4790434 93ZJ Secc 7 Cooling System

8/4/2019 4790434 93ZJ Secc 7 Cooling System

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COOLING SYSTEM

C O N T E N T S

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DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ENGINE ACCESSORY DRIVE BELTS . . . . . . . . . 32

ENGINE BLOCK HEATER . . . . . . . . . . . . . . . . . . 38

SERVICE PROCEDURES . . . . . . . . . . . . . . . . . . . 6

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . 40

INDEX

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Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Cooling System Components . . . . . . . . . . . . . . . . . 1

General Information . . . . . . . . . . . . . . . . . . . . . . . . 1System Coolant Routing . . . . . . . . . . . . . . . . . . . . . 1

GENERAL INFORMATIONThroughout this group, references are made to par-

ticular vehicle models by alphabetical designation or

by th e particular vehicle na meplate. A char t showing

a breakdown of alphabetical designations is included

i n t h e I n t r od u ct i on s e ct i on a t t h e b eg in n i n g of t h i s

m a n u a l .

COOLING SYSTEMThe cooling system regulates engine operating tem-

peratur e. I t a llows the engine to reach n ormal operat-

ing temperature as quickly as possible. I t also main-

t a in s n or m a l op er a t in g t e mp er a t u r e a n d p r eve n t soverheating.

The cooling system also provides a mean s of heating

t h e p a s s en g er com p a r t m e n t a n d cool in g t h e a u t o -

matic tran smission fluid (if equipped). The cooling

s ys t e m i s p r e s s u r iz ed a n d u s e s a ce n t r ifu g a l w a t e r

pump to circulate coolant throughout the system.

An optiona l factory insta lled m aximum dut y cooling

package is a vailable on most models. This package

will provide additional cooling capa city for vehicles

used under extreme conditions such as trailer towing

in high ambient temperatures.

COOLING SYSTEM COMPONENTSThe cooling system consists of:

A radiator

Cooling fan

Thermal viscous fan drive

F a n s h r ou d

Radiator pressure cap

Thermostat

Coolant reserve/overflow system

Tra nsmission oil cooler (if equipped with an au to-

matic tran smission)

Coolant

Water pump

Hoses and hose clamps

SYSTEM COOLANT ROUTINGFor cooling system routings refer to (Figs. 1 or 2).

Fig. 1 Engine Cooling System4.0LEngineTypical

Z COOLING SYSTEM 7 - 1


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D I A G N O S I S

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATING

Establish what driving conditions caused the com-

plaint. Abnormal loads on the cooling system such as

the following may be the cause.

1. PROLONGED IDLE, VERY HIGH AMBIENT

TEMPERATURE, SLIGHT TAIL WIND AT IDLE,

S LOW TR AF FIC, TR AF FIC J AMS , H IGH

SPEED, OR STEEP GRADES:

Driving techniques that avoid overheating are:

Idle with A/C off when temperature gauge is at end

of normal ran ge.

Increasing engine speed for more air flow is recom-

mended.

2. TRAILER TOWING:

Consult Trailer Towing section of owners manu al.

Do not exceed limits.

3. AIR CONDITIONING; ADD-ON OR AFTER

MARKET:

A maximum cooling package should have been or-

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

installed. If not, maximum cooling system compo-

n e n t s s h ou l d b e i n st a l le d for m od e l i n vol ve d p e r

ma nu factur ers specificat ions.

4. RECENT SERVICE OR ACCIDENT REPAIR:

Determine if any recent service has been performed

on vehicle t hat may effect cooling system. This may

be :

Engine adjustments (incorrect timing)

Slipping engine accessory drive belt(s)

Brak es (possibly dra gging)

C h a n g ed p a r t s (i n cor r e ct w a t e r p u m p r ot a t i n g i n

wrong direction)

Reconditioned ra diator or cooling system refilling(possibly under-filled or air tr apped in system).

Rubber and foam air seals not properly installed to

radiator or A/C condenser after a repair.

If investigation reveals none of the above as a cause

for engine overhea ting complaint, refer to following

Symptom and Action chart.

Fig. 2 Engine Cooling System5.2L EngineTypical

7 - 2 COOLING SYSTEM Z


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SYMPTOM AND ACTIONSEE PRELIMINARY CHECKS FIRST



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SYSTEM DIAGNOSIS



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SYSTEM DIAGNOSIS (CONT.)



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SERVI CE PROCEDURES

INDEX

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Automatic Transmission Oil Coolers . . . . . . . . . . . 31Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Coolant Reserve/Overflow System . . . . . . . . . . . . 23Cooling System Cleaning/Reverse Flushing . . . . . 20Cooling System Fan . . . . . . . . . . . . . . . . . . . . . . . 28Cooling System Hoses . . . . . . . . . . . . . . . . . . . . . 27Draining Cooling System . . . . . . . . . . . . . . . . . . . 19Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Radiator Pressure Cap . . . . . . . . . . . . . . . . . . . . . 23Refilling Cooling System . . . . . . . . . . . . . . . . . . . . 20Testing Cooling System for Leaks . . . . . . . . . . . . . 21Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Water Pump Bypass Hose5.2L Engine . . . . . . . 12Water Pump Tests . . . . . . . . . . . . . . . . . . . . . . . . . 6Water PumpsGeneral Information . . . . . . . . . . . . 6Water PumpsRemoval/Installation . . . . . . . . . . . . 7

WATER PUMPS GENERAL INFORMATIONA ce nt r ifu ga l w at er p u mp cir cu la t es coola n t

through the water jackets, passages, intake man ifold,

radiator core, cooling system hoses and heater core.

The pump is driven from the engine crankshaft by a

single serpentine drive belt on all engines.The water pump impeller is pressed onto the rear of

a shaft that rotates in bearings pressed into the hous-

ing. The housing has two small holes to allow seepage

to escape. The water pump seals are lubricated by t he

antifreeze in the coolant mixture. No additional lubri-

cation is necessary.

CAUTION: All 4.0L 6 cylinder engines are equipped

with a reverse (counterclockwise) rotating water

pump and thermal viscous fan drive assembly. RE-

VERSE is stamped or imprinted on the cover of the

viscous fan drive and inner side of the fan. Theletter R is stamped into the back of the water pump

impeller (Fig. 1). Engines from previous model

years, depending upon application, may have been

equipped with a forward (clockwise) rotating water

pump. Installation of the wrong water pump or vis-

cous fan drive will cause engine over heating.

A quick test to determine if the pump is working is

t o ch e ck i f t h e h e a t e r w a r m s p r op e r ly. A d e fe ct i ve

water pump will not be able to circulate heated cool-

ant through the long heater hose to the heater core.

5.2L ENGINE: O n e of t h e h e a t er h os es is con -

nected to the water pump with a metal coolant returnt u b e (F i g. 2 ). A r u b be r O -r in g for m s a s ea l a t t h e

water pump end of the tube.

WATER PUMP TESTS

LOOSE IMPELLER

DO NOT WASTE reusable coolant. If solution is

clean, drain coolant into a clean container for reuse.

WARNING: DO NOT REMOVE THE CYLINDER

BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR

DRAINCOCK WITH THE SYSTEM HOT AND UNDERPRESSURE. SERIOUS BURNS FROM THE COOL-

ANT CAN OCCUR.

(1 ) D r a in t h e cool in g s ys t e m . R efe r t o D r a in i n g

Cooling System in this group.

(2) Loosen the fan belt. Refer to Belt Service in the

Engine Accessory Drive Belt section of this group.

(3 ) D is con n e ct t h e l ow er r a d i a t or h os e fr om t h e

water pump.

(4 ) B e n d a s t iff w el di n g r od or s im i la r d e vi ce a s

shown in (Fig. 3). To prevent breakage of rod, m ini-

mum thickness should be 3/16 inch (.187 inches).

(5 ) P os it i on t h e r od i n t h e w a t e r p u m p i n le t a n d

a t t e m p t t o h o ld t h e i m pe ll er w h il e t u r n i n g t h e fa n

pulley. If equipped with a thermal viscous fan drive,

r o t a t e t h e w a t e r p u m p s h a f t w i t h a w r e n c h a t t a c h e d

to one of the fan pulley mounting nuts. If the impeller

i s l o o s e a n d c a n b e h e l d w i t h t h e r o d w h i l e t h e f a n

b la d e s a r e t u r n i n g , t h e p u m p i s d e fe ct i ve . D o n ot

Fig. 1 Reverse Rotating Water Pump4.0L 6Cylinder



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use excessive force when rotating pump shaft. If the

impeller turns, the pump is OK.

Connect the hose and install the coolant, or proceed

with repairs.

INSPECTING FOR INLET RESTRICTIONS

Inadequate heater performance may be caused by a

m e t a l c a s t in g r e s t r ict i on i n t h e w a t e r p u m p h e a t e r

hose inlet.

DO NOT WASTE reusable coolant. If solution is

cl ea n , d r a i n t h e cool a n t i n t o a cl ea n con t a i n e r for

reuse.

WARNING: DO NOT LOOSEN THE RADIATOR

DRAINCOCK WITH THE SYSTEM HOT AND UNDER

PRESSURE. SERIOUS BURNS FROM THE COOL-

ANT CAN OCCUR.

(1 ) D r a in s u ffi ci en t cool a n t fr om t h e r a d i a t or t o

decrease the level below the water pump heater hose

inlet.

(2) Remove the h eater h ose.

(3) Inspect the inlet for metal casting flash or other

restrictions.

R e m o v e t h e p u m p f r o m t h e e n g i n e b e f o r e r e -

m o v i n g r e s t r i c t i o n t o p r e v e n t c o n t a m i n a t i o n o f

t h e c o o la n t w i t h d e b ri s . R e fe r t o Wa t e r P u m p

R e m o v a l i n t h i s g r o u p .

WATER PUMPS REMOVAL/I NSTALLATION

4.0L 6 CYLINDER ENGINE

REMOVAL

T h e w a t e r p u m p on a ll m od els ca n b e r e m ov ed

without discharging the air conditioning system (if

equipped).

