07 cooling system

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COOLING SYSTEM

TABLE OF CONTENTS

page page

DESCRIPTION AND OPERATIONCOOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . 2

COOLANT RESERVE/OVERFLOW SYSTEM . . . . . 2

THERMOSTAT5.2L/5.9L ENGINES . . . . . . . . . . 3

THERMOSTAT4.7L ENGINE . . . . . . . . . . . . . . . 4

RADIATOR P RESSURE CAP . . . . . . . . . . . . . . . . . 4

RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

WATER PUMP BYPASS4.7L. . . . . . . . . . . . . . . 6

WATER PUMP BYPASS HOSE5.2L/5.9L

ENGINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7AUTOMATIC TRANSMISSION OIL COOLERS. . . . 7

AUTOMATIC BELT TENSIONER . . . . . . . . . . . . . . 7

BLOCK HEATER . . . . . . . . . . . . . . . . . . . . . . . . . . 8

HOSE CLAMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . . . 9

DIAGNOSIS AND TESTINGON-BOARD DIAGNOSTICS (OBD) . . . . . . . . . . . 10

DRB SCAN TOOL . . . . . . . . . . . . . . . . . . . . . . . . 10

PRELIMINARY CHECKS . . . . . . . . . . . . . . . . . . . 10

ELECTRIC COOLING FAN . . . . . . . . . . . . . . . . . . 15

RADIATOR COOLANT FLOW CHECK . . . . . . . . . 16COOLING SYSTEMTESTING FOR LEAKS. . . . 16

VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . . 18

ACCESSORY DRIVE BELT DIAGNOSIS. . . . . . . . 19

THERMOSTATGAS ENGINES . . . . . . . . . . . . . 21

RADIATOR CAP-TO-FILLER NECK

SEALPRESSURE RELIEF CHECK. . . . . . . . . 21

RADIATOR CAP PRESSURE TESTING. . . . . . . 21

COOLANT LOW LEVEL AERATION . . . . . . . . . 22

COOLING SYSTEMDEAERATION . . . . . . . . . . 22

SERVICE PROCEDURES

COOLANT ROUTINE LEVEL CHECK. . . . . . . . . 22

COOLANT SERVICE . . . . . . . . . . . . . . . . . . . . . . 22

COOLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

COOLANT SELECTION AND ADDITIVES . . . . . . 23

COOLANTADDING ADDITIONAL. . . . . . . . . . . 23

COOLANT LEVEL CHECK . . . . . . . . . . . . . . . . . . 23

COOLING SYSTEMDRAINING AND

FILLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

COOLING SYSTEM CLEANING/REVERSE

FLUSHING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

REMOVAL AND INSTALLATIONCOOLANT RESERVE/OVERFLOW TANK . . . . . . . 25

WATER PUMP5.2L/5.9L ENGINES . . . . . . . . . 25

WATER PUMP 4.7L ENGINES . . . . . . . . . . . . . . 27

WATER PUMP BYPASS HOSE5.2L/5.9LENGINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

THERMOSTAT5.2L/5.9L ENGINE . . . . . . . . . . 32

THERMOSTAT 4.7L ENGINE. . . . . . . . . . . . . . 34

RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

BLOCK HEATER . . . . . . . . . . . . . . . . . . . . . . . . . 37

ACCESSORY DRIVE BELT5.2L/5.9L

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

ACCESSORY BELT REPLACEMENT4.7L

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

AUTOMATIC BELT TENSIONER 5.2L/5.9L

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39AUTOMATIC BELT TENSIONER 4.7L

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

RADIATOR DRAINCOCK . . . . . . . . . . . . . . . . . . . 40

VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . . 41

CLEANING AND INSPECTIONRADIATOR CAP . . . . . . . . . . . . . . . . . . . . . . . . . 42

RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . 43

FAN BLADE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

SPECIFICATIONSCOOLING SYSTEM CAPACITIES. . . . . . . . . . . . . 43

COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . 44

SPECIAL TOOLSCOOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

DN COOLING SYSTEM 7 - 1


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DESCRIPTION AND OPERATION

COOLING SYSTEM

DESCRIPTIONThe cooling system consists of:

Ra d ia t o r C ooling fan (mechan ical/Electrica l)

Thermal viscous fan drive

F a n sh r o u d

Ra d ia t o r p r e ssu r e ca p

Thermostat

Co ola n t r e se r ve /over f low sy st e m (in t e gr a l t o

upper fan shroud)

Tr a n sm ission oi l cooler (i f e q u ip pe d w it h a n

a u t o m a t ic t r a n sm ission )

Coolant

Wa ter pump

H ose s a n d h ose cla m p s

OPERATIONThe cooling system regulates engine operating tem-

p e r a t u r e . I t a l lo w s t h e e n g in e t o r e a ch n o r m a l o p e r -

a t i ng t em per a t u re a s q u ick ly a s pos si bl e. I t a l so

m a i n t a i n s n or m a l op er a t i n g t e m pe ra t u r e a n d p re-

vents overheating.

The cooling syst em a lso provides a means of heat-

ing the passenger compartment and cooling the auto-

ma tic tra nsmission fluid (if equipped). The cooling

s y st e m i s p re ss u ri ze d a n d u s es a ce nt r i fu g a l w a t e rpump to circulate coolant throughout the system.

An op t ion a l f a ct or y in st a l led m a x im u m d u t y cool-

in g p a ck a g e is a va i la ble o n m ost m od e ls. Th is p a ck-

a g e w i ll pr ov id e a d d it i on a l cool in g ca p a ci t y f or

v eh i cl es u s ed u n d er ex t r em e con d it i on s s u ch a s

t r a i le r t o w in g in h ig h a m bien t t e m pe r a t u r e s.

COOLANT RESERVE/OVERFLOW SYSTEM

DESCRIPTIONThe coolan t reserve/overflow t a nk is integra l t o the

u p p e r f a n sh r o u d a sse m bly a n d is m a d e o f h ig h t e m -

perature plastic.

Fig. 1 Engine Cooling System Flow5.2L/5.9L EnginesTypical1 HEATER

2 BYPASS*

3 CROSSFLOW RADIATOR

7 - 2 COOLING SYSTEM DN


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T h e sa m e t h e r m o st a t is u se d f o r w in t e r a n d su m -

mer seasons. An engine should not be operated with-

ou t a t h er m os t a t , e xce pt f or s er v ici n g or t e st i n g.

Operating without a thermostat causes longer engine

w a r m u p t i me, u n rel ia b le w a r m u p per for m a n ce,increased exha ust emissions and crankcase condensa-

t io n t h a t ca n r e su lt in slu d g e f o r m a t io n .

OPERATIONTh e w a x p elle t is loca t e d in a se a led con t a in e r a t

t h e sp r in g e n d o f t h e t h e r m o st a t . W h e n h e a t e d , t h e

p elle t e xp a n d s, over com in g closin g sp r in g t e n sion

a n d w a t e r p u m p p r e ssu r e t o f o r ce t h e va lve t o o p e n .

THERMOSTAT 4.7L ENGINE

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

A p e llet -t y p e t h e r m ost a t con t r o ls t h e op er a t in g

temperature of the engine by controlling the amount

of cool a n t f low t o t h e r a d i a t or. O n a l l e ng in es t h e

thermostat is closed below 195F (90 C). Above t his

t e m p e r a t u r e , co o la n t is a l lo w e d t o f lo w t o t h e r a d ia -

tor. This provides quick engine warm up and overall

temperature control. On the 4.7L engine the thermo-

s t a t i s d es ig ned t o b lock t h e f low of t h e cool a n t

bypass journa l by 50% instead of completely blocking

t h e f low . Th is d e sig n con t r o ls coola n t t e m pe r a t u r e

more accurately (Fig. 5).T h e sa m e t h e r m o st a t is u se d f o r w in t e r a n d su m -

mer seasons. An engine should not be operated with-

ou t a t h e rm os t a t , ex cep t f or s er v ici n g or t e st i n g.

