chrysler dakota part6

7/28/2019 chrysler dakota part6

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COOLING SYSTEM

CONTENTS

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DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3ENGINE ACCESSORY DRIVE BELTS . . . . . . . . . 39ENGINE BLOCKHEATERS . . . . . . . . . . . . . . . . . 47

SERVICE PROCEDURES . . . . . . . . . . . . . . . . . . 12SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . 48

GENERAL INFORMATIONThroughout this group, references are made to par-

ticular vehicle models by alphabetical designation or

by the parti cular vehicle nameplate. A chart showing

a breakdown of alphabetical designations is included

in the I ntroduction section at the beginning of thismanual.

COOLINGSYSTEMThe cooling system regulates engine operating tem-

perature. I t allows the engine to reach normal oper-

ating temperature as quickly as possible. I t alsomaintains normal operating temperature and pre-vents overheating.

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

An optional factory installed maximum duty cool-ing package is available on most models. This pack-age will provide additional cooling capacity forvehicles used under extreme conditions such astrailer towing in high ambient temperatures.

Fig. 1 Engine Cooling System2.5L EngineTypical

COOLING SYSTEM 7 - 1


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COOLINGSYSTEM COMPONENTSThe cooling system consists of:

A radiator

Cooli ng fan (electri cal for 2.5L 4-cylinder enginemechanical for 3.9L /5.2L engines) Thermal viscous fan drive3.9L/5.2L Engines Fan shroud Radiator pressure cap Thermostat

Coolant reserve/overflow system

Transmission oil cooler (if equipped with an auto-

matic transmission)

Coolant Water pump Hoses and hose clamps

SYSTEM COOLANTROUTINGFor cooling system routings refer to (F igs. 1 or 2).

Fig. 2 Engine Cooling System3.9L/5.2L EngineTypical

7 - 2 COOLING SYSTEM


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DIAGNOSIS

INDEX

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DRB Scan Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4On-Board Diagnostics (OBD) . . . . . . . . . . . . . . . . . . 3

Preliminary Checks . . . . . . . . . . . . . . . . . . . . . . . . . 4

ON-BOARD DIAGNOSTICS (OBD)

FOR CERTAIN COOLING SYSTEM

COMPONENTS

The powertrain control module (PCM) has beenprogrammed to monitor certain cooli ng system com-ponents: I f the engine has remained cool for too long a pe-riod, such as with a stuck open thermostat, a Diag-nostic Trouble Code (DTC) number 17 can be

observed at the malfunction indicator lamp. Thislamp is displayed on the instrument panel as theCHE CK EN GINE lamp (Fig. 3). I f an open or shorted condition has developed inthe r elay circuit controlling the electric radiator fan,a Diagnostic Trouble Code (DTC) number 35 can beobserved at the CHECK ENGI NE lamp (2.5L 4-cylin-der engine only).

I f the problem is sensed in a monitored circuit of-ten enough to indicate an actual problem, a DTC isstored. The DTC will be stored in the PCM memory

for eventual display to the service technician. I f theproblem is r epaired or ceases to exist, the PCM can-cels the DT C after 51 engine starts.

Certain criteria must be met for a DTC to be en-tered into PCM memory. The criteria may be a spe-cifi c range of engine rpm, engine temperature and/orinput voltage to the PCM.

A DTC indicates that the PCM has recognized anabnormal signal in a circuit or the system. A DTCmay indicate the result of a failure, but never iden-

tify the failed component directly.I t is possible that a DTC for a monitored circuit

may not be entered into memory even though a mal-function has occurred. Refer to On-Board Diagnostics(OBD) in Group 14, Fuel Systems for additional in-formation.

ACCESSING DIAGNOSTIC TROUBLE CODES

A stored Diagnostic Trouble Code (DTC) can be dis-played by cycling the ignition key On-Off-On-Off-Onwithi n three seconds and observing the malfunctionindicator lamp. This lamp is displayed on the instru-ment panel as the CHE CK EN GIN E lamp (Fi g. 3).

They can also be displayed through the use of theDiagnostic Readout Box (DRB) scan tool. The DRBconnects to the data link connector in the enginecompartment (Fi g. 4). F or operation of the DRB , referto the appropriate Powertrain Diagnostic Proceduresservice manual.

EXAMPLES:

I f the lamp (Fig. 3) flashes 1 time, pauses andflashes 2 more times, a flashing Diagnostic TroubleCode (DTC) number 12 is indicated. I f this code isobserved, it is indicating that the battery has beendisconnected within the last 50 key-on cycles. I tcould also indicate that battery voltage has been dis-connected to the P CM. I n either case, other DTCsmay have been erased. I f the lamp flashes 1 time, pauses and flashes 7more times, a flashing Diagnostic Trouble Code(DTC) number 17 is indicated. I f the lamp flashes 3 times, pauses and flashes 5more times, a flashing Diagnostic Trouble Code(DTC) number 35 is indicated.

Fig. 3 Check Engine Lamp

COOLING SYSTEM DIAGNOSIS 7 - 3


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After any stored DTC information has been ob-served, the display will end with a flashing DT Cnumber 55. This will indicate the end of all stored in-formation.

ERASING TROUBLE CODES

After the problem has been repaired, use the DRBscan tool to erase a DTC. Refer to the appropriatePowertr ain Diagnostic Procedures service manual foroperation of the DRB scan tool.

DRBSCAN TOOLFor operation of the DRB scan tool, refer to the ap-

propriate P owertr ain Diagnostic Procedures servicemanual.

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATING

Establish what driving conditions caused the com-plaint. Abnormal loads on the cooli ng system such asthe following may be the cause:

1. PROLONGED IDLE, VERY HIGH AMBIENT

TEMPERATURE, SLIGHT TAIL WIND AT IDLE,

SL OW T RAF FI C, T RAF FI C J AMS, HI GH

SPEED, OR STEEP GRADES.

Driving techniques that avoid overheating are:

I dle with A/C off when temperature gauge is at

end of normal range.

I f vehicle is equipped with a 2.5L 4-cylinder en-gine, do not increase engine speed for more air flow.

Cooling systems with electri c cooling fans do not re-

spond to engine rpm. The added cooling from higher

coolant flow is more than offset by increased heat

from higher engine output.

I f vehicle is equipped with a 3.9L V-6 or 5.2L V-8

engine, increasing engine speed for more air flow is

recommended.

2. TRAILER TOWING:

Consult Trailer Towing section of owners manual.

Do not exceed li mits.

3. AIR CONDITI ONING; ADD-ON OR AFTERMARKET:

A maximum cooling package should have been or-

dered with vehicle if add-on or after market A/C is

installed. I f not, maximum cooling system compo-

nents should be installed for model involved per

manufacturers specifications.

4. RECENT SERVICE OR ACCIDENT RE PAIR:

Determine if any recent service has been performed

on vehicle that may effect cooli ng system. T his may

be: Engine adjustments (incorrect timing) Slipping engine accessory drive belt(s) Brakes (possibly dragging) Changed parts. I ncorrect water pump, or pump ro-tating in wrong direction due to belt not correctlyrouted Reconditioned radiator or cooling system refill ing(possibly under fil led or air trapped in system).

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

These charts are to be used as a quick-referenceonly. Refer to the group text for information.

Fig. 4 Data Link ConnectorTypical

7 - 4 COOLING SYSTEM DIAGNOSIS


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COOLING SYSTEM DIAGNOSIS



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COOLING SYSTEM DIAGNOSIS (CONT.)



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SERVICE PROCEDURES

INDEX

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Automatic Transmission Oil Coolers . . . . . . . . . . . . 32Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Coolant Reserve/Overflow System . . . . . . . . . . . . . 27Cooling System Cleaning/Reverse Flushing . . . . . . 25Cooling System Fan2.5L 4-Cylinder Engine . . . . 33Cooling System Fan3.9L/5.2L Engine . . . . . . . . . 36Cooling System Hoses . . . . . . . . . . . . . . . . . . . . . 32Draining Cooling System . . . . . . . . . . . . . . . . . . . . 24Pressure Testing Radiator Caps . . . . . . . . . . . . . . 28

Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Radiator Pressure Cap . . . . . . . . . . . . . . . . . . . . . 27Refilling Cooling System . . . . . . . . . . . . . . . . . . . . 24Testing Cooling System for Leaks . . . . . . . . . . . . . 25Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Viscous Fan Drive3.9L/5.2L Engine . . . . . . . . . . 37Water Pump Bypass Hose3.9L/5.2L Engine . . . . 17Water PumpsGeneral Information . . . . . . . . . . . . 12Water PumpsRemoval/Installation . . . . . . . . . . . 12

WATER PUMPSGENERAL INFORMATIONA centrifugal water pump circulates coolant

through the water jackets, passages, intake manifold,

radiator core, cooli ng system hoses and heater core.

The pump is driven from the engine crankshaft by adrive belt.

The water pump impeller is pressed onto the rear

of a shaft that rotates in a bearing pressed into the

water pump body. The body has a small hole for ven-

tilation. The water pump seals are lubricated by an-

tifreeze in the coolant mixture. Additional lubrication

is not necessary.

A quick test to determine if pump is working is to

check if heater warms properly. A defective water

pump will not be able to circulate heated coolant

through the long heater hose to the heater core.

WATER PUMPSREMOVAL/INSTALLATIONThe water pump on all models can be removed

without discharging the air conditioning system (if

equipped).

