cable from battery. (8) Remove four bolts securing fan blade assembly (2) The thermal viscous fan drive/fan blade assem- to viscous fan drive (Fig. 20).bly is attached (threaded) to the fan pulley shaft(Fig. 20). Remove fan blade/viscous fan drive assem- FAN BLADE INSTALLATIONbly from fan pulley by turning mounting nut counter- (1) Install fan blade assembly to viscous fan drive.clockwise as viewed from front. Threads on viscous Tighten bolts (Fig. 20) to 23 N·m (200 in. lbs.) torque.fan drive are RIGHT HAND. Snap-On௡ 36 MM Fan (2) Position fan shroud and fan blade/viscous fanWrenches (number SP346) can be used to turn the drive assembly to vehicle as a complete unit.mounting nut and to hold the fan pulley from rotat- (3) Install and tighten fan shroud bolts to 3 N·ming. (31 in. lbs.) torque. (3) Do not attempt to remove fan/viscous fan drive (4) Install fan blade/viscous fan drive assembly toassembly from vehicle at this time. fan pulley shaft (Fig. 20). (4) Do not unbolt fan blade assembly from viscous (5) Connect negative battery cable.fan drive at this time. VISCOUS FAN DRIVE The thermal viscous fan drive (Fig. 21) is a sili- cone-fluid-filled coupling. It connects the fan blade assembly to the fan pulley. The coupling allows the fan to be driven in a normal manner. This is done at low engine speeds while limiting the top speed of the fan to a predetermined maximum level at higher engine speeds. A bimetallic spring coil is located on the front face. This spring coil reacts to the temper- ature of the radiator discharge air. It engages the viscous fan drive for higher fan speed if the air tem- perature from the radiator rises above a certain point. Until additional engine cooling is necessary, the fan will remain at a reduced rpm regardless of engine speed. Fig. 20 Thermal Viscous Fan Drive and Blade Assembly (5) Remove the fan shroud mounting bolts. One of Fig. 21 Viscous Fan Drivethe bolts is mounted vertically at the bottom ofshroud. The viscous fan drive will only engage when suffi- (6) Remove fan shroud and fan blade/viscous fan cient heat is present. This is when the air flowingdrive assembly as a complete unit from vehicle. through the radiator core causes a reaction from the
  • 60. XJ COOLING SYSTEM 7 - 21REMOVAL AND INSTALLATION (Continued)bimetallic coil. It then increases fan speed to provide TOOLS DESIGNED FOR SERVICING THIS TYPE OFthe necessary additional engine cooling. CLAMP (Fig. 17). ALWAYS WEAR SAFETY Once the engine has cooled, the radiator discharge GLASSES WHEN SERVICING CONSTANT TENSIONtemperature will drop. The bimetallic coil again CLAMPS.reacts and the fan speed is reduced to the previousdisengaged speed. CAUTION: A number or letter is stamped into theCAUTION: Some engines equipped with serpentine tongue of constant tension clamps (Fig. 18). Ifdrive belts have reverse rotating fans and viscous replacement is necessary, use only an originalfan drives. They are marked with the word equipment clamp with matching number or letter.REVERSE to designate their usage. Installation ofthe wrong fan or viscous fan drive can result in (2) Remove the upper radiator hose at the thermo-engine overheating. stat housing. (3) Remove the four thermostat housing bolts (Fig. 22)NOISENOTE: It is normal for fan noise to be louder (roar-ing) when: • The underhood temperature is above the engage-ment point for the viscous drive coupling. This mayoccur when ambient (outside air temperature) is veryhigh. • Engine loads and temperatures are high such aswhen towing a trailer. • Cool silicone fluid within the fan drive unit isbeing redistributed back to its normal disengaged(warm) position. This can occur during the first 15seconds to one minute after engine start-up on a coldengine.LEAKS Viscous fan drive operation is not affected by smalloil stains near the drive bearing. If leakage appearsexcessive, replace the fan drive unit.THERMOSTAT Fig. 22 Thermostat Removal/InstallationREMOVAL (4) Remove the thermostat housing from the waterWARNING: DO NOT REMOVE THE CYLINDER manifold.BLOCK DRAIN-PLUG, THE COOLANT TANK CAP, (5) Remove the thermostat and rubber seal fromTHE RADIATOR FILL VENT VALVE, OR LOOSEN the water manifold.THE RADIATOR DRAINCOCK WITH THE SYSTEM (6) Thoroughly clean the rubber seal mating sur-HOT AND PRESSURIZED. SERIOUS BURNS FROM faces.THE COOLANT CAN OCCUR. INSTALLATION DO NOT WASTE reusable coolant. If the solution (1) Install a new rubber seal around the outer lipis clean, drain the coolant into a clean container for of the thermostat (a notch is provided in the rubberreuse. seal). Do not apply any adhesive to this seal. (1) Drain the coolant from the radiator until the (2) Install the replacement thermostat and rubberlevel is below the thermostat housing. Refer to seal as one assembly into the water manifold adapterDraining Cooling System for procedures. (the pointed end of the thermostat should be facing towards the front of engine (Fig. 22). Observe theWARNING: CONSTANT TENSION HOSE CLAMPS recess groove in the water manifold adapter. Be sureARE USED ON MOST COOLING SYSTEM HOSES. the thermostat vent is in the 12 o’clock position (Fig.WHEN REMOVING OR INSTALLING, USE ONLY 22).
