1998 gmc savana service repair manual

2002 ENGINES
Engine Cooling - Chevy Express & Savana
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
Fig. 1: Fastener Tightening Specifications
Courtesy of GENERAL MOTORS CORP.
SCHEMATIC AND ROUTING DIAGRAMS
2002 Chevrolet Chevy Express G1500
2002 ENGINES Engine Cooling - Chevy Express & Savana
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Saturday, March 28, 2009 9:40:32 PM Page 1 © 2005 Mitchell Repair Information Company, LLC.
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ENGINE COOLING SCHEMATICS
Fig. 2: Engine Cooling Schematics
COMPONENT LOCATOR
COOLING SYSTEM COMPONENT VIEWS
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Fig. 3: Coolant Recovery Tank
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Fig. 4: Instrument Panel, Driver Outer Knee Bolster Bracket
COOLING SYSTEM CONNECTOR END VIEWS
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Fig. 5: Coolant Level Switch (Diesel)
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Fig. 6: Coolant Level Module (Diesel)
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DIAGNOSTIC INFORMATION AND PROCEDURES
DIAGNOSTIC STARTING POINT - ENGINE COOLING
Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the
Description and Operation information will help you determine the correct symptom diagnostic
procedure when a malfunction exists. Reviewing the Description and Operation information will
also help you determine if the condition described by the customer is normal operation. Refer to
Symptoms - Engine Cooling in order to identify the correct procedure for diagnosing the
system and where the procedure is located.
DIAGNOSTIC SYSTEM CHECK - ENGINE COOLING
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. Lack of communication may be due to a partial malfunction of the class 2 serial data
circuit or due to a total malfunction of the class 2 serial data circuit. The specified
procedure will determine the particular condition.
3. Determine if the Powertrain Control Module (PCM) has set DTCs which may affect
Engine Cooling operation are present.
4. The presence of DTCs which begin with "U" indicate some other module is not
communicating. The specified procedure will compile all the available information before
tests are performed.
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Fig. 7: Diagnostic System Check - Engine Cooling
SCAN TOOL DATA LIST
Fig. 8: Powertrain Control Module (PCM) Scan Tool Data List
SCAN TOOL DATA DEFINITIONS
ECT Sensor- Range: -40°C to 150°C (-40°F to 302°F): The PCM applies 5.0 volts to the ECT
sensor circuit. The sensor is a thermistor which changes internal resistance as the engine
temperature changes. When the sensor is cold (internal resistance high), the PCM senses a high
signal voltage and interprets the voltage as a cold engine. As the sensor warms (internal resistance
decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm
engine.
DIAGNOSTIC TROUBLE CODE (DTC) LIST
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Fig. 9: Diagnostic Trouble Code (DTC) List
DTC P1258
Circuit Description
The PCM uses the ECT sensor to monitor the engine for an over temperature condition. This
condition occurs when the coolant temperature is above 131°C (268°F). When an over
temperature condition is present, DTC P1258 will set. The PCM will disable two groups of four
cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders,
the PCM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The PCM detects an engine over temperature condition.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which
the diagnostic test has been run and failed.
The PCM will turn ON the Service Engine Soon indicator.
The PCM will alternately disable 2 groups of four cylinders by turning OFF the fuel
injectors.
The PCM will store conditions which were present when the DTC set as Freeze Frame and
File Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL OFF after 3 consecutive trips that the diagnostic has been run
and passed.
The history DTC will clear after 40 consecutive warm-up cycles have occurred without a
malfunction.
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The DTC can be cleared by using the scan tool Clear DTC Information function.
Fig. 10: DTC P1258
SYMPTOMS - ENGINE COOLING
Important: Review the system operation in order to familiarize yourself with the system
functions. Refer to Cooling System Description and Operation .
Visual/Physical Inspection
Inspect for aftermarket devices which could affect the operation of the Cooling System.
Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.
Inspect the coolant recovery reservoir for the proper coolant level.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
INTERMITTENT OR POOR CONNECTIONS .
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:
Low Engine Coolant Indicator Always On
Engine Overheating
Loss of Coolant
Thermostat Diagnosis
Fan Clutch Diagnosis
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LOW ENGINE COOLANT INDICATOR ALWAYS ON
Fig. 11: Low Engine Coolant Indicator Always On
ENGINE OVERHEATING
Preliminary Overheating Diagnostic Inspection
1. Does overheating occur while pulling a trailer?
Does the trailer weigh less than 454 kg (1,000 lb)?