2.5L 4-CYLINDER ENGINE

The water pump used on 2.5L engines consists of a

die-cast aluminum body and housing, and a stamped

steel impeller. A gasket is used to seal between the

pump body and housing. The water pump assembly

bolts directly to the engine cylinder block. A rubber

o-ring provides the seal between water pump and cyl-

inder block (Fig. 1).

REMOVAL

(1) Drain cooling system.

(2) Remove accessory drive belt.

(3) Remove generator. Refer to Group 8B, Battery/

Starter/Generator Service.

CAUTION: If vehicle is equipped with air condition-

ing, the solid mount accessory drive bracket must

be removed according to the following procedure:

(a) Remove air conditioning compressor drive

belt idler (Fig. 2).

(b) Remove air conditioning compressor from

soli d mount bracket. Air conditioning system does

not have to be discharged.

WARNING: THE A/C SYSTEM IS UNDER PRESSURE

EVEN WITH ENGINE OFF. REFER TO REFRIGER-

ANT WARNINGS IN GROUP 24, HEATING AND AIR

CONDITIONING.

(c) Secure compressor with mechanics wire.

(d) Remove solid mount accessory bracketmounting bolts 1, 4, 5, 6 and 7 at side of bracket.Refer to (F ig. 2).

(e) Remove mounting nut (number 2 in F ig. 2) atfront of bracket.

(f) Remove mounting bolt (number 3 in Fig. 2) atfront of bracket.

(g) Pivot solid mount accessory bracket awayfrom engine. Sli de bracket forward off of mountingnut/stud to remove.

(h) I nstall front mounting bolt (number 3 in Fig.2) in bolt hole until bracket is reinstalled.

Fig. 1 Water Pump Components2.5L Engine

7 - 12 COOLING SYSTEM SERVICE PROCEDURES


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WARNING: CONSTANT TENSION HOSE CLAMPS

ARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OFCLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (FIG. 3). SNAP-ON CLAMP TOOL (NUMBERHPC-20) MAY BE USED FOR LARGER CLAMPS. AL-WAYS WEAR SAFETY GLASSES WHEN SERVICINGCONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps (Fig. 4). If re-placement is necessary, use only an original equip-ment clamp with matching number or letter.

(4) Disconnect radiator lower hose clamp (Fig. 3)

and hose.(5) Disconnect heater hoses clamps (Fig. 3) and

hoses.(6) Remove water pump mounting screws, water

pump and o-ring seal (Fig. 5).

DISASSEMBLY

(1) Remove water pump pulley mounting screws.(2) Remove water pump body-to-housing screws.

Separate housing from body.(3) Clean water pump housing and body gasket

surfaces.

(4) Remove o-ring seal (housing-to-cylinder block

seal) and clean o-ring groove i n housing. Also clean

sealing surface on engine block.

INSPECTION

Replace water pump body assembly if it has any ofthe following conditions: Water pump body is cracked or damaged Water leaks from shaft seal. This is evident bytraces of coolant below vent hole L oose or rough turning bearing

Fig. 2 Solid Mount Accessory Bracket2.5L Engine

Fig. 3 Hose Clamp ToolTypical

COOLING SYSTEM SERVICE PROCEDURES 7 - 13


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REMOVAL

The water pump can be removed and installed

without discharging the air conditioning system (if

equipped).

(1) Disconnect negative battery cable from battery.

(2) Drain cooling system. Refer to Draining Cooling

System in this group.

Do not waste reusable coolant. If solution is clean,drain coolant into a clean container for reuse.

(3) Remove throttle cable at top of fan shroud.

(4) U nsnap coolant overflow tank (up and out)from fan shroud and lay aside. Do not disconnecthose or drain coolant from tank.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OF

CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER6094) (FIG. 3). SNAP-ON CLAMP TOOL (NUMBER

HPC-20) MAY BE USED FOR LARGER CLAMPS. AL-WAYS WEAR SAFETY GLASSES WHEN SERVICING

CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps (Fig. 4). If re-placement is necessary, use only an original equip-

ment clamp with matching number or letter.

(5) Remove upper radiator hose clamp (F ig. 3) andhose at radiator.

(6) The thermal viscous fan drive is attached

(threaded) to the water pump hub shaft (Fig. 6). Re-move fan/viscous fan drive assembly from waterpump by turning mounting nut counterclockwise asviewed from front. Threads on viscous fan drive areRIGHT HAND. A Snap-On 36 MM Fan Wrench(number SP346 from Snap-On Cummins Diesel ToolSet number 2017DSP) can be used. Pl ace a bar orscrewdriver between water pump pulley bolts (Fig. 6)to prevent pulley from rotating. Do not attempt to re-move fan/viscous fan drive assembly from vehicle atthis time.

I f water pump is being replaced, do not unbolt fanblade assembly (Fig. 6) from thermal viscous fan

drive.(7) Remove fan shroud attaching hardware (two

bolts at bottom-two clips at top).(8) Remove fan shroud and fan blade/viscous fan

drive assembly from vehicle as a complete unit.After removing fan blade/viscous fan drive assem-

bly, do not place thermal viscous fan drive in hori-zontal position. I f stored horizontally, silicone fluid inviscous fan drive could drain into its bearing assem-bly and contaminate lubricant.

Do not remove water pump pulley bolts at thistime.

(9) Remove accessory drive belt as follows: The

drive belt is equipped with a spring l oaded automatic

tensioner (Fi g. 7). Relax tension from belt by rotating

tensioner clockwise (as viewed from front) (Fig. 7).

When all belt tension has been relaxed, remove ac-

cessory drive belt.

Fig. 6 Fan Blade and Viscous Fan Drive3.9L/5.2LEngine

Fig. 7 Automatic Belt Tensioner Assembly3.9L/5.2L Engine



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(10) Remove four water pump pulley-to-water

pump hub bolts (Fig. 6) and remove pulley from ve-

hicle.

(11) Remove lower radiator hose clamp and remove

lower hose at water pump.

(12) Remove heater hose clamp (Fig. 3) and heater

hose from heater hose coolant return tube.

(13) L oosen heater hose coolant return tubemounting bolt (Fig. 8) and remove tube from water

pump. Discard the old tube o-ring.

(14) Remove seven water pump mounting bolts

(Fig. 9).

(15) L oosen clamp at water pump end of bypass

hose (Fig. 6). Slip bypass hose from water pump

while removing pump from vehicle. Discard old gas-

ket.

CAUTION: Do not pry water pump at timing chain

case/cover. The machined surfaces may be dam-

aged resulting in leaks.

INSPECTION

Replace water pump assembly if it has any of the

following conditions:

The body is cracked or damaged

Water leaks from shaft seal. This is evident by

traces of coolant below vent hole

L oose or rough turning bearing. Also inspect vis-

cous fan drive

I mpeller rubs either the pump body or timingchain case/cover

INSTALLATION

(1) Clean gasket mating surfaces.(2) Using a new gasket, install water pump to en-

gine as follows: Guide water pump nipple into bypasshose as pump is being installed. I nstall water pumpbolts (Fig. 9). Tighten water pump mounting bolts to40 Nm (30 ft. lbs.) torque.

(3) Position bypass hose clamp to bypass hose.(4) Spin water pump to be sure that pump impeller

does not rub against timing chain case/cover.(5) I nstall a new o-ring to the heater hose coolant

return tube (Fig. 8). Coat the new o-ring with anti-

freeze before installation.(6) I nstall coolant return tube and its mounting

bolt to engine (Fig. 8). Be sure the slot in tubebracket is bottomed to mounting bolt. This will prop-erly position return tube.

(7) Connect radiator lower hose to water pump.(8) Connect heater hose and hose clamp to coolant

return tube.(9) I nstall water pump pulley. Tighten bolts to 27

Nm (20 ft. lbs.) torque. Pl ace a bar or screwdriverbetween water pump pulley bolts (Fig. 6) to preventpulley from rotating.

(10) Relax tension from belt tensioner (Fig. 7). In-stall drive belt.

CAUTION: When installing the serpentine accessory

drive belt, belt must be routed correctly. If not, en-gine may overheat due to water pump rotating inwrong direction. Refer to (Fig. 10) for correct beltrouting. The correct belt with correct length must

be used.

(11) Position fan shroud and fan blade/viscous fandrive assembly to vehicle as a complete unit.

(12) I nstall fan shroud.

Fig. 8 Coolant Return Tube3.9L/5.2L EngineTypical

Fig. 9 Water Pump Bolts3.9L/5.2L Engine



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(13) I nstall fan blade/viscous fan drive assembly to

water pump shaft.

(14) Fill cooling system. Refer to Refilli ng the Cool-

ing System in this group.

(15) Connect negative battery cable.

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

WATER PUMP BYPASS HOSE3.9L/5.2L ENGINEA water pump bypass hose (Fi g. 11) is used be-

tween the intake manifold and water pump on all3.9L /5.2L engines. To test for leaks, refer to Testing

Cooling System for L eaks in this group.

WITHOUT AIR CONDITIONING (A/C)

REMOVAL

(1) Partially drain cooling system. Refer to Drain-

ing Cooling System in this group.

Do not waste reusable coolant. If solution is clean,

drain coolant into a clean container for reuse.


ARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLY

TOOLS DESIGNED FOR SERVICING THIS TYPE OF

CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (FIG. 12). SNAP-ON CLAMP TOOL (NUMBER

HPC-20) MAY BE USED FOR LARGER CLAMPS. AL-

WAYS WEAR SAFETY GLASSES WHEN SERVICING


CAUTION: A number or letter is stamped into the

tongue of constant tension clamps (Fig. 13). If re-

placement is necessary, use only an original equip-


(2) L oosen both bypass hose clamps (Fi g. 12) and

position to center of hose. Remove hose from vehicle.