CAUTION: All 4.0L 6 cylinder engines have a reverse

(counter-clockwise) rotating water pump. The letter

R is stamped into the back of the water pump impel-

ler (Fig. 1) to identify. Engines from previous model

years, depending upon application, may be

equipped with a forward (clockwise) rotating water

pump. Installation of the wrong water pump will

cause engine over heating.

The water pump impeller is pressed on the rear of

t h e p u m p s h a ft a n d b ea r in g a s se m bly. T h e w a t er

pump is serviced only as a complete assembly.

WARNING: DO NOT REMOVE THE BLOCK DRAIN

PLUG(S) OR LOOSEN RADIATOR DRAINCOCK WITH

THE SYSTEM HOT AND UNDER PRESSURE. SERI-

OUS BURNS FROM COOLANT CAN OCCUR.

DO NOT WASTE r eusable coolan t. If t he solut ion is

clean, drain coolant into a clean container for reuse.

(1) Disconnect negative battery cable at battery.

(2) Drain the cooling system. Refer to Cooling Sys-

tem Dra ining in this group.

(3) Loosen (but do not remove at this time) the four

fan hub-to-water pump pulley mounting nu ts.

The engine accessory drive belt must be r emoved

prior to removing the fan.

(4) Remove engine dr ive belt a s follows:

Fig. 2 Coolant Return Tube5.2L Engine

Fig. 3 Impeller TestTypical



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(a) Loosen two rear power steering pump mount-

ing bolts A (Fig. 4).

(b ) L oos e n u p p er p u m p p iv ot b ol t B a n d l ow er

lock nut C (Figs. 5 or 6).

(c) Loosen pump adjusting bolt D (Fig. 4) un til

belt can be removed.

(d) Remove belt.

(5) Check condit ion of all pulleys.

(6 ) Th e p ow er s t ee r in g p u m p m u s t b e r e m ov ed

from its cast mounting bracket to gain access to bolt

E . B r a ck e t m ou n t in g b olt E is loca t e d b eh in d t h epower steering pump (Fig. 6).

(7) Remove two bolts A (Fig. 4).

(8) Remove locknut C a nd belt adjustment bolt D

(Figs. 5 or 6).

(9) Remove bolt B (Fig. 5). Position power steering

pump to the side. Hold pump in position with wire.

Do not disconnect hydraulic lines from pump.

(10) Remove bolts E, F and G (Fig. 6) and remove

pump mounting bracket.

(11) Remove idler pu lley mount ing bolt an d r emove

idler pulley. This must be done to gain clearance for

t h e w a t e r p u m p m ou n t e d h e a t e r h os e f it t i n g w h e n

water pump is being removed.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING THIS TYPE OFCLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-

ING THIS CLAMP.

(12) Remove lower radiator hose from water pump.

Remove heater hose from water pump fit t ing. Miller

C la m p Tool n u m b er 6 09 4 (F ig . 7 ) m a y b e u s ed t o

remove the constant tension clamps.

(13) Remove the four fan hub-to-water pump pulley

mounting nuts.(14) Remove the two fan shroud-to-upper radiator

crossmember attaching nuts (Fig. 8).

(15) Remove the fan assembly and fan shroud (to-

gether as one unit) from the vehicle.

(16) Remove the four pump mounting bolts (Fig. 9)

and remove pump from vehicle. Discard old gasket.

N ot e t h a t on e of t h e fou r b ol ts is l on g er t h a n t h e

oth er bolts.

(1 7) I f p u m p is t o b e r e pl a ce d, t h e h e a t er h os e

fit t ing m ust be removed. Note position of fit t ing be-

fore removal.

Fig. 4 P.S. Pump Rear Mounting Bolts4.0L Engine

Fig. 5 P.S. Pump Front Mounting Bolt/Locknut4.0L

Engine

Fig. 6 Bracket Mounting Bolts4.0L Engine



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INSTALLATION

(1 ) I f p u m p i s b ei n g r e p l a ce d , i n s t a ll t h e h e a t e r

hose fi t t ing to the pump. Use a sealant on the fi t t ing

such as Mopar Thread Sealant With Teflon. Refer

to the directions on the package.

(2) Clean the gasket mating surfaces. If the origi-

nal pump is used, remove any deposits or other for-

eign material . Inspect the cylinder block and water

p u m p m a t i n g s u r fa ce s for e r os ion or d a m a g e fr om

cavitation.

( 3 ) I n s t a l l t h e g a s k e t a n d w a t e r p u m p ( t h e g a s k e t

is installed dry). Tighten mounting bolts to 30 Nm

(2 2 f t . l b s.) t or q u e . R ot a t e t h e s h a ft b y h a n d t o b e

sure it turns freely.

(4 ) C on n e ct t h e r a d i a t or a n d h e a t e r h os e s t o t h e

water pump.

(5) Position the fan assembly an d fan shroud (to-

gether as one u nit) to the engine.

(6 ) P os it ion fa n s h r ou d t o r a d ia t or . B e s u r e t h e

alignment tabs at the lower part of shroud are placed

into the slots near lower part of radiator. Install and

tighten the two fan shroud mounting nuts.

(7) I ns ta ll fa n a ss em bly t o wa t er p um p h u b.

T i g h t e n f a n d r i v e m o u n t i n g n u t s t o 2 4 Nm (1 8 f t .

l bs .) t o r q u e. B e s u r e of a t l ea s t 2 5 m m (1 .0 i n ch e s )

between tips of fan blades and fan shroud.

(8) Position power steering pump bracket to engine.

Install bolts E, F and G (Fig. 6). Tighten bolts F and

G t o 3 8 Nm (28 ft. lbs.) torque. Tighten bolt E to 27

Nm (20 ft. lbs.) torque.

(9 ) P os it ion p ow er s t ee r in g p u m p t o m ou n t in g

b r a ck e t . I n s t a ll p iv ot b ol t B (F i g. 5 ) f in g er t i gh t .Install locknut C an d a djustment bolt D (Figs. 5 or 6)

finger tight.

(10) Install two a djustment bolts A (Fig. 4) finger

tight.

(11) Ins ta ll idler pulley.

CAUTION: When installing the serpentine engine ac-

cessory drive belt, the belt MUST be routed cor-

rectly. If not, the engine may overheat due to the

water pump rotating in the wrong direction. Refer to

Fig. 10 for appropriate belt routing.

Fig. 7 Hose Clamp Tool

Fig. 8 Fan Shroud Mounting

Fig. 9 Water Pump Remove/Install4.0L 6 Cylinder

Engine



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(12) Position drive belt to pu lleys.

(13) Tighten belt adjustment bolt D (Fig. 4) to the

proper tension. Refer to the Specifications section at

the end of this group for belt tension.

(14) Tighten bolts A (Fig. 4) to 27 Nm (20 ft. lbs.)

torque.

(15) Tighten pivot bolt B (Fig. 5) to 27 Nm (20 ft.

lbs.) torque.

(16) Tighten locknut C (Fig. 5) to 27 Nm (2 0 f t .

lbs.) torque.

(17) After the power steering pump has been t ight-ened, recheck belt tension.

(18) Fill cooling system with coolant an d check for

leaks. Refer t o Refilling Cooling System in th is group.

(19) Connect battery cable to battery.

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

5.2L V-8 ENGINE

REMOVAL

The water pump on 5.2L engines is bolted directly

to t he engine t iming chain case/cover.

A gasket is used as a seal between the water pump

an d timing chain case/cover.If water pump is replaced because of bearing/shaft

damage, or leaking shaft seal, the mechanical cooling

fan assembly should also be inspected. Inspect for

fatigue cracks, loose blades, or loose rivets that could

have resulted from excessive vibration. Replace fan if

an y of th ese conditions ar e foun d. Also check condi-

tion of th e therma l Viscous Fan Drive. Refer to Vis-

cous Fan Drive in this group.

T h e w a t er p u m p on a ll m od els ca n b e r e mov ed

without discharging the air conditioning system (if

equipped).

(1) Disconnect negative bat tery cable from batt ery.

(2) Drain cooling system. Refer t o Draining Cooling

System in this group.

Do not waste reusable coolant. If solution is clean,

drain coolant into a clean container for reuse.

(3 ) T h e t h e r ma l Vi scou s F a n D r ive is a t t a ch e d

(t h r e a de d) t o t h e w a t er p u m p h u b s h a ft (F i g. 11 ).

Remove fan/viscous fan drive assembly from waterpump by tur ning mounting n ut count erclockwise a s

viewed from front. Threads on viscous fan drive are

R I GH T H AN D . A S n a p -O n 3 6 MM F a n Wr en ch

(number SP346 from Snap-On Cummins Diesel Tool

S e t n u m b er 2 01 7D S P ) ca n b e u s e d . P l a ce a b a r or

screwdriver between water pump pulley bolts (Fig.

11) to prevent pulley from rotating. Do not attempt to

remove fan/viscous fan drive assembly from vehicle at

this t ime.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON MOST COOLING SYSTEM HOSES.

WHEN REMOVING OR INSTALLING THIS TYPE OF

CLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-

ING THIS CLAMP, SUCH AS MILLER TOOL 6094

(FIG. 12).

(4) If water pump is being replaced, do not unbolt

fan blade assembly (Fig. 11) from thermal viscous fan

drive.

(5) Remove two fan shroud-to-radiator nuts (Fig.

1 3). D o n ot a t t e m pt t o r e m ov e f a n s h r ou d a t t h is

time.

Fig. 10 Belt Routing4.0L 6 Cylinder Engine

Fig. 11 Fan Blade and Viscous Fan Drive5.2LEngine



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(6) 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, d o n o t place thermal viscous fan drive in hori-

zontal position. If stored horizontally, silicone fluid in

viscous fan drive could drain into i ts bearing assem-bly an d conta minate lubricant .

D o n o t r e m ov e w a t e r p u m p p u ll ey b ol t s a t t h i s

time.

(7) Remove accessory drive belt as follows: The

drive belt is equipped with a spring loaded a utomatic

belt tensioner (Fig. 14). Relax tension from belt by

rotating tensioner clockwise (as viewed from front)

(F i g. 1 4). W h en a l l b e lt t e n s ion h a s b ee n r e la x ed ,

remove accessory drive belt.