O pe r a t in g w it h ou t a t h e r m ost a t ca u ses ot h e r p r o b-

lems. These are: longer engine warmup t ime, unreli-

a b le w a r m up per for ma n ce, in cr ea s ed exh a us t

emissions and crankcase condensation. This conden-

sa t io n ca n r e su lt in slu dg e f or m a t ion .

OPERATIONTh e w a x p elle t is loca t e d in a sea le d con t a in er a t

t h e sp r in g e n d o f t h e t h e r m o st a t . W h e n h e a t e d , t h e

p ellet e xp a n d s, ove rcom in g closin g sp r in g t e n siona n d w a t e r p u m p p r e ssu r e t o f o r ce t h e va lve t o o p e n .

RADIATOR PRESSURE CAP

DESCRIPTIONAl l r a d i a t or s a r e eq u ip ped w i t h a p re ss u r e c a p .

Th i s ca p r el ea s e s p res s ur e a t s om e p oi n t w i t h in a

ra nge of 124-to-145 kP a (18-to-21 psi). The pressu re

relief point (in pounds) is engraved on top of the cap

Th e cool in g s y st em w i ll oper a t e a t pr es su r es

slightly a bove a tmospheric pressure. This r esults in a

Fig. 3 Upper Fan Shroud with Integral Coolant

Reserve/Overflow System1 RADIATOR

2 WASHER FLUID RESERVOIR

3 COOLANT OVERFLOW/RESERVOIR

4 FAN SHROUD (UPPER)

5 SCREW

6 INTERLOCKING PINS

7 FAN SHROUD (LOWER)

Fig. 4 ThermostatTypical1 THERMOSTAT HOUSING

2 GASKET

3 INTAKE MANIFOLD

4 THERMOSTAT

5 MACHINED GROOVE


DESCRIPTION AND OPERATION (Continued)


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higher coolant boiling point allowing increased r adi-

a t o r cool in g ca p a ci t y. Th e ca p con t a i n s a s pr i ng -

loaded pressure relief valve. This valve opens when

system pressure reaches the release range of 124-to-

145 kP a (18-to-21 ps i).

A rubber gasket seals the radiator filler neck. This

is done to m aint ain vacuum during coolant cool-down

a n d t o p r e ve n t le a k a g e w h e n sy st e m is u n d e r p r e s-

sure.

OPERATIONA v en t v a l ve i n t h e c en t er of t h e ca p w i l l r e m a inshut as long as the cooling system is pressurized. As

t h e coola n t cools , i t con t r a ct s a n d cre a t e s a va cu u m

in co o lin g sy st e m . T h is ca u se s t h e va cu u m va lve t o

op en a n d cool a n t i n r es er v e/ov er f low t a n k t o b e

d r a w n t h r o u g h co n n e ct in g h o se in t o r a d ia t o r . I f t h e

v a cu um v a lv e i s s t uck s h ut , or ov er fl ow h os e i s

kinked, ra diat or h oses will collapse on cool-down.

RADIATOR

DESCRIPTIONThe radiator is a aluminum cross-flow design with

h or iz on t a l t u bes t h r o ug h t h e r a d ia t o r cor e a n d ver t i-

ca l p la st ic s id e t a n k s.

OPERATIONThe radiator supplies sufficient heat transfer using

t h e coolin g f in s in t e r la ced bet w e e n t h e h or iz on t a l

t u b es i n t h e r a d a i t or cor e t o c ool t h e e ng in e a n dautomatic transmission oil (if equipped).

WATER PUMP

DESCRIPTIONTh e w a t e r p um p i s l oca t e d on t h e e ng in e f r on t

cover, a n d h a s a n in t eg r a l p u lley a t t a ch e d (F ig . 8).

Th e w a t e r p u m p im p elle r is p r essed on t o t h e r e a r

o f a s h a f t t h a t r o t a t e s i n a b e a r i n g p r e s s e d i n t o t h e

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

t i la t i on . Th e w a t er p um p s ea l s a r e l ub r ica t e d b y

Fig. 5 Thermostat Cross Section View 4.7L1 FROM HEATER

2 FROM RADIATOR

3 TO WATER PUMP

4 ENGINE BYPASS

5 THERMOSTAT

Fig. 6 Radiator Pressure CapTypical1 FILLER NECK SEAL

2 VACUUM VENT VALVE

3 PRESSURE RATING

4 PRESSURE VALVE




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antifreeze in the coolant mixture. Additional lubrica-

tion is not necessary.

OPERATIONA cen t r if ug a l w a t e r p um p ci rcu la t e s cool a n t

t h r o ug h t h e w a t e r ja cke t s, p a ssa g e s, in t a k e m a n if old ,

radiator core, cooling system hoses and heater core,

t h i s c ool a n t a b s or b s t h e h ea t g en er a t e d w h e n t h e

engine is running. The pump is driven by the engine

cr a n k sh a f t via a d r ive be lt .

WATER PUM P BYPASS 4. 7L

DESCRIPTIONTh e 4.7L e n g in e u ses a n in t e rn a l w a t e r /coola n t

by pa ss sy st em . Th e d e sig n u se s g a l ler ies in t h e t im -

in g ch a in cover t o cir cu la t e coola n t d u r in g e n g in e

w a r m -u p pr ev en t in g t h e coola n t f rom f low in gt h r ou g h t h e r a d i a t or. Th e t h er m os t a t u s es a s t u b

sh a f t lo ca t e d a t t h e r e a r o f t h e t h e r m o st a t (F ig . 9) t o

control f low through the bypass gallery.

OPERATIONW h e n t h e t h e r m o st a t is in t h e clo se d p o sit io n t h e

bypass gallery is not obstructed allowing 100% flow.

When the thermostat is in the open posit ion the stub

s h a f t en t e rs t h e b y pa s s g a l le ry ob s t ru ct i n g b y pa s s

coolan t f low by 50%. This design allows the coolan t

t o r e a ch op er a t in g t e m pe r a t u r e q u ick ly w h e n cold ,

w h ile a d d in g e x t r a coolin g d u r in g n o r m a l t e m pe r a -

ture operation.

Fig. 7 RadiatorTypical1 RADIATOR

2 A/C CONDENSER (IF EQUIPPED)

3 TRANSMISSION AUXILIARY OIL COOLER

Fig. 8 Water Pump LocationTypical1 WATER PUMP BYPASS HOSE

2 FAN BLADE ASSEMBLY

3 VISCOUS FAN DRIVE

4 WATER PUMP AND PULLEY

Fig. 9 Water/Coolant Bypass Flow and Thermostat4.7L Engine

1 FROM HEATER

2 FROM RADIATOR

3 TO WATER PUMP

4 ENGINE BYPASS

5 THERMOSTAT




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WATER PUMP BYPASS HOSE 5.2L/5.9LENGINES

DESCRIPTIONA rubber water pump bypass hose (Fig. 10) is used

be t w e e n t h e in t a k e m a n if o ld a n d w a t e r p u m p o n a l l

5.2L/5.9L en gin es.

OPERATION

Wh e n t h e t h e r m ost a t is in t h e close d p osit ion t h eb y pa s s h os e a l low s t h e w a t e r p um p t o c ir cu la t e t h e

e n gin e coola n t t h r o ug h t h e cy lin d er block w h ile a t

t h e sa m e t im e p r e ve n t in g t h e coola n t f r om f low in g

t h r o u g h t h e r a d ia t o r , t h is a l lo w s t h e co o la n t t o h e a t

u p q u ick e r t h u s br in g t h e e n g in e t o o p e r a t in g t e m -

perature faster.

AUTOMATIC TRANSMISSION OIL COOLERS

DESCRIPTION

CAUTION: On in-radiator type oil coolers, if trans-

mission oil cooler is leaking, engine coolant mayenter cooler, or transmission oil may enter engine

cooling system. Both engine cooling system andtransmission oil circuit should be drained, flushed,and inspected.

