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TJ COOLING SYSTEM 7 - 1

COOLING SYSTEM

CONTENTS

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GENERAL INFORMATIONACCESSORY DRIVE BELTS . . . . . . . . . . . . . . . 3BLOCK HEATER . . . . . . . . . . . . . . . . . . . . . . . . 3COOLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2COOLING SYSTEM CIRCULATION . . . . . . . . . . 2COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 1RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . 2

DESCRIPTION AND OPERATIONBLOCK HEATER . . . . . . . . . . . . . . . . . . . . . . . . 3COOLANT PERFORMANCE . . . . . . . . . . . . . . . 4COOLANT RESERVE/OVERFLOW SYSTEM . . . 3COOLANT SELECTION AND ADDITIVES . . . . . 4COOLING SYSTEM HOSES . . . . . . . . . . . . . . . 5RADIATOR PRESSURE CAP . . . . . . . . . . . . . . 4THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . 4TRANSMISSION OIL COOLER . . . . . . . . . . . . . 3VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . 6WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . 5

DIAGNOSIS AND TESTINGACCESSORY DRIVE BELT DIAGNOSIS . . . . . . 7COOLANT—LOW LEVEL AERATION . . . . . . . 20COOLING SYSTEM DEAERATION . . . . . . . . . 20COOLING SYSTEM DIAGNOSIS . . . . . . . . . . . 11COOLING SYSTEM—TESTING FOR LEAKS . 17ON-BOARD DIAGNOSTICS (OBD) . . . . . . . . . . 7PRELIMINARY CHECKS . . . . . . . . . . . . . . . . . 10RADIATOR CAP TO FILLER NECK SEAL—

PRESSURE RELIEF CHECK . . . . . . . . . . . . . 19RADIATOR CAP—PRESSURE TESTING . . . . 20RADIATOR COOLANT FLOW CHECK . . . . . . . 17VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . 18

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SERVICE PROCEDURESCOOLANT LEVEL—ROUTINE CHECK . . . . . . 20COOLANT—ADDING ADDITIONAL . . . . . . . . 20COOLING SYSTEM—DRAINING . . . . . . . . . . 21COOLING SYSTEM—REFILLING . . . . . . . . . . 21COOLING SYSTEM—REVERSE FLUSHING . . 21SERVICE COOLANT LEVEL . . . . . . . . . . . . . . 21

REMOVAL AND INSTALLATIONACCESSORY DRIVE BELT . . . . . . . . . . . . . . . 28AUTOMATIC TRANSMISSION OIL COOLER . 22BLOCK HEATER . . . . . . . . . . . . . . . . . . . . . . . 26COOLANT RESERVE/OVERFLOW BOTTLE . . . 22RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . 26THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . 25VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . 28VISCOUS FAN . . . . . . . . . . . . . . . . . . . . . . . . 27WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . 22

CLEANING AND INSPECTIONCOOLING SYSTEM HOSES . . . . . . . . . . . . . . 30COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . 30FAN BLADE . . . . . . . . . . . . . . . . . . . . . . . . . . 30RADIATOR PRESSURE CAP . . . . . . . . . . . . . 29RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

ADJUSTMENTSACCESSORY DRIVE BELT . . . . . . . . . . . . . . . 30

SPECIFICATIONSACCESSORY DRIVE BELT TENSION . . . . . . . 31COOLING SYSTEM CAPACITIES . . . . . . . . . . 31TORQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

SPECIAL TOOLSCOOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

GENERAL INFORMATION

COOLING SYSTEMThe cooling system is designed to maintain engine

temperature at an efficient level during all engineoperating conditions. Coolant circulation is controlledby the thermostat. The thermostat remains closeduntil the coolant reaches operating temperature. Thisprovides for fast engine warm up. When the enginereaches operating temperature, the thermostat opens

and the coolant is circulated through the radiator tokeep the engine from overheating.

The cooling system also provides a means of heat-ing the passenger compartment and cooling the auto-matic transmission fluid (if equipped). The coolingsystem is pressurized and uses a centrifugal waterpump to circulate coolant throughout the system.

7 - 2 COOLING SYSTEM TJ

GENERAL INFORMATION (Continued)

COMPONENTSThe components of the cooling system are:• A heavy duty radiator• Cooling fan (mechanical)• Thermal viscous fan drive• Fan shroud• Radiator pressure cap• Thermostat• Coolant reserve/overflow system• Automatic transmission oil cooler

(internal to radiator)• Coolant• Water pump• Coolant hoses and clamps

COOLING SYSTEM CIRCULATIONFor cooling system flow routings, refer to (Fig. 1)

(Fig. 2).

WATER PUMPA centrifugal water pump circulates coolant

through the water jackets, passages, intake manifold,radiator core, cooling system hoses and heater core.The pump is driven from the engine crankshaft by adrive belt on all engines.

COOLANTThe cooling system is designed around the coolant.

Coolant flows through the engine water jacketsabsorbing heat produced during engine operation.The coolant carries heat to the radiator and heatercore. Here it is transferred to the ambient air pass-ing through the radiator and heater core fins. Thecoolant also removes heat from the automatic trans-mission fluid in vehicles equipped with an automatictransmission.

RADIATORA heavy duty down-flow aluminum/plastic radiator

is used. The radiator consists of an aluminum coreand plastic end tanks, which are fastened to the corewith clinch tabs and sealed with a high temperaturerubber gasket. On automatic transmission equippedvehicles, the lower tank contains a concentric-tubetransmission oil cooler.

CAUTION: Plastic tanks, while stronger than brass,are subject to damage by impact, such aswrenches, mishandling, etc.

If the plastic tank has been damaged, individualparts are not available, and the radiator must bereplaced.

Fig. 1 Coolant Circulation—2.5L Engine


GENERAL INFORMATION (Continued)

ACCESSORY DRIVE BELTSWhen installing an accessory drive belt, the belt

MUST be routed correctly. If not, the engine mayoverheat due to water pump rotating in wrong direc-tion. Refer to the appropriate engine Belt Schematicin this group for the correct belt routing, or refer tothe Belt Routing Label located in the engine com-partment.

BLOCK HEATERAn 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 engineproviding easier engine starting and faster warm-upin low temperatures. The heater is mounted in a corehole of the engine cylinder block (in place of a freezeplug) with the heating element immersed in enginecoolant. Connect the power cord to a grounded 110-120 volt AC electrical outlet with a grounded, three-wire extension cord.

WARNING: DO NOT OPERATE ENGINE UNLESSBLOCK HEATER CORD HAS BEEN DISCONNECTEDFROM POWER SOURCE AND SECURED IN PLACE.

Fig. 2 Coolant Circulation—4.0L Engine

DESCRIPTION AND OPERATION

TRANSMISSION OIL COOLERAll models equipped with an automatic transmis-

sion are equipped with a transmission oil cooler(water-to-oil) mounted internally within the radiatortank. This internal cooler is supplied as standardequipment on all models equipped with an automatictransmission.

Transmission oil is cooled when it passes throughthis separate cooler. In case of a leak in the internalradiator mounted transmission oil cooler, engine cool-ant may become mixed with transmission fluid ortransmission fluid may enter the cooling system.Both cooling system and transmission should bedrained and inspected if the internal radiatormounted transmission cooler is leaking.

These models do not come equipped with “auxilia-ry” transmission air-to-oil coolers.

COOLANT RESERVE/OVERFLOW SYSTEMThe system works along with the radiator pressure

cap. This is done by using thermal expansion andcontraction of the coolant to keep the coolant free oftrapped air. It provides:

• A volume for coolant expansion and contraction.• A convenient and safe method for checking/ad-

justing coolant level at atmospheric pressure. This isdone without removing the radiator pressure cap.

• Some reserve coolant to the radiator to coverminor leaks and evaporation or boiling losses.

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 coolantrecovery bottle (Fig. 3), a tube (hose) connecting theradiator and recovery bottle, and an overflow tube onthe side of the bottle.

BLOCK HEATERThe heater unit is mounted in a block core hole

and is immersed in coolant. The heater uses ordinaryhouse current (110 Volt A.C.) and should never beplugged in unless it is immersed in coolant.

WARNING: DO NOT OPERATE ENGINE UNLESSBLOCK HEATER CORD HAS BEEN DISCONNECTEDFROM POWER SOURCE AND SECURED IN PLACE.

BLOCK HEATER SPECIFICATIONS• 2.5L 4-Cylinder Engine: 115 Volts 400 Watts• 4.0L 6-Cylinder Engine: 120 Volts 600 Watts


DESCRIPTION AND OPERATION (Continued)

THERMOSTATA pellet-type thermostat controls the operating

temperature of the engine by controlling the amountof coolant flow to the radiator. On all engines thethermostat is closed below 195°F (90°C). Above thistemperature, coolant is allowed to flow to the radia-tor. This provides quick engine warm-up and overalltemperature control.