INSTALLATION

(1) Position bypass hose clamps (F ig. 12) to center

of hose.

(2) I nstall bypass hose to engine.

(3) Secure both hose clamps (Fi g. 12).

(4) Fill cooling system. Refer to Refilling the Cool-

ing System in this group.


Fig. 10 Belt Routing3.9L/5.2L Engine Fig. 11 Water Pump Bypass Hose3.9L/5.2L Engine




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WITH AIR CONDITIONING (A/C)

REMOVAL

I f equipped with A/C, the generator and A/C com-pressor along with their common mounting bracket(Fig. 14) must be parti ally removed. Removing gener-ator or A/C compressor from their mounting bracketis not necessary. Also, discharging A/C system is notnecessary. Do not remove any refrigerant lines fromA/C compressor.

WARNING: THE A/C SYSTEM IS UNDER PRESSURE

EVEN WITH ENGINE OFF. REFER TO REFRIGER-

ANT WARNINGS IN GROUP 24, HEATING AND AIR

CONDITIONING.


(2) Parti ally drain cooling system. Refer to Drain-

ing Cooling System in this group.Do not waste reusable coolant. I f solution is clean,drain coolant into a clean container for reuse.

(3) Remove upper radiator hose clamp (Fig. 12)and hose at radiator.

(4) Unplug wiring harness from A/C compressor.(5) Remove air cleaner assembly.(6) Remove accessory drive belt as follows: The

drive belt is equipped with a spring l oaded automatictensioner (Fig. 15). Relax tension from belt by rotat-ing tensioner clockwise (as viewed from front) (Fig.15). When all belt tension has been relaxed, removeaccessory drive belt.

(7) The drive belt idler pulley must be removed togain access to one of A/C compressor/generator

bracket mounting bolts. Remove idler pulley bolt andremove idler pulley (Fi g. 14).

(8) Remove oil dipstick tube mounting bolt at sideof A/C-generator mounting bracket.

(9) Disconnect throttle body control cables. Refer toAccelerator Pedal and Throttle Cable in Group 14,Fuel System.

(10) Remove heater hose clamp and heater hosefrom heater hose coolant return tube.

(11) Remove heater hose coolant return tubemounting bolt (Fig. 16) and remove tube from engine.Discard the old tube o-ring.

Fig. 13 Clamp Number/Letter Location

Fig. 14 GeneratorA/C Compressor MountingBracket3.9L/5.2L Engine

Fig. 15 Automatic Belt Tensioner Assembly



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(12) Remove bracket-to-intake manifold bolts

(number 1 and 2Fi g. 14).

(13) Remove six bracket bolts (number 3Fig. 14).

(14) L ift and position generator and A/C compres-

sor (along with their common mounting bracket) to

gain access to bypass hose. A block of wood may be

used to hold assembly in position.

(15) L oosen and position both hose clamps to cen-

ter of bypass hose. Remove hose from vehicle.

INSTALLATION

(1) Position bypass hose clamps to center of hose.

(2) I nstall bypass hose to engine.

(3) Secure both hose clamps (Fi g. 12).

(4) I nstall generator-A/C mounting bracket assem-

bly to engine. Tighten bolts (number 1 and 2Fig.

14) to 54 N m (40 ft. lbs.) torque. Tighten bolts (num-

ber 3Fig. 14) to 40 N m (30 ft. lbs.) torque.

(5) I nstall a new o-ring to the heater hose coolantreturn tube (Fig. 16). Coat the new o-ring with anti-freeze before installation.

(6) I nstall coolant return tube and its mountingbolt to engine (Fig. 16).

(7) Connect throttle body control cables.(8) I nstall oil dipstick mounting bolt.(9) I nstall idler pulley. Tighten bolt to 54 N m (40

ft. lbs.) torque.(10) Relax tension from belt tensioner (Fi g. 15). I n-

stall drive belt.

CAUTION: When installing serpentine accessory

drive belt, belt must be routed correctly. If not, en-gine may overheat due to water pump rotating in

wrong direction. Refer to (Fig. 17) for correct belt

routing. The correct belt with correct length must

be used.

(11) I nstall air cleaner assembly.

(12) I nstall upper radiator hose to radiator.

(13) Connect wiring harness to A/C compressor.

(14) Fill cooling system. Refer to Refilli ng the Cool-

ing System in this group.(15) Start and warm the engine. Check for leaks.

THERMOSTAT

GENERAL INFORMATIONALL ENGINES

On 2.5L 4-cylinder engines, the thermostat is lo-cated inside the water box at front of engine on radi-ator side (Fig. 18). This thermostat does not have anair bleed notch.

On 3.9L and 5.2L engines, the thermostat is lo-cated beneath the thermostat housing at front of in-take manifold (Fig. 19). This thermostat has an airbleed notch.

All thermostats (2.5L , 3.9L and 5.2L engines) are of

the wax-pellet-driven, reverse-poppet-choke-type. Thewax pellet is located in a sealed container at springend of thermostat. When heated, the pell et expands,overcoming closing spring tension and water pumppressure to force valve to open. Coolant leakage intopell et container will cause thermostat to fail in openposition. Do not attempt to free a sticking thermostatwith a prying device.

The thermostat controls the operating temperatureof the engine by controlling the amount of coolantflow to radiator. On all engines (2.5L, 3.9L and 5.2L ),thermostat is closed below 88C (192F). When cool-

Fig. 16 Coolant Return Tube3.9L/5.2L EngineTypical

Fig. 17 Belt Routing3.9L/5.2L Engine



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ant reaches this temperature, thermostat begins to

open allowing coolant flow to radiator. T his provides

quick engine warm-up and overall temperature con-

trol. The thermostat is designed to provide a mini-mum engine operating temperature range of from 88

to 93C (192 to 199F). The thermostat should be

fully open for maximum coolant flow during opera-

tion in hot ambient temperatures of approximately

104C (220F). Above 104C (220F), coolant temper-

ature is controlled by radiator, fan and ambient tem-

perature.

An arrow, plus the word UP is stamped on front

flange next to air bleed. The words TO RAD are

stamped on one arm of thermostat. They indicate

proper installed position.

The same thermostat is used for winter and sum-

mer seasons.

CAUTION: Do not operate an engine without a ther-

mostat, except for servicing or testing.

An engine should not be operated without a ther-

mostat, except for servicing or testing. Operating

without a thermostat causes longer engine warmup

time, unreliable warmup performance, increased ex-

haust emissions and crankcase condensation that can

result in sludge formation.

ON-BOARD DIAGNOSTICS (OBD)

FOR COOLINGSYSTEM COMPONENTS

All models are equipped with On-Board Diagnostics

for certain cooli ng system components. Refer to On-

Board Diagnostics (OBD) in the Diagnosis section of

this group for additional information. I f the power-

train control module (PCM ) detects low engine cool-ant temperature, it will record a Diagnostic Trouble

Code (DTC) in the PCM memory. The DTC number

for low coolant temperature is 17. Do not change a

thermostat for lack of heat as indicated by the in-

strument panel gauge or heater performance unless a

DTC number 17 is present. Refer to the Di agnosis

section of this group for other probable causes. For

other DTC numbers, refer to On-Board Diagnostics

in the General Diagnosis section of Group 14, Fuel

Systems.

The DTC can also be accessed through the DRB

scan tool. Refer to the appropriate P owertrain Diag-nostic Procedures manual for diagnostic information

and operation of the DRB scan tool.

REMOVAL2.5L 4-CYLINDER ENGINE

WARNING: DO NOT LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND PRESSURIZED. SE-

RIOUS BURNS FROM COOLANT CAN OCCUR.

Do not waste reusable coolant. I f solution is clean,

drain coolant into a clean container for reuse.

I f thermostat is being replaced, be sure that re-

placement is the specified thermostat for vehiclemodel and engine type.


(2) Drain cooling system until coolant level is be-

low thermostat. Refer to Draining Cooling System in

this group.

Fig. 18 Thermostat2.5L 4-Cylinder EngineTypical

Fig. 19 Thermostat3.9L/5.2L Engine



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ARE USED ON MOST COOLING SYSTEM HOSES.

WHEN REMOVING OR INSTALLING, USE ONLY





WAYS WEAR SAFETY GLASSES WHEN SERVICINGCONSTANT TENSION CLAMPS.





(3) Remove radiator hose clamp (Fig. 12) and radi-

ator hose at thermostat housing.

(4) Remove ignition coil /coil mounting bracket as-

sembly. Do not remove coil from mounti ng bracket.

(5) Remove thermostat housing stud/bolts, thermo-stat housing, gasket and thermostat (Fig. 18). Dis-

card old gasket.

(6) Clean gasket mating surfaces.

INSTALLATION2.5L ENGINE


placement is specifi ed thermostat for vehicle model

and engine type.

(1) Dip replacement gasket in water and position

on water box (Fi g. 18).

(2) Assemble the thermostat and thermostat hous-

ing as shown in (Fig. 18). Be sure the thermostat iscentered into thermostat housing and that spring

side is installed towards cyli nder head.

CAUTION: Tightening housing unevenly or without

thermostat centered, may result in a cracked hous-

ing.

(3) Install housing stud/bolts. Tighten housingstud/bolts to 23 Nm (200 in. lbs.) torque.

(4) I nstall ignition coil/coil mounting bracket as-sembly.