Th er e a r e t w o t y pe s of t r a n s m i ss ion oi l cool er s

used. One type of cooler is the in-radiator type or oil

to coolant type. This type oil cooler is not serviceable.

Th e se con d t y p e u se d is a r e m ot e t y p e a u x il ia r y oi l

cooler or oil to air cooler. The oil to air type cooler is

located in front of the radiator, and is serviceable.

AUTOMATIC BELT TENSIONER

DESCRIPTIONC or r ect d r iv e b el t t e ns ion i s r eq u ir ed t o en s u re

optimum performance of the belt driven engine acces-sor ies. I f sp ecif ied t e n sion is n ot m a in t a in ed , belt

s li ppa g e m a y ca u s e; en g in e ov er h ea t i ng , l a ck of

power steering assist , loss of air conditioning capac-

i t y, r ed uced g en er a t or ou t pu t r a t e, a n d g rea t l y

reduced belt life.

I t i s n o t n ece ss a r y t o a d ju s t b el t t e ns ion on t h e

4. 7L , 5. 2L or 5. 9L en gi nes . Th es e en g in es a r e

e q u ip p e d w it h a n a u t o m a t ic be lt t e n sio n e r (F ig . 13)

(Fig. 14). The tensioner ma inta ins correct belt ten-

sion at all t imes. Due to use of this belt tensioner, do

Fig. 10 Water Pump Bypass Hose5.2L/5.9LEngines

1 WATER PUMP BYPASS HOSE


3 VISCOUS FAN DRIVE


Fig. 11 Oil Flow to CoolerTop View (Typical)1 TRANSMISSION OIL COOLER

2 AUTOMATIC TRANSMISSION

3 RETURN LINE

4 PRESSURE LINE

Fig. 12 Auxiliary Transmission Oil CoolerTypical1 RADIATOR

2 A/C CONDENSER (IF EQUIPPED)

3 TRANSMISSION AUXILIARY OIL COOLER




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not at tempt to use a belt tension gauge on 4.7L, 5.2L

or 5.9L engines.

OPERATIONTh e a u t om a t ic be lt t e n sion e r m a in t a in s belt t e n -

s ion b y u s in g i n t er n a l s pr i ng p re ss u re , a p iv ot i n g

a r m a n d p u lle y t o p r e ss a g a in st t h e d r ive be lt .

BLOCK HEATER

DESCRIPTION

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

THE POWER CORD MUST BE SECURED IN ITSRETAINING CLIPS AND ROUTED AWAY FROMEXHAUST MANIFOLDS AND MOVING PARTS.

An optional engine block heater is available for all

m od e ls. Th e h e a t e r is e q u ip pe d w it h a p ow e r cor d .

The cord is at tached to an engine compartment com-

p on e n t w it h t ie -st r a p s. Th e h e a t e r is m ou n t e d in a

cor e h ole o f t h e e n g in e cyl in de r block in p la ce of a

f r ee ze p lu g w i t h t h e h ea t i n g e le me nt i m m er s ed i n

engine coolant.

OPERATION

Th e h ea t e r w a r m s t h e e ng in e p rov id in g e a s ie re n g in e st a r t in g a n d f a st e r w a r m - u p in lo w t e m p e r a -

t u r es . Th e pow e r cor d m u st b e con n ect ed t o a

g r ou n d ed 110-120 volt AC e le ct r ica l ou t let w it h a

g r ou n d ed , t h r e e w ir e e xt e n sion cor d , t h is p r ovid es

t h e e le ct r ici t y t o w a r m t h e h e a t in g e le m e n t .

HOSE CLAMPS

DESCRIPTIONTh e coolin g sy st e m u t i liz es bot h w o r m d r ive a n d

s pr in g t y pe h os e cl a m ps . I f a s pr in g t y pe cl a m p

r e pla cem e n t is n e ce ssa r y, r e pla ce w it h t h e or ig in a l

Mopar equipment spring type clamp.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps. If replacementis necessary, use only a original equipment clampwith matching number or letter (Fig. 16).

OPERATIONThe worm type hose clamp uses a specified torque

va lu e t o m a in t a in p r op er t e n sion on a h ose con n e c-

tion.

Fig. 13 Automatic Belt Tensioner5.2L/5.9L Engines1 AUTOMATIC TENSIONER

2 COIL AND BRACKET

3 SCREW AND WASHER

Fig. 14 Automatic Belt Tensioner4.7L Engine1 AUTOMATIC TENSIONER ASSEMBLY

Fig. 15 Block Heater4.7L1 ENGINE BLOCK HEATER




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Th e sp rin g t y p e h o se cla m p a p p lies con st a n t t e n -

sion on a hose connection. To remove a spring t ype

h ose cla m p , on ly u se con st a n t t e n sion cla m p p lier s

designed to compress the hose clamp.

VISCOUS FAN DRIVE

DESCRIPTION

CAUTION: Engines equipped with accessory drivebelts have reverse rotating fans and viscous fandrives. They are marked with the word REVERSE to

designate their usage. Installation of the wrong fanor viscous fan drive can result in engine overheat-ing.

Th e t h e r m a l viscou s f a n d r ive is a s i licon e -f luid -

f i l le d co u p lin g u se d t o co n n e ct t h e f a n bla d e s t o t h e

w a t e r p u m p sh a f t . T h e co u p lin g a l lo w s t h e f a n t o be

d r iv en i n a n or m a l m a n n er. Th is i s d on e a t l ow

engine speeds while limiting the top speed of the fan

t o a p r e d e t e r m in e d m a x im u m le ve l a t h ig h e r e n g in e

speeds.

On all 4.7L an electrical cooling fan located in the

fan shroud aids in low speed cooling, I t is designed to

a u g men t t h e v is cou s f a n , H ow e ver, i t d oes n ot

replace the viscous fan.

A thermostatic bimetallic spring coil is located on

t h e f r on t f a ce of t h e v is cou s f a n d r iv e u n it . Th i s

sp r in g co il r e a ct s t o t h e t e m p e r a t u r e o f t h e r a d ia t o r

d i sch a r g e a i r. I t e ng a g es t h e v is cou s f a n d r iv e f or

h ig h er f a n s peed i f t h e a i r t em per a t u re f rom t h e

r a d ia t o r r ise s a bo ve a ce r t a in p o in t . U n t i l a d d it io n a l

e n g in e co o lin g is n e ce ssa r y , t h e f a n w il l r e m a in a t a

reduced rpm regardless of engine speed.

OPERATIONWh e n su f ficien t h e a t is p r ese n t , t h e viscou s f a n

d r iv e w i ll en ga g e. Th is i s w h en t h e a i r f low i ngt h r ou g h t h e r a d ia t o r cor e c a u s es a r ea c t ion t o t h e

bimetallic coil. I t then increases fan speed to provide

the necessary addit ional engine cooling.

Once the engine has cooled, the radiator discharge

t e m pe ra t u r e w i l l d r op . Th e b im e t a ll ic coi l a g a i n

r e a ct s a n d t h e f a n sp e e d is r e d u ce d t o t h e p r e vio u s

disengaged speed.

Fig. 16 Spring Clamp Size Location

1 SPRING CLAMP SIZE LOCATION

Fig. 17 Fan Blade/Viscous Fan Drive4.7L/5.2L/5.9LEngines

1 VISCOUS FAN DRIVE

2 FAN BLADE

3 SCREW AND WASHER

Fig. 18 Viscous Fan Drive4.7L/5.2L/5.9L Engines

Typical1 VISCOUS FAN DRIVE

2 THERMOSTATIC SPRING

3 MOUNTING NUT TO WATER PUMP HUB




10/44

DIAGNOSIS AND TESTING

ON-BOARD DIAGNOSTICS (OBD)

COOLING SYSTEM RELATED DIAGNOSTICSTh e p ow e r t r a in con t r o l m od u le (PCM) h a s bee n

programmed to monitor certain cooling system com-ponents:

I f t h e e ng in e h a s r em a i n ed cool f or t oo l on g a

period, such as with a stuck open thermostat , a Diag-

nostic Trouble C ode (DTC) ca n be set .