An arrow plus the word UP is stamped on thefront flange next to the air bleed. The words TORAD are stamped on one arm of the thermostat.They indicate the proper installed position.

The same thermostat is used for winter and sum-mer seasons. An engine should not be operated with-out a thermostat, except for servicing or testing.Operating without a thermostat causes other prob-lems. These are: longer engine warm-up time, unre-liable warm-up performance, increased exhaustemissions and crankcase condensation. This conden-sation can result in sludge formation.

CAUTION: Do not operate an engine without athermostat, except for servicing or testing.

COOLANT PERFORMANCEThe required ethylene-glycol (antifreeze) and water

mixture depends upon climate and vehicle operatingconditions. The coolant performance of various mix-tures follows:

Pure Water- Water can absorb more heat than amixture of water and ethylene-glycol. This is for pur-pose of heat transfer only. Water also freezes at ahigher temperature and allows corrosion.

100 percent Ethylene-Glycol- The corrosioninhibiting additives in ethylene-glycol need the pres-

Fig. 3 Coolant Recovery Bottle

ence of water to dissolve. Without water, additivesform deposits in system. These act as insulationcausing temperature to rise to as high as 149°C(300°F). This temperature is hot enough to melt plas-tic and soften solder. The increased temperature canresult in engine detonation. In addition, 100 percentethylene-glycol freezes at -22°C (-8°F).

50/50 Ethylene-Glycol and Water -Is the recom-mended mixture, it provides protection against freez-ing to -37°C (-34°F). The antifreeze concentrationmust always be a minimum of 44 percent, year-round in all climates. If percentage is lower, engineparts may be eroded by cavitation. Maximum protec-tion against freezing is provided with a 68 percentantifreeze concentration, which prevents freezingdown to -67.7°C (-90°F). A higher percentage willfreeze at a warmer temperature. Also, a higher per-centage of antifreeze can cause the engine to over-heat because specific heat of antifreeze is lower thanthat of water.

CAUTION: Richer antifreeze mixtures cannot bemeasured with normal field equipment and cancause problems associated with 100 percent ethyl-ene-glycol.

COOLANT SELECTION AND ADDITIVESCoolant should be maintained at the specified level

with a mixture of ethylene glycol-based antifreezeand low mineral content water.

CAUTION: Do not use coolant additives that areclaimed to improve engine cooling.

RADIATOR PRESSURE CAPAll radiators are equipped with a pressure cap.

This cap releases pressure at some point within arange of 83-124 kPa (12-18 psi). The pressure reliefpoint (in pounds) is engraved on top of the cap (Fig.4).

The cooling system will operate at pressuresslightly above atmospheric pressure. This results in ahigher coolant boiling point allowing increased radi-ator cooling capacity. The cap contains a spring-loaded pressure relief valve. This valve opens whensystem pressure reaches the release range of 83-124kPa (12-18 psi).

A vent valve in the center of the cap allows a smallcoolant flow through the cap when coolant is belowboiling temperature. The valve is completely closedwhen boiling point is reached. As coolant cools, itcontracts and creates a vacuum in the cooling sys-tem. This causes the vacuum valve to open and cool-ant in reserve/overflow tank to be drawn through



connecting hose into radiator. If the vacuum valve isstuck shut, radiator hoses will collapse on cool-down.

A rubber gasket seals the radiator filler neck. Thisis done to maintain vacuum during coolant cool-downand to prevent leakage when system is under pres-sure.

WATER PUMPThe water pump impeller is pressed onto the rear

of a shaft that rotates in bearings pressed into thehousing. The housing has a small hole to allow seep-age to escape. The water pump seals are lubricatedby 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-cous fan drive assembly. REVERSE is stamped orimprinted on the cover of the viscous fan drive andinner side of the fan. The letter R is stamped intothe back of the water pump impeller (Fig. 5).

Engines from previous model years, dependingupon application, may have been equipped with a for-ward (clockwise) rotating water pump. Installation ofthe wrong water pump will cause engine overheating.

Fig. 4 Radiator Pressure Cap

COOLING SYSTEM HOSESRubber hoses route coolant to and from the radia-

tor, intake manifold and heater core.Radiator lower hoses are spring-reinforced to pre-

vent collapse from water pump suction at moderateand high engine speeds.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OFCLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER6094) (Fig. 6). SNAP-ON CLAMP TOOL (NUMBERHPC-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 thetongue of constant tension clamps (Fig. 7). Ifreplacement is necessary, use only an originalequipment clamp with matching number or letter.

Inspect the hoses at regular intervals. Replacehoses that are cracked, feel brittle when squeezed, orswell excessively when the system is pressurized.

For all vehicles: In areas where specific routingclamps are not provided, be sure that hoses are posi-tioned with sufficient clearance. Check clearancefrom exhaust manifolds and pipe, fan blades, drivebelts and sway bars. Improperly positioned hoses canbe damaged, resulting in coolant loss and engineoverheating.

Fig. 5 Reverse Rotating Water Pump—Typical



Ordinary worm gear type hose clamps (whenequipped) can be removed with a straight screw-driver or a hex socket. To prevent damage tohoses or clamps, the hose clamps should betightened to 4 N·m (34 in. lbs.) torque. Do notover tighten hose clamps.

When performing a hose inspection, inspect theradiator lower hose for proper position and conditionof the internal spring.

VISCOUS FAN DRIVEThe thermal viscous fan drive (Fig. 8) is a silicone-

fluid-filled coupling used to connect the fan blades toeither 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.

Fig. 6 Hose Clamp Tool—Typical

Fig. 7 Clamp Number/Letter Location

top speed of the fan to a predetermined maximumlevel at higher engine speeds

A thermostatic bimetallic spring coil is located onthe front face of the viscous fan drive unit (a typicalviscous unit is shown in (Fig. 9). This spring coilreacts to the temperature of the radiator dischargeair. It engages the viscous fan drive for higher fanspeed if the air temperature from the radiator risesabove a certain point. Until additional engine coolingis necessary, the fan will remain at a reduced rpmregardless of engine speed.

Only when sufficient heat is present, will the vis-cous fan drive engage. This is when the air flowingthrough the radiator core causes a reaction to the

Fig. 8 Water Pump Mounted Fan Drive

Fig. 9 Viscous Fan Drive—Typical



bimetallic coil. It then increases fan speed to providethe necessary additional engine cooling.

Once the engine has cooled, the radiator dischargetemperature will drop. The bimetallic coil againreacts and the fan speed is reduced to the previousdisengaged speed.

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.

DIAGNOSIS AND TESTING

ON-BOARD DIAGNOSTICS (OBD)

COOLING SYSTEM RELATED DIAGNOSTICSThe Powertrain Control Module (PCM) has been

programmed to monitor the certain following coolingsystem components:

• If the engine has remained cool for too long aperiod, such as with a stuck open thermostat, a Diag-nostic Trouble Code (DTC) can be set.

• If an open or shorted condition has developed inthe relay circuit controlling the electric radiator fan,a Diagnostic Trouble Code (DTC) can be set.

If the problem is sensed in a monitored circuitoften enough to indicate an actual problem, a DTC isstored. The DTC will be stored in the PCM memoryfor eventual display to the service technician. (Referto Group 25, Emission Control Systems for properprocedures)

ACCESSING DIAGNOSTIC TROUBLE CODESTo read DTC’s and to obtain cooling system data,

refer to Group 25, Emission Control Systems forproper procedures.

ACCESSORY DRIVE BELT DIAGNOSIS

VISUAL DIAGNOSISWhen diagnosing serpentine accessory drive belts,

small cracks that run across the ribbed surface of thebelt from rib to rib (Fig. 10), 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. 10). Also replace the belt if it hasexcessive wear, frayed cords or severe glazing.

Refer to the Accessory Drive Belt Diagnosis chartsfor further belt diagnosis.

NOISE DIAGNOSISNoises generated by the accessory drive belt are

most noticeable at idle. Before replacing a belt toresolve a noise condition, inspect all of the accessorydrive pulleys for alignment, glazing, or excessive endplay.