Is the vehicle equipped with a heavy duty cooling package?
2. Is the vehicle equipped with an add-on, or aftermarket, air conditioning system? If so, was a
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heavy duty radiator installed?
3. If overheating occurs after prolonged idle in gear with the A/C system operating, instruct the
owner on the following driving techniques to avoid overheating:
Idle the engine in N (Neutral) as much as possible. Increase the engine RPM in order
to get the coolant flowing through the radiator.
If overheating is indicated by a hot lamp or the temperature gage, turn the A/C system
off during extended idles of the engine.
4. If overheating occurs after prolonged driving in slow city traffic, or traffic jams, instruct the
owner on the following driving techniques to avoid overheating:
Idle the engine in N (Neutral) as much as possible. Increase the engine RPM in order
to get the coolant flowing through the radiator.
If overheating is indicated by a hot lamp or the temperature gage, turn the A/C system
off during extended idles of the engine.
If any of the above conditions apply, instruct the operator on driving techniques that would
reduce the possibility of engine overheating.
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Fig. 12: Engine Overheating (1 Of 2)
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Fig. 13: Engine Overheating (2 Of 2)
LOSS OF COOLANT
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Fig. 14: Loss Of Coolant (1 Of 2)
Fig. 15: Loss Of Coolant (2 Of 2)
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THERMOSTAT DIAGNOSIS
Tools Required
J 24731-188 188°F Tempilstick
J 24731-206 206°F Tempilstick
Thermostat Test
The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a
pencil like device. It has a wax material containing certain chemicals which melt at a given
temperature.
Temperature sticks can be used to determine a thermostat's operating range, by rubbing 87°C
(188°F) and 97°C (206°F) sticks on the thermostat housing.
1. Use a tempilstick in order to find the opening and the closing temperatures of the coolant
thermostat.
J 24731-188 tempilstick melts at 87°C (188°F). The thermostat should begin to open.
J 24731-206 tempilstick melts at 97°C (206°F). The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature
range.
COOLANT HEATER INOPERATIVE
Fig. 16: Coolant Heater Inoperative (1 Of 2)
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Fig. 17: Coolant Heater Inoperative (2 Of 2)
ENGINE FAILS TO REACH NORMAL OPERATING TEMPERATURE
Fig. 18: Engine Fails To Reach Normal Operating Temperature
FAN CLUTCH DIAGNOSIS
Fan Noise
Fan noise is sometimes evident under the following conditions:
When the clutch is engaged for maximum cooling.
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During the first 15 seconds to 1 minute after start-up until the clutch can redistribute the
silicone fluid back to the fluid's normal disengaged operating condition (after overnight
settling).
Fan noise, or an excessive roar, generally occurs continuously under all high engine speed
conditions (2500 RPM and up) if the clutch assembly locks up because of an internal failure. If
you cannot rotate the fan by hand, or if there is a rough grating feel as the fan is turned, replace
the clutch. Refer to Fan Clutch Replacement .
Looseness
Under various temperature conditions, a lateral movement is visible at the tip of the fan blade.
About 6.5 mm (1/4 in) maximum lateral movement, measured at the fan tip, is allowable.
Replacement of the fan clutch is not necessary.
Ensure that the fan blade is installed properly. If the fan is installed incorrectly, the fan will cause
an overheating problem.
Silicone Fluid Leaks
Small fluid leaks, occurring in the area around the bearing assembly, do not affect the operation
of the fan blade clutch.
If leakage appears replace the fan clutch. Refer to Fan Clutch Replacement .
Engine Overheating
1. In order to ensure complete fan blade clutch disengagement, begin testing with a cool
engine.
2. If the fan blade clutch assembly free wheels with no drag, (revolves more than 5 times when
spun by hand), replace the fan clutch. Refer to Fan Clutch Replacement . If the clutch
performs properly with a slight drag, refer to step 3. Testing a fan blade clutch by holding
the small hub with 1 hand, and rotating the aluminum housing in a
clockwise/counterclockwise motion, causes the clutch to free wheel. Consider this operation
normal and this test should not determine replacement.