I f an open or shorted condition has developed in

the relay circuit controlling the electric radiator fan,

a Dia gnostic Trouble C ode (DTC) can be set .

I f t h e p rob le m i s s en s ed i n a m on i t or ed ci r cu it

of t e n e n ou g h t o in d ica t e d a n a ct u a l p r oblem , a D TC

is st o r e d . T h e D T C w il l be st o r e d in t h e PCM m e m -

or y f or e ve nt u a l d is pl a y t o t h e s er v ice t e ch n ici a n .

Refer to Group 25, Emission Control Systems for the

correct procedures .

ACCESSING DIAGNOSTIC TROUBLE CODESTo r e a d D TCs a n d t o o bt a in coolin g sy st e m d a t a ,

r e fe r t o G r ou p 25, Em ission Co n t r ol Sy st e m s f or t h e

correct procedures .

ERASING TROUBLE CODESAfter the problem has been repaired, use the DRB

s ca n t ool t o e r a s e a D TC . R ef er t o t h e a p pr op ri a t e

Powertrain Diagnostic Procedures service manual for

op er a t io n o f t h e D RB sca n t o ol .

DRB SCAN TOOLF or op er a t i on of t h e D R B s ca n t ool , r e f er t o t h e

a p p r op r ia t e P ow e r t r a in D ia g n o st ic P r oced u r es se r-

vice m a n u a l .

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATINGEst a blish w h a t d r ivin g con d it ion s ca u sed t h e com -

plaint . Abnormal loads on the cooling system such as

t h e f o l lo w in g m a y be t h e ca u se :

P R OL ON G E D I D LE , VE RY H I G H AM B IE NT

TEMP ERATU RE , SL I G HT TAI L WI N D AT I D L E,

S L O W TR AF F I C , TR AF F I C J AM S , H I G H S P E E D ,

O R S T E E P G R A D E S .

D r ivin g t e ch n iq u es t h a t a vo id ove rh e a t in g a r e :

I d le w it h A/C of f w h e n t e m p er a t u r e g a u g e is a t

e n d o f n o r m a l r a n g e . Increase engine speed for more air flow is recom-

mended.

(1) TRAILER TOWING:

Consult Trailer Towing section of own ers ma nua l.

Do not exceed limits.

(2) AI R CO N D I TI O N I N G; AD D -O N O R AF TER

MARKET:

A m a x im u m cool in g p a ck a g e s h ou ld h a v e b ee n

ordered w ith vehicle if add-on or a fter ma rket A/C is

in st a l led . I f n ot , m a x im u m coolin g sy st e m com p o-

n en t s s h ou ld b e i n st a l l ed f or m od el i n vol ved p er

ma nufacturers specificat ions.

(3) RECE N T SERV I CE O R ACCI D EN T REPAI R:D et er m in e i f a n y r ecen t s er vi ce h a s b een per -

f or m e d on ve hicle t h a t m a y e ff ect coolin g sy st e m .

This may be:

Engine adjustments (incorrect t iming)

Slipping engine a ccessory drive belt(s)

Brakes (possibly dragging)

Ch a n g e d p a r t s . I n co r r e ct w a t e r p u m p , o r p u m p

r ot a t in g in w r o n g d ir e ct ion d u e t o be lt n ot cor r e ct ly

routed

Reconditioned ra diat or or cooling system refill-

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

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

Th e se ch a r t s a r e t o be u sed a s a q u ick -r e fe r en ce

only. Refer to the group text for information.



11/44

COOLING SYSTEM DIAGNOSIS CHART

CONDITION POSSIBLE CAUSES CORRECTION

TEMPERATURE GAUGEREADS LOW

1. Has a Diagnostic Trouble Code(DTC) been set indicating a stuck open

thermostat?

1. Refer to Group 25, Emission Systemsfor On-Board Diagnostics and DTC

information. Replace thermostat ifnecessary.

2. Is the temperature sending unit

connected?

2. Check the temperature sensor

connector. Refer to Group 8E. Repairconnector if necessary.

3. Is the temperature gauge operating

OK?

3. Check gauge operation. Refer to

Group 8E. Repair as necessary.

4. Coolant level low in cold ambient

temperatures accompanied with poorheater performance.

4. Check coolant level in the coolant

reserve/overflow tank and the radiator.Inspect system for leaks. Repair leaksas necessary. Refer to the Coolantsection of the manual text for

WARNINGS and CAUTIONS associatedwith removing the radiator cap.

5. Improper operation of internal heater

doors or heater controls.

5. Inspect heater and repair as

necessary. Refer to Group 24, Heatingand Air Conditioning for procedures.

TEMPERATURE GAUGEREADS HIGH OR THECOOLANT WARNING

LAMP ILLUMINATES.COOLANT MAY OR MAYNOT BE LOST OR

LEAKING FROM THECOOLING SYSTEM

1. Trailer is being towed, a steep hill isbeing climbed, vehicle is operated inslow moving traffic, or engine is being

idled with very high ambient (outside)temperatures and the air conditioning ison. Higher altitudes could aggravate

these conditions.

1. This may be a temporary conditionand repair is not necessary. Turn off theair conditioning and attempt to drive the

vehicle without any of the previousconditions. Observe the temperaturegauge. The gauge should return to the

normal range. If the gauge does notreturn to the normal range, determinethe cause for overheating and repair.Refer to Possible Causes (2-20).

2. Is the temperature gauge readingcorrectly?

2. Check gauge. Refer to Group 8E.Repair as necessary.

3. Is the temperature warningilluminating unnecessarily?

3. Check warning lamp operation. Referto Group 8E. Repair as necessary.

4. Coolant low in coolant reserve/overflow tank and radiator?

4. Check for coolant leaks and repair asnecessary. Refer to Testing CoolingSystem for Leaks in this Group.

5. Pressure cap not installed tightly. If

cap is loose, boiling point of coolant willbe lowered. Also refer to the followingStep 6.

5. Tighten cap

6. Poor seals at the radiator cap. 6. (a) Check condition of cap and capseals. Refer to Radiator Cap. Replace

cap if necessary.

(b) Check condition of radiator fillerneck. If neck is bent or damaged,

replace radiator.


DIAGNOSIS AND TESTING (Continued)


12/44


7. Coolant level low in radiator but notin coolant reserve/overflow tank. This

means the radiator is not drawingcoolant from the coolant reserve/

overflow tank as the engine cools

7. (a) Check condition of radiator capand cap seals. Refer to Radiator Cap in

this Group. Replace cap if necessary.

(b) Check condition of radiator filler

neck. If neck is bent or damaged,replace radiator.

(c) Check condition of the hose from the

radiator to the coolant tank. It should fittight at both ends without any kinks ortears. Replace hose if necessary.

(d) Check coolant reserve/overflow tankand tanks hoses for blockage. Repair asnecessary.

8. Incorrect coolant concentration 8. Check coolant. Refer to Coolantsection in this Group for correctcoolant/water mixture ratio.

9. Coolant not flowing through system 9. Check for coolant flow at radiator fillerneck with some coolant removed,engine warm and thermostat open.

Coolant should be observed flowingthrough radiator. If flow is not observed,determine area of obstruction and repairas necessary.