Fig. 10 Belt Wear Patterns


DIAGNOSIS AND TESTING (Continued)

ACCESSORY DRIVE BELT DIAGNOSIS CHART

CONDITION POSSIBLE CAUSES CORRECTION

RIB CHUNKING (One ormore ribs has separatedfrom belt body)

1. Foreign objects imbedded in pulleygrooves.

1. Remove foreign objects from pulleygrooves. Replace belt.

2. Installation damage 2. Replace belt

RIB OR BELT WEAR 1. Pulley misaligned 1. Align pulley(s)2. Abrasive environment 2. Clean pulley(s). Replace belt if

necessary3. 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 belt

BELT SLIPS 1. Belt slipping because of insufficienttension

1. Adjust tension

2. Belt or pulley exposed to substancethat has reduced friction (belt dressing,oil, ethylene glycol)

2. Replace belt and clean pulleys

3. Driven component bearing failure(seizure)

3. Replace faulty component or bearing

4. Belt glazed or hardened from heatand excessive slippage

4. Replace belt.

LONGITUDAL BELTCRACKING

1. Belt has mistracked from pulleygroove

1. Replace belt

2. Pulley groove tip has worn awayrubber to tensile member

2. Replace belt

9GROOVE JUMPING9(Belt does not maintaincorrect position on pulley)

1. Belt tension either too low or toohigh

1. Adjust belt tension

2. Pulley(s) not within design tolerance 2. Replace pulley(s)3. Foreign object(s) in grooves 3. Remove foreign objects from grooves4. Pulley misalignment 4. Align component5. Belt cordline is broken 5. Replace belt

BELT BROKEN(Note: Identify and correctproblem before new belt isinstalled)

1. Excessive tension 1. Replace belt and adjust tension tospecification

2. Tensile member damaged during beltinstallation

2. Replace belt

3. Severe misalignment 3. Align pulley(s)4. Bracket, pulley, or bearing failure 4. Replace defective component and

belt

NOISE(Objectionable squeal,squeak, or rumble is heardor felt while drive belt is inoperation)

1. Belt slippage 1. Adjust belt2. Bearing noise 2. Locate and repair3. Belt misalignment 3. Align belt/pulley(s)4. Belt to pulley mismatch 4. Install correct belt5. Driven component induced vibration 5. Locate defective driven component

and repair6. System resonant frequency inducedvibration

6. Vary belt tension withinspecifications.




TENSION SHEETINGFABRIC FAILURE(Woven fabric on outside,circumference of belt hascracked or separated frombody of belt)

1. Tension sheeting contactingstationary object

1. Correct rubbing condition

2. Excessive heat causing woven fabricto age

2. Replace belt

3. Tension sheeting splice has fractured 3. Replace belt

CORD EDGE FAILURE(Tensile member exposed atedges of belt or separatedfrom belt body)

1. Excessive tension 1. Adjust belt tension2. Belt contacting stationary object 2. Replace belt3. Pulley(s) out of tolerance 3. Replace pulley4. Insufficient adhesion between tensilemember and rubber matrix

4. Replace belt and adjust tension tospecifications



PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATINGEstablish what driving conditions caused the com-

plaint. Abnormal loads on the cooling system such asthe following may be the cause.

PROLONGED IDLE, VERY HIGH AMBIENT TEMPERATURE,SLIGHT TAIL WIND AT IDLE, SLOW TRAFFIC, TRAFFICJAMS, HIGH SPEED, OR STEEP GRADES:

Driving techniques that avoid overheating are:• Idle with A/C off when temperature gauge is at

end of normal range.• Increasing engine speed for more air flow is rec-

ommended.

TRAILER TOWINGConsult Trailer Towing section of owners manual.

Do not exceed limits.

AIR CONDITIONING; ADD-ON OR AFTER MARKETThese models are equipped with a “heavy duty”

cooling system and therefore will accommodate

add-on or aftermarket air conditioning. No modifica-tions are necessary to the cooling system.

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(s)• Brakes (possibly dragging)• Changed parts (incorrect water pump rotating in

wrong direction)• Reconditioned radiator or cooling system refill-

ing (possibly under- filled or air trapped in system).

NOTE: If investigation reveals none of the previousitems as a cause for an engine overheating com-plaint, refer to following Cooling System Diagnosischarts.



COOLING SYSTEM DIAGNOSIS

COOLING SYSTEM DIAGNOSIS CHART


TEMPERATURE GAUGEREADS LOW

1. Has a Diagnostic TroubleCode (DTC) been set indicatinga stuck open engine thermostat.

1. Refer to group 25, Emission ControlSystems. Replace thermostat if necessary.If a Diagnostic Trouble Code (DTC) has notbeen set, the problem may be with thetemperature gauge.

2. Is the temperature gauge (ifequipped) connected to thetemperature gauge coolantsensor on the engine?

2. Check the engine temperature sensorconnector in the engine compartment. Referto Group 8E. Repair as necessary.

3. Is the temperature gauge (ifequipped) operating OK?

3. Check gauge operation. Refer to Group8E. Repair as necessary.

4. Coolant level low in coldambient temperaturesaccompanied with poor heaterperformance.

4. Check coolant level in the coolantreserve/overflow tank and the radiator.Inspect system for leaks. Repair leaks asnecessary. Refer to the Coolant section ofthe manual text for Warnings andprecautions before removing the radiatorcap.

5. Improper operation of internalheater doors or heater controls.

5. Inspect heater and repair as necessary.Refer to Group 24, Heating and AirConditioning for procedures.

TEMPERATURE GAUGEREADS HIGH OR ENGINECOOLANT WARNING LAMPILLUMINATES. COOLANT MAYOR MAY NOT BE LOST ORLEAKING FROM COOLINGSYSTEM

1. Trailer is being towed, asteep hill is being climbed,vehicle is operated in slowmoving traffic, or engine isbeing idled with very highambient (outside) temperaturesand the air conditioning is on.Higher altitudes couldaggravate these conditions.

1. This may be a temporary condition andrepair is not necessary. Turn off the airconditioning and attempt to drive the vehiclewithout any of the previous conditions.Observe the temperature gauge. The gaugeshould return to the normal range. If thegauge does not return to normal range,determine the cause for overheating andrepair. Refer to POSSIBLE CAUSES(numbers 2 through 18).

2. Is temperature gauge (ifequipped) reading correctly?

2. Check gauge. Refer to Group 8E. Repairas necessary.

3. Is temperature warning lamp(if equipped) illuminatingunnecessarily?

3. Check warning lamp operation. Refer toGroup 8E. Repair as necessary.

4. Coolant low in coolantreserve/overflow tank andradiator?

4. Check for coolant leaks and repair asnecessary. Refer to Testing Cooling Systemfor Leaks in this group.

5. Pressure cap not installedtightly. If cap is loose, boilingpoint of coolant will be lowered.Also refer to the following step6.

5. Tighten cap.

6. Poor seals at radiator cap. 6. (a) Check condition of cap and capseals. Refer to Radiator Cap. Replace capif necessary.(b) Check condition of radiator filler neck. Ifneck is bent or damaged, replace radiator.




TEMPERATURE GAUGEREADS HIGH OR ENGINECOOLANT WARNING LAMPILLUMINATES. COOLANT MAYOR MAY NOT BE LOST ORLEAKING FROM COOLINGSYSTEM - CONT.

7. Coolant level low in radiatorbut not in coolant reserve/overflow tank. This means theradiator is not drawing coolantfrom the coolant reserve/overflow tank as the enginecools.As the engine cools, a vacuumis formed in the cooling systemof the engine and radiator. Ifradiator cap seals are defective,or cooling system has leaks, avacuum can not be formed.

7. (a) Check condition of radiator cap andcap seals. Refer to Radiator Cap in thisgroup. Replace cap if necessary.(b) Check condition of radiator filler neck. Ifneck is bent or damaged, replace radiator.(c) Check the condition of the hose from theradiator to the coolant tank. It should fit tightat both ends without any kinks or tears.Replace hose if necessary.(d) Check coolant reserve/overflow tank andtank hoses for blockage. Repair asnecessary

8. Freeze point of antifreeze notcorrect. Mixture may be toorich.

8. Check antifreeze. Refer to Coolantsection of this group. Adjust antifreeze-to-water ratio as required.

9. Coolant not flowing throughsystem.

9. Check for coolant flow at radiator fillerneck with some coolant removed, enginewarm and thermostat open. Coolant shouldbe observed flowing through radiator. If flowis not observed, determine reason for lackof flow and repair as necessary.

10. Radiator or A/C condenserfins are dirty or clogged.

10. Clean insects or debris. Refer toRadiator Cleaning in this group.

11. Radiator core is corroded orplugged.

11. Have radiator re-cored or replaced.

12. Fuel or ignition systemproblems.

12. Refer to Fuel and Ignition Systemgroups for diagnosis. Also refer to theappropriate Powertrain DiagnosticProcedures service manual for operation ofthe DRB scan tool.

13. Dragging brakes. 13. Check and correct as necessary. Referto Group 5, Brakes in the manual text.

14. Bug screen is being usedreducing airflow.

14. Remove bug screen.

15. Thermostat partially orcompletely shut. This is moreprevalent of high mileagevehicles.

15. Check thermostat operation and replaceas necessary. Refer to Thermostats in thisgroup.

16. Thermal viscous fan drivenot operating properly.

16. Check fan drive operation and replace ifnecessary. Refer to Viscous Fan Drive inthis group.

17. Cylinder head gasketleaking.

17. Check for cylinder head gasket leaks.Refer to Testing Cooling System for Leaksin this group. For repair, refer to Group 9,Engines.