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

hu b bolts (Fig. 11) and remove pulley from vehicle.

(9) Remove lower radiator hose clamp and remove

lower hose at water pump.

(10) Remove heater hose clamp (Fig. 15) and heater

hose from heater hose coolant return tube.

(11) Loosen heater hose coolant return tube mount-

ing bolt and nut (Fig. 15) and remove tube from water

pump. Discard the old tube O-ring.

(1 2) Re m ov e s e ve n w a t e r p u m p m ou n t i n g b ol t s

(Fig. 16).


Fig. 13 Fan Shroud Nuts

Fig. 14 Belt Tensioner Assembly5.2L Engine




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(1 3) L oos en cl a m p a t w a t e r p u m p e n d of b y p a ss

h os e (F i g. 11 ). S li p b yp a s s h os e fr om w a t e r p u m p

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

R e p l a c e w a t e r p u m p a s s e m b l y i f i t h a s a n y o f t h e

following conditions:

The body is cracked or damaged

Wa t e r l ea k s fr om s h a ft s ea l . T h i s i s e vi de n t b y

traces of coolant below vent hole Loose or rough turn ing bearing. Also inspect vis-

cous fan drive

I m pe lle r r u b s e it h e r t h e p u m p b od y or t im in g

chain case/cover

INSTALLATION

(1) Clean gasket ma ting surfaces.

( 2 ) U s i n g a n e w g a s k e t , i n s t a l l w a t e r p u m p t o e n -

gine as follows: Guide water pump nipple into bypass

h os e a s p u m p i s b e in g i n st a l le d . I n s t a ll w a t e r p u m p

bolts (Fig. 16). Tighten water pump mounting bolts to

40 Nm (30 ft. lbs.) torque.

(3) Spin water pump to be sure that pump impellerdoes not rub against timing chain case/cover.

(4) Install a new O-ring to the heater hose coolant

return tube (Fig. 15). Coat the new O-ring with anti-

freeze before insta llat ion.

(5) Install coolant return tube to engine (Fig. 15).

B e s u r e t h e s l o t i n t u b e b r a c k e t i s b o t t o m e d t o t h e

m ou n t i n g b ol t . T h is w il l p r op e r ly p os it i on r e t u r n

tube.

(6) Connect radiator lower hose to water pump.

(7) Connect heater hose and hose clamp to coolant

r e t u r n t u b e.

(8) In stall water pump pulley. Tighten bolts t o 27

Nm (20 ft . lbs.) torque. Place a bar or screwdriver

between water pump pulley bolts (Fig. 11) to prevent

pulley from rotating.

(9) Relax tension from belt tensioner (Fig. 14). In-

stall drive belt.

CAUTION: When installing the serpentine accessorydrive belt, belt must be routed correctly. If not, en-gine may overheat due to water pump rotating inwrong direction. Refer to (Fig. 17) for correct beltrouting. The correct belt with correct length must be

used.

(10) Position fan shroud and fan blade/viscous fan

drive assembly to vehicle as a complete unit.

(11) Install two fan shroud-to-radiator nuts (Fig.

13).

Be sure of at least 25 mm (1.0 inches) between t ips

of fan blades and fan shroud.

(12) Install fan blade/viscous fan drive assembly to

water pump shaft.

(13) Fill cooling syst em. Refer to Refilling t he Cool-ing System in this group.

(14) Connect negative battery cable.


WATER PUMP BYPASS HOSE 5. 2L ENGINEA water pump bypass hose (Fig. 18) is used between

the intake manifold and water pump on all 5.2L V-8

engines. To t est for leaks, refer to Testing Cooling

System for Leaks in this group.

Fig. 16 Water Pump Bolts5.2L EngineTypical

Fig. 17 Belt Routing5.2L Engine



13/40

WITHOUT AIR CONDITIONING (A/C)

REMOVAL

(1) Par tially drain cooling system. Refer to Dra in-

ing Cooling System in this group.



WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON ALL COOLING SYSTEM HOSES.

WHEN REMOVING OR INSTALLING THIS TYPE OFCLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-ING THIS TYPE OF CLAMP SUCH AS MILLERCLAMP TOOL 6094 (FIG. 19).

(2) Loosen both bypass hose clamps (Fig. 19) and

position to center of hose. Remove hose from vehicle.

INSTALLATION

(1) Position bypass hose clamps (Fig. 19) to center

of hose.

(2) Install bypass hose to engine.

(3) Secur e both hose clam ps (Fig. 19).

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

ing System in this group.


WITH AIR CONDITIONING (A/C)

REMOVAL

If equipped with A/C, t he generator and A/C com-

pressor along with their common mounting bracket

(Fig. 20) must be partially removed. Removing gen-

erat or or A/C compressor from t heir m ounting br acket

is not necessary. Also, discharging A/C system is not

necessary. D o n o t remove any refrigerant lines from

A/C compressor.

WARNING: THE A/C SYSTEM IS UNDER PRESSURE

EVEN WITH ENGINE OFF. REFER TO REFRIGERANTWARNINGS IN GROUP 24, HEATING AND AIR CON-DITIONING.

(1) Disconnect negative bat tery cable from batt ery.

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

ing Cooling System in this group.



(3) Remove upper radiator hose clamp (Fig. 19) and

hose a t radiator.

(4) Unplu g wiring h arn ess from A/C compressor.

(5) Remove air duct at throttle body.

Fig. 18 Water Pump Bypass Hose5.2L Engine


Fig. 20 GeneratorA/C Compressor MountingBracket5.2L Engine



14/40

(6) Disconnect A/C lines from clip at intake mani-

fold.

(7) Remove heater hose coolant return tube m ount -

ing bolt and nut (Fig. 21). Remove tube from engine

and discard the old tube O-ring.

(8) Remove accessory drive belt as follows: The

drive belt is equipped with a spring loaded a utomatic

belt tensioner (Fig. 22). Relax tension from belt by

rotating tensioner clockwise (as viewed from front)

(F i g. 2 2). W h en a l l b e lt t e n s ion h a s b ee n r e la x ed ,remove accessory drive belt.

(9) The drive belt idler pulley must be removed to

g a in a cce s s t o on e of A/C com p r e ss or /g en e r a t or

bracket mounting bolts. Remove idler pulley bolt and

remove idler pulley (Fig. 20).

(10) Remove oil dipstick tube mounting bolt at side

of A/C-generat or m ounting bracket.

(11) Disconnect speed control cable and throttle

cable at throttle body. Refer to Accelerator Pedal and

Throttle Cable in Group 14, Fuel System for throttle

cable removal and installation. Refer to Group 8H for

removal an d inst allation of speed contr ol cable.(12) Remove bra cket-to-inta ke m an ifold bolts (nu m-

ber 1 and 2Fig. 20).

(13) Remove six bra cket bolts (number 3Fig. 20).

(14) Lift 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) Loosen an d position both hose clamps to cent er

of bypass hose. Remove hose from vehicle.

INSTALLATION

(1) Position bypass h ose clamps to cent er of hose.

(2) Install bypass hose to engine.

(3) Secur e both hose clam ps (Fig. 19).

(4) Install generator-A/C mounting bra cket assem-

b ly t o e n gi n e. T ig h t en b ol t s (n u m b e r 1 a n d 2 F i g.

20) to 54 Nm (40 ft. lbs.) torque. Tighten bolts (num -

ber 3Fig. 20) to 40 Nm (30 ft. lbs.) torque.

(5) Install a new O-ring to the heater hose coolant

return tube (Fig. 21). Coat the new O-ring with anti-freeze before installation.

(6) Install coolant return tube to engine (Fig. 21).

Be sure the slot in tube bracket is bottomed to the

m ou n t i n g b ol t . T h is w il l p r op e r ly p os it i on r e t u r n

tube.

(7) Conn ect thr ottle body cont rol cables.

(8) Inst all oil dipstick m oun ting bolt.

(9) Install idler pulley. Tighten pulley bolt to 54

Nm (40 ft. lbs.) torque.

(10) Relax tension from belt tensioner (Fig. 22).

Install 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. 23) for correct belt

routing. The correct belt with correct length must be

used.

(11) Install air duct to throttle body.

(12) Install upper radiator hose to radiator.

(13) Conn ect wiring ha rn ess t o A/C compressor.

(14) Conn ect A/C lines t o clip a t intak e ma nifold.


Fig. 22 Belt Tensioner Assembly5.2L Engine



15/40

(15) Fill cooling syst em. Refer t o Refilling t he Cool-

ing System in th is group.


THERMOSTAT

DESCRIPTI ON AND OPERATION

A pellet-type thermostat controls the operating tem-

perature of the engine by controlling the amount of

coolant flow to the radiator. On all engines the ther-

mostat is closed below 195F (90C). Above this tem-

peratur e, coolant is a llowed t o flow to t he radiator.

This provides quick engine warm up and overall tem-

perature control.

An arrow, plus the word U P is stamped on the front

flange next to the air bleed. The words TO RAD a r e

stamped on one arm of the thermostat. They indicate

the proper installed position.

T h e s a m e t h e r m o s t a t i s u s e d f o r w i n t e r a n d s u m -

mer seasons. An engine should not be operated with-

out a thermostat, except for servicing or testing. Op-

erating without a thermostat causes other problems.

T h e se a r e : l on g er e n gi n e w a r m u p t i m e, u n r e l ia b lew a r m u p p e r for m a n c e, i n cr e a s ed e xh a u s t e m is s ion s

and crank case condensation. This condensation can

result in sludge formation.

CAUTION: Do not operate an engine without a ther-mostat, except for servicing or testing.

The more common type of thermostat failure, usu-

ally found on high milage vehicles, is a thermostat

failed in the shut position. The temperatur e gauge (if

equipped) will give an indication of this condition.

Depending u pon length of t ime that vehicle is oper-

a t e d , p r e s s u r e c a p m a y v e n t . T h i s w i l l e x p e l s t e a m

and coolant to coolant reserve/overflow tank and to

surface below vehicle. Refer to the Diagnosis section

of th is group.