10. Radiator or A/C condenser fins aredirty or clogged.

10. Remove insects and debris. Refer toRadiator Cleaning in this Group.

11. Radiator core is corroded orplugged.

11. Have radiator re-cored or replaced.

12. Aftermarket A/C installed withoutproper radiator.

12. Install proper radiator.

13. Fuel or ignition system problems. 13. Refer to Fuel and Ignition SystemGroups for diagnosis.

14. Dragging brakes. 14. Check and correct as necessary.Refer to Group 5, Brakes for correctprocedures.

15. Bug screen or cardboard is beingused, reducing airflow.

15. Remove bug screen or cardboard.

16. Thermostat partially or completelyshut.

16. Check thermostat operation andreplace as necessary. Refer toThermostats in this Group.

17. Viscous fan drive not operatingproperly.

17. Check fan drive operation andreplace as necessary. Refer to ViscousFan Drive in this Group.

18. Cylinder head gasket leaking. 18. Check for cylinder head gasketleaks. Refer to Cooling System-TestingFor Leaks in this Group. For repair, refer

to Group 9, Engines.

19. Heater core leaking. 19. Check heater core for leaks. Referto Group 24, Heating and Air

Conditioning. Repair as necessary.




13/44


TEMPERATURE GAUGEREADING IS

INCONSISTENT(FLUCTUATES, CYCLES

OR IS ERRATIC)

1. During cold weather operation, withthe heater blower in the high position,

the gauge reading may drop slightly.

1. A normal condition. No correction isnecessary.

2. Temperature gauge or engine

mounted gauge sensor defective orshorted. Also, corroded or loose wiringin this circuit.

2. Check operation of gauge and repair

if necessary. Refer to Group 8E,Instrument Panel and Gauges.

3. Gauge reading rises when vehicle isbrought to a stop after heavy use(engine still running)

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

4. Gauge reading high after re-starting awarmed up (hot) engine.

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

5. Coolant level low in radiator (air willbuild up in the cooling system causing

the thermostat to open late).

5. Check and correct coolant leaks.Refer to Cooling System-Testing for

leaks in this group.

6. Cylinder head gasket leaking allowingexhaust gas to enter cooling system

causing a thermostat to open late.

6. (a) Check for cylinder head gasketleaks. Refer to Cooling System-Testing

for Leaks in this group.

(b) Check for coolant in the engine oil.

Inspect for white steam emitting from theexhaust system. Repair as necessary.

7. Water pump impeller loose on shaft. 7. Check water pump and replace as

necessary. Refer to water Pumps in thisgroup.

8. Loose accessory drive belt. (waterpump slipping)

8. Refer to Accessory Drive Belts in thisgroup. Check and correct as necessary.

9. Air leak on the suction side of the

water pump allows air to build up incooling system causing thermostat toopen late.

9. Locate leak and repair as necessary.

PRESSURE CAP IS

BLOWING OFF STEAMAND/OR COOLANT TOCOOLANT TANK.TEMPERATURE GAUGEREADING MAY BE ABOVE

NORMAL BUT NOT HIGH.

COOLANT LEVEL MAY BEHIGH IN COOLANTRESERVE/OVERFLOW

TANK

1. Pressure relief valve in radiator cap

is defective.

1. Check condition of radiator cap and

cap seals. Refer to Radiator Caps in thisgroup. Replace cap as necessary.

COOLANT LOSS TO THEGROUND WITHOUTPRESSURE CAPBLOWOFF. GAUGE

READING HIGH OR HOT

1. Coolant leaks in radiator, coolingsystem hoses, water pump or engine.

1. Pressure test and repair asnecessary. Refer to Cooling System-Testing For Leaks in this group.




14/44


DETONATION ORPRE-IGNITION (NOT

CAUSED BY IGNITIONSYSTEM). GAUGE MAY

OR MAY NOT BEREADING HIGH

1. Engine overheating. 1. Check reason for overheating andrepair as necessary.

2. Freeze point of coolant not correct.

Mixture is too rich or too lean.

2. Check coolant concentration. Refer to

the Coolant section of this group andadjust ratio as required.

HOSE OR HOSES

COLLAPSE WHILEENGINE IS RUNNING

1. Vacuum created in cooling system on

engine cool-down is not being relievedthrough coolant reserve/overflowsystem.

1. (a) Radiator cap relief valve stuck.

Refer to Radiator Cap in this group.Replace if necessary

(b) Hose between coolant reserve/overflow tank and radiator is kinked.

Repair as necessary.

(c) Vent at coolant reserve/overflow tankis plugged. Clean vent and repair as

necessary.(d) Reserve/overflow tank is internally

blocked or plugged. Check for blockageand repair as necessary.

NOISY VISCOUSFAN/DRIVE

1. Fan blades loose. 1. Replace fan blade assembly. Refer toCooling System Fans in this Group

2. Fan blades striking a surroundingobject.

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

3. Air obstructions at radiator or airconditioning condenser.

3. Remove obstructions and/or cleandebris or insects from radiator or A/Ccondenser.

4. Thermal viscous fan drive hasdefective bearing.

4. Replace fan drive. Bearing is notserviceable. Refer to Viscous Fan Drivein this group.

5. A certain amount of fan noise may beevident on models equipped with athermal viscous fan drive. Some of this

noise is normal.

5. Refer to Viscous Fan Drive in thisgroup for an explanation of normal fannoise.




15/44


INADEQUATE HEATERPERFORMANCE.

THERMOSTAT FAILED INOPEN POSITION

1. Has a Diagnostic trouble Code (DTC)been set?

1. Refer to Group 25, Emissions forcorrect procedures and replace

thermostat if necessary

2. Coolant level low 2. Refer to Cooling System-Testing ForLeaks in this group.

3. Obstructions in heater hose/fittings 3. Remove heater hoses at both endsand check for obstructions

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

necessary

5. Water pump is not pumping water

to/through the heater core. When theengine is fully warmed up, both heaterhoses should be hot to the touch. If onlyone of the hoses is hot, the water pumpmay not be operating correctly or the

heater core may be plugged. Accessorydrive belt may be slipping causing poorwater pump operation.

5. Refer to Water Pump in this group. If

a slipping belt is detected, refer toAccessory Drive Belts in this group. Ifheater core obstruction is detected, referto Group 24, Heating and AirConditioning.

STEAM IS COMING FROM

THE FRONT OF VEHICLENEAR THE GRILL AREAWHEN WEATHER IS WET,ENGINE IS WARMED UPAND RUNNING, AND

VEHICLE IS STATIONARY.TEMPERATURE GAUGEIS IN NORMAL RANGE

1. During wet weather, moisture (snow,

ice or rain condensation) on the radiatorwill evaporate when the thermostatopens. This opening allows heatedwater into the radiator. When themoisture contacts the hot radiator,

steam may be emitted. This usuallyoccurs in cold weather with no fan orairflow to blow it away.

1. Occasional steam emitting from this

area is normal. No repair is necessary.

COOLANT COLOR 1. Coolant color is not necessarily anindication of adequate corrosion ortemperature protection. Do not rely oncoolant color for determining conditionof coolant.

1. Refer to Coolant in this group forcoolant concentration information. Adjustcoolant mixture as necessary.

COOLANT LEVEL

CHANGES IN COOLANTRESERVE/OVERFLOWTANK. TEMPERATUREGAUGE IS IN NORMAL

RANGE

1. Level changes are to be expected as

coolant volume fluctuates with enginetemperature. If the level in the tank wasbetween the FULL and ADD marks atnormal operating temperature, the level

should return to within that range afteroperation at elevated temperatures.

1. A normal condition. No repair is

necessary.

ELECTRIC COOLING FANTh e p ow e r t r a in con t r o l m o d u le (P CM) w ill se t a

diagnostic t rouble code (DTC) in memory if it detects

a problem in the electric cooling fan relay or circuit .

Refer t o On-B oard D iagnostics in G roup 25, Emission

Control Systems for more information on accessing a

DTC.

Th e D TC ca n a l s o b e a c ce ss ed t h r ou g h t h e D R B

sca n t o o l . Re f e r t o t h e a p p r o p r ia t e Po w e r t r a in D ia g -

nostic Procedures manual for diagnostic information

a n d o p e r a t io n o f t h e D RB sca n t o o l .