(5) I nstall upper radiator hose to thermostat hous-

ing.(6) Connect negative battery cable to battery.(7) Fill cooling system. Refer to Refilli ng Cooling

System in this group.

REMOVAL3.9L/5.2L ENGINE

WARNING: DO NOT LOOSEN RADIATOR DRAIN-COCK WITH SYSTEM HOT AND PRESSURIZED. SE-

RIOUS BURNS FROM COOLANT CAN OCCUR.

Do not waste reusable coolant. If solution is clean,drain coolant into a clean container for reuse.


placement is specified thermostat for vehicle model

and engine type.

Factory installed thermostat housings on 3.9L /5.2L

engines are installed on a gasket with an anti-stick

coating. This will aid in gasket removal and clean-up.

(1) Disconnect negative battery cable at battery.

(2) Drain cooling system until coolant level is be-low thermostat. Refer to Draining Cooling System in

this group.

(3) Air Conditioned vehicles: Remove support

bracket (generator mounting bracket-to-intake mani-

fold) located near rear of generator (Fig. 20).

(4) On air conditioning equipped vehicles, the gen-

erator must be partiall y removed.

(a) Remove generator drive belt as follows: Drive

belts on both 3.9L and 5.2L engines are equipped

with a spring loaded automatic belt tensioner (Fig.

21).

(b) Attach a socket/wrench to pulley mounting

bolt of automatic tensioner (Fig. 21).(c) Rotate tensioner assembly clockwise (as

viewed from front) until tension has been relieved

from belt.

(d) Remove belt from vehicle.

(e) Remove two generator mounting bolts. Do not

remove any wiring at generator. I f equipped with

4WD, unplug 4WD indicator lamp wiring harness

(located near rear of generator).

(f) Remove generator. Position generator to gain

access for thermostat gasket removal.

Fig. 20 Generator Support Bracket3.9L/5.2L

Engine



22/48














(5) Remove upper radiator hose clamp (Fig. 12)

and upper radiator hose at thermostat housing.

(6) Position wiring harness (behind thermostat

housing) to gain access to thermostat housing.

(7) Remove thermostat housing mounting bolts,

thermostat housing, gasket and thermostat (Fig. 22).

Discard old gasket.

INSTALLATION3.9L/5.2L ENGINE

(1) Clean mating areas of intake manifold and

thermostat housing.

(2) I nstall thermostat (spring side down) into re-

cessed machined groove on intake manifold (Fig. 22).

(3) I nstall gasket on intake manifold and over

thermostat (Fig. 22).

(4) Position thermostat housing to intake manifold.Note the word FRONT stamped on housing (Fig. 23).For adequate clearance, this must be placed towards

front of vehicle. The housing is slightly angled for-

ward after installation to i ntake manifold.

(5) I nstall two housing-to-intake manifold bolts.

Tighten bolts to 23 Nm (200 in. lbs.) torque.

CAUTION: Housing must be tightened evenly and

thermostat must be centered into recessed groove

in intake manifold. If not, it may result in a cracked

housing, damaged intake manifold threads or cool-

ant leak.

Fig. 21 Automatic Belt Tensioner3.9L/5.2L Engine Fig. 22 Thermostat3.9L/5.2L Engine

Fig. 23 Thermostat Position3.9L/5.2L Engine



23/48

(6) I nstall upper radiator hose to thermostat hous-

ing.

(7) Air Conditi oned vehicles:

(a) I nstall generator. Tighten bolts to 41 Nm (30

ft. lbs.).

(b) I nstall support bracket (generator mounting

bracket-to-intake manifold) (Fi g. 20). Tighten bolts

to 54 Nm (40 ft. lbs.) torque.

CAUTION: When installing the serpentine accessory

drive belt, belt must be routed correctly. If not, en-

gine may overheat due to water pump rotating in

wrong direction. Refer to (Fig. 24) for correct 3.9L/5.2L engine belt routing. The correct belt with cor-rect length must be used.

(c) Position drive belt over all pulleys exceptidler pulley (located between generator and A/Ccompressor).

(d) Attach a socket/wrench to pulley mountingbolt of automatic tensioner (Fi g. 21).

(e) Rotate socket/wrench clockwise. Pl ace belt

over idler pulley. L et tensioner rotate back intoplace. Remove wrench. Be sure belt is properlyseated on all pulleys.(8) Fill cooling system. Refer to Refilli ng Cooling

System in this group.(9) Connect negative battery cable to battery.(10) Start and warm the engine. Check for leaks.

COOLANTThe cooling system is designed around the coolant.

Coolant flows through the engine water jackets ab-sorbing heat produced during engine operation. The

coolant carries heat to radiator and heater core. Here

it is transferred to ambient air passing through radi-

ator and heater core fins. The coolant also removes

heat from automatic transmission fluid in vehicles

equipped with an automatic transmission.

COOLANT PERFORMANCE

The required ethylene-glycol (antifreeze) and watermixture depends upon climate and vehicle operating

conditions. The coolant performance of various mix-

tures follows:

Pure Water-Water can absorb more heat than a

mixture of water and ethylene-glycol. This is for pur-

pose of heat transfer only. Water also freezes at a

higher temperature and allows corrosion.

100% Ethylene-Glycol-The corrosion inhibiting

additives in ethylene-glycol need the presence of wa-

ter to dissolve. Without water, additives form depos-

its in system. These act as insulation causing

temperature to rise to as high as 149C (300F). This

temperature is hot enough to melt plastic and soften

solder. The increased temperature can result in en-

gine detonation. I n addition, 100 percent ethylene-

glycol freezes at -22C (-8F).

50/50 Ethylene-Glycol and Water-Is the recom-

mended mixture, i t provides protection against freez-

ing to -37C (-35F). The antifreeze concentration

must always be a minimum of 44 percent, year-

round in all climates. I f percentage i s lower, engine

parts may be eroded by cavitation. Maximum protec-

tion against freezing is provided with a 68 percent

antifreeze concentration, which prevents freezing

down to -67.7C (-90F). A higher percentage willfreeze at a warmer temperature. Also, a higher per-

centage of antifreeze can cause the engine to over-

heat because specifi c heat of antifreeze is lower than

that of water.

CAUTION: Richer antifreeze mixtures cannot be

measured with normal field equipment and can

cause problems associated with 100 percent ethyl-

ene-glycol.

COOLANT SELECTION-ADDITIVES

Coolant should be maintained at the specifi ed level

with a mixture of ethylene glycol-based antifreeze

and low mineral content water. Only use an anti-

freeze containing ALUGARD 340-2 .

CAUTION: Do not use coolant additives that are

claimed to improve engine cooling.

COOLANT SERVICE

I t is recommended that the cooling system be

drained and flushed at 84,000 kil ometers (52,500

Fig. 24 Belt Routing3.9L/5.2L Engine



24/48

miles), or 3 years, whichever occurs first. Then every

two years, or 48,000 kilometers (30,000 miles),

whichever occurs first.

COOLANT LEVEL CHECK-ROUTINE

Do not remove radiator cap for routine cool-

ant level inspections. The coolant level can be

checked at coolant reserve/overflow tank.The coolant reserve/overflow system provides a

quick visual method for determining coolant level

without removing radiator pressure cap. With engine

idling and at normal operating temperature, observe

coolant level in reserve/overflow tank. The coolant

level should be between ADD and F UL L marks.

ADDING ADDITIONAL COOLANT-ROUTINE

Do not remove radiator cap to add coolant to

system. When adding coolant to maintain correct

level, do so at coolant reserve/overflow tank. Use a

50/50 mixture of ethylene-glycol antifreeze containing

Alugard 340-2 and low mineral content water. Re-move radiator cap only for testing or when refilling

system after service. Removing cap unnecessari ly can

cause loss of coolant and allow air to enter system,which produces corrosion.

COOLANT LEVEL CHECK-SERVICE

The 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. I fnot, inspect for a leak between radiator and coolantreserve/overflow system connection. Remove radiatorcap. The coolant level should be to top of radiator. I fnot, and if coolant level in reserve/overflow tank is atADD mark, check for: An air leak in coolant reserve/overflow tank or itshose An air leak i n radiator filler neck L eak in pressure cap seal to radiator filler neck

LOW COOLANT LEVEL-AERATION

I f the coolant level in radiator drops below top ofradiator core tubes, air will enter cooli ng system. On2.5L engines, air can gather in the water box con-taining the thermostat.

L ow coolant level can cause thermostat pellet to besuspended in air instead of coolant. Thi s will causethermostat to open later, which in turn causes highercoolant temperature. Air trapped in cooling system

also reduces amount of coolant circulating in heater

core resulting in low heat output.

DEAERATION

As the engine operates, any air trapped in cooling

system gathers under the radiator cap. T he next time

the engine i s operated, thermal expansion of coolant

will push any trapped air past radiator cap into thecoolant reserve/overflow tank. Here it escapes to the

atmosphere into the tank. When the engine cools

down the coolant, it will be drawn from the reserve/overflow tank into the radiator to replace any re-moved air.

DRAININGCOOLINGSYSTEM

WARNING: DO NOT REMOVE CYLINDER BLOCKDRAIN PLUGS OR LOOSEN RADIATOR DRAIN-COCK WITH SYSTEM HOT AND UNDER PRESSURE.SERIOUS BURNS FROM COOLANT CAN OCCUR.

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

(1) Start engine and place heater control tempera-ture selector in Full On position. Engine vacuum isneeded to actuate heater controls.