ON-BOARD DIAGNOSTICS

All models are equipped with On-Board Diagnos-

tics. If t he Powertrain Contr ol Module (PCM) com-

puter detects low engine coolant temperature, i t will

record a Diagnostic Trouble Code (DTC). The code

number for low coolant temperature is 17. For other

DTC nu mbers, refer to On-Board Diagnostics in the

General Diagnosis section of Group 14, Fuel Systems.

REMOVAL4.0L 6 CYLINDER ENGINE

WARNING: DO NOT LOOSEN THE RADIATORDRAINCOCK WITH THE SYSTEM HOT AND PRES-

SURIZED. SERIOUS BURNS FROM THE COOLANTCAN OCCUR.

DO NOT WASTE r eusable coolan t. If t he solut ion iscl ea n , d r a i n t h e cool a n t i n t o a cl ea n con t a i n e r for

reuse.

(1 ) D r a in t h e cool a n t fr om t h e r a d ia t o r u n t i l t h e

level is below the thermostat housing.

WARNING: CONSTANT TENSION HOSE CLAMPS

ARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING THIS TYPE OFCLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-ING THIS CLAMP.

(2) Remove radiator upper hose and heater hose at ther-

mostat housing. Miller Clamp Tool number 6094 (Fig. 24)may be u sed to remove the consta nt tension clamps.

(3) Disconnect wiring conn ector at engine coolan t

temperatur e sensor.





16/40

(4 ) R em ov e t h e r m os t a t h ou s in g m ou n t i n g b ol t s,

thermostat housing, gasket and thermostat (Fig. 25).

Discard old gasket.

(5) Clean t he gasket ma ting surfaces.

INSTALLATION4.0L 6 CYLINDER ENGINE

( 1 ) I n s t a l l t h e r e p l a c e m e n t t h e r m o s t a t s o t h a t t h e

pellet , which is encircled by a coil spring, faces the

e n gi ne . A ll t h e r mos t a t s a r e m a r k ed on t h e ou t e rflange to indicate the proper installed position.

(a) Observe the recess groove in the engine cylin-

der head (Fig. 26).

(b) Position thermostat in groove with a rrow and

air bleed hole on outer flange pointing up.

(2 ) I n st a ll r e pla ce m en t ga s k et a n d t h e r m os t a t

housing.

CAUTION: Tightening the thermostat housing un-

evenly or with the thermostat out of its recess, may

result in a cracked housing.

(3) Tighten the housing bolts to 22 Nm (16 ft. lbs.)

torque.

(4) Install hoses to th ermostat housing.

(5) In stall electrical connector to coolan t tempera -

ture sensor.

(6 ) B e s u r e t h a t t h e r a d ia t o r d r a i n cock i s t i gh t l y

closed. Fill the cooling system to the correct level with

the required coolant mixture. Refer to Refilling Cool-

ing System in th is group.


REMOVAL5.2L V-8 ENGINE

WARNING: DO NOT LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND PRESSURIZED. SE-

RIOUS BURNS FROM COOLANT CAN OCCUR.



I f t h e r m os t a t is b ein g r e pla ce d, b e s u r e t h a t r e -

placement is specified thermostat for vehicle model

and engine type.

Factory insta lled t hermostat housings on 5.2L en-

gin e s a r e in s t a ll ed on a g a sk et w it h a n a n t i-s t ick

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

(1) Disconnect negative battery cable at battery.

(2) Dra in cooling system un til coolan t level is below

thermostat. Refer to Draining Cooling System in t his

group.

(3 ) Ai r C on d it i on e d v eh i cl es : R em ov e s u p p or t

bracket (generator mounting bracket-to-intake mani-

fold) located near rear of genera tor (Fig. 27).

(4) On Air Conditioning equipped vehicles, the gen-

erator m ust be part ially removed.

(a) Remove genera tor drive belt a s follows: Drive

belts on the 5.2L engine a re equipped with a spring

loaded au tomatic belt t ensioner (Fig. 28).

(b ) A t t a ch a s ock e t /w r e n ch t o p u ll ey m ou n t i n g

bolt of au tomatic belt tensioner (Fig. 28).

(c) R ot a t e t e n sion e r a s se m bly clock w is e (a s

viewed from front) until tension has been relieved

from belt.

(d) Remove belt from veh icle.

Fig. 25 Thermostat Removal/Installation4.0L

Engine

Fig. 26 Thermostat Recess4.0L Engine



17/40

(e) Remove two generator mounting bolts. Do not

r e m ov e a n y w ir i n g a t g en e r a t or . I f e qu i pp e d w it h

4WD, un plug 4WD indicator lamp wiring h arn ess

(located near rear of generator).

(f) Remove genera tor. Position genera tor to gain

access for thermostat gasket removal.

(5) Remove upper radiator hose clamp (Fig. 24) and

upper radiator hose at thermostat housing.

(6 ) P os it i on w ir i n g h a r n e s s (b eh i n d t h e r m os t a t

housing) to gain access to thermostat housing.

(7 ) Re m ov e t h e r m os t a t h ou s in g m ou n t i n g b ol t s,

thermostat housing, gasket and thermostat (Fig. 29).

Discard old gasket.

INSTALLATION5.2L V-8 ENGINE

(1) Clean mating ar eas of intake ma nifold and t her-

mostat housing.

(2 ) I n s t a l l t h e r m os t a t (s p r in g s id e d ow n ) i n t o r e -

cessed m achined groove on inta ke man ifold (Fig. 29).

(3) Install gasket on intake m anifold and over ther-

mostat (Fig. 29).

(4) Position thermostat housing to intake manifold.

Note th e word F RONT sta mped on housing (Fig. 30).

For adequate clearance, this m u s t be placed towards

front of vehicle. The housing is sl ightly a ngled for-

ward after installation to intake manifold.

(5) Install 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.

(6) Install upper radiator hose to thermostat hous-

ing.

(7) Air Condit ioned veh icles:

(a) Install generator. Tighten bolts to 41 N m (30

ft. lbs.).

(b) Install support bracket (generator mounting

bracket-to-inta ke ma nifold) (Fig. 27). Tighten bolts

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

Fig. 27 Generator Support Bracket5.2L Engine

Fig. 28 Automatic Belt Tensioner5.2L Engine

Fig. 29 Thermostat5.2L Engine



18/40

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. 31) for correct 5.2L

engine belt routing. The correct belt with correct

length must be used.

(c) Position drive belt over all pulleys e x c e p t

i dl er p u ll ey (l oca t e d b et w e en g en e r a t or a n d A/C

compressor).

(d ) A t t a ch a s ock e t /w r e n ch t o p u ll ey m ou n t i n g

bolt of au tomatic belt tensioner (Fig. 28).

(e) Rotate socket/wrench clockwise. Place belt

ov er i dl er p u l le y. L et t e n s ion e r r ot a t e b a ck i n t o

p la ce . R em ov e w r en ch . B e s u r e b el t i s p r op e r ly

seated on all pulleys.

(8) F ill cooling system. Refer to Refilling Cooling

System in this group.(9) Connect negative battery cable to battery.


COOLANT

GENERAL IN FORMATI ON

The cooling system is designed around the coolant.

Coolant flows t hrough the engine water jackets ab-

sorbing heat produced during engine operation. The

coolant carries heat to the radiator and heater core.

Here i t is transferred to ambient air passing through

t h e r a d i a t or a n d h e a t e r cor e fi n s. T h e cool a n t a l so

removes h eat from t he automatic tra nsmission fluid

in vehicles equipped with an automatic transmission.

COOLANT PERFORMANCE

The required ethylene-glycol (antifreeze) and water

mixture depends upon climate and vehicle operating

conditions. The coolan t performa nce of various mix-

tures follows:

P ur e Wa t e r -Wa t e r ca n a b sor b m or e h e a t t h a n a

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

p os e of h e a t t r a n s fe r on l y. Wa t e r a l so fr e ez es a t a

higher temperature and allows corrosion.

1 0 0% E t hy l e ne -G ly c o l -The corrosion inhibitingadditives in ethylene-glycol need the presence of wa-

ter to dissolve. Without water, a dditives form deposits

in system. These act as insulation causing tempera-

t u r e t o r i s e t o a s h i gh a s 1 49 C (3 00 F ). T h is t e m -

p er a t u r e is h ot e n ou gh t o m e lt p la s t ic a n d s oft e n

s ol de r. T h e i n cr e a s ed t e m p er a t u r e ca n r e s u lt i n e n -

gine detonation. In addition, 100 percent ethylene-

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

5 0 /5 0 E t hy l e ne -G ly c o l a nd Wa t e r -Is the recom-

mended mixture, it provides protection against freez-

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

m u s t a l w a y s b e a m in im u m of 4 4 p er ce n t , y e a r-round in all climates. If percentage is lower, engine

parts may be eroded by cavitation. Maximum protec-

tion against freezing is pr ovided with a 68 percent

a n t i fr e ez e con ce n t r a t i on , w h ich p r e ve n t s fr e ez in g

down to -67.7C (-90F). A higher percentage will

freeze at a warmer temperature. Also, a higher per-

centage of antifreeze can cause the engine to overheat

because specific heat of an tifreeze is lower than that

of water.

Fig. 30 Thermostat Position5.2L Engine




19/40

CAUTION: Richer antifreeze mixtures cannot be

measured with normal field equipment and can

cause problems associated with 100 percent

ethylene-glycol.

COOLANT SELECTION-ADDITIVES

Coolant should be maintained at the specified level

with a mixture of ethylene glycol-based ant ifreeze

a n d low m in e r a l con t e n t w a t er. O n ly u s e a n a n t i-

freeze containing ALUGARD 340-2 .

CAUTION: Do not use coolant additives that are

claimed to improve engine cooling.

COOLANT SERVICE

I t is r e com m e n de d t h a t t h e coolin g s ys t em b e

d r a i n ed a n d fl u sh e d a t 8 4,00 0 k i lom e t er s (5 2,50 0

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

two years, or 48,000 kilometers (30,000 miles), which-ever occurs first.