RADIATOR FAN MOTOR INOPERATIVE

Equipment Required:

DR B Sca n Tool

Volt/Ohm met er

Wir in g D ia g r a m s se ct ion of t h is m a n u a l




16/44

Test Procedure:

(1) I n sp ect 10A f u se in ju n ct ion block a n d 40A

m a x i f u se in P D C (F ig . 20).

(2) Re m o ve Co o lin g F a n Re la y f r o m t h e PD C a n dmake the following checks at the relay connector:

Apply 12 volts (using a fused 14-gauge wire) to

circuit C25 (relay terminal 87). If fan does not come

on, check for open in circuit C25 or Z1. If circuits are

o.k., replace the cooling fan motor.

With the ignition key off check for battery volt-

a g e a t c ir cu it C28 (r e la y t e r m in a l 30). I f n o ba t t e r y

volta ge present check for open/shorted circuit C28

be t w e e n t h e PD C a n d r e la y .

With the ignit ion key in the run posit ion check

for battery voltage at circuit F18 (relay terminal 86).

If no ba tt ery volta ge present, check for open/short in

circuit F18 between the junction block and the relay. I f n o pr ob lem s a r e d et ect ed , i ns t a ll t h e D R B

(r e f e r t o t h e a p p r o p r ia t e Po w e r t r a in D ia g n o st ic Pr o -

ced u r es m a n u a l f o r D RB sca n t o ol o p er a t in g in st r u c-

t io n s) a n d st a r t t h e e n g in e . Clip a 12V t e st l ig h t t o

t h e ba t t e r y p osit ive t e r m in a l a n d p r obe circuit C27

(r e la y t e r m ina l 85). Wh e n t h e e n gin e t e m pe r a t u r e

reaches 110 C (230 F), or A/C is r equested, th e test

light should light . I f not , check circuit C27 for open.

I f no problems are detected at this point , replace

the cooling fan relay.

RADIATOR COOLANT FLOW CHECKUse the following procedure t o determine if coolan t

is f lowing through cooling system.

(1) I d le e ng in e u n t il op er a t i n g t e m pe ra t u r e i s

r e a ch e d . I f u p p er r a d ia t o r h o se is w a r m t o t h e t ou ch ,

t h e r m o st a t is o p e n in g a n d co o la n t is f lo w in g t o r a d i-

ator.

WARNING: HOT, PRESSURIZED COOLANT CANCAUSE 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) D r a in a sm a ll a m o u n t o f co o la n t f r o m r a d ia t o r

u n t i l e n d s of r a d ia t or t u bes a r e visible t h r o ug h f i ller

neck. Idle engine at normal operating temperature. If

coolant is f lowing past exposed tubes, coolant is cir-

culating.

COOLING SYSTEM TESTING FOR LEAKS

ULTRAVIOLET LIGHT METHODA le a k d e t e ct io n a d d it ive is a va i la ble t h r o u g h t h e

p a r t s d ep a r t m en t t h a t ca n b e a d d e d t o c ool in g s y s-

tem. The addit ive is highly visible under ultraviolet

l igh t (bla ck l igh t ). P ou r on e ou n ce of a d d it ive in t o

coolin g sy st e m . P la ce h e a t e r con t r o l u n it in HE AT

p os it ion . S t a r t a n d oper a t e en g in e u n t il r a d ia t or

u p p e r h o se is w a r m t o t o u ch . Aim t h e co m m e r cia l ly

a v a ila b le b la ck lig ht t ool a t com pon en t s t o b e

Fig. 19 Electrical Cooling Fan1 RADIATOR

2 ELECTRIC FAN ASSEMBLY


4 SCREW

Fig. 20 Power Distribution Center (PDC)1 POWER DISTRIBUTION CENTER (PDC)




17/44

ch e ck e d . I f le a k s a r e p r e se n t , bla ck l ig h t w il l ca u se

additive to glow a bright green color.

The black light can be used in conjunction with a

p re ss u re t e st e r t o d et e rm i ne i f a n y e xt e rn a l l ea k s

exist (Fig. 21).

PRESSURE TESTER METHODThe engine should be at normal operating temper-

a t u r e. Re ch e ck t h e sy st e m cold i f ca u se of coola n t

lo ss is n o t lo ca t e d d u r in g t h e w a r m e n g in e e x a m in a -

tion.

WARNING: HOT, PRESSURIZED COOLANT CANCAUSE INJURY BY SCALDING.

Carefully remove radiator pressure cap from filler

n e ck a n d ch e ck coola n t level . P u sh d ow n on ca p t o

disengage it from stop ta bs. Wipe inside of f iller neck

a n d e xa m i n e l ow e r i n si de s ea l i ng s ea t f or n i ck s ,

cr a ck s, p a in t , d ir t a n d so ld e r r e sid u e . I n sp e ct r a d ia -

t or -t o- r es er v e/ov er f low t a n k h os e f or i n t er n a lob s t ru ct i on s . I n s er t a w i r e t h r o ug h t h e h os e t o b e

sure it is not obstructed.

I n sp ect ca m s on ou t sid e o f f i ller n e ck . I f ca m s a r e

d a m a g e d, s ea t i n g of p re ss u r e c a p v a l ve a n d t e st e r

seal will be affected.

At t a ch p r essu r e t e st er (7700 o r a n e q u iva le n t ) t o

radiator filler neck (Fig. 22).

O pe r a t e t e st er p u m p t o a p p ly 103.4 k P a (15 p si)

p r essu r e t o sy st e m . I f h ose s e n la r g e e xce ssively or

bu lg es w h ile t e st in g, r e pla ce a s n e ce ssa r y . O bse r ve

gauge pointer an d determine condition of cooling sys-tem according to following criteria :

Holds Steady: I f p oi n t er r em a i n s s t ea d y f or t w ominutes, serious coolant leaks are not present in sys-

t e m . H ow e ver, t h e r e cou ld be a n in t er n a l lea k t h a t

d oe s n o t a p pe a r w it h n or m a l sy st e m t e st p r essu r e. I f

i t is ce r t a in t h a t co o la n t is be in g lo st a n d le a k s ca n -

not be detected, inspect for interior leakage or per-

form Int ernal Leaka ge Test .

Drops Slowly: I n d ica t e s a sm a ll le a k or se ep a g eis occurring. Examine all connections for seepage or

s li gh t l ea k a g e w i t h a f la s h l ig h t . I n s pe ct r a d i a t or,

hoses, gasket edges and heater. Seal small leak holes

w it h a Se a le r L u br ica n t (or e q u iva le n t ). Re p a ir lea k

h oles a n d in spect s ys tem a g a in w it h pr es su re

applied.

Drops Quickly: I n d ica t e s t h a t se r io u s le a k a g e isoccu r r in g. Ex a m in e sy st e m f or e xt e r n a l lea k a g e. I f

lea k s a r e n ot visible , in sp ect f or in t er n a l lea k a g e .

L a r g e r a d ia t o r l ea k h ol es s h ou ld b e r e pa i r ed b y a

reputable radiator repair shop.

INTERNAL LEAKAGE INSPECTIONR em ov e en g in e oi l pa n d r a in pl ug a n d d r a in a

sm a ll a m o u n t of e n g in e o i l. I f coola n t is p r e sen t in

t h e p a n , i t w il l d r a in f ir st be ca u se i t is h e a vie r t h a noil. An alternative method is to operate engine for a

s h or t p er iod t o ch u r n t h e oi l. Af t er t h i s i s d on e,

r e m ove e n gin e d ip st ick a n d in spe ct f or w a t e r g lob-

u les. Also in sp ect t r a n sm ission d ipst ick f or w a t e r

globules and transmission fluid cooler for leakage.

Fig. 21 Leak Detection Using Black LightTypical1 TYPICAL BLACK LIGHT TOOL

Fig. 22 Pressure Testing Cooling SystemTypical1 TYPICAL COOLING SYSTEM PRESSURE TESTER




18/44

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 COMBUSTIONLEAK IS PRESENT. TO RELEASE PRESSURE,

ROCK TESTER FROM SIDE TO SIDE. WHEN

REMOVING TESTER, DO NOT TURN TESTER MORETHAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.