  • 61. 7 - 22 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) (3) Position the thermostat housing and four bolts 24) does not have to be removed. The pump impellerto the water manifold. is pressed on the rear of the pump shaft and bearing assembly. The pump is serviced only as a completeCAUTION: Tightening the thermostat housing assembly with the impeller, housing, hub and bear-unevenly or with the thermostat out of its recess ing.groove, may result in a cracked housing. A rubber o-ring seal (instead of a gasket) is used as a seal between the water pump and the water pump (4) Tighten the four housing bolts to 11 N·m (98 adapter.in. lbs.) torque. (5) Install radiator hose to thermostat housing. (6) Be sure that the radiator drain is tightlyclosed. Fill the cooling system to the correct levelwith the required coolant mixture. Refer to RefillingCooling System in this group for procedures. (7) Start and warm the engine. Check thermostatand hose for leaks.DRIVE BELTCAUTION: The drive belt on the 2.5L diesel engineis equipped with a spring loaded automatic belt ten-sioner. After belt installation, do not attempt tocheck belt tension with a belt tension gauge.AUTOMATIC BELT TENSIONER Fig. 24 WATER PUMP REMOVAL/INSTALL— TYPICAL WARNING: DO NOT REMOVE THE CYLINDER BLOCK DRAIN-PLUG, THE COOLANT TANK CAP, THE RADIATOR FILL VENT VALVE, OR LOOSEN THE RADIATOR DRAINCOCK WITH THE SYSTEM HOT AND PRESSURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR. DO NOT WASTE reusable coolant. If the solution is clean, drain coolant into a clean container for Fig. 23 Automatic Belt Tensioner Assembly reuse. (1) Disconnect negative battery cable at battery.WATER PUMP (2) Drain the cooling system. Refer to Draining Cooling System in this group.REMOVAL (3) The thermal viscous fan drive and the fan The water pump can be removed without discharg- blade assembly are attached (threaded) to the faning the air conditioning system (if equipped). pulley shaft (Fig. 25). Remove the fan/fan drive The water pump is serviced by replacing the pump assembly from the fan pulley by turning the mount-and its impeller only. The water pump adapter (Fig. ing nut counterclockwise (as viewed from front).
  • 62. XJ COOLING SYSTEM 7 - 23REMOVAL AND INSTALLATION (Continued)Threads on the fan drive are RIGHT HAND. Snap- CAUTION: A number or letter is stamped into theOn௡ 36 MM Fan Wrenches (number SP346) can be tongue of constant tension clamps (Fig. 27). Ifused to turn the mounting nut and to hold the fan replacement is necessary, use only an originalpulley from rotating. equipment clamp with matching number or letter. (4) If the water pump is being replaced, do notunbolt the fan blade assembly (Fig. 25) from thethermal viscous fan drive. Fig. 26 Hose Clamp Tool Fig. 25 Thermal Viscous Fan Drive and Blade Assembly (5) Remove the upper fan shroud-to-upper cross-member mounting bolts. One of the bolts is mountedvertically at the bottom of the fan shroud. (6) Slip the fan shroud rearward. Remove the fanshroud and viscous drive/fan blade together as oneassembly from the engine compartment. (7) Loosen but do not remove the 3 water pumppulley bolts (Fig. 24). (8) Remove the drive belt by removing the auto-matic belt tensioner. For procedures, refer to Belt Fig. 27 Clamp Number/Letter LocationRemoval/Installation in the Engine Accessory Drive (9) A metal coolant tube (used to connect rubberBelts section of this group. coolant hoses), and its mounting bracket are attached to the front of the water pump (Fig. 28). A rubberWARNING: CONSTANT TENSION HOSE CLAMPS hose connects this tube to the engine. Disconnect theARE USED ON MOST COOLING SYSTEM HOSES. hose clamp and rubber hose at the back of the ther-WHEN REMOVING OR INSTALLING, USE ONLY mostat. Position the hose to the side.TOOLS DESIGNED FOR SERVICING THIS TYPE OF (10) Remove the 3 water pump pulley bolts (Fig.CLAMP (Fig. 26). ALWAYS WEAR SAFETY 24).GLASSES WHEN SERVICING CONSTANT TENSION (11) Remove the water pump pulley from theCLAMPS. water pump.