COOLANT LEVEL CHECK-ROUTINE

D o n o t r e m o v e r a d i a t o r c a p f o r r o u t i n e c o o l -

a n t l e v e l i n s p e c t i o n s . T h e c o o l a n t l e v e l c a n b e

c h e c k e d a t c o o l a n t r e s e r v e /o v e r fl o w t a n k .

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 FULL marks.

ADDING ADDITI ONAL COOLANT-ROUTI NE

D o n o t r e m o v e r a d i a t o r c a p t o a d d c o o l a n t t o

s y s t e m . W h en a d d in g cool a n t t o m a i n t a in cor r e ct

level, do so a t coolant reserve/overflow tan k. Use a

50/50 mixture of ethylene-glycol antifreeze containing

Al u ga r d 3 40 -2 a n d l ow m i n er a l con t e n t w a t e r.

Remove radiator cap only for testing or when refilling

system after service. Removing cap unnecessarily can

cause loss of coolant and allow air to enter system,

which produces corrosion.

COOLANT LEVEL CHECK-SERVI CE

The cooling system is closed and designed to main-ta in coolant level to t op of radiator.

WARNING: DO NOT OPEN RADIATOR DRAINCOCKWITH ENGINE RUNNING OR WHILE ENGINE IS HOTAND COOLING SYSTEM IS UNDER PRESSURE.

W h en v eh i cl e s e r vi ci n g r e qu i r es a cool a n t l ev el

check in radiator, drain several ounces of coolant from

radiator drain cock. Do t his while observing coolant

reserve/overflow system tank . The coolant level in

reserve/overflow tank should drop slightly. If not, in-

s pe ct for a le ak b et we en r a dia t or a n d coola n t

reserve/overflow system conn ection. Remove rad iator

cap. The coolant level should be to top of radiator. If

not and if coolant level in reserve/overflow tank is at

ADD m ark , check for:

An air leak in coolant reserve/overflow tank or its

hose

An air leak in radiator filler neck

Leak in pressure cap seal to radiator filler neck

LOW COOLANT LEVEL-AERATION

If 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 cause

thermostat to open later, which in turn causes higher

coolant temperatur e. Air tra pped 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. The next t ime

the engine is operated, thermal expansion of coolant

w i l l p u s h a n y t r a p p e d a i r p a s t r a d i a t o r c a p i n t o t h e

coolant reserve/overflow tank. Here it escapes to the

a t m os ph e r e in t o t h e t a n k . Wh e n t h e e n gin e cool s

d ow n t h e coola n t, it will be d ra wn fr om t h e

reserve/overflow tank into the radiator to replace any

removed a ir.

DRAINING COOLING SYSTEM

WARNING: DO NOT REMOVE THE CYLINDERBLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR

DRAINCOCK WITH SYSTEM HOT AND UNDER

PRESSURE. SERIOUS BURNS FROM COOLANT

CAN OCCUR.



reuse.

DRAINING ENTIRE SYSTEM

Use this procedure if the entire cooling system is to

be drained, such as for engine removal.

(1) DO NOT remove radiator cap first. With enginecol d, r a i se v eh i cl e on a h oi st a n d l oca t e r a d i a t or

draincock.

4.0L E ngine: Radiator draincock is located on the

right/lower side of radiat or facing t o rea r of vehicle.


left/lower side of radiator facing to rear of vehicle.

(2) Attach one end of a hose to the draincock. Put

the other end into a clean container. Open draincock

and drain coolant from radiator. This will empty the

coolant reserve/overflow t ank . The coolan t does not

have to be removed from the tank unless the system



20/40

is being refil led with a fresh mixture. When tank is

e m p t y, r e m ov e r a d i a t or ca p a n d con t i n u e d r a i n in g

cooling system.

To drain the 4.0L 6 cylinder engine of coolant, re-

move the cylinder block drain plug located on the side

of cylinder block (Fig. 32).

To drain the 5.2L V-8 engine of coolant, remove the

cy li n d er b lock d r a i n p lu g s l oca t e d on t h e s id e s of cylinder block above the oil pan rail (Fig. 33).

PARTIAL DRAINING

Use this procedure if the coolant is to be partially

drained, such a s for engine thermostat removal.

(1) With engine cold, slowly r emove the radiator

ca p . R a is e ve h icle on a h ois t a n d loca t e r a d ia t or

draincock.


right/lower side of radiat or facing to r ear of vehicle.


left/lower side of radiator facing to rear of vehicle.

(2) Attach one end of a hose to the draincock. Put

the other end into a clean container.

(3 ) O p en d r a i n cock a n d d r a i n d e si r ed a m ou n t of

coolant from radiator.

REFILLING COOLING SYSTEM(1) Tighten the radiator dr aincock and the cylinder

block drain plug(s) (if removed).

(2) Fill system using a 50/50 mixture of water and

antifreeze as described in the Coolant Section of this

g r ou p . F i ll r a d i a t or t o t o p a n d i n st a l l r a d i a t or ca p .

Add sufficient coolant to the reserve/overflow tank to

raise level to FULL ma rk.

(3) With heater control unit in the HEAT position,

operate engine with radiator cap in place.

(4) After engine h as reached n ormal operating tem-

perature, shut engine off and allow it to cool. When

engine is cooling down, coolant will be drawn into the

radiator from the reserve/overflow tank.(5) Add coolan t to r eserve/overflow ta nk as neces-

sary. O n ly a d d c o o l a n t t o t h e r e s e r v e /o v e r fl o w

t a n k w h e n t h e e n g i n e i s c o l d . C o o l a n t l e v e l i n a

w a r m e n g i n e w i l l b e h i g h e r d u e t o t h e r m a l e x -

p a n s i o n . To purge the cooling system of all air, this

heat up/cool down cycle (adding coolant to cold en-

gine) must be performed three t imes. Add necessary

c o o l a n t t o r a i s e t a n k l e v e l t o t h e F U L L m a r k a f t e r

each cool down period.

COOLING SYSTEM CLEANING/REVERSE FLUSHING

CAUTION: The cooling system normally operates at97-to-124 kPa (14-to-18 psi) pressure. Exceeding thispressure may damage the radiator or hoses.

CLEANING

D r a in cool in g s ys t e m a n d r e fi ll w it h w a t e r. R u n

engine with radiator cap installed until upper radia-

t or h os e i s h ot . S t op e n gi n e a n d d r a in w a t e r fr om

system. If water is dirty, f i l l system with water, run

e n g i n e a n d d r a i n s y s t e m . R e p e a t u n t i l w a t e r d r a i n s

clean.

REVERSE FLUSHING

Reverse flushing of the cooling system is the forcing

of w a t e r t h r o u gh t h e cool in g s ys t e m . T h i s i s d on e

using air pressure in the opposite direction of normal

coolant flow. It is usually only necessary with very

dirty systems with evidence of partial plugging.

REVERSE FLUSHIN G RADIATOR

D is con n e ct t h e r a d i a t or h os e s fr om t h e r a d i a t or

fittings. Attach a section of radiator hose to the radia-

tor bottom outlet f i t t ing and insert the flushing gun.

C o n n e c t a w a t e r s u p p l y h o s e a n d a i r s u p p l y h o s e t o

the flushing gun.

Fig. 32 Drain Plug4.0L 6 Cylinder Engine

Fig. 33 Drain Plugs5.2L V-8 Engine



21/40

CAUTION: The cooling system normally operates at

97-to-124 kPa (14-to-18 psi) pressure. Exceeding thispressure may damage the radiator or hoses.

Allow the radiator to fill with water. When radiator

is filled, apply air in short blasts allowing radiator to

refill between blasts. Continue this reverse flushing

until clean water flows out through rear of radiator

cooling tube passages. For more information, refer to

operating instructions supplied with flushing equip-

m e n t . H a v e r a d i a t or cl ea n e d m or e e xt e n s iv el y b y a

radiator repair shop.

REVERSE FLUSHING ENGINE

Drain the cooling system. Remove th e thermostat

housing and thermostat. Install the thermostat hous-

ing. Disconnect the radiator upper hose from the ra-

d i a t o r a n d a t t a c h t h e f l u s h i n g g u n t o t h e h o s e . D i s -

connect the radiator lower hose from the water pump.

At t a ch a le a d a w a y h os e t o t h e w a t er p u m p in le t

fitting.Connect the water supply hose and air supply hose

t o t h e fl u sh i n g g u n . A ll ow t h e e n gi n e t o fi ll w it h

w a t e r. W h en t h e e n gi n e i s fi ll ed , a p p ly a i r i n s h or t

blasts, allowing the system to fil l between air blasts.

C on t i n u e u n t i l c le a n w a t e r fl ow s t h r o u gh t h e l ea d

away hose. For more information, refer to operating

instructions supplied with flushing equipment.

R em ov e t h e l ea d a w a y h os e , f lu s h i n g g u n , w a t e r

supply hose an d air supply hose. Remove the thermo-

s t a t h ou s in g a n d i n st a l l t h e r m os t a t . I n s t a l l t h e t h e r -

mostat housing with a replacement gasket. Refer t o

Thermostat Replacement. Connect the radiator hoses.

Refill t he coolin g syst em wit h t he cor rectantifreeze/water mixture.

CHEMICAL CLEANING

I n s om e i n st a n c es , u s e a r a d i a t or cl ea n e r (M op a r

Radiator Kleen or equivalent) before flushing. This

will soften scale and other deposits and aid the flush-

ing operation.

CAUTION: Be sure instructions on the container are

followed.

TESTING COOLING SYSTEM FOR LEAKS

ULTRAVIOLET LIGHT METHOD

Al l J e e p m od el s h a v e a l ea k d e t ect i on a d d it i ve

a d d ed t o t h e cool in g s ys t e m b efor e t h e y l ea v e t h e

factory. The additive is highly visible under ultravio-

let light (black light). If t he factory original coolan t

has been drained, pour one ounce of additive into t he

cooling system. The additive is available through the

p a r t s d e pa r t m e n t . P l a ce t h e h e a t e r con t r o l u n i t i n

HEAT position. Star t and operate t he engine unt il the

r a d i a t or u p p er h os e i s w a r m t o t h e t ou ch . Ai m t h e

black light (tool 7138 or an equivalent), at the compo-

n e n t s t o b e c h e c k e d . I f l e a k s a r e p r e s e n t , t h e b l a c k

l ight will cause t he additive to glow a bright green

color.