(2) Turn ignition off.(3) Do not remove radiator cap when draining cool-

ant from reserve/overflow tank. Open radiator drain-cock and when tank is empty, remove radiator cap. I fcoolant reserve/overflow tank does not drain, refer toTesting Cooling System for L eaks section in thisgroup. The coolant need not be removed from tank

unless system is being refilled with a fresh mixture.(4) On 3.9L and 5.2L engines, remove cylinder

block drain plugs located on sides of block towardsfront of engine just above oil pan.

(5) Remove radiator pressure cap.(6) I f vehicle is equipped with a 2.5L engine, re-

move plug at top of water box for faster draining(Fig. 25).

REFILLING COOLINGSYSTEMClean cooling system prior to refilli ng. Refer to

Cooling System Cleaning section of this group.(1) I f vehicle is equipped with a 3.9L/5.2L engine,

install cylinder block drain plugs.(2) Close radiator drain plug.(3) Fill cooling system with a 50/50 mixture of wa-

ter and antifreeze. Be sure that antifreeze containsAlugard 340-2 as specified in Coolant section ofthis group.

I f vehicle is equipped with a 2.5L 4-cylinder engine,remove plug at top of water box to vent air trappedin engine. The thermostat is not equipped with a airbleed hole. When coolant level reaches plug hole, in-stall plug and ti ghten to 20 N m 15 (ft. lbs.) torque.Then continue filling cooling system until full.



25/48

(4) Fi ll coolant reserve/overflow tank to FU L L

mark.

(5) Start and operate engine until thermostat

opens (upper radiator hose warm to touch).

(6) I f necessary, add a 50/50 water and antifreeze

mixture to the coolant reserve/overfl ow tank. This is

done to maintain coolant level between the FUL L

and ADD marks. The level in the reserve/overflow

tank may drop below the ADD mark after three or

four warm-up and cool-down cycles.

COOLINGSYSTEM CLEANING/REVERSEFLUSHING

CLEANING

Drain cooling system and refill with water. Run en-gine with radiator cap installed until upper radiator

hose is hot. Stop engine and drain water from sys-

tem. I f water is dirty, fill system with water, run en-

gine and drain system. Repeat until water drains

clean.

REVERSE FLUSHING

Reverse flushing of cooling system is the forcing of

water through the cooling system. This is done using

air pressure in the opposite direction of normal cool-

ant flow. It is usually only necessary with very dirty

systems with evidence of parti al plugging.

REVERSE FLUSHING RADIATOR

Disconnect radiator hoses from radiator inlet and

outlet. Attach a section of radiator hose to radiator

bottom outlet fitting and insert flushing gun. Con-

nect a water supply hose and air supply hose to

flushing gun.

CAUTION: Internal radiator pressure must not ex-

ceed 138 kPa (20 psi) as damage to radiator may re-

sult.

Allow radiator to fil l with water. When radiator is

filled, apply air in short blasts. All ow radiator to r e-fill between blasts. Continue this reverse flushinguntil clean water flows out through rear of radiatorcooling tube passages. Have radiator cleaned moreextensively by a radiator repair shop.

REVERSE FLUSHING ENGINE

Drain cooli ng system. Remove thermostat housingand thermostat. I nstall thermostat housing. Discon-nect radiator upper hose from radiator and attachflushing gun to hose. Disconnect radiator lower hosefrom water pump and attach a lead-away hose to wa-ter pump inlet fitting.

CAUTION: On vehicles equipped with a heater watercontrol valve, be sure heater control valve is closed

(heat off). This will prevent coolant flow with scaleand other deposits from entering heater core.

Connect water supply hose and air supply hose toflushing gun. Allow engine to fill with water. Whenengine i s filled, apply air in short blasts, allowingsystem to fill between air blasts. Continue until cleanwater flows through the l ead away hose.

Remove lead away hose, flushing gun, water supplyhose and air supply hose. Remove thermostat hous-ing and install thermostat. I nstall thermostat hous-ing with a replacement gasket. Refer to T hermostatReplacement. Connect radiator hoses. Refill coolingsystem with correct antifreeze/water mixture. Referto Refilling the Cooling System.

CHEMICAL CLEANING

I n some instances, use a radiator cleaner (MoparRadiator K leen or equivalent) before flushing. Thi swill soften scale and other deposits and aid flushingoperation.

CAUTION: Follow manufacturers instructions whenusing these products.

Aluminum Hydroxide Deposition is a type of corro-sion encountered in cooli ng system of engines thatare of an aluminum composition. This would be on a2.5L engine with aluminum cylinder head. I t appearsas dark grey when wet, but, when dry i t is white.This type of corrosion can usually be r emoved with acommercially available two part cleaner (oxcil ac acidand neutralizer). Follow manufacturers directions foruse. However, it is recommended that engine be op-erated one extra hour if acid is in coolant.

TESTING COOLINGSYSTEM FOR LEAKS

ULTRAVIOLET LIGHT METHOD

A leak detection additive i s available through theparts department that can be added to cooling sys-tem. The additive is highly visible under ultraviolet

Fig. 25 Thermostat Housing Drain/Fill Plug2.5LEngineTypical



26/48

light (black light). Pour one ounce of additive into

cooling system. Place heater control unit in HE AT

position. Start and operate engine until radiator up-

per hose i s warm to touch. Aim the commercially

available black light tool at components to be

checked. I f leaks are present, black light will cause

additive to glow a bright green color.

The black light can be used in conjunction with apressure tester to determine if any external leaks ex-

ist (Fig. 26).

PRESSURE TESTER METHOD

The engine should be at normal operating tempera-ture. Recheck the system cold if cause of coolant loss isnot located during the warm engine examination.

WARNING: HOT, PRESSURIZED COOLANT CANCAUSE INJURY BY SCALDING.

Carefully remove radiator pressure cap from fi llerneck and check coolant level. Push down on cap todisengage it from stop tabs. Wipe inside of filler neckand examine lower inside sealing seat for nicks,

cracks, paint, dirt and solder residue. I nspect radia-tor-to-reserve/overflow tank hose for internal obstruc-tions. Insert a wire through the hose to be sure it isnot obstructed.

I nspect cams on outside of filler neck. I f cams arebent, seating of pressure cap valve and tester sealwill be affected. Replace cap if cams are bent.

Attach pressure tester (7700 or an equivalent) toradiator fill er neck (Fig. 27).

Operate tester pump to apply 103.4 kPa (15 psi)pressure to system. If hoses enlarge excessively orbulges while testing, replace as necessary. Observe

gauge pointer and determine condition of cooling sys-

tem according to following criteria:

Holds Steady: I f pointer remains steady for two

minutes, serious coolant leaks are not present in sys-

tem. However, there could be an internal leak that

does not appear with normal system test pressure. I f

it is certain that coolant is being lost and leaks can-

not be detected, inspect for interior leakage or per-

form I nternal L eakage Test.

Drops Slowly: I ndicates a small leak or seepage is

occurring. Examine all connections for seepage or

slight leakage with a flashlight. I nspect radiator,

hoses, gasket edges and heater. Seal small leak holes

with a Sealer L ubricant (or equivalent). Repair leak

holes and inspect system again with pressure ap-

plied.Drops Quickly: I ndicates that serious leakage is

occurring. Examine system for external leakage. I f

leaks are not visible, inspect for internal leakage.

L arge radiator leak holes should be repaired by a

reputable radiator repair shop.

INTERNAL LEAKAGE INSPECTION

Remove engine oil pan drain plug and drain asmall amount of engine oil. I f coolant is present inthe pan, it will drain first because it is heavier thanoil. An alternative method is to operate engine for ashort period to churn the oil. After this is done, re-move engine dipstick and inspect for water globules.Al so inspect transmission dipstick for water globulesand transmission flui d cooler for leakage.

WARNING: WITH RADIATOR PRESSURE TESTERTOOL INSTALLED ON RADIATOR, DO NOT ALLOWPRESSURE TO EXCEED 110 KPA (20 PSI). PRES-SURE WILL BUILD UP QUICKLY IF A COMBUSTION

LEAK IS PRESENT. TO RELEASE PRESSURE,ROCK TESTER FROM SIDE TO SIDE. WHEN RE-MOVING TESTER, DO NOT TURN TESTER MORETHAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.

Fig. 26 Leak Detection Using Black LightTypical

Fig. 27 Pressure Testing Cooling SystemTypical



27/48

Operate engine without pressure cap on radiator

until thermostat opens. Attach a Pressure Tester to

filler neck. I f pressure builds up quickly it indicates a

combustion leak exists. T his is usually the result of a

cylinder head gasket leak or crack in engine. Repair

as necessary.

I f there is not an immediate pressure increase,

pump the Pressure Tester. Do this until indicatedpressure is within system range of 110 kP a (16 psi).

Fluctuation of gauge pointer indicates compression or

combustion leakage i nto cooling system.

Because the vehicle is equipped with a catalytic

converter, do not remove spark plug cables or short

out cylinders to isolate compression leak.

I f the needle on dial of pressure tester does not

fluctuate, race engine a few times to check for an ab-

normal amount of coolant or steam. This would be

emitti ng from exhaust pipe. Coolant or steam fromexhaust pipe may indicate a faulty cylinder head gas-

ket, cracked engine cylinder block or cylinder head.A convenient check for exhaust gas leakage intocooli ng system is provided by a commercially avail-able Block L eak Check tool. Follow manufacturers in-structions when using this product.

COMBUSTION LEAKAGE TESTWITHOUT

PRESSURE TESTER

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

WARNING: DO NOT REMOVE CYLINDER BLOCK

DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-COCK WITH SYSTEM HOT AND UNDER PRESSURE.SERIOUS BURNS FROM COOLANT CAN OCCUR.