  • 63. 7 - 24 COOLING SYSTEM XJREMOVAL AND INSTALLATION (Continued) (14) Install and tighten fan shroud mounting bolts to 3 N·m (31 in. lbs.) torque. (15) Fill cooling system with coolant and check for leaks. Refer to Refilling Cooling System in this group. (16) Connect battery cable to battery. (17) Start and warm the engine. Check for leaks. CLEANING AND INSPECTION WATER PUMP INSPECTION Replace the water pump assembly if it has any of the following conditions: Fig. 28 Coolant Tube at Water Pump • The body is cracked or damaged • Water leaks from the shaft seal. This is evident (12) Disconnect the drain hose from the vent tube by traces of coolant below the vent tube drain hoseat the bottom of water pump (Fig. 24). • Loose or rough turning bearing. (13) Remove the 4 water pump mounting bolts • Impeller rubs either the water pump body or(Fig. 24). water pump adapter. (14) Remove water pump from engine. RADIATOR CLEANINGINSTALLATION The radiator and air conditioning fins should be (1) Clean the o-ring mating surfaces. If the origi- cleaned when an accumulation of bugs, leaves etc.nal pump is to be reinstalled, remove any deposits or has occurred. Clean radiator fins are necessary forother foreign material. Inspect the water pump, good heat transfer. With the engine cold, apply coldwater pump adapter and water pump mating sur- water and compressed air to the back (engine side) offaces for erosion or damage from cavitation. the radiator to flush the radiator and/or A/C con- (2) Position a new rubber o-ring seal (Fig. 24) denser of debris.between the pump and pump adapter. Hold the sealwith petroleum jelly. FAN BLADE (3) Position the pump to the engine. (4) Position the metal coolant tube and its mount- INSPECTIONing bracket to the pump. The fan cannot be repaired. If fan is damaged, it (5) Install the four water pump mounting bolts. must be replaced. Inspect fan as follows:Tighten bolts to 24 N·m (18 ft. lbs.) torque. (1) Remove fan blade and viscous fan drive as an (6) Install drain hose to vent tube at bottom of assembly from the engine.pump. (2) Remove fan blade assembly from viscous fan (7) Position the water pump pulley to the water drive unit (four bolts) (Fig. 29).pump. (3) Lay fan on a flat surface with leading edge fac- (8) Install the water pump pulley bolts finger ing down. With tip of blade touching flat surface,tight. replace fan if clearance between opposite blade and (9) Install the rubber coolant hose near the ther- surface is greater than 2.0 mm (.090 inch). Rockingmostat. motion of opposite blades should not exceed 2.0 mm (10) Install the drive belt and belt tensioner. For (.090 inch). Test all blades in this manner.procedures, refer to Belt Removal/Installation in theEngine Accessory Drive Belts section of this group. WARNING: DO NOT ATTEMPT TO BEND OR (11) Tighten the water pump pulley bolts to 24 STRAIGHTEN FAN BLADES IF NOT WITHIN SPECI-N·m (18 ft. lbs.) torque. FICATIONS. (12) Position the viscous drive/fan blade and fanshroud to the engine compartment as one assembly. (4) Inspect fan assembly for cracks, bends, loose (13) Install the thermal viscous fan drive and fan rivets or broken welds. Replace fan if any damage isblade to fan pulley. Tighten to 56 N·m (41 ft. lbs.) found.torque.