3. Perform the following steps:
1. Sufficiently cover the radiator grille in order to induce a high engine temperature.
2. Start the engine.
3. Turn on the air conditioning (A/C) if equipped.
4. Operate the engine at 2000 RPM.
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4. Inspect the coolant temperature when the clutch engages. Allow about 5 to 10 minutes for
the temperature to become high enough in order to engage the fan blade clutch. This will be
indicated by an increase, or roar, in fan air noise and by a drop in the coolant temperature
reading of about 3-10°C (5-15°F).
If the clutch did not engage between 110-121°C (230-250°F), replace the assembly.
Ensure that the fan blade clutch was disengaged at the beginning of the test.
If you did not observe a sharp increase in the fan noise or a temperature drop, and the
fan noise level was constantly high from the start of the test, replace the assembly. Do
not continue this test past a thermometer reading of 121°C (250°F) in order to prevent
engine overheating.
5. When the clutch engages, do the following steps:
1. Remove the radiator grille cover.
2. Turn off the A/C in order to assist in engine cooling.
3. Operate the engine at about 2500 RPM.
6. After several minutes, the fan blade clutch should disengage as indicated by a reduction in
fan speed and roar. If the fan blade clutch fails to function as described, replace the fan
blade clutch. Refer to Fan Clutch Replacement .
REPAIR INSTRUCTIONS
DRAINING AND FILLING COOLING SYSTEM
Draining Procedure
WARNING: Under pressure, the temperature of the solution in the
radiator can be considerably higher, without boiling.
Removing the radiator cap while the engine is hot (pressure
is high), will cause the solution to boil instantaneously, with
explosive force. The solution will spew out over the engine,
fenders, and the person removing the cap. Serious bodily
injury may result. Flammable antifreeze, such as alcohol, is
not recommended for use at any time. Flammable antifreeze
could cause a serious fire.
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Fig. 19: Identifying Radiator Drain
1. Place a drain pan under the radiator drain cock.
2. Place the end of the tube in the drain pan.
3. After the engine cools down, remove the radiator cap.
4. Turn the drain cock counterclockwise in order to allow the coolant to drain.
5. Allow the coolant to drain from the system until the flow stops.
6. Place a drain pan under the engine block drain hole plug.
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7. Remove the drain hole plug from the engine block.
8. If equipped with the 4.3L, remove the drain hole plug from the engine block.
Fig. 20: Removing Drain Hole Plug From Engine Block (4.3L)
9. If equipped with the 5.0L and 5.3L, remove the drain hole plug from the engine block.
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Fig. 21: Removing Drain Hole Plug From Engine Block (5.0L & 5.3L)
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12. Allow the coolant to drain from the block until the flow stops. There may be more drainage
from the radiator at this time.
13. Apply Teflon Pipe Sealant GM P/N 12346004 (Canadian P/N 10953480) or equivalent to
the threads of the engine block coolant drain hole plugs.
CAUTION: Use the correct fastener in the correct location.
Replacement fasteners must be the correct part number
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14. Install the engine block coolant drain hole plugs.
Tighten
Tighten the 4.3L, 5.0L, 5.7L and 8.1L engine block drain hole plugs to 20 N.m (15 ft lbs).
Tighten the 6.5L engine block drain hole plugs to 25 N.m (18 ft lbs).
Close the radiator drain cock.
for that application. Fasteners requiring replacement or
fasteners requiring the use of thread locking compound
or sealant are identified in corrosion inhibitors on
fasteners or fastener joint surfaces unless specified.
These coatings affect fastener torque and joint clamping
force and may damage the fastener. Use the correct
tightening sequence and specifications when installing
fasteners in order to avoid damage to parts and systems.
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Filling Procedure
CAUTION: When adding coolant, use DEX-COOL coolant. If silicated
coolant is added to the system, premature engine, heater core
or radiator corrosion may result. In addition, the engine
coolant will require change sooner-at 50 000 km (30,000 mi) or
24 months.
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1. Inspect to make sure that the radiator drain cock is closed.
2. Inspect to make sure that the block drain hole plug is tight.
3. Add the DEX-COOL(R) to the radiator, then add clean drinkable water to the cooling
system. If you use the old coolant, make sure the solution is clean and clear, and that the
solution is a 50/50 mixture of glycol and water.