Drain sufficient coolant to allow thermostat re-moval. Refer to Thermostat Replacement. Disconnectwater pump drive belt.

Add coolant to radiator to bring l evel to within 6.3mm (1/4 in) of top of thermostat housing.

CAUTION: Avoid overheating. Do not operate en-gine for an excessive period of time. Open drain-cock immediately after test to eliminate boil over.

Start engine and accelerate rapidly three times, to

approximately 3000 rpm while observing coolant. I finternal engine combustion gases are leaking intocooli ng system, bubbles will appear in coolant. I f bub-bles do not appear, internal combustion gas leakageis not present.

COOLANTRESERVE/OVERFLOW SYSTEMThe coolant reserve/overflow system (Fig. 28) works

in conjunction with the radiator pressure cap. I t uti-li zes thermal expansion and contraction of coolant tokeep coolant free of trapped air. I t provides a volumefor expansion and contraction of coolant. I t also pro-

vides a convenient and safe method for checking cool-

ant level and adjusting level at atmospheric

pressure. This is done without removing the radiator

pressure cap. The system also provides some reserve

coolant to the radiator to cover minor leaks and

evaporati on or boil ing losses.

As the engine cools, a vacuum i s formed in the

cooling system of both the r adiator and engine. Cool-ant will then be drawn from the coolant tank and re-

turned to a proper level in the radiator.

Refer to Coolant L evel CheckService, Deaeration

and Radiator Pr essure Cap sections in this group for

coolant reserve/overfl ow system operation and ser-

vice.

Should the reserve/overflow tank become coated

with corrosion or emulsifiable oil, it can be cleaned

with detergent and water. Rinse tank thoroughly be-

fore refilling cooling system as described in the Cool-

ant section of this group.

TANK REMOVAL

(1) Remove overflow hose at reserve/overflow tank.

(2) Unsnap the coolant reserve/overflow tank from

fan shroud. L ift straight up. The fan shroud is

equipped with T-shaped slots to attach the tank.

TANK INSTALLATION

(1) Snap tank into fan shroud.(2) I nstall overflow hose to tank.

RADIATOR PRESSURE CAPRadiators are equipped with a pressure cap, which

releases pressure at some point within a r ange of 97-

124 kPa (14-18 psi). The pressure relief point (in

pounds) i s engraved on top of cap.

The cooling system will operate at pressures

slightly above atmospheric pressure. This results in a

higher coolant boiling point allowing i ncreased radi-

ator cooling capacity. The cap (Fig. 29) contains a

Fig. 28 Coolant Reserve/Overflow System



28/48

spring-loaded pressure relief valve that opens when

system pressure reaches release range of 97-124 kPa

(14-18 psi).

A vent valve in the center of cap allows a small

coolant flow through cap when coolant is below boil-

ing temperature. The valve is completely closed whenboiling point is reached. As the coolant cools, it con-

tracts and creates a vacuum in the cooling system.

This causes the vacuum valve to open and coolant in

the reserve/overflow tank to be drawn through its

connecting hose into radiator. If the vacuum valve is

stuck shut, the radiator hoses will collapse on cool-

down. Clean the vent valve (F ig. 29).

A rubber gasket seals radiator filler neck to pre-

vent leakage. This is done to keep system under

pressure. I t also maintains vacuum during coolantcool-down allowing coolant to return from reserve/overflow tank.

RADIATOR CAP-TO-FILLER NECK SEAL

PRESSURE RELIEF CHECK

The pressure cap upper gasket (seal) pressure re-lief can be tested by removing overflow hose from ra-diator filler neck nipple. Attach hose of pressuretester tool 7700 (or equivalent) to nipple. I t will benecessary to disconnect hose from its adapter forfiller neck. Pump air into radiator. T he pressure capupper gasket should r elieve at 69-124 kPa (10-18 psi)and hold pressure at a minimum of 55 kPa (8 psi).

WARNING: THE WARNING WORDS DO NOTOPEN HOT ON RADIATOR PRESSURE CAP, ARE

A SAFETY PRECAUTION. WHEN HOT, PRESSUREBUILDS UP IN COOLING SYSTEM. TO PREVENTSCALDING OR INJURY, RADIATOR CAP SHOULDNOT BE REMOVED WHILE SYSTEM IS HOT AND/OR

UNDER PRESSURE.

Do not remove radiator cap at any time except forthe following purposes:

(1) Check and adjust antifreeze freeze point.(2) Refill system with new antifreeze.(3) Conducting service procedures.

(4) Checking for vacuum leaks.

WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,

WAIT AT LEAST 15 MINUTES BEFORE REMOVING

RADIATOR CAP. WITH A RAG, SQUEEZE RADIATOR

UPPER HOSE TO CHECK IF SYSTEM IS UNDER

PRESSURE. PLACE A RAG OVER CAP AND WITH-

OUT PUSHING CAP DOWN, ROTATE IT COUNTER-CLOCKWISE TO FIRST STOP. ALLOW FLUID TO

ESCAPE THROUGH THE COOLANT RESERVE/

OVERFLOW HOSE INTO RESERVE/OVERFLOW

TANK. SQUEEZE RADIATOR UPPER HOSE TO DE-

TERMINE WHEN PRESSURE HAS BEEN RE-LEASED. WHEN COOLANT AND STEAM STOPBEING PUSHED INTO TANK AND SYSTEM PRES-

SURE DROPS, REMOVE RADIATOR CAP COM-PLETELY.

PRESSURE TESTING RADIATOR CAPS

Remove cap from radiator. Be sure that sealingsurfaces are clean. Moisten rubber gasket with waterand install cap on pressure tester 7700 or an equiv-alent (Fig. 30).

Operate tester pump to bring pressure to 104 kPa(15 psi) on gauge. I f pressure cap fails to hold pres-sure of at least 97 kPa (14 psi) replace cap. Refer tofollowing CAUTION.

The pressure cap may test properly while posi-tioned on tool 7700 (or equivalent). I t may not holdpressure or vacuum when installed on radiator. I f so,inspect radiator fil ler neck and caps top gasket fordamage. Also inspect for dirt or distortion that mayprevent cap from sealing properl y.

Fig. 29 Radiator Pressure Cap and Filler Neck

Fig. 30 Pressure Testing Radiator CapTypical



29/48

CAUTION: Radiator pressure testing tools are very

sensitive to small air leaks, which will not cause

cooling system problems. A pressure cap that does

not have a history of coolant loss should not be re-

placed just because it leaks slowly when tested

with this tool. Add water to tool. Turn tool upside

down and recheck pressure cap to confirm that cap

needs replacement.

INSPECTION

Hold cap at eye level, right side up. The vent valve

(Fig. 29) at bottom of cap should open. I f rubber gas-

ket has swollen and prevents vent valve from open-

ing, replace cap.

Hold cap at eye level, upside down. I f any light can

be seen between vent valve and rubber gasket, re-

place cap. Do not use a replacement cap that has

a spring to hold vent shut. A replacement cap

must be the type designed for a coolant reserve/over-

flow system with a completely sealed diaphragmspring and a rubber gasket. This gasket is used to

seal to radiator fil ler neck top surface. U se of proper

cap will allow coolant return to r adiator.

RADIATORThe radiators used in these models are of the

down-flow type (vertical tubes) and have plastic

tanks. The radiator supplies sufficient heat transfer

to cool engine.

CAUTION: Although plastic radiator tanks are stron-

ger than brass, they are more susceptible to dam-age from impact or excessive hose clamp torque.

I n the event of damage to a plastic radiator tank,

replacement tanks and o-ring seals (Fig. 31) are

avail able through the parts department. Tank repair

should be performed by qualified personnel using

proper equipment.

RADIATOR COOLANT FLOW CHECK

Use the following procedure to determine if coolant

is flowing through cooling system.

(1) I dle engine until operating temperature is

reached. I f upper radiator hose is warm to the touch,thermostat is opening and coolant is flowing to radi-

ator.

WARNING: HOT, PRESSURIZED COOLANT CAN

CAUSE INJURY BY SCALDING. USING A RAG TO

COVER RADIATOR PRESSURE CAP, OPEN RADIA-

TOR CAP SLOWLY TO FIRST STOP. ALLOW ANYBUILT-UP PRESSURE TO VENT TO THE RESERVE/OVERFLOW TANK. AFTER PRESSURE BUILD-UPHAS BEEN RELEASED, REMOVE CAP FROM

FILLER NECK.

(2) Drain a small amount of coolant from radiator

until ends of r adiator tubes are visible through filler

neck. I dle engine at normal operating temperature. I f

coolant is flowing past exposed tubes, coolant is cir-culating.

RADIATOR REMOVAL2.5L 4-CYLINDER

ENGINE



DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND UNDER PRESSURE.

SERIOUS BURNS FROM COOLANT CAN OCCUR.


System.










Fig. 31 Radiator ComponentsTypical



30/48





(3) Remove hose clamps (Fi g. 32) and hoses from

radiator. Remove coolant reserve/overflow tank hose

from radiator filler neck nipple.

(4) Disconnect electric cooling fan motor connector.

Remove fan and shroud upper attaching clips. L ift

fan and shroud assembly up and out. Do not allow

fan shroud to contact radiator cooling fins. Radiator

fin damage could result.

(5) Remove radiator upper mounting screws (F ig.

34). L ift radiator up and out of engine compartment.

Do not allow cooling fins of radiator to contact any other

vehicle component. Radiator fin damage could result.