O pe r a t e e n gin e w it h ou t p r essu r e ca p on r a d ia t o r

u n t i l t h e r m ost a t op en s. At t a ch a P r e ssu r e Te st er t o

filler neck. If pressure builds up quickly it indicat es a

combustion leak exists. This is usually the result of a

cylinder head gasket leak or crack in engine. Repair

as necessary.

I f t h er e i s n ot a n i m m ed ia t e p re ss u r e i n cr ea s e ,

p um p t h e P r e s su r e Te st e r. D o t h i s u n t il i n di ca t e d

pressure is within system range of 110 kPa (16 psi).

Fluctuation of gauge pointer indicates compression or

combustion leakage into cooling system.B e ca u s e t h e v eh i cl e i s e q ui pp ed w i t h a ca t a l y t ic

converter, do not remove spark plug cables or shortout cylinders to isolate compression leak.

I f t h e n ee dl e o n d i a l of p re ss u r e t e s t er d oe s n ot

f lu ct u a t e , r a ce e ng in e a f ew t i m es t o ch eck f or a n

abnormal amount of coolant or steam. This would be

e m it t in g f r om e xh a u st p ip e. Co ola n t or st e a m f r om

e xh a u st p ip e m a y in d ica t e a f a u lt y cy l in d e r h e a d g a s-

ket, cracked engine cylinder block or cylinder head.

A con ven ien t che ck f or e xh a u st g a s lea k a g e in t o

cooling system is provided by a commercially ava il-

a ble B lo ck L e a k Ch e ck t o ol . F o llow m a n u f a ct u r e r s

instructions when using this product.

COMBUSTION LEAKAGE TEST WITHOUTPRESSURE TESTER

D O N O T WASTE r e u sa ble coola n t . I f solu t ion is

clean, drain coolant into a clean container for reuse.

WARNING: DO NOT REMOVE CYLINDER BLOCKDRAIN PLUGS OR LOOSEN RADIATOR DRAIN-

COCK WITH SYSTEM HOT AND UNDER PRESSURE.SERIOUS BURNS FROM COOLANT CAN OCCUR.

D r a in s uff icien t cool a nt t o a l low t h er mos t a t

removal. Refer to Thermosta t Replacement. D iscon-n e ct w a t e r p u m p d r ive be lt .

Add coolant to radiator to bring level to within 6.3

mm (1/4 in) of top of t hermosta t housing.

CAUTION: Avoid overheating. Do not operateengine for an excessive period of time. Open drain-

cock immediately after test to eliminate boil over.

St a r t e n g in e a n d a cce le r a t e r a p id ly t h r e e t im e s, t o

approximat ely 3000 rpm while observing coolant . I f

i n t er n a l e ng in e com b us t i on g a s es a r e l ea k i ng i n t o

cooling syst em, bubbles w ill appear in coolant . I f bub-

ble s d o n o t a p p e a r , in t e r n a l co m bu st io n g a s le a k a g e

is not present.

VISCOUS FAN DRIVEI f t h e f a n a sse m bly f r e e - w h e e ls w it h o u t d r a g ( t h e

f a n b la d e s w i ll r ev ol ve m or e t h a n f iv e t u r n s w h e nsp u n by h a n d ), r e p la ce t h e f a n d r ive . T h is sp in t e st

must be performed when the engine is cool.

F o r t h e f ol low in g t e st , t h e coolin g sy st e m m u st be

in g o o d co n d it io n . I t a lso w il l e n su r e a g a in st e x ce s-

sively high coolant temperature.

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

(1) Dr ill a 3.18-mm (1/8-in) dia meter hole in the

t o p cen t e r of t h e f a n sh r ou d .

(2) O bt a in a d ia l t h e r m om e t er w it h a n 8 in ch st e m

(or e q ui va l en t ). I t s h ou ld h a v e a r a n g e o f -18 t o105C (0 to 220 F). Insert thermometer through the

h ol e i n t h e s h r ou d . B e s u r e t h a t t h e re i s a d e q ua t e

cle a r a n ce f r om t h e f a n bla d es.

(3) Co n n ect a t a ch om e t er a n d a n e n gin e ig n it 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 ed a s a s t r ob e

light).

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

a sh e et of p la st ic in f r on t of t h e r a d ia t o r (or a ir con -

dit ioner condenser). Use tape at the top to secure the

p la st ic a n d be su r e t h a t t h e a ir f lo w is blo ck e d .

(5) B e sure t ha t the a ir conditioner (if equipped) is

turned off .

WARNING: USE EXTREME CAUTION WHEN THEENGINE IS OPERATING. DO NOT STAND IN ADIRECT LINE WITH THE FAN. DO NOT PUT YOURHANDS NEAR THE PULLEYS, BELTS OR FAN. DO

NOT WEAR LOOSE CLOTHING.

(6) S t a r t t h e en gi ne a n d oper a t e a t 2400 r pm .

Within ten minutes the air temperature (indicated on

the dia l th ermometer) should be up t o 88 C (190 F).

F a n d r iv e engagement should have started to occura t b et w e en 74 t o 8 2 C (165 t o 1 80 F ). E n g a g e-

ment is dist inguishable by a definite increase in f a n

flow noise (roar ing). The t iming light also w ill indi-ca t e a n in cr e a se in t h e sp e e d o f t h e f a n .

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

F ), r e m o ve t h e p la st ic sh e e t . F a n d r ive disengage-ment sh ou ld h a ve st a r t e d t o o ccu r a t bet w e e n 57 t o79 C (135 t o 175 F ). A d e f in i t e decrease o f f a nflow noise (roaring) should be noticed. If not , replace

the defective viscous fan drive unit .




19/44

ACCESSORY DRIVE BELT DIAGNOSIS

VISUAL DIAGNOSISWhen diagnosing serpentine accessory drive belts,

small cracks that run across the ribbed surface of the

belt from rib to r ib (Fig. 23), are considered normal.

These are not a reason to replace the belt . However,cr a ck s r u n n in g a lo n g a r ib (n o t a cr o ss) a r e not nor-m a l . An y be lt w it h cr a ck s r u n n in g a lo n g a r ib m u st

be replaced (Fig. 23). Also replace t he belt if i t ha s

excessive wear, frayed cords or severe glazing.

Refer to the Accessory Drive Belt Diagnosis charts

for further belt diagnosis.

NOISE DIAGNOSISN oises g en e r a t e d by t h e a cce ssor y d r ive belt a r e

m os t n ot i cea b l e a t i dl e. B e f or e r ep la c in g a b el t t o

resolve a noise condition, inspect all of the accessory

drive pulleys for alignment, glazing, or excessive end

play.