The black l ight can be used along with a pressure

t e s t er t o d e t er m i n e i f a n y e xt e r n a l l ea k s e xi st (F i g.

34).

PRESSURE TESTER METHOD

The engine should be at the normal operating tem-

p e r a t u r e . R e ch e ck t h e s ys t e m col d i f t h e ca u s e of coolant loss is not located during warm engine exami-

nation.

WARNING: HOT, PRESSURIZED COOLANT CAN

CAUSE INJURY BY SCALDING.

C a r e fu l ly r e m ov e t h e r a d i a t or p r e ss u r e ca p fr om

the filler neck and check the coolant level. Push down

on t h e ca p t o d i s en g a ge i t fr om t h e s t op t a b s . W ip e

t h e in n e r p a r t of t h e fille r n e ck a n d e xa m in e t h e

lower inside sealing seat for nicks, cracks, paint, dirt

and solder residue. Inspect the reserve/overflow tank

tube for internal obstructions. Insert a wire throughthe tube t o be sure i t is n ot obstructed.

I n s p ect t h e ca m s on t h e ou t s i de p a r t of t h e fi ll er

n e c k . I f t h e c a m s a r e b e n t , s e a t i n g o f p r e s s u r e c a p

valve and tester seal will be affected. Bent cams can

be reformed if done carefully. Attach pressure tester

7700 or an equivalent to the radiator filler neck (Fig.

35).

O p er a t e t h e t e s t er p u m p t o a p p ly 1 2 4 k P a (1 8 p s i)

p r e ss u r e t o t h e s ys t e m . I f t h e h os e s e n la r g e e xce s -

sively or bulge while testing, replace as necessary.

Fig. 34 Leak Detection Using Black LightTypical



22/40

Observe the gauge pointer and determine the condi-

tion of th e cooling system according t o th e following

criteria:

Holds Steady: If the pointer remains steady for two

m i n u t e s, t h e r e a r e n o s e r i ou s cool a n t l ea k s i n t h e

system. H owever, th ere could be a n internal leak tha t

d oe s n ot a p p ea r w it h n or m a l s ys t e m t e s t p r e ss u r e .

Inspect for interior leakage or do the Internal Leak-

age Test. Do this if i t is certain that coolant is being

lost and no leaks can be detected.

D r op s S low ly : S h ow s a s m a l l l e a k or s e ep a ge i s

occurring. Examine all connections for seepage or

slight leakage with a flashlight. Inspect the radiator,

h os e s, g a s ke t e d ge s a n d h e a t e r. S e a l a n y s m a ll l ea k

holes with a Sealer Lubricant or equivalent. Repair

l ea k h ol es a n d r e in s p ect t h e s ys t e m w it h p r e ss u r eapplied.

D r op s Q u ick l y: S h ow s t h a t a s er i ou s l ea k a g e i s

occurring. Examine the system for serious external

leakage. If n o leaks are visible, inspect for internal

leakage. Large r adiator leak holes should be repaired

by a reputable radiator repair shop.

INTERNAL LEAKAGE INSPECTION

R e m o v e t h e o i l p a n d r a i n p l u g a n d d r a i n a s m a l l

a m ou n t of e n gi n e oi l. C ool a n t , b ei n g h e a vi er , w il l

drain first , or operate engine to churn oil, th en exam-

ine dipstick for water globules. Inspect t he tra nsmis-

sion dipstick for water globules. Inspect the transmis-

s ion fl u id cool er for l ea k a g e. O p er a t e t h e e n gi n e

w i t h o u t t h e p r e s s u r e c a p o n t h e r a d i a t o r u n t i l t h e r -

mostat opens.

Attach a Pressure Tester to the fi l ler neck. If pres-

s u r e b u il ds u p q u ick l y, a l ea k e xi st s a s r e s u lt of a

fa u l t y c yl in d e r h e a d g a s ke t or cr a ck i n t h e e n gi n e.

Repair as necessary.

WARNING: DO NOT ALLOW PRESSURE TO EXCEED124 KPA (18 PSI). TURN THE ENGINE OFF. TO RE-LEASE THE PRESSURE, ROCK THE TESTER FROM

SIDE TO SIDE. WHEN REMOVING THE TESTER, DO

NOT TURN THE TESTER MORE THAN 1/2 TURN IF

THE SYSTEM IS UNDER PRESSURE.

I f t h e r e i s n o i m m e d i a t e p r e s s u r e i n c r e a s e , p u m p

t h e P r e s s u r e Te s t er u n t i l t h e i n d ica t e d p r e ss u r e i s

w it h in t h e s ys t em r a n ge . Vib r a t ion of t h e g a u ge

pointer indicat es compression or combustion leakageinto t he cooling system.

WARNING: DO NOT DISCONNECT THE SPARK

PLUG WIRES WHILE THE ENGINE IS OPERATING.

CAUTION: Do not operate the engine with a spark

plug shorted for more than a minute. The catalytic

converter may be damaged.

Isolate the compression leak by shorting each spark

plug to the cylinder block. The gauge pointer should

stop or decrease vibration when spark plug for leak-ing cylinder is shorted. This happens because of the

absence of combustion pressur e.

COMBUSTION LEAKAGE TEST (WITHOUT

PRESSURE TESTER)



reuse.




PRESSURE. SERIOUS BURNS FROM COOLANTCAN OCCUR.

Drain sufficient coolant to allow for thermostat re-

moval. Refer to Thermostat Replacement. Disconnect

the water pump drive belt .

Disconnect th e u pper r adiator hose from the ther-

mostat housing. Remove the housing and thermostat.

Install the thermostat housing.

Ad d cool a n t t o t h e r a d i a t or t o b r i n g t h e l ev el t o

w it h i n 6 .3 m m (1 /4 i n ) of t h e t op of t h e t h e r m os t a t

housing.

CAUTION: Avoid overheating. Do not operate the

engine for an excessive period of time. Open the

draincock immediately after the test to eliminate boil

over of coolant.

Start the engine and accelerate rapidly three t imes

(to approxima tely 3000 r pm) wh ile observing t he cool-

ant. If internal engine combustion gases are leaking

i n t o t h e cool in g s ys t e m , b u b b le s w il l a p p e a r i n t h e

coolant. If bubbles do not appear, there is no internal

combustion gas leakage.

Fig. 35 Pressurizing SystemTypical



23/40

COOLANT RESERVE/OVERFLOW SYSTEMThis system works along with t he r adiator pressure

ca p . T h i s i s d on e b y u s i n g t h e r m a l e xp a n s ion a n d

contraction of the coolant to keep the coolant free of

trapped air. It provides:

A volume for coolant expansion and contraction.

A con ven ien t a n d sa fe m et h od for

checking/adjusting coolant level at atmospheric pres-s u r e. T h is is d on e w it h ou t r e m ovin g t h e r a d ia t or

pressure cap.

S om e r e s er v e cool a n t t o cov er m i n or l ea k s a n d

evaporation or boiling losses.

The coolant reserve/overflow system has a radiator

m ou n t e d p r e ss u r i ze d ca p , a n ov er fl ow t u b e a n d a

p la s t ic cool a nt r e se r ve /ove r flow t a n k (F ig. 3 6)

mounted to th e right inner fender.

RADIATOR PRESSURE CAPAll radiators are equipped with a pressure cap. This

cap releases pressure at some point within a range of

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

(in pounds) is engraved on top of the cap (Fig. 37).

T he coolin g s ys te m w ill op er a t e a t p r es su r es

slightly above atmospheric pressure. This results in ahigher coolant boiling point allowing increased radia-

t or cool in g ca p a ci t y. T h e ca p (F i g. 3 7) con t a i n s a

spring-loaded pressure relief valve. This valve opens

w h e n s ys t e m p r e ss u r e r e a ch e s t h e r e le a s e r a n g e of

97-to-124 kP a (14-to-18 psi).

A vent valve in t he center of the cap allows a small

coolant flow through the cap when coolant is below

boiling temperatur e. The valve is completely closed

when boiling point is reached. As the coolant cools, it

con t r a c t s a n d cr e a t e s a v a cu u m i n cool in g s ys t e m .

This causes the vacuum valve to open and coolant in

reserve/overflow tank to be drawn through connecting

hose into radiator. If the vacuum valve is stuck shut,

radiator hoses will collapse on cool-down.

A rubber gasket seals the radiator fi l ler neck. This

is done to maintain vacuum during coolant cool-down

a n d t o p r e v e n t l e a k a g e w h e n s y s t e m i s u n d e r p r e s -

sure.

RADIATOR CAP-TO-FILLER NECK

SEALPRESSURE RELIEF CHECK

With radiator cap installed on fi ller neck, remove

coolant reserve/overflow tan k hose from nipple on

filler neck. Connect a han d operated vacuum pu mp to

nipple. Operate pump until a reading of 47-to-61 kP a

(1 4-t o-1 8 i n . H g ) a p p e a r s on g a u ge . I f t h e r e a d in g

s t a ys s t ea d y, or d r op s s lig h t ly a n d t h e n r e m a in s

steady, the pressure valve seal is good. Replace radia-tor cap if reading does not hold.

WARNING: THE WARNING WORDS DO NOT OPENHOT ON THE RADIATOR PRESSURE CAP (FIG.37) ARE A SAFETY PRECAUTION. WHEN HOT,PRESSURE BUILDS UP IN COOLING SYSTEM. TO

PREVENT SCALDING OR INJURY, THE RADIATORCAP SHOULD NOT BE REMOVED WHILE THE SYS-TEM IS HOT AND/OR UNDER PRESSURE.