  • 64. XJ COOLING SYSTEM 7 - 25CLEANING AND INSPECTION (Continued) COOLING SYSTEM CLEANING/REVERSE FLUSHING CAUTION: The cooling system normally operates at 90-to-117 kPa (13- to-17 psi) pressure. Exceeding this pressure may damage the radiator or hoses. CLEANING Drain cooling system and refill with water. Run engine with coolant tank pressure/vent cap installed until upper radiator hose is hot. Stop engine and drain water from system. If water is dirty, fill system with water, run engine and drain system. Repeat until water drains clean. REVERSE FLUSHING Reverse flushing of the cooling system is the forc- ing of water through the cooling system. This is done using air pressure in the opposite direction of normal coolant flow. It is usually only necessary with very dirty systems with evidence of partial plugging. REVERSE FLUSHING RADIATOR Disconnect the radiator hoses from the radiator fit- tings. Attach a section of radiator hose to the radia- tor bottom outlet fitting and insert the flushing gun. Fig. 29 Thermal Viscous Fan Drive and Blade Connect a water supply hose and air supply hose to Assembly the flushing gun.CAUTION: If fan blade assembly is replacedbecause of mechanical damage, the fan pulley bear- CAUTION: The cooling system normally operatesing and viscous fan drive should also be inspected. at 90-to-117 kPa (13- to-17 psi) pressure. ExceedingThese components could have been damaged due this pressure may damage the radiator or hoses.to excessive vibration. Allow the coolant tank and radiator to fill with water. When radiator is filled, apply air in shortCAUTION: Some engines equipped with serpentine blasts allowing radiator to refill between blasts. Con-drive belts have reverse rotating fans and viscous tinue this reverse flushing until clean water flowsfan drives. They are marked with the word out through rear of radiator cooling tube passages.REVERSE to designate their usage. Installation of For more information, refer to operating instructionsthe wrong fan or viscous fan drive can result in supplied with flushing equipment. Have radiatorengine overheating. cleaned more extensively by a radiator repair shop. REVERSE FLUSHING ENGINEPRESSURE/VENT CAP Drain the cooling system. Remove the thermostat housing and thermostat. Install the thermostat hous-INSPECTION ing. Disconnect the radiator upper hose from the Visually inspect the gasket on the cap. Replace cap radiator and attach the flushing gun to the hose. Dis-if the gasket is swollen, torn or worn. Inspect the connect the radiator lower hose from the waterarea around the coolant tank filler neck for white pump. Attach a lead away hose to the water pumpdeposits that indicate a leaking cap. inlet fitting. The cap must be replaced by a similar threaded-onunit with the correct operating pressures if replace- CAUTION: Be sure that the heater water controlment is necessary. valve is closed (heat off). This is done to prevent coolant flow with scale and other deposits from entering the heater core. Connect the water supply hose and air supply hose to the flushing gun. Allow the engine to fill with
  • 65. 7 - 26 COOLING SYSTEM XJCLEANING AND INSPECTION (Continued)water. When the engine is filled, apply air in short SPECIFICATIONSblasts, allowing the system to fill between air blasts.Continue until clean water flows through the lead COOLING SYSTEM CAPACITYaway hose. For more information, refer to operating 2.5L Diesel Engine: 9.8 Liters (10.4 qts.)instructions supplied with flushing equipment. Remove the lead away hose, flushing gun, water THERMOSTATsupply hose and air supply hose. Remove the thermo- Starts to open at 80°C (176°F).stat housing and install thermostat. Install the ther-mostat housing with a new replacement rubber seal. TORQUE SPECIFICATIONSRefer to Thermostat Installation. Connect the radia-tor hoses. Refill the cooling system with the correct DESCRIPTION TORQUEantifreeze/water mixture. Automatic Belt Tensioner-to-Mounting Bracket Bolt (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 N·mCHEMICAL CLEANING Automatic Belt Tensioner to Block In some instances, use a radiator cleaner (Mopar Bolts (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 N·mRadiator Kleen or equivalent) before flushing. This Coolant Tankwill soften scale and other deposits and aid the flush- Cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 N·ming operation. Fan Shroud-to-Radiator MountingCAUTION: Be sure instructions on the container Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 N·mare followed. Fan Blade-to-Thermal Viscous Fan Drive Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 N·m Hose Clamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 N·mADJUSTMENTS Radiator-to-A/C Condenser Isolator Nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 N·mDRIVE BELT TENSION Thermal Viscous Fan Drive-to-Fan Hub Initial belt adjustment is done with a adjustabletensioner pulley. After the initial adjustment is per- Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 N·mformed, an automatic belt tensioner is used to main- Thermostat Housingtain correct belt tension at all times. For other Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 N·mtensioner information and removal/installation proce- Water Pump Mountingdures, refer to Automatic Belt Tensioner in this Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 N·mgroup. Due to use of this belt tensioner, DO NOT Water Pump Pulleyattempt to use a belt tension gauge on the 2.5L die- Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 N·msel engine.

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