18. Heater core leaking. 18. Check heater core for leaks. Refer toGroup 24, Heating and Air Conditioning.Repair as necessary.




TEMPERATURE GAUGEREADING IS INCONSISTENT(FLUCTUATES, CYCLES OR ISERRATIC)

1. During cold weatheroperation, with the heaterblower in the high position, thegauge reading may dropslightly.

1. A normal condition. No correction isnecessary.

2. Temperature gauge or enginemounted gauge sensordefective or shorted. Also,corroded or loose wiring in thecircuit.

2. Check operation of gauge and repair ifnecessary. Refer to Group 8E, InstrumentPanel and Gauges.

3. Gauge reading rises whenvehicle is brought to a stopafter heavy use (engine stillrunning).

3. A normal condition. No correction isnecessary. Gauge reading should return tonormal range after vehicle is driven.

4. Gauge reading high afterrestarting a warmed-up (hot)engine.

4. A normal condition. No correction isnecessary. The gauge should return tonormal range after a few minutes of engineoperation.

5. Coolant level low in radiator(air will build up in the coolingsystem causing the thermostatto open late).

5. Check and correct coolant leaks. Refer toTesting Cooling System for Leaks in thisgroup.

6. Cylinder head gasket leakingallowing exhaust gas to entercooling system causingthermostat to open late.

6. (a) Check for cylinder head gasket leakswith a commercially available Block LeakTester. Repair as necessary.(b) Check for coolant in the engine oil.Inspect for white steam emitting fromexhaust system. Repair as necessary.

7. Water pump impeller looseon shaft.

7. Check water pump and replace asnecessary. Refer to Water Pumps in thisgroup.

8. Loose accessory drive belt(water pump slipping).

8. Refer to Engine Accessory Drive Belts inthis group. Check and correct as necessary.

9. Air leak on the suction sideof water pump allows air tobuild up in cooling systemcausing thermostat to open late.

9. Locate leak and repair as necessary.

PRESSURE CAP IS BLOWINGOFF STEAM AND/ORCOOLANT TO COOLANTTANK. TEMPERATURE GAUGEREADING MAY BE ABOVENORMAL BUT NOT HIGH.COOLANT LEVEL MAY BEHIGH IN COOLANT RESERVE/OVERFLOW TANK

1. Pressure relief valve inradiator cap is defective.

1. Check condition of radiator cap and capseals. Refer to Radiator Caps in this group.Replace cap as necessary.

COOLANT LOSS TO THEGROUND WITHOUTPRESSURE CAP BLOWOFF.GAUGE IS READING HIGH ORHOT

1. Coolant leaks in radiator,cooling system hoses, waterpump or engine.

1. Pressure test and repair as necessary.Refer to Testing Cooling System for Leaksin this group.




DETONATION OR PRE-IGNITION (NOT CAUSED BYIGNITION SYSTEM). GAUGEMAY OR MAY NOT BEREADING HIGH

1. Engine overheating. 1. Check reason for overheating and repairas necessary.

2. Freeze point of antifreeze notcorrect. Mixture is too rich ortoo lean.

2. Check antifreeze. Refer to the Coolantsection of this group. Adjust antifreeze-to-water ratio as required.

HOSE OR HOSESCOLLAPSED WHEN ENGINEIS COOLING

1. Vacuum created in coolingsystem on engine cool-down isnot being relieved throughcoolant reserve/overflowsystem.

1. (a) Radiator cap relief valve stuck. Referto Radiator Cap in this group. Replace ifnecessary.(b) Hose between coolant reserve/overflowtank and radiator is kinked. Repair asnecessary.(c) Vent at coolant reserve/overflow tank isplugged. Clean vent and repair asnecessary.(d) Reserve/overflow tank is interallyblocked or plugged. Check for blockage andrepair as necessary.

NOISY FAN 1. Fan blades loose. 1. Replace fan blade assembly. Refer toCooling System Fans in this group.

2. Fan blades striking asurrounding object.

2. Locate point of fan blade contact andrepair as necessary.

3. Air obstructions at radiator orair conditioning condenser.

3. Remove obstructions and/or clean debrisor insects from radiator or A/C condenser.

4. Thermal viscous fan drivehas defective bearing.

4. Replace fan drive. Bearing is notserviceable. Refer to Viscous Fan Drive inthis group.

5. A certain amount of fan noise(roaring) may be evident fromthe thermal viscous fan drive.Some of this noise is normal.

5. Refer to Viscous Fan Drive in this groupfor an explanation of normal fan noise.

INADEQUATE AIRCONDITIONERPERFORMANCE (COOLINGSYSTEM SUSPECTED)

1. Radiator and/or A/Ccondenser is restricted,obstructed or dirty (insects,leaves etc.)

1. Remove restriction and/or clean asnecessary. Refer to Radiator Cleaning inthis group.

2. Thermal viscous fan drive isfree-wheeling.

2. Refer to Viscous Fan Drive for diagnosis.Repair as necessary.

3. Engine is overheating (heatmay be transferred fromradiator to A/C condenser. Highunderhood temperatures due toengine overheating may alsotransfer heat to A/Ccomponents).

3. Correct overheating condition. Refer totext in Group 7, Cooling.

4. Some models with certainengines are equipped with airseals at the radiator and/or A/Ccondenser. If these seals aremissing or damaged, notenough air flow will be pulledthrough the radiator and A/Ccondenser.

4. Check for missing or damaged air sealsand repair as necessary.




INADEQUATE HEATERPERFORMANCE.THERMOSTAT FAILED INOPEN POSITION

1. Has a diagnostic troublecode (DTC) been set?

1. Refer to group 25, Emission ControlSystem and replace thermostat ifnecessary.

2. Coolant level low. 2. Refer to Testing Cooling System forLeaks in the manual text. Repair asnecessary.

3. Obstructions in heater hosefittings at engine.

3. Remove heater hoses at both ends andcheck for obstructions. Repair as necessary.

4. Heater hose kinked. 4. Locate kinked area and repair asnecessary.

5. Water pump is not pumpingwater to heater core. When theengine is fully warmed up, bothheater hoses should be hot tothe touch. If only one of thehoses is hot, the water pumpmay not be operating correctly.The accessory drive belt mayalso be slipping causing poorwater pump operation.

5. Refer to Water Pumps in this group.Repair as necessary. If a slipping belt isdetected, refer to Engine Accessory DriveBelts in this group. Repair as necessary.

HEAT ODOR 1. Various heat shields areused at certain drive linecomponents. One or more ofthese shields may be missing.

1. Locate missing shields and replace orrepair as necessary.

2. Is temperature gauge readingabove the normal range?

2. Refer to the previous Temperature GaugeReads High in these Diagnosis Charts.Repair as necessary.

3. Is cooling fan operatingcorrectly.

3. Refer to Cooling System Fan in thisgroup for diagnosis. Repair as necessary

4. Has undercoating beenapplied to any unnecessarycomponent.

4. Clean undercoating as necessary.

5. Engine may be running richcausing the catalytic converterto overheat.

5. Refer to the DRB scan tool and theappropriate Powertrain DiagnosticProcedures service manual. Repair asnecessary.

POOR DRIVEABILITY(THERMOSTAT POSSIBLYSTUCK OPEN). GAUGE MAYBE READING LOW

1. For proper driveability, goodvehicle emissions and forpreventing build-up of engine oilsludge, the thermostat must beoperating properly. Has adiagnostic trouble code (DTC)been set?

1. Refer to group 25, Emission ControlSystem. DTC’s may also be checked usingthe DRB scan tool. Refer to the properPowertrain Diagnostics Procedures servicemanual for checking the thermostat usingthe DRB scan tool. Replace thermostat ifnecessary.




STEAM IS COMING FROMFRONT OF VEHICLE NEARGRILL AREA WHEN WEATHERIS WET, ENGINE IS WARMEDUP AND RUNNING, ANDVEHICLE IS STATIONARY.TEMPERATURE GAUGE IS INNORMAL RANGE

1. During wet weather, moisture(snow, ice or rain condensation)on the radiator will evaporatewhen the thermostat opens.This opening allows heatedwater into the radiator. Whenthe moisture contacts the hotradiator, steam may be emitted.This usually occurs in coldweather with no fan or airflow toblow it away.

1. Occasional steam emitting from this areais normal. No repair is necessary.

COOLANT COLOR 1. Coolant color is notnecessarily an indication ofadequate corrosion ortemperature protection. Do notrely on coolant color fordetermining condition ofcoolant.

1. Refer to Coolant in this group forantifreeze tests. Adjust antifreeze-to-waterratio as necessary.

COOLANT LEVEL CHANGESIN COOLANT RESERVE/OVERFLOW TANK.TEMPERATURE GAUGE IS INNORMAL RANGE

1. Level changes are to beexpected as coolant volumefluctuates with enginetemperature. If the level in thetank was between the FULLand ADD marks at normalengine operating temperature,the level should return to withinthat range after operation atelevated temperatures.