There is no n eed to remove th e ra diator cap e x c e p t

for the following purposes:

Fig. 36 Coolant Reserve/Overflow TankTypical

Fig. 37 Radiator Pressure CapTypical



24/40

To check and adjust antifreeze freeze point.

To refill system with new ant ifreeze.

For conducting ser vice procedur es.

When checking for vacuum leaks.

WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,WAIT AT LEAST 15 MINUTES BEFORE REMOVING

RADIATOR CAP. WITH A RAG, SQUEEZE RADIATORUPPER HOSE TO CHECK IF SYSTEM IS UNDERPRESSURE. PLACE A RAG OVER THE CAP ANDWITHOUT PUSHING DOWN, ROTATE CAPCOUNTER-CLOCKWISE TO THE FIRST STOP. AL-

LOW FLUID TO ESCAPE THROUGH OVERFLOWHOSE INTO COOLANT RESERVE/OVERFLOW TANK.SQUEEZE RADIATOR UPPER HOSE TO DETERMINEWHEN PRESSURE HAS BEEN RELEASED. WHEN

COOLANT AND STEAM STOP BEING PUSHED INTOTANK AND SYSTEM PRESSURE DROPS, REMOVERADIATOR CAP COMPLETELY.

PRESSURE TESTI NG RADIATOR CAPS

R em ov e c a p fr om r a d i a t or . B e s u r e t h a t s e a li n g

surfaces are clean. Moisten rubber gasket with water

and install the cap on pr essure tester (tool 7700 or an

equivalent) (Fig. 38).

O pe r a t e t h e t e st e r p u m p a n d ob se r ve t h e ga u g e

pointer at i ts highest point. The cap release pressure

should be 97-to-124 kPa (14-to-18 psi). The cap is

satisfactory when the pressure holds steady. It is also

g ood i f i t h ol ds p r e ss u r e w it h i n t h e 9 7-t o-1 24 k P a

(14-to-18 psi) r ange for 30 seconds or more. If th e

point er drops quickly, replace t he cap.

INSPECTION

Vi su a l ly i n s pe ct t h e p r e ss u r e v a lv e g a s k e t on t h e

ca p . R ep la ce ca p i f t h e g a sk e t i s s w ol le n , t or n or

worn. Inspect the area around radiator fil ler neck for

white deposits tha t indicate a leaking cap.

RADIATOR

GENERAL IN FORMATI ON

All vehicles are equipped with a cross flow type

radiator with plastic side ta nks.

Plastic tanks, while stronger t han brass, are subject

to damage by impact, such as from tools or wrenches.

Handle radiator with care.

RADIATOR COOLANT FLOW CHECK

The following pr ocedure will determine if coolant is

flowing t hrough the cooling system.

If engine is cold, idle engine until normal operating

temperature is reached. Then feel the upper radiator

hose. If hose is hot, the thermostat is open and wateris circulat ing t hrough cooling system.

REMOVAL




PRESSURE. SERIOUS BURNS FROM COOLANT

CAN OCCUR. REFER TO COOLING SYSTEM DRAIN-

ING IN THIS GROUP.

D o n o t w a s t e r e u s a bl e cool a n t . I f t h e s ol u t ion i s


reuse.

WARNING: CONSTANT TENSION HOSE CLAMPS

ARE USED ON MOST COOLING SYSTEM HOSES.

WHEN REMOVING OR INSTALLING THIS TYPE OF

CLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-

ING THIS CLAMP, SUCH AS MILLER TOOL 6094

(FIG. 39)

CAUTION: When removing the radiator or A/C con-

denser for any reason, note the location of all

radiator-to-body and radiator-to-A/C condenser rub-ber air seals. To prevent overheating, these seals

must be installed to their original positions.

(1) Disconnect the negative battery cable at battery.

(2 ) O b se r ve t h e p r e vi ou s WAR N I N GS a n d C AU -

TIONS.

(3) Drain coolant from radiator. Refer to Dra ining

Cooling System in this group.

(4) 4 .0 L E ng i ne : Remove t he four fan hu b-to-water

pump pulley mounting nuts (Fig. 40). Car efully re-

move the fan assembly from the water pump pulley

Fig. 38 Pressure Testing Radiator Pressure Cap



25/40

and position to center of fan shroud. Fan belt removal

i s n o t n e c e s s a r y a s t h e w a t e r p u m p s t u d s w i l l h o l d

the pump pulley in position.

Do not remove fan/viscous fan drive assembly fromvehicle at this time.

5 . 2 L E n g i n e : T h e t h e r m a l Vi scou s F a n D r iv e i s

atta ched (threaded) to the water pump h ub sha ft (Fig.

41). Remove fan/viscous fan drive assembly from wa-

ter pump by turning mounting nut counterclockwise

as viewed from front. Thr eads on viscous fan drive

a r e RIGHT HAND . A Snap-On 36 MM Fan Wrench

(number SP346 from Snap-On Cummins Diesel Tool

S e t n u m b er 2 01 7D S P ) ca n b e u s e d . P l a ce a b a r or

screwdriver between water pump pulley bolts (Fig.

4 1) t o p r e ve n t p u ll ey fr om r ot a t i n g. D r iv e b el t r e -

moval is not necessary for removal of fan drive.

D o n ot a t t e m p t t o r e m ov e fa n /v is cou s fa n d r iv e

assembly from vehicle at this time.

(5) Remove the two fan shroud-to-upper radiator

crossmember mounting nuts (Fig. 42).

(6 ) R e m ov e t h e fa n a s s em b ly a n d fa n s h r ou d (a s

one unit) from vehicle.

(7) Special quick-connect fi t t ings are used to join

t h e t r a n s m i s si on cool in g l in e s t o t h e r a d i a t or . R e-

moval procedures are different between the 4.0L and

5.2L engine. Disconnect the cooling lines from the ra-


Fig. 40 Fan Mounting Nuts4.0L Engine

Fig. 41 Fan Blade and Viscous Fan Drive5.2LEngine

Fig. 42 RadiatorA/C Condenser Mounting



26/40

diator. Refer to Gr oup 21 for t ran smission cooling line

removal and installation.

(8) The radiator upper crossmember (Fig. 43) can

b e a d ju s t e d l eft or r i gh t t h r o u gh t h e u s e of s l ot t e d

holes. Before removal, mark the original position of

the crossmember.

(9) Eight clips are u sed to retain a rubber seal (Fig.

43) to the body. Gently pry up the outboard clips (two

p e r s id e ) u n t i l r u b b er s e a l ca n b e r e m o ve d . D o n o t

remove the clips entirely. Fold back the seal on both

sides for access to (the hidden) gril le opening r ein-forcement mount ing bolts (Fig. 43). Remove th ese t wo

bolts.

(10) Remove th e grill. Refer t o group 23, Body.

(11) Remove the upper brace bolt from each of the

two radiator braces (Fig. 42).

(1 2) R em ov e t h e t w o cr os s m em b er -t o-r a d i a t or

mounting nuts (Fig. 43).

(1 3) Wor k i n g t h r o u gh g r il l op e n in g , r e m ov e t h e

lower bracket bolt securing lower part of h ood latch

s u p p or t b r a ck e t t o l ow er fr a m e cr os s m em b er (F i g.

42).

(14) Remove the remaining four bolts securing the

radiator u pper crossmember t o the body. Do not re-m ov e t h e h ood l a t ch or h ood l a t ch ca b le fr om t h e

crossmember. Lift the crossmember str aight up and

lay to the side.

(15) Equipped with air conditioning: Remove the

two A/C condenser-to-radiator mounting bolts (Fig.

4 2). T h es e t w o b o lt s a r e a l so u s e d t o r e t a i n t h e s id e

mounted rubber air seals. These seals are compressed

b et w ee n t h e A/C con d en s er a n d t h e r a d ia t or . T h e

l ow er p a r t of t h e a i r s e a ls a r e com p r e ss e d b e t w ee n

the radiator and the A/C condenser mounting brack-

ets (Fig. 44).

Not equipped with air conditioning: Remove th e t wo

b o l t s r e t a i n i n g t h e s i d e m o u n t e d r u b b e r a i r s e a l s t o

the radiator. The lower part of the air seals are com-

pressed between the radiator and the radiator lower

crossmember.

CAUTION: Note the location of all rubber air seals.

To prevent overheating, they must be installed backto their original positions.

(16) Disconnect the coolant reserve/overflow t ank

hose (Fig. 43) at radiator.

(17) Remove upper radiator hose at radiator. Miller

C la m p Tool n u m b e r 6 09 4 (F i g. 3 9) m a y b e u s e d t o

remove the constant tension hose clamps.

(18) 4.0L Engine Only: Remove the lower radiator

h os e a t t h e w a t e r p u m p e n d .

(19) To gain access to lower radiator hose clamp at

radiator, gently l ift the radiator a sl ight amount. Re-

move hose clamp and hose.

T h e l ow er p a r t of r a d i a t or i s e q u ip p ed w it h t w oalignment dowel pins (Figs. 42 or 44). They are lo-

ca t e d on t h e b ot t om of r a d i a t or t a n k a n d fit in t o

r u bb er gr om m et s. T he se r u bb er gr om m et s a r e

pressed into the radiator lower crossmember.

Fig. 43 Radiator Upper CrossmemberTypical

Fig. 44 Radiator Alignment Dowels



27/40

WARNING: THE AIR CONDITIONING SYSTEM (IF

EQUIPPED) IS UNDER A CONSTANT PRESSURE

EVEN WITH THE ENGINE OFF. REFER TO REFRIG-

ERANT WARNINGS IN GROUP 24, HEATING AND

AIR CONDITIONING BEFORE HANDLING ANY AIR

CONDITIONING COMPONENT.

(20) If equipped with an auxiliary aut omatic tran s-mission oil cooler, use caution when removing radia-

tor. The oil cooler l ines are routed through a rubber

air seal on the left side of radiator. Do not cut or tear

this seal.

(2 1) G e n t l y l ift u p a n d r e m ov e r a d ia t or fr om v e-

h icle . B e ca r e fu l n ot t o s cr a p e t h e r a d ia t or fin s

against any other component. Also be careful not to

distur b t he air conditioning condenser (if equipped).