RADIATOR INSTALLATION2.5L ENGINE

The radiator has two alignment pins on bottom of

lower tank. These fit into alignment holes in radiator

lower support.

(1) L ower the radiator into engine compartment.

Position alignment pins into alignment holes in radi-

ator lower support.

(2) L ower radiator fan and shroud assembly intoretaining pockets on radiator lower tank.

(3) Attach retaining clips at top of shroud.

(4) Connect fan motor electri cal connector to har-

ness connector.

(5) I nstall radiator hoses and coolant reserve/over-

flow tank to radiator hose.

(6) Connect negative battery cable to battery.

(7) Fill cooling system. Refer to Refilli ng Cooling

System section in this group.


RADIATOR REMOVAL3.9L/5.2L ENGINE



DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND UNDER PRESSURE.

SERIOUS BURNS FROM COOLANT CAN OCCUR.


System.

(3) Remove throttle cable at fan shroud.

(4) Unsnap coolant reserve/overfl ow tank from fan

shroud (T-shaped slots) (F ig. 34). L ift straight up.

(5) Remove fan shroud retaining hardware (twoclips at top-two bolts at bottom) (Fi g. 34).

(6) Position fan shroud towards engine. Fan

shroud does not have to be removed from vehicle.

(7) Disconnect transmission cooler lines at radiator

(if equipped).














(8) Remove upper and lower radiator hose clamps

(Fig. 32) and hoses at radiator.


Fig. 33 Clamp Number/Letter Location



31/48

(9) Remove two upper radiator-to-radiator support

bolts (Fig. 34). T he radiator has two alignment pins to

align l ower part of radiator to lower radiator support.

(10) L ift radiator up and out of engine compart-ment. Do not allow cooling fins of radiator to contact

any other vehicle component. Radiator fin damage

could result.

RADIATOR INSTALLATION3.9L/5.2L ENGINE

The radiator has two alignment pins on bottom oflower tank. These fit into alignment holes in radiatorlower support.

(1) L ower radiator into engine compartment. Posi-tion alignment pins into alignment holes in radiatorlower support.

(2) I nstall two upper radiator bolts.

(3) I nstall transmission cooler lines (if equipped).(4) I nstall both radiator hoses and hose clamps

(Fig. 32).(5) I nstall fan shroud to radiator (two clips at top-

two bolts at bottom).(6) I nstall coolant reserve/overflow tank. Snaps

into position.(7) Connect throttle cable to fan shroud. Snaps in.(8) Connect negative battery cable to battery.(9) Fill cooling system. Refer to Refilli ng Cooling

System section in this group.(10) Start and warm the engine. Check for leaks.

RADIATOR DRAINCOCK SERVICE

WARNING: DO NOT LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND PRESSURIZED. SE-RIOUS BURNS FROM COOLANT CAN OCCUR.

REMOVAL

(1) Unscrew draincock stem (counterclockwise rota-

tion). When stem is completely unscrewed, pull it

from radiator tank and draincock body (Fig. 35).

Fig. 34 Radiator and Fan Shroud Removal/InstallationTypical

Fig. 35 Draincock Assembly



32/48

(2) Using a pair of needle nose pliers, compress

draincock body and pull straight out of radiator (F ig.

36).

INSTALLATION

(1) I nstall draincock stem loosely into body (Fig.

37). The draincock assembly cannot be installed if

stem is threaded into the body.

(2) Push draincock assembly into opening i n radia-

tor tank. I t will snap i nto place when fully seated.

(3) Tighten draincock (clockwise) to 2.0 to 2.7 Nm

(18-25 in. lbs.) torque.

RADIATOR CLEANING

The radiator and air conditioning fins should becleaned when an accumulation of bugs, leaves etc.

has occurred. Clean radiator fins are necessary for

good heat transfer. With the engine cold, apply cold

water and compressed air to the back (engine side) of

the radiator to flush the r adiator and/or A/C con-

denser of debri s.

COOLINGSYSTEM HOSESRadiator lower hoses are spring-reinforced to pre-

vent collapse from water pump suction at moderate

and high engine speeds.

I nspect hoses at regular intervals. Replace hoses

that are cracked, feel brittle when squeezed, or swell

excessively when system is pressurized. The use ofmolded replacement hoses is recommended. Whenperforming a hose inspection, inspect radiator lowerhose for proper position and condition of spring.

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 (NUMBER

6094) (FIG. 32). SNAP-ON CLAMP TOOL (NUMBERHPC-20) MAY BE USED FOR LARGER CLAMPS. AL-WAYS WEAR SAFETY GLASSES WHEN SERVICINGCONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps (Fig. 33). If re-placement is necessary, use only an original equip-ment clamp with matching number or letter.

2.5L 4-Cylinder Engine: Be sure that radiatorlower hose and heater hose are installed in enginelower mounting bracket (Fig. 38).

For all vehicles: I n 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. I mproperl y 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 Nm (34 in. lbs.) torque. Do notover tighten hose clamps.

AUTOMATIC TRANSMISSION OIL COOLERS

MAIN COOLERIN RADIATOR LOWER TANK

The automatic transmission oil is cooled when itpasses through a cooler in radiator l ower tank (Figs.39 and 40).

CAUTION: If transmission oil cooler is leaking, en-gine coolant may enter cooler, or transmission oilmay enter engine cooling system. Both engine cool-ing system and transmission oil circuit should bedrained cleaned and inspected.

REPLACING MAIN COOLER

Vehicles equipped with plastic radiator tanks willrequire special crimping tools for servicing. The ser-vicing should be performed by a qualified repair fa-cility.

Fig. 36 Draincock Body Removal

Fig. 37 Draincock Assembled for Installation



33/48

Once repaired or replacement radiator has been in-

stalled, fil l cooling system and inspect for leaks. Re-

fer to Refill ing Cooling System and Testing Cooling

System F or L eaks sections in this group. I f transmis-

sion operates properly after repairing leak, drain

transmission and torque converter while hot. Remove

transmission oil pan and inspect for sludge and/or

rust. I nspect for a dirty or plugged inlet filter. I f none

of these conditions are found, transmission may not

require reconditioning. Refer to Group 21 for auto-

matic transmission servicing.

AUXILIARY OIL-TO-AIR COOLER

Oil -to-air transmission coolers are mounted ahead

of radiator. They operate in conjunction with main

cooler located in radiator lower tank (Fig. 41). The

transmission oil is routed through main cooler in ra-

diator lower tank fi rst. I t is then routed through aux-

il iary cooler before returning to transmission.

COOLINGSYSTEM FAN2.5L 4-CYLINDER

ENGINEModels equipped with 2.5L 4-cylinder engines have

an electrical cooling fan (Fig. 42). The fan is electri-

cally controlled by the powertrain control module

(PCM ) through the fan control relay. This relay is l o-

Fig. 38 Radiator Hoses

Fig. 39 Oil Flow to CoolerTop View

Fig. 40 Transmission Oil Cooler Tube in RadiatorLower TankTypical



34/48

cated in the power distribution center (PDC) (Fig.

43). For the location of the relay within the PDC, re-

fer to label on PDC cover.

The PCM regulates fan operation based on input

from the engine coolant temperature sensor and ve-

hicle speed.

The fan is not energized during engine cranking re-

gardless of the electri cal input from the engine cool-

ant temperature sensor. However, if engine operati ng

conditions warrant fan engagement, the fan will run

once engine starts.The fan is energized whenever the engine is run-

ning and the air conditioning compressor clutch is

engaged.

When the air conditioning compressor clutch i s dis-

engaged, the fan operates at vehicle speeds above 40

mph. This is done i f engine coolant temperature is

above 110C (230F ). The same i s true for vehicles

that are not equipped with air conditioning. T he fan

will turn off when coolant temperature drops to

104C (220F). At speeds below 40 mph, the fan

turns on when coolant temperature reaches 99C

(210F) and turns off when coolant temperaturedrops to 93C (200F).

TESTING ELECTRICAL COOLING FAN2.5L

ENGINE

The powertrain control module (PCM) will enter a

diagnostic trouble code (DTC) number 35 in memory

if it detects a problem in the electric cooling fan relay

or circuit. This will be read as a flashing signal at

the instrument panel mounted malfunction indicator

lamp (displayed on the instrument panel as the

CHE CK EN GIN E lampfigure 44). Refer to On-

Board Diagnostics in Group 14, Fuel Systems for

more information on accessing a DTC.The DTC can also be accessed through the DRB

scan tool. Refer to the appropriate P owertrain Diag-

nostic Procedures manual for diagnostic information

and operation of the DRB scan tool.

The cooling fan motor can be tested by applying 12

volts + to the fan motor connector. Disconnect fan

motor connector from harness connector. Using 14-

gage wire and ensuring correct polarity (Fig. 42), con-

nect battery voltage (12 volts) to fan motor connector.

I f fan operates normally, fan motor is functioning

properly. I f fan does not operate, replace fan. I f motor

has signs of being overheated such as melted wire in-sulation or charred contacts, the system charging

voltage may be too high. Refer to Group 8A, Battery/

Starting/Charging System Diagnostics.

RADIATOR FAN MOTOR INOPERATIVE

Equipment Required:

DRB Scan Tool

Volt/Ohm meter

Wiring Diagrams section of this manual

Test Procedure

Fig. 41 Transmission Oil Auxiliary CoolerTypical

Fig. 42 Electric Fan Motor2.5L EngineTypical

Fig. 43 Power Distribution Center (PDC)



35/48

Test fan by connecting battery voltage to motor

connector. Refer to Testing Electrical Cooling Fan

2.5L Engine in this group. I f fan operates, perform

the following procedure:

(1) With ignition switch in OFF position, check for

battery voltage at terminal-1 of fan relay connector.