4. Place a large top funnel in the radiator filler neck or surge tank.
5. Slowly pour in the coolant. Because the thermostat is closed, filling the cooling system may
be slow.
6. Using the following procedures, bleed the air from the engine cooling system.
1. Remove the cap from the surge tank.
2. Remove the bleed screw (slotted) from the top of the thermostat housing.
3. Pour coolant into the surge tank, and watch for coolant flowing from the bleed screw.
4. When a constant flow of coolant is reached, closed the bleed screw at the top of the
thermostat housing.
5. Continue to fill the surge tank to the proper level.
6. Install the cap on the surge tank.
7. After filling the cooling system to 13 mm (0.5 in) below the radiator filler neck (4.3L, 5.0L,
and 5.7L) or to the full mark on the surge tank (6.5L, 8.1L), start the engine and let the
cooling system warm up. When the thermostat opens, the coolant level may drop. If the level
drops, add coolant as necessary.
8. Install the radiator or surge tank cap.
9. Inspect the coolant level in the coolant recovery reservoir (4.3L, 5.0L, and 5.7L) or the
surge tank (6.5L, 8.1L). Add coolant as necessary.
FLUSHING
Important: If the engine is damaged internally and a new engine assembly is installed in the
vehicle, make sure all foreign material is completely flushed out of the cooling system. The oil
cooler system should also be flushed out, if equipped. Failure to rid the oil or cooling system of
debris can result in damage to the replacement engine.
Important: Remove the thermostat before flushing the cooling system. Refer to Thermostat
Replacement (4.3L) or Thermostat Replacement (5.0L and 5.7L) or Thermostat
Replacement (6.5L) or Thermostat Replacement (8.1L) .
You can use various methods and equipment to flush the cooling system. If special equipment is
used, such as a back flusher, follow the manufacturer's instructions. However, always remove the
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thermostat before flushing the system.
Scale Removal Procedure
In order to remove hardened scale from the radiator, a direct chemical action is necessary.
1. Add a flushing compound, at the specified rate of 30 grams-per-liter (4 ounces-per-gallon)
of radiator capacity, to the coolant water as a dissolved solution while the engine is running.
2. Operate the engine for 15 minutes.
3. Drain the cooling system. Then, flush the system with clean drinkable water.
There are various types of flushing compounds commercially available. Obtain these from a
reliable source.
Most compounds attack metals and these should not remain in the engine for more than a few
minutes. Use a neutralizer in the cooling system immediately after using a de-scaling solvent. For
extremely hard, stubborn coatings, such as lime scale, use a stronger solution. The corrosive
action of a stronger solution affects the thin metals of the radiator, reducing the operating life of
the radiator. Because of this, flushing and rinsing the radiator is required.
After you use the solvent and the neutralizer, and after you flush the system, do the following:
1. Drain the entire cooling system. Refer to Draining and Filling Cooling System .
2. Fill the system with clean drinkable water and a rust inhibitor or high boiling type
antifreeze.
3. After filling the cooling system, check the radiator and hoses for coolant leaks.
RADIATOR CLEANING
Important: Remove bugs, leaves, dirt and other debris by blowing compressed air through the
engine side of the radiator.
Some conditions may require the use of warm water and a mild detergent.
WARNING: NEVER spray water on a hot radiator. The resulting steam
could cause personal injury.
CAUTION: The radiator fins are necessary for good heat transfer. Do not
brush the fins. This may cause damage to the fins, reducing
heat transfer
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Clean the A/C condenser fins.
Clean between the A/C condenser and radiator.
Clean the radiator cooling fins.
Straighten any damaged cooling fins.
SURGE TANK REPLACEMENT
Removal Procedure
1. Partially drain the engine coolant. Refer to Draining and Filling Cooling System .
2. Remove the overflow hose from the top of the surge tank.
3. Remove the inlet hose from the top of the radiator and from the surge tank.
4. Remove the outlet hose from the bottom of the surge tank.
5. Disconnect the coolant level sensor electrical connector.
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Fig. 24: Removing Overflow Hose, Inlet Hose & Outlet Hose
6. Remove the surge tank retaining bolt.
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7. Remove the surge tank from the cowl tabs.
8. Remove the surge tank from the vehicle.
9. Clean the surge tank with soap and water.
10. Rinse the surge tank with clean water.
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1998 gmc savana service repair manual

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