INSTALLATION

(1) Equipped with air conditioning: Gently lower

the radiator into the vehicle. Guide the two radiator

alignment dowels through the holes in the rubber air

seals first and then through the A/C support brackets

(Fig. 44). Continue to guide the alignment dowels into

the rubber grommets located in lower radiator cross-

member (Fig. 44). The holes in the L-shaped brackets

(located on bottom of A/C condenser) m ust be posi-

tioned between bottom of rubber air seals and top of

rubber grommets.

Not equipped with air conditioning: Gently lower

the radiator into the vehicle. Guide the two radiator

alignment dowels through the holes in the rubber air

s e a ls . C on t i n u e t o g u id e t h e a l ig n m en t d ow el s i n t o

the rubber grommets located in lower radiator cross-member.

(2) Connect the lower radiator hose and hose clamp

to radiator.

CAUTION: The tangs on the hose clamp must be

positioned straight down.

(3) 4.0L Engine: Connect the lower radiator hose at

t h e w a t e r p u m p .

(4) Connect the u pper radiator hose at th e radiator.

(5) Equipped with air conditioning: Install the two

A/C condenser-to-ra diator mount ing bolts (Fig. 42).

These two bolts are also used to retain the rubber air

seal to the sides of radiator.

Not equipped with A/C: Install the two bolts retain-

ing the rubber a ir seal to sides of radiator.

(6) Install coolant reserve/overflow tank hose at ra-

diator.

(7) If radiator-to-upper crossmember rubber isola-

t or s w er e r em ove d fr om r a dia t or, in s ta ll t h em .

Tigh t en m ou n t in g n u t s t o 3 Nm (2 4-3 6 i n . l bs .)

torque. Position upper radiator crossmember to radia-

tor.

(8 ) Wor k in g t h r ou gh g rill op en in g , in s t a ll a n d

tighten the hood latch support bracket-to-lower frame

crossmember bolt (Fig. 42).

(9) Install the four bolts securing the radiator up-

per crossmember to t he body (Fig. 43).

(1 0) I n s t a l l t w o n u t s s e cu r i n g t h e r a d i a t or t o t h e

upper radiator crossmember (Fig. 43). Tighten nuts to

2 Nm (18-21 in. lbs.) torque.(11 ) I n s t a l l t h e u p p er b ol t t o e a ch r a d i a t or b r a ce

(Fig. 42).

(12) Inst all th e grill. Refer to group 23, Body.

(1 3) I n s t a l l t h e r u b b er s e a l ( F ig . 4 3 ) t o t h e fou r

(outer) seal mounting clips on vehicle body. Press

down on clips until seated.

(14) Inst all th e tra nsmission cooler l ines to ra dia-

tor. Refer to Group 21 for insta llation.

(15) Position the fan assembly and fan shroud (as

one unit) to the vehicle.

(1 6) P o s it i on fa n s h r ou d t o r a d i a t or . B e s u r e t h e

alignment tabs at the lower part of shroud are placed

into the slots near lower part of radiator.

(17) Install the two nuts securing the fan shroud to

the upper radiator crossmember (Fig. 42).

(18) 4.0L En gine: Install the four nuts securing th e

fa n a s s em b ly t o t h e w a t e r p u m p (F i g. 4 0). T ig h t en

n u t s t o 2 7 Nm (20 ft. lbs.) torque.

5.2L E ngine: Insta ll the fan/viscous fan drive as-

sembly to the water pump.

(19) Rotate the fan blades (by hand) and check for

interference at fan shroud.

Be sure of at least 25 mm (1.0 inches) between t ips

of fan blades and fan shroud.

(20) Fill cooling system. Refer to Refilling Cooling

System in this group.

(21) Connect battery cable at battery.

(22) Start and warm engine. Check for leaks.

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

tor, intake manifold and heater core.

The lower radiator hose is spring-reinforced to pre-

vent collapse from water pump suction at moderate

and high engine speeds.

WARNING: CONSTANT TENSION HOSE CLAMPSARE USED ON ALL COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING THIS TYPE OFCLAMP, ONLY USE TOOLS DESIGNED FOR SERVIC-

ING THIS TYPE OF CLAMP SUCH AS MILLERCLAMP TOOL 6094 (FIG. 45)

I n sp ect t h e h os es a t r e gu la r in t e r va ls . R ep la ce

hoses that are cracked, feel brittle when squeezed, or

swell excessively when the system is pressurized.

Be sure that the hoses are positioned with sufficient

clearance from the exhaust system, fan blades, drive

b elt s a n d s wa y b a r s. T h is s h ou ld b e d on e in a r e a s

w h e r e s p eci fi c r o u t in g cl a m ps a r e n ot p r ov id ed . I f



28/40

i m pr op e r ly p os it i on e d , t h e h os e s w il l b e d a m a g ed ,

resulting in coolant loss and overheating.

When performing a hose inspection, inspect the ra-

diator lower hose for proper position and condition ofthe internal spring.

COOLING SYSTEM FAN

VISCOUS FAN DRIVE OPERATION

Al l m o de ls a r e e qu i pp e d w i t h a t e m p er a t u r e con -

t r oll ed fa n . T h e t h e r ma l Vis cou s F a n D r iv e is a

torque-and-temperat ure sensitive clutch unit . I t auto-

matically increases or decreases fan speed to provide

proper engine cooling.

The therma l Viscous Fan Drive is a si licone-fluid-

filled coupling. It connects the fan assembly to t he

fan/water pump pulley (Figs. 46 or 47). The coupling

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

is done at low engine speeds while l imiting the top

s p ee d of f a n t o a p r e de t er m i n ed m a x im u m l ev el a t

higher engine speeds. A bimetallic spring coil is lo-

cated on the front face. This spring coil reacts to the

temperature of radiator discharge air. I t engages the

viscous fan drive for higher fan speed if air tempera-

ture from radiator rises above a certain point. Until

additional engine cooling is necessary, the fan will

remain at a reduced rpm regardless of engine speed.

Only when sufficient heat is present, will the vis-

cou s fa n d r iv e c lu t c h e n ga g e. T h is i s w h e n t h e a i r

flowing through the radiator core causes a reaction

from the bimetallic coil. It then increases fan speed to

provide the necessary a dditiona l en gine cooling.

Once the engine has cooled, the radiator discharge

temperatur e will drop. The bimetallic coil again re-

a ct s a n d t h e fa n s pe ed is r e du ce d t o t h e p r eviou s

disengaged speed.

CAUTION: 4.0L 6 cylinder engines equipped with

serpentine accessory drive belts have reverse rotat-ing fans and viscous fan drives. They are marked

with the word REVERSE to designate their usage.

Installation of the wrong fan or fan drive can result

in engine overheating.

Inspect fan assembly for cracks, bends, loose rivets

or broken welds. Replace fan if any damage is found.

CAUTION: If the fan blade assembly is replaced

because of mechanical damage, the water pump and

viscous fan drive should also be inspected. These

components could have been damaged due to ex-

cessive vibration.


Fig. 46 Viscous Fan Drive4.0L EngineTypical

Fig. 47 Viscous Fan Drive5.2L EngineTypical



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VISCOUS FAN DRIVE TEST

The cooling system must be in good condition. This

is checked prior to performing the following t est . I t

also will ensure against excessively high coolant tem-

p e r a t u r e .

CAUTION: Be sure that there is adequate fan blade

clearance before drilling.

(1) Drill a 3.18-mm (1/8-in) diameter hole in th e top

center of the fan shroud.

(2) Obtain a dial thermometer with an 8 inch stem

(or e qu i va l en t ). I t s h ou l d h a v e a r a n g e of -1 8-t o-

105C (0-to-220 F). Insert thermometer through the

h ole in t h e s h r ou d . B e s u r e t h a t t h e r e i s a d e qu a t e

clearance from the fan blades.

(3 ) C on n e ct a t a ch om e t er a n d a n e n gi n e i gn i t ion

t i m in g l ig h t (t i m in g l ig h t i s t o b e u s e d a s a s t r ob e

light).

(4) Block the air f low through the radiator. Secure

a s h ee t of p la s t ic in fr on t of t h e r a d ia t or (or a ir

conditioner condenser). Use tape at the top to secure

the plastic and ensure t hat the air f low is blocked.

(5) Be sure t hat the air conditioner is turn ed off.

WARNING: USE EXTREME CAUTION WHEN THE EN-

GINE IS OPERATING. DO NOT STAND IN A DIRECT

LINE WITH THE FAN. DO NOT PUT YOUR HANDS

NEAR THE PULLEYS, BELTS OR FAN. DO NOT

WEAR LOOSE CLOTHING.

( 6 ) S t a r t t h e e n g i n e a n d o p e r a t e a t 2 4 0 0 r p m w i t h

the timing light (strobe light) aimed at the fan blades.Within ten minutes the air temperature (indicated on

the dial thermometer) should be 88 C (190 F). Satis-

fa ct or y op e r a t ion of t h e fa n d r iv e r e q u i r es t h a t i t

e n ga g e b efor e or a t 8 8 C (1 90 F ) . E n g a g em e n t i s

distinguishable by a definite increase in flow noise.

The t iming l ight also will indicate an increase in the

speed of the fan.

(7) When the air temperature reaches 88 C (190

F), remove the plastic sheet. Satisfactory operation of

the viscous fan drive requires the air temperature to

d r op 2 0 F (11 C ) or m or e . A d e fi n it e d ecr e a s e of

au dible-fan-air-flow-noise s hould be n oticed. Repla ce

defective fan assemblies.

VISCOUS FAN DRIVE REPLACEMENT

4.0L 6 CYLINDER ENGINE

REMOVAL

(1) Remove the four fan hub-to-water pump pulley

m ou n t i n g n u t s (F i g. 4 8). C a r e fu l ly r e m ov e t h e fa n

assembly from the water pump pulley and position to

center of fan shroud. Fan belt removal is not neces-

s a r y a s t h e w a t e r p u m p s t u d s w i ll h o ld t h e p u m p

Documents

4790434 93ZJ Secc 7 Cooling System