Refer to the wiring diagrams section of Group 8W.

I f battery voltage i s present, proceed to step (2)

I f battery voltage is not present, check the car-

tridge fuse in the power distribution center (PDC)(Fig. 43). I nspect for an open or short to ground incircuit-C26. Refer to Group 8W, Wiring Diagrams

(2) Connect a 14-gauge jumper wire between fanrelay connector terminals-(B) and (D). Refer to Group8W, Wiring Diagrams. I f fan operates, proceed to step (3) I f fan does not operate, check for an open in cir-cuit-C25. Check this between terminal-(D) of fan re-lay connector and fan motor connector

Start engine and allow it to reach normal operatingtemperature.

(3) I nspect wire connectors in circuits-C9, C25 and

C26 for proper engagement. Refer to the wiring dia-grams section of Group 8W. The circuit number ap-pears in front of wire gauge and color description.

(4) Connect the DRB Scan Tool (DRB) to the datalink connector. The data link connector is located inthe engine compartment (Fi g. 45). Check on-board di-agnostics of powertr ain control module (PCM) for di-agnostic trouble codes (DTC). Refer to theappropriate P owertr ain Diagnostic Procedures man-ual for DRB scan tool operating instructions.

(5) I f the DTC, Radiator Fan Relay Circuit is dis-played on the DRB screen, proceed to step 6.

(6) With ignition switch in RUN position, test for

battery voltage at circuit-C26 connection of fan relay.

I f voltage reading is correct, proceed to step 7a

I f voltage is 0-1 volt, proceed to step 7b

(7) With the ignition OFF, disconnect the 60-way

connector from PCM (Fig. 46). The PCM is located in

the engine compartment. Turn ignition switch to ON

(RUN) position. Test for battery voltage at cavity-31of 60-way connector (Fig. 46).

I f battery voltage i s present at cavity-31 and fe-male terminal is not damaged, r eplace PCM I f voltage is 0, repair open or short in circuit-C27.Refer to Group 8W, Wiring Diagrams

(8) With igniti on off, disconnect 60-way connectorfrom P CM (Fig. 46). The PCM is located inside en-gine compartment on right fender well. Turn ignitionswitch to RUN position. Test for battery voltage atcir cuit-C26 connection of fan relay. I f battery voltage i s present, replace PCM I f voltage reading is 0-1 volt, proceed to step 8

(9) With ignition switch in ON position, test forbattery voltage at circuit-C27 connection of fan relay.Refer to Group 8W, Wiring Diagrams.

Fig. 44 Check Engine Lamp Fig. 45 Data Link Connector

Fig. 46 PCM 60-Way Connector (Terminal End)



36/48

I f battery voltage is present, replace fan relay

I f voltage reading is 0, repair open or short in cir-

cuit-C27

(10) Turn igniti on switch off. Connect 60-way con-

nector to P CM . Test system operation.

FAN REMOVAL2.5L ENGINE

The fan blade is not repairable. I f the fan is bent,warped, cracked or damaged in any way, it must be

replaced only with recommended replacement fan.

This is done to be sure of adequate strength, perfor-

mance and safety.


(2) Disconnect fan motor wire connector.

(3) Remove the two fan shroud mounting clips con-

necting the upper part of fan shroud to the radiator

(Fig. 34).

(4) Remove fan, shroud and motor fr om radiator as

an assembly.

(5) Support fan motor and shaft on a bench. Do

not allow fan blades to contact bench. Remove

fan retaining clip (Fig. 47).

FAN INSTALLATION2.5L ENGINE

(1) Position fan on motor shaft.(2) Support motor and shaft on a bench without

allowing fan blades to contact bench. This willprevent damage to fan from excessive force. I nstallfan retaining clip.

(3) I nstall the lower part of fan blade/fan motor as-sembly into the two pockets l ocated on the radiatorlower tank.

(4) I nstall two mounting clips.(5) Connect fan motor wire connector to harness

connector.(6) Connect negative battery cable to battery.

COOLING SYSTEM FAN3.9L/5.2L ENGINEFor additional information, also refer to Viscous

Fan Drive in this group.

REMOVAL

(1) Disconnect negative battery cable from battery.(2) Remove throttle cable at top of fan shroud.

(3) Unsnap coolant reserve/overfl ow tank from fanshroud and lay aside. The tank is held to shroudwith T-shaped slots. Do not disconnect hose or draincoolant from tank.

(4) The thermal viscous fan drive/fan blade assem-bly is attached (threaded) to water pump hub shaft(Fig. 48). Remove fan blade/viscous fan drive assem-bly from water pump by turni ng mounting nut coun-terclockwise as viewed from front. Threads onviscous fan drive are RIGHT HAND. A Snap-On 36MM Fan Wrench (number SP346 from Snap-OnCummins Diesel Tool Set number 2017DSP) can beused. Place a bar or screwdriver between water

pump pulley bolts (Fig. 48) to prevent pulley from ro-tating.

Do not attempt to remove fan/viscous fan drive as-sembly from vehicle at this time.

Do not unbolt fan blade assembly (Fig. 48) fromviscous fan drive at this time.

(5) Remove fan shroud attaching hardware (twobolts at bottom-two clips at top).

(6) Remove fan shroud and fan blade/viscous fandrive assembly as a complete unit from vehicle.

After removing fan blade/viscous fan drive assem-bly, do not place viscous fan drive i n horizontal po-sition. If stored horizontally, silicone fluid in the

Fig. 47 Radiator Fan Retaining Clip2.5L EngineTypical

Fig. 48 Fan Blade/Viscous Fan Drive3.9L/5.2L

Engine



37/48

viscous fan drive could drain into its bearing assem-

bly and contaminate lubricant.

CAUTION: Do not remove water pump pulley-to-wa-

ter pump bolts (Fig. 48). This pulley is under spring

tension.

(7) Remove four bolts securing fan blade assembly

to viscous fan drive (Fig. 48).

INSPECTION

The fan blades cannot be repaired. I f fan is dam-

aged, it must be replaced. I nspect fan as follows:

(1) Remove fan blade and viscous fan drive as an

assembly from the engine. Refer to preceding Re-

moval procedure.

(2) Remove fan blade assembly from viscous fan

drive unit (four bolts).

(3) L ay fan on a flat surface with leading edge fac-

ing down. With tip of blade touching flat surface, re-

place fan if clearance between opposite blade andsurface is greater than 2.0 mm (.090 inch). Rocking

motion of opposite blades should not exceed 2.0 mm

(.090 inch). Test all blades in this manner.

WARNING: DO NOT ATTEMPT TO BEND OR

STRAIGHTEN FAN BLADES IF FAN IS NOT WITHIN

SPECIFICATIONS.

(4) I nspect fan assembly for cracks, bends, loose

rivets or broken welds. Replace fan if any damage is

found.

CAUTION: If fan blade assembly is replaced be-cause of mechanical damage, water pump and vis-

cous fan drive should also be inspected. These

components could have been damaged due to ex-cessive vibration.

INSTALLATION

(1) I nstall fan blade assembly to viscous fan drive.Tighten bolts (Fig. 48) to 23 Nm (17 ft. lbs.) torque.

(2) Position fan shroud and fan blade/viscous fandrive assembly to vehicle as a complete unit.

(3) I nstall fan shroud.

(4) I nstall fan blade/viscous fan drive assembly towater pump shaft (Fi g. 48).

(5) I nstall coolant reserve/overflow tank to fanshroud. Snaps into position.

(6) I nstall throttle cable to fan shroud.(7) Connect negative battery cable.

VISCOUS FAN DRIVE3.9L/5.2L ENGINE

DESCRIPTIONAND OPERATION

Also refer to the previous section on Cooling Sys-tem Fan3.9L /5.2L Engine.

The thermal viscous fan drive (Figs. 48 or 49) is a

sili cone-fluid-filled coupling used to connect the fan

blades to the water pump shaft. The coupling allows

the fan to be driven in a normal manner. This is

done at low engine speeds while limiting the top

speed of the fan to a predetermined maximum l evel

at higher engine speeds.

A thermostatic bimetallic spring coil is located onthe front face of the viscous fan drive unit (a typical

viscous unit is shown in figure 49). This spring coil

reacts to the temperature of the radiator discharge

air. It engages the viscous fan drive for higher fan

speed if the air temperature from the radiator rises

above a certain point. Until additional engine cooli ng

is necessary, the fan will remain at a reduced rpm re-

gardless of engine speed.

Only when sufficient heat is present, will the vis-

cous fan drive engage. This is when the air flowing

through the radiator core causes a reaction to the bi-

metallic coil. I t then increases fan speed to provide

the necessary additional engine cooli ng.

Once the engine has cooled, the radiator discharge

temperature will drop. The bimetallic coil again re-

acts and the fan speed i s reduced to the previous dis-

engaged speed.

CAUTION: Engines equipped with serpentine drivebelts have reverse rotating fans and viscous fan

drives. They are marked with the word REVERSE to

designate their usage. Installation of the wrong fan

or viscous fan drive can result in engine overheat-

ing.

Fig. 49 Viscous Fan Drive3.9L/5.2L EngineTypical



38/48

CAUTION: If the viscous fan drive is replaced be-

cause 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 are

found. Also inspect water pump bearing and shaft

assembly for any related damage due to a viscousfan drive malfunction.

NOISE

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