1. A normal condition. No repair isnecessary.



RADIATOR COOLANT FLOW CHECKThe following procedure will determine if coolant is

flowing through the cooling system.If engine is cold, idle engine until normal operating

temperature is reached. Then feel the upper radiatorhose. If hose is hot, the thermostat is open and wateris circulating through cooling system.

COOLING SYSTEM—TESTING FOR LEAKS

ULTRAVIOLET LIGHT METHODAll Jeep models have a leak detection additive

added to the cooling system before they leave the fac-tory. The additive is highly visible under ultravioletlight (black light). If the factory original coolant hasbeen drained, pour one ounce of additive into thecooling system. The additive is available through thepart’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.11).

PRESSURE TESTER METHODThe engine should be at the normal operating tem-

perature. Recheck the system cold if the cause ofcoolant loss is not located during warm engine exam-ination.

Fig. 11 Leak Detection Using Black Light—Typical

WARNING: HOT, PRESSURIZED COOLANT CANCAUSE INJURY BY SCALDING.

Carefully remove the radiator pressure cap fromthe filler neck and check the coolant level. Pushdown on the cap to disengage it from the stop tabs.Wipe the inner part of the filler neck and examinethe lower inside sealing seat for nicks, cracks, paint,dirt and solder residue. Inspect the reserve/overflowtank tube for internal obstructions. Insert a wirethrough the tube to be sure it is not obstructed.

Inspect the cams on the outside part of the fillerneck. If the cams are bent, seating of pressure capvalve and tester seal will be affected. Replace cap ifcams are bent.

Attach pressure tester 7700 (or an equivalent) tothe radiator filler neck (Fig. 12).

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 followingcriteria:

• Holds Steady: If the pointer remains steady fortwo minutes, there are no serious coolant leaks inthe system. However, there could be an internal leakthat does not appear with normal system test pres-sure. Inspect for interior leakage or do the InternalLeakage Test. Do this if it is certain that coolant isbeing lost and no leaks can be detected.

• Drops Slowly: Shows a small leak or seepage isoccurring. Examine all connections for seepage orslight leakage with a flashlight. Inspect the radiator,hoses, gasket edges and heater. Seal any small leakholes with a Sealer Lubricant or equivalent. Repairleak holes and reinspect the system with pressureapplied.

• Drops Quickly: Shows that a serious leakage isoccurring. Examine the system for serious external

Fig. 12 Pressurizing System—Typical



leakage. If no leaks are visible, inspect for internalleakage. Large radiator leak holes should be repairedby a reputable radiator repair shop.

INTERNAL LEAKAGE INSPECTIONRemove the engine oil pan drain plug and drain a

small amount of engine oil. Coolant, being heavierthan engine oil, will drain first. Another way of test-ing is to operate the engine and check for water glob-ules on the engine oil dipstick. Also inspect theautomatic transmission oil dipstick for water glob-ules. Inspect the automatic transmission fluid coolerfor leakage. Operate the engine without the pressurecap on the radiator until thermostat opens.

Attach a pressure tester to the filler neck. If pres-sure builds up quickly, a leak exists as a result of afaulty cylinder head gasket or crack in the engine.Repair as necessary.

WARNING: DO NOT ALLOW PRESSURE TOEXCEED 124 KPA (18 PSI). TURN THE ENGINE OFF.TO RELEASE THE PRESSURE, ROCK THE TESTERFROM SIDE TO SIDE. WHEN REMOVING THETESTER, DO NOT TURN THE TESTER MORE THAN1/2 TURN IF THE SYSTEM IS UNDER PRESSURE.

If there is no immediate pressure increase, pumpthe pressure tester until the indicated pressure iswithin the system range. Vibration of the gaugepointer indicates compression or combustion leakageinto the cooling system.

WARNING: DO NOT DISCONNECT THE SPARKPLUG WIRES WHILE THE ENGINE IS OPERATING.

CAUTION: Do not operate the engine with a sparkplug shorted for more than a minute. The catalyticconverter may be damaged.

Isolate the compression leak by shorting eachspark plug to the cylinder block. The gauge pointershould stop or decrease vibration when spark plugfor leaking cylinder is shorted. This happens becauseof the absence of combustion pressure.

COMBUSTION LEAKAGE TEST (WITHOUTPRESSURE TESTER)

DO NOT WASTE reusable coolant. If the solutionis clean, drain the coolant into a clean container forreuse.

WARNING: DO NOT REMOVE THE CYLINDERBLOCK DRAIN PLUGS OR LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND UNDERPRESSURE. SERIOUS BURNS FROM COOLANTCAN OCCUR.

Drain sufficient coolant to allow for thermostatremoval. Refer to Thermostat Replacement. Discon-nect the water pump drive belt.

Disconnect the upper radiator hose from the ther-mostat housing. Remove the housing and thermostat.Install the thermostat housing.

Add coolant to the radiator to bring the level towithin 6.3 mm (1/4 in) of the top of the thermostathousing.

CAUTION: Avoid overheating. Do not operate theengine for an excessive period of time. Open thedraincock immediately after the test to eliminateboil over of coolant.

Start the engine and accelerate rapidly three times(to approximately 3000 rpm) while observing thecoolant. If internal engine combustion gases are leak-ing into the cooling system, bubbles will appear inthe coolant. If bubbles do not appear, there is nointernal combustion gas leakage.

VISCOUS FAN DRIVE

NOISE

NOTE: 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.

LEAKSViscous fan drive operation is not affected by small

oil stains near the drive bearing. If leakage appearsexcessive, replace the fan drive unit.

TESTINGIf the fan assembly free-wheels without drag (the

fan blades will revolve more than five turns whenspun by hand), replace the fan drive. This spin testmust be performed when the engine is cool.

For the following test, the cooling system must bein good condition. It also will ensure against exces-sively high coolant temperature.

WARNING: BE SURE THAT THERE IS ADEQUATEFAN BLADE CLEARANCE BEFORE DRILLING.



(1) Drill a 3.18-mm (1/8-in) diameter hole in thetop center of the fan shroud.

(2) Obtain a dial thermometer with an 8 inch stem(or equivalent). It should have a range of -18°-to-105°C (0°-to-220° F). Insert thermometer through thehole in the shroud. Be sure that there is adequateclearance from the fan blades.

(3) Connect a tachometer and an engine ignitiontiming light (timing light is to be used as a strobelight).

(4) Block the air flow through the radiator. Securea sheet of plastic in front of the radiator (or air con-ditioner condenser). Use tape at the top to secure theplastic and be sure that the air flow is blocked.

(5) Be sure that the air conditioner (if equipped) isturned off.

WARNING: USE EXTREME CAUTION WHEN THEENGINE IS OPERATING. DO NOT STAND IN ADIRECT 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 85° C (165° to 185° 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° to82° C (135° to 180° F). A definite decrease of fanflow noise (roaring) should be noticed. If not, replacethe defective viscous fan drive unit.

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.

RADIATOR CAP TO FILLER NECK SEAL—PRESSURE RELIEF CHECK

With radiator cap installed on filler neck, removecoolant reserve/overflow tank hose from nipple onfiller neck. Connect a hand operated vacuum pumpto nipple. Operate pump until a reading of 47 to 61kPa (14 to 18 in. Hg) appears on gauge. If the read-ing stays steady, or drops slightly and then remainssteady, the pressure valve seal is good. Replace radi-ator cap if reading does not hold.

WARNING: THE WARNING WORDS (DO NOT OPENHOT) ON THE RADIATOR PRESSURE CAP (Fig. 13)ARE A SAFETY PRECAUTION. WHEN HOT, PRES-SURE BUILDS UP IN COOLING SYSTEM. TO PRE-VENT SCALDING OR INJURY, THE RADIATOR CAPSHOULD NOT BE REMOVED WHILE THE SYSTEMIS HOT AND/OR UNDER PRESSURE.

There is no need to remove the radiator capexcept for the following purposes:

(1) To check and adjust antifreeze freeze point.(2) To refill system with new antifreeze.(3) For conducting service procedures.(4) When checking for vacuum leaks.

Fig. 13 Radiator Pressure Cap



WARNING: IF VEHICLE HAS BEEN RUNRECENTLY, WAIT AT LEAST 15 MINUTES BEFOREREMOVING RADIATOR CAP. WITH A RAG,SQUEEZE RADIATOR UPPER HOSE TO CHECK IFSYSTEM IS UNDER PRESSURE. PLACE A RAGOVER THE CAP AND WITHOUT PUSHING DOWN,ROTATE CAP COUNTER-CLOCKWISE TO THEFIRST STOP. ALLOW FLUID TO ESCAPE THROUGHOVERFLOW HOSE INTO COOLANT RESERVE/OVERFLOW TANK. SQUEEZE RADIATOR UPPERHOSE TO DETERMINE WHEN PRESSURE HASBEEN RELEASED. WHEN COOLANT AND STEAMSTOP BEING PUSHED INTO TANK AND SYSTEMPRESSURE DROPS, REMOVE RADIATOR CAPCOMPLETELY.

RADIATOR CAP—PRESSURE TESTINGRemove cap from radiator. Be sure that sealing

surfaces are clean. Moisten rubber gasket with waterand install the cap on pressure tester (tool 7700 oran equivalent) (Fig. 14).

Operate the tester pump and observe the gaugepointer at its highest point. The cap release pressureshould be 83 to 124 kPa (12 to 18 psi). The cap issatisfactory when the pressure holds steady. It is alsogood if it holds pressure within the 83 to 124 kPa (12to 18 psi) range for 30 seconds or more. If the pointerdrops quickly, replace the cap.

CAUTION: Radiator pressure testing tools are verysensitive to small air leaks, which will not cause

Fig. 14 Pressure Testing Radiator PressureCap—Typical

cooling system problems. A pressure cap that doesnot have a history of coolant loss should not bereplaced just because it leaks slowly when testedwith this tool. Add water to tool. Turn tool upsidedown and recheck pressure cap to confirm that capneeds replacement.

INSPECTIONVisually inspect the pressure valve gasket on the

cap. Replace cap if the gasket is swollen, torn orworn. Inspect the area around radiator filler neck forwhite deposits that indicate a leaking cap.

COOLANT—LOW LEVEL AERATIONIf the coolant level in radiator drops below top of

radiator core tubes, air will enter cooling system.Low coolant level can cause thermostat pellet to be

suspended in air instead of coolant. This will causethermostat to open later, which in turn causes highercoolant temperature. Air trapped in cooling systemalso reduces amount of coolant circulating in heatercore resulting in low heat output.

COOLING SYSTEM DEAERATIONAs the engine operates, any air trapped in cooling

system gathers under the radiator cap. The next timethe engine is operated, thermal expansion of coolantwill push any trapped air past radiator cap into thecoolant reserve/overflow tank. Here it escapes to theatmosphere into the tank. When the engine coolsdown the coolant, it will be drawn from the reserve/overflow tank into the radiator to replace anyremoved air.

SERVICE PROCEDURES

COOLANT LEVEL—ROUTINE CHECK

NOTE: Do not remove radiator cap for routinecoolant level inspections. The coolant level can bechecked at coolant reserve/overflow tank.

The coolant reserve/overflow system provides aquick visual method for determining coolant levelwithout removing radiator pressure cap. With engineidling and at normal operating temperature, observecoolant level in reserve/overflow tank. The coolantlevel should be between ADD and FULL marks.

COOLANT—ADDING ADDITIONALDo not remove radiator cap to add coolant to

system. When adding coolant to maintain correctlevel, do so at coolant reserve/overflow tank. Use a50/50 mixture of ethylene-glycol antifreeze containinglow mineral content water. Remove radiator cap only


for testing or when refilling system after service.Removing cap unnecessarily can cause loss of coolantand allow air to enter system, which produces corro-sion.

SERVICE COOLANT LEVELThe cooling system is closed and designed to main-

tain coolant level to top of radiator.

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/overflowtank or its hose

• An air leak in radiator filler neck• Leak in pressure cap seal to radiator filler neck

COOLING SYSTEM—DRAINING

WARNING: DO NOT REMOVE THE CYLINDERBLOCK DRAIN PLUGS OR LOOSEN THE RADIATORDRAINCOCK WITH SYSTEM HOT AND UNDERPRESSURE. SERIOUS BURNS FROM COOLANTCAN OCCUR.


DO NOT remove the radiator cap when drainingthe coolant from the reserve/overflow tank. Open theradiator draincock and when the tank is empty,remove the radiator cap. The coolant does not haveto be removed from the tank unless the system isbeing refilled with a fresh mixture.

(1) Drain the coolant from the radiator by loosen-ing the draincock.

(2) Drain coolant from engine block by removingdrain plug at left rear side of block (Fig. 15).

COOLING SYSTEM—REFILLING(1) Tighten the radiator draincock and the cylinder

block drain plug(s).(2) Fill system using a 50/50 mixture of water and

antifreeze. This is described in the Coolant section ofthis group. Fill the radiator to the top and install the

SERVICE PROCEDURES (Continued)

radiator cap. Add sufficient coolant to the reserve/overflow tank to raise the level to the FULL mark.

(3) Operate the engine with both the radiator capand reserve/overflow tank cap in place. After theengine has reached the normal operating tempera-ture, shut the engine off and allow it to cool.

(4) Add coolant to the reserve/overflow tank asnecessary. Only add coolant when the engine iscold. Coolant level in a warm engine will behigher due to thermal expansion.

COOLING SYSTEM—REVERSE FLUSHINGReverse flushing of the cooling system is the forc-

ing of water through the cooling system. This is doneusing air pressure in the opposite direction of normalcoolant flow. It is usually only necessary with verydirty systems with evidence of partial plugging.

REVERSE FLUSHING RADIATORDisconnect 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.Connect a water supply hose and air supply hose tothe flushing gun.

CAUTION: The cooling system normally operatesat 97 to 124 kPa (14 to 18 psi) pressure. Exceedingthis pressure may damage the radiator or hoses.

Allow the radiator to fill with water. When radiatoris filled, apply air in short blasts allowing radiator torefill between blasts. Continue this reverse flushinguntil clean water flows out through rear of radiatorcooling tube passages. For more information, refer tooperating instructions supplied with flushing equip-

Fig. 15 Draining Coolant From Block—2.5L/4.0LEngines


SERVICE PROCEDURES (Continued)

ment. Have radiator cleaned more extensively by aradiator repair shop.

REVERSE FLUSHING ENGINEDrain the cooling system. Remove the thermostat

housing and thermostat. Install the thermostat hous-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.

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, watersupply hose and air supply hose. Remove the thermo-stat housing and install thermostat. Install the ther-mostat housing with a replacement gasket. Refer toThermostat Replacement. Connect the radiatorhoses. Refill the cooling system with the correct anti-freeze/water mixture.

REMOVAL AND INSTALLATION

AUTOMATIC TRANSMISSION OIL COOLERThe internal transmission oil cooler located within

the radiator is not serviceable. If it requires service,the radiator must be replaced.

Once the repaired or replacement radiator hasbeen installed, fill the cooling system and inspect forleaks. Refer to the Filling Cooling System and Test-ing Cooling System For Leaks sections in this group.If the transmission operates properly after repairingthe leak, drain the transmission and remove thetransmission oil pan. Inspect for sludge. Inspect for adirty or plugged inlet filter. If none of these condi-tions are found, the transmission and torque con-verter may require reconditioning. Refer to Group 21for automatic transmission servicing.

COOLANT RESERVE/OVERFLOW BOTTLE

REMOVAL/INSTALLATION(1) Disconnect the hose from radiator filler neck.(2) Remove coolant recovery bottle (Fig. 16).(3) Reverse the preceding steps for installation.

WATER PUMP

CAUTION: If the water pump is replaced becauseof mechanical damage, the fan blades and viscousfan drive should also be inspected. These compo-

nents could have been damaged due to excessivevibration.

REMOVALThe water pump can be removed without discharg-

ing the air conditioning system (if equipped).

CAUTION: All engines have a reverse (counter-clockwise) rotating water pump. The letter R isstamped into the back of the water pump impeller(Fig. 17) to identify. Engines from previous modelyears, depending upon application, may beequipped with a forward (clockwise) rotating waterpump. Installation of the wrong water pump willcause engine over heating.

The water pump impeller is pressed on the rear ofthe pump shaft and bearing assembly. The waterpump is serviced only as a complete assembly.

WARNING: 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.

(1) Disconnect negative battery cable at battery.(2) Drain the cooling system.(3) Loosen (but do not remove at this time) the

four fan hub-to-water pump pulley mounting nuts(Fig. 18).

NOTE: The engine accessory drive belt must beremoved prior to removing the fan.

Fig. 16 Coolant Reserve/Overflow Bottle


REMOVAL AND INSTALLATION (Continued)

(4) Remove accessory drive belt.(5) Remove power steering pump (Fig. 19). (Refer

to Group 19 Steering).

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OFCLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER6094) (Fig. 20) SNAP-ON CLAMP TOOL (NUMBERHPC-20) MAY BE USED FOR LARGER CLAMPS.

Fig. 17 Reverse Rotating Water Pump—Typical

Fig. 18 Fan Mounting Nuts

ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-ING CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps (Fig. 21). Ifreplacement is necessary, use only an originalequipment clamp with matching number or letter.

(6) Remove lower radiator hose from water pump.Remove heater hose from water pump fitting.

(7) Remove four nuts previously loosened andremove the fan blade assembly and pulley.

(8) After removing fan blade/viscous fan driveassembly, do not place thermal viscous fan drive inhorizontal position. If stored horizontally, siliconefluid in viscous fan drive could drain into its bearingassembly and contaminate lubricant.

(9) Remove the four pump mounting bolts (Fig. 22)and remove pump from vehicle. Discard old gasket.Note that one of the four bolts is longer than theother bolts.

(10) If pump is to be replaced, the heater hose fit-ting must be removed. Note position of fitting beforeremoval.

INSTALLATION(1) If pump is being replaced, install the heater

hose fitting to the pump. Use a sealant on the fittingsuch as Mopary Thread Sealant With Teflon. Referto 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 waterpump mating surfaces for erosion or damage fromcavitation.

(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 thewater pump.

(5) Position water pump pulley to water pumphub.

(6) Install fan and four nuts to water pump hub.Tighten or nuts to 27 N·m (20 ft. lbs.) torque.

(7) Install power steering pump.

CAUTION: When installing the serpentine engineaccessory drive belt, the belt MUST be routed cor-rectly. If not, the engine may overheat due to thewater 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.



Fig. 19 Power Steering Pump Attachment

(8) Install and tension accessory drive belt. Referto Accessory Drive Belt removal and installation inthis group.

(9) Fill cooling system with coolant and check forleaks. Refer to Refilling Cooling System in thisgroup.

(10) Connect battery cable to battery.(11) Start and warm the engine. Check for leaks.

Fig. 20 Hose Clamp Tool–Typical

Fig. 21 Clamp Number/Letter Location



THERMOSTAT

REMOVAL

WARNING: DO NOT LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND PRES-SURIZED. SERIOUS BURNS FROM THE COOLANTCAN OCCUR.


(1) Drain the coolant from the radiator until thelevel is below the thermostat housing.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OFCLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER6094) (Fig. 20). SNAP-ON CLAMP TOOL (NUMBERHPC-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 thetongue of constant tension clamps (Fig. 21). If

Fig. 22 Water Pump Remove/Install—Typical

replacement is necessary, use only an originalequipment clamp with matching number or letter.

(2) Remove radiator upper hose and heater hose atthermostat housing.

(3) Disconnect wiring connector at engine coolanttemperature sensor.

(4) Remove thermostat housing mounting bolts,thermostat housing, gasket and thermostat (Fig. 23).Discard old gasket.

(5) Clean the gasket mating surfaces.

INSTALLATION(1) Install the replacement thermostat so that the

pellet, which is encircled by a coil spring, faces theengine. All thermostats are marked on the outerflange to indicate the proper installed position.

(2) Observe the recess groove in the engine cylin-der head (Fig. 24).

(3) Position thermostat into this groove with arrowand air bleed hole on outer flange pointing up.

(4) Install replacement gasket and thermostathousing.

CAUTION: Tightening the thermostat housingunevenly or with the thermostat out of its recessmay result in a cracked housing.

(5) Tighten the housing bolts to 20 N·m (15 ft. lbs.)torque.

(6) Install hoses to thermostat housing.(7) Install electrical connector to coolant tempera-

ture sensor.

Fig. 23 Thermostat Removal/Installation



(8) Be sure that the radiator draincock is tightlyclosed. Fill the cooling system to the correct levelwith the required coolant mixture. Refer to RefillingCooling System in this group.

(9) Start and warm the engine. Check for leaks.

RADIATOR

REMOVAL

WARNING: DO NOT REMOVE THE CYLINDERBLOCK DRAIN PLUGS OR LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND PRES-SURIZED. SERIOUS BURNS FROM THE COOLANTCAN OCCUR.

(1) Disconnect negative battery cable at battery.(2) Observe the previous WARNING. Remove the

radiator cap.(3) Position drain pan under draincock. Open radi-

ator draincock and drain radiator. DO NOT WASTEreusable coolant. If solution is clean, drain coolantinto a clean container for reuse.

(4) Remove radiator upper and lower hose clamps.Remove radiator hoses.

(5) Disconnect coolant reserve/overflow tank hosefrom radiator.

(6) Remove the four fan shroud mounting bolts(Fig. 25). On some models the power steering fluidreservoir tank is attached to the side of the fanshroud. Tie the reservoir back to prevent spillage.Position the fan shroud back over the fan blades.

(7) If equipped, disconnect and plug automatictransmission fluid cooler lines.

Fig. 24 Thermostat Recess

(8) Remove six radiator mounting bolts. Positionthe front axle vent hose (Fig. 25) to the side.

(9) Lift radiator straight up and out of vehicle tak-ing care not to damage radiator fins.

(10) When removing radiator, note position of therubber seals located on the top and bottom of radia-tor (on certain models only) (Fig. 25). To prevent pos-sible overheating, these seals must be installed totheir original positions.

INSTALLATION(1) Position the radiator. Install and tighten the

six mounting bolts (Fig. 25) to 8 N·m (72 in. lbs.)torque.

(2) Close radiator draincock.(3) Position fan shroud and power steering reser-

voir tank (if equipped). Install and tighten fourmounting bolts to 8 N·m (72 in. lbs.) torque.

(4) If equipped, remove plugs and connect auto-matic transmission fluid cooler lines. Tighten fittingsto 16 N·m (140 in. lbs.)

(5) Connect radiator hoses and install hose clamps.(6) Connect battery negative cable.(7) Fill cooling system with correct coolant. Refer

to Cooling Sytem Refilling in this group.(8) Connect coolant recovery bottle hose.(9) Install radiator cap.(10) Check and adjust automatic transmission

fluid level (if equipped).(11) Start engine and check for leaks.

BLOCK HEATER

REMOVAL

WARNING: DO NOT REMOVE THE CYLINDERBLOCK DRAIN PLUGS OR LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND PRES-SURIZED. SERIOUS BURNS FROM THE COOLANTCAN OCCUR.

DO NOT WASTE reusable coolant. If solution isclean, drain coolant into a clean container for reuse.

(1) Drain coolant from radiator and engine cylin-der block.

(2) Unplug power cord from block heater.(3) Loosen screw in center of block heater (Fig. 26)

or (Fig. 27).(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 4 N·m (31 in. lbs.) torque.



Fig. 25 Radiator—Remove/Install

(4) Fill cooling system with coolant. Pressurizesystem and inspect for leaks.

(5) Plug power cord into block heater. Route cordaway from moving parts, linkages and exhaust sys-tem components. Secure cord in place with tie-straps.

Fig. 26 Block Heater and Cord—2.5L Engine

VISCOUS FAN

REMOVAL(1) Loosen but do not remove at this time, the four

fan hub mounting nuts (Fig. 28).

Fig. 27 Block Heater and Cord—4.0L Engine



(2) Remove accessory drive belt. Refer to Belt Ser-vice in the Engine Accessory Drive Belt section ofthis group.

(3) Some models with certain engines may requirethe removal of the fan shroud to remove the viscousfan drive. The fan shroud and fan blade/viscous fandrive should be removed from the vehicle as oneassembly.

(4) Remove four fan hub mounting nuts (Fig. 28)and remove fan/viscous fan drive assembly from vehi-cle.

(5) After removing fan blade/viscous fan driveassembly, do not place thermal viscous fan drive inhorizontal position. If stored horizontally, siliconefluid in viscous fan drive could drain into its bearingassembly and contaminate lubricant.

INSTALLATION(1) Assemble fan blade to viscous fan drive.

Tighten mounting bolts to 27 N·m (20 ft. lbs.) torque.(2) Position mounting flange of fan blade/viscous

fan drive assembly onto hub. Install four nuts andtighten to 24 N·m (18 ft. lbs.) torque. Tighten thefirst two nuts 180 degrees apart. Then tighten lasttwo nuts.

CAUTION: When installing an accessory drive belt,the belt MUST be routed correctly. If not, the enginemay overheat due to the water pump rotating in thewrong direction. Refer to Serpentine Drive BeltRemoval and Installation in this group for correctbelt routing.

Fig. 28 Fan Mount

VISCOUS FAN DRIVERefer to Cooling System Fan for removal and

installation procedures of the viscous drive unit.Viscous Fan Drive Fluid Pump Out Require-

ment: After installing a new viscous fan drive, bringthe engine speed up to approximately 2000 rpm andhold for approximately two minutes. This will ensureproper fluid distribution within the drive.

ACCESSORY DRIVE BELTCorrect drive belt tension is required to ensure

optimum performance of the belt driven engine acces-sories. There are different types of adjustmentgauges for checking either a serpentine or a V-typebelt. Refer to the instructions supplied with thegauge. Use the correct gauge when checking belt ten-sion. Place gauge in the middle of the section of beltbeing tested (between two pulleys) to check tension.Do not allow the gauge (or gauge adapter) to contactanything but the belt.

BELT SCHEMATICSThe belt routing schematics are published from the

latest information available at the time of publica-tion. Vehicles not equipped with Power Steering havean idler pulley in place of the power steering pumppulley. If anything differs between these sche-matics and the Belt Routing Label, use theschematics on Belt Routing Label. This label islocated in the engine compartment.

Refer to (Fig. 29) (Fig. 30) and (Fig. 31) for correctbelt routing, or refer to Belt Routing Label located inthe vehicle engine compartment.

Fig. 29 2.5L/4.0L Engines–With A/C



BELT REPLACEMENT

REMOVALBelt tension is adjusted at the power steering

pump bracket and idler pulley assembly.(1) Disconnect negative battery cable from battery.(2) Loosen idler pulley bolt (Fig. 32).(3) Loosen tension adjusting bolt (Fig. 32) and

remove accessory drive belt.

Fig. 30 2.5L/4.0L Engines—Without A/C

Fig. 31 2.5L/4.0L Engines—Without A/C or P/S

INSTALLATION(1) Check condition of all pulleys.

CAUTION: When installing the serpentine acces-sory drive belt, the belt MUST be routed correctly. Ifnot, the engine may overheat due to the waterpump rotating in the wrong direction. Refer to (Fig.29) (Fig. 30) (Fig. 31) for correct belt routing.

(2) Install new belt. Install belt tension gaugeC-4162 and tighten adjustment bolt (Fig. 32) untilbelt tension is within specification range. Refer to theend of this group for Drive Belt Tension specifica-tions.

(3) Tighten idler pulley bolt and re-check belt ten-sion. Adjust if necessary.

CLEANING AND INSPECTION

RADIATOR PRESSURE CAPVisually inspect the pressure valve gasket on the

cap. Replace cap if the gasket is swollen, torn orworn. Inspect the area around radiator filler neck forwhite deposits that indicate a leaking cap.

RADIATORThe radiator and air conditioning fins should be

cleaned when an accumulation of bugs, leaves etc.has occurred. Clean radiator fins are necessary forgood heat transfer. With the engine cold, apply coldwater and compressed air to the back (engine side) ofthe radiator to flush the radiator and/or A/C con-denser of debris.

Fig. 32 Power Steering Pump Bracket and IdlerPulley


CLEANING AND INSPECTION (Continued)

COOLING SYSTEM

CAUTION: The cooling system normally operatesat 97 to 124 kPa (14 to 18 psi) pressure. Exceedingthis pressure may damage the radiator or hoses.

CLEANINGDrain cooling system and refill with water. Run

engine 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 BLADEThe fan blades cannot be repaired. If fan is dam-

aged, it must be replaced. Inspect fan as follows:(1) Remove fan blade and viscous fan drive as an

assembly from the engine. Refer to Removal proce-dure.

(2) Remove fan blade assembly from viscous fandrive unit (four bolts).

(3) Lay fan on a flat surface with leading edge fac-ing down. With tip of blade touching flat surface,replace fan if clearance between opposite blade andsurface is greater than 2.0 mm (.090 inch). Rockingmotion of opposite blades should not exceed 2.0 mm(.090 inch). Test all blades in this manner.

WARNING: DO NOT ATTEMPT TO BEND ORSTRAIGHTEN FAN BLADES IF NOT WITHIN SPECI-FICATIONS.

(4) Inspect fan assembly for cracks, bends, looserivets or broken welds. Replace fan if any damage isfound.

CAUTION: If fan blade assembly is replacedbecause of mechanical damage, water pump andviscous fan drive should also be inspected. Thesecomponents could have been damaged due toexcessive vibration.

COOLING SYSTEM HOSESInspect the hoses at regular intervals. Replace

hoses that are cracked, feel brittle when squeezed, orswell excessively when the system is pressurized.

For all vehicles: In areas where specific routingclamps are not provided, be sure that hoses are posi-tioned with sufficient clearance. Check clearancefrom exhaust manifolds and pipe, fan blades, drivebelts and sway bars. Improperly positioned hoses canbe damaged, resulting in coolant loss and engineoverheating.

Ordinary worm gear type hose clamps (whenequipped) can be removed with a straight screw-

driver or a hex socket. To prevent damage tohoses or clamps, the hose clamps should betightened to 4 N·m (34 in. lbs.) torque. Do notover tighten hose clamps.

When performing a hose inspection, inspect theradiator lower hose for proper position and conditionof the internal spring.

ADJUSTMENTS

ACCESSORY DRIVE BELTCorrect drive belt tension is required to ensure

optimum performance of the belt driven engine acces-sories. There are different types of adjustmentgauges for checking either a serpentine or a V-typebelt. Refer to the instructions supplied with thegauge. Use the correct gauge when checking belt ten-sion. Place gauge in the middle of the section of beltbeing tested (between two pulleys) to check tension.Do not allow the gauge (or gauge adapter) to contactanything but the belt.

With the engine off (not running), visually inspectaccessory drive belt for glazing, cracks or chunksmissing. Also inspect pulleys for misalignment ordefects. Refer to accessory drive belt diagnosis in thisgroup for the correct belt diagnostic procedures.

(1) Disconnect battery negative cable.(2) Install belt tension gauge C-4162 and compare

reading with those in the accessory drive belt tensionspecification chart.

If tension is within specifications and no adjust-ment is needed, remove belt tension gauge C-4162and connect battery negative cable.

If belt tension is out of specification and adjust-ment is necessary, continue with the following proce-dure.

(3) Loosen idler pulley bolt (Fig. 33).(4) Adjust tension adjusting bolt (Fig. 33) until

reading is within specification.(5) Tighten idler pulley bolt and re-check belt ten-

sion. Adjust if necessary.

ACCESSORY DRIVE BELT TENSION CHART

BELT TENSION

**NEW SERPENTINEBELT

800-900 N (180-200 lbs.)

USED SERPENTINEBELT

623-712 N (140-160 lbs.)

**Belt is considered new if it has been used 15minutes or less.

Specifications for use with a belt tension gauge. Referto operating instructions supplied with gauge.


ADJUSTMENTS (Continued)

SPECIFICATIONS

COOLING SYSTEM CAPACITIES

NOTE: Cooling system capacity does not vary withor without A/C since the components are the same.

Fig. 33 Power Steering Pump Bracket and IdlerPulley

ENGINE CAPACITY

2.5L 8.5L (9.0 Qts.)

4.0L 9.9L (10.5 Qts.)

ACCESSORY DRIVE BELT TENSION

TORQUE

DESCRIPTION TORQUEBlock Heater

Fastener . . . . . . . . . . . . . . . . . . 4 N·m (31 in. lbs.)Fan Blade–to–Viscous Fan Drive

Bolts . . . . . . . . . . . . . . . . . . . . 24 N·m (18 ft. lbs.)Fan Shroud—2.5L

Screws . . . . . . . . . . . . . . . . . . . 8 N·m (72 in. lbs.)Fan Shroud—4.0L

Screws . . . . . . . . . . . . . . . . . . . 8 N·m (72 in. lbs.)Generator Pivot

Bolt . . . . . . . . . . . . . . . . . . . . . 38 N·m (28 ft. lbs.)Generator Rear Adjusting

Bolt . . . . . . . . . . . . . . . . . . . . . 27 N·m (20 ft. lbs.)Radiator

Bolts . . . . . . . . . . . . . . . . . . . . . 8 N·m (72 in. lbs.)Thermostat Housing

Bolts . . . . . . . . . . . . . . . . . . . . 20 N·m (15 ft. lbs.)Transmission Cooler Lines

Fittings at Radiator . . . . . . . 16 N·m (140 in. lbs.)Pressure Fitting at Trans. . . 20 N·m (180 in. lbs.)

Viscous Fan Drive-to-Water PumpNuts . . . . . . . . . . . . . . . . . . . 23 N·m (200 in. lbs.)

Viscous Fan Drive to Water PumpStuds . . . . . . . . . . . . . . . . . . 11 N·m (100 in. lbs.)

Water Pump—2.5L/4.0LBolts . . . . . . . . . . . . . . . . . . . . 30 N·m (22 ft. lbs.)

BELT TENSION

**NEW SERPENTINEBELT

800-900 N (180-200 lbs.)

USED SERPENTINEBELT

623-712 N (140-160 lbs.)

**Belt is considered new if it has been used 15minutes or less.

Specifications for use with a belt tension gauge. Referto operating instructions supplied with gauge.


SPECIAL TOOLS

COOLING

Hose Clamp Pliers—6094

Belt Tension Gauge —C-4162

Cooling System Pressure Tester—7700–A

Quick Disconnect Tool—6935

cooling system - jeepstock jeep/1998_tj_manuel_atelier... · (internal to radiator) † coolant †...

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