ACCESSORY DRIVE BELT DIAGNOSIS CHART


RIB CHUNKING (One ormore ribs has separated

from belt body)

1. Foreign objects imbedded in pulleygrooves.

1. Remove foreign objects from pulleygrooves. Replace belt.

2. Installation damage 2. Replace belt

RIB OR BELT WEAR 1. Pulley misaligned 1. Align pulley(s)

2. Abrasive environment 2. Clean pulley(s). Replace belt ifnecessary

3. Rusted pulley(s) 3. Clean rust from pulley(s)

4. Sharp or jagged pulley groove tips 4. Replace pulley. Inspect belt.

5. Belt rubber deteriorated 5. Replace belt

BELT SLIPS 1. Belt slipping because of insufficienttension

1. Inspect/Replace tensioner ifnecessary

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

2. Replace belt and clean pulleys

3. Driven component bearing failure(seizure)

3. Replace faulty component or bearing

4. Belt glazed or hardened from heatand excessive slippage

4. Replace belt.

Fig. 23 Belt Wear Patterns1 NORMAL CRACKS BELT OK

2 NOT NORMAL CRACKS REPLACE BELT




20/44


LONGITUDAL BELTCRACKING

1. Belt has mistracked from pulleygroove

1. Replace belt

2. Pulley groove tip has worn away

rubber to tensile member

2. Replace belt

GROOVE JUMPING(Belt does not maintaincorrect position on pulley)

1. Incorrect belt tension 1. Inspect/Replace tensioner ifnecessary

2. Pulley(s) not within design tolerance 2. Replace pulley(s)

3. Foreign object(s) in grooves 3. Remove foreign objects from grooves

4. Pulley misalignment 4. Align component

5. Belt cordline is broken 5. Replace belt

BELT BROKEN(Note: Identify and correct

problem before new belt is

installed)

1. Incorrect belt tension 1. Replace Inspect/Replace tensioner ifnecessary

2. Tensile member damaged during beltinstallation 2. Replace belt

3. Severe misalignment 3. Align pulley(s)

4. Bracket, pulley, or bearing failure 4. Replace defective component andbelt

NOISE

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

1. Incorrect belt tension 1. Inspect/Replace tensioner if

necessary

2. Bearing noise 2. Locate and repair

3. Belt misalignment 3. Align belt/pulley(s)

4. Belt to pulley mismatch 4. Install correct belt

5. Driven component induced vibration 5. Locate defective driven componentand repair

TENSION SHEETINGFABRIC FAILURE(Woven fabric on outside,

circumference of belt hascracked or separated frombody of belt)

1. Tension sheeting contactingstationary object

1. Correct rubbing condition

2. Excessive heat causing woven fabric

to age

2. Replace belt

3. Tension sheeting splice has fractured 3. Replace belt

CORD EDGE FAILURE

(Tensile member exposedat edges of belt orseparated from belt body)

1. Incorrect belt tension 1. Inspect/Replace tensioner if

necessary

2. Belt contacting stationary object 2. Replace belt

3. Pulley(s) out of tolerance 3. Replace pulley

4. Insufficient adhesion between tensilemember and rubber matrix

4. Replace belt




21/44

THERMOSTAT GAS ENGINES

ON-BOARD DIAGNOSTICSAll gasoline powered models a r e e q u ip pe d w it h

On-B oard Dia gnostics for certa in cooling syst em com-

ponents. Refer to On-Board Diagnostics (OBD) in the

D ia g n o sis se ct ion of t h is g r ou p f or a d d it ion a l in f or -m a t i on . I f t h e pow e rt r a i n con t r ol m od ul e (P C M )

detects low engine coolant temperature, it will record

a D ia g n o st ic Tr ou ble Co d e (D TC) in t h e P CM m e m -

o r y . D o n o t c h a n g e a t h e r m o s t a t f o r l a c k o f h e a t a s

in d ica t e d by t h e in st r u m e n t p a n e l g a u g e o r by p o o r

heater performance unless a DTC is present. Refer to

the Diagnosis section of this group for other probable

ca u ses. F or ot h e r D TC n u m ber s, r e fe r t o O n -B oa r d

D i a gn os t ics i n t h e G e n er a l D i a gn os is s ect i on of

Group 25, Emission Systems.

Th e D TC ca n a l s o b e a c ce ss ed t h r ou g h t h e D R B

sca n t o o l . Re f e r t o t h e a p p r o p r ia t e Po w e r t r a in D ia g -

nostic Procedures manual for diagnostic informationa n d o p e r a t io n o f t h e D RB sca n t o o l .

RADIATOR CAP-TO-FILLER NECK SEALPRESSURE RELIEF CHECK

Th e p re ss u re ca p u pp er g a s k et (s ea l ) p re ss u r e

relief can be tested by removing overflow h ose from

r a d ia t or f i ller n e ck n ipp le . At t a ch h ose of p r essu r e

t e st er t o ol 7700 (or e q u iva le n t ) t o n ipp le . I t w il l be

n eces s a r y t o d is con n ect h os e f r om i t s a d a p t e r f or

filler neck. Pump air into radiator. The pressure cap

upper gasket should relieve at 69-124 kPa (10-18 psi)

a n d h o ld p r e ssu r e a t a m in im u m o f 55 k Pa (8 p si) .

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.

D o n o t r e m o ve r a d ia t o r ca p a t a n y t im e except f orthe 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 RADIATORUPPER HOSE TO CHECK IF SYSTEM IS UNDERPRESSURE. PLACE A RAG OVER CAP AND WITH-OUT PUSHING CAP DOWN, ROTATE IT COUNTER-

CLOCKWISE TO FIRST STOP. ALLOW FLUID TOESCAPE THROUGH THE COOLANT RESERVE/

OVERFLOW HOSE INTO RESERVE/OVERFLOWTANK. SQUEEZE RADIATOR UPPER HOSE TODETERMINE WHEN PRESSURE HAS BEENRELEASED. WHEN COOLANT AND STEAM STOPBEING PUSHED INTO TANK AND SYSTEM PRES-

SURE DROPS, REMOVE RADIATOR CAP COM-

PLETELY.

RADIATOR CAP PRESSURE TESTINGR em ov e c a p f r om r a d i a t or. B e s u re t h a t s ea l i ng

su r f a ce s a r e cle a n . Mo ist e n r u bber g a sk et w it h w a t e r

a n d in st a l l ca p o n p r e ssu r e t e st e r 7700 o r a n e q u iv-

alent (Fig. 24).

O pe r a t e t e st er p u m p t o br in g p r e ssu r e t o 117 k Pa

(17 psi) on gauge. If pressure cap fails to hold pres-

sure of a t least 110 kPa (16 psi) replace cap. R efer to

following CAUTION.Th e p re ss u r e ca p m a y t e st p rop er l y w h i le p os i-

tioned on tool 7700 (or equivalent). I t may not hold

pressure or vacuum when installed on radiator. I f so,

in spe ct r a d ia t o r f i ller n e ck a n d ca p s t o p g a sk e t f or

d a m a g e . Also in sp e ct f o r d ir t o r d ist o r t io n t h a t m a y

prevent cap from sealing properly.

Fig. 24 Pressure Testing Radiator CapTypical1 PRESSURE CAP

2 TYPICAL COOLING SYSTEM PRESSURE TESTER




22/44

CAUTION: Radiator pressure testing tools are verysensitive to small air leaks, which will not causecooling system problems. A pressure cap that doesnot have a history of coolant loss should not bereplaced 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 capneeds replacement.

COOLANT LOW LEVEL AERATIONIf the coolant level in the radiator drops below the

t o p o f t h e r a d ia t o r co r e t u be s, a ir w il l e n t e r t h e sy s-

tem.

L ow coola n t level ca n ca u se t h e t h e r m ost a t p elle t

t o be su sp e n d e d in a ir in st e a d o f co o la n t . T h is w il l

ca u s e t h e t h er m os t a t t o o pe n l a t e r, w h i ch i n t u r n

ca u ses h ig h er coola n t t e m pe r a t u r e . Air t r a p pe d in

coolin g sy st e m a lso r e du ce s t h e a m o u n t of coola n t

circulating in the heater core. This may result in lowh e a t ou t p u t .

COOLING SYSTEM DEAERATIONAs 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 pu s h a n y t r a p pe d a i r p a s t r a d ia t o r c a p i n t o t h e

coolant reserve/overflow ta nk. Here it escapes to the

a t m o sp he re i n t o t h e t a n k . Wh en t h e e ng in e cool s

d o w n t h e co o la n t , i t w il l be d r a w n f r o m t h e r e se r ve /

ov er flow t a n k in t o t h e r a dia t or t o r epl a ce a n y

removed air.

SERVICE PROCEDURES

COOLANT ROUTINE LEVEL CHECK

NOTE: Do not remove radiator cap for routine cool-ant level inspections. The coolant level can be

checked at coolant recovery bottle (Fig. 25).

The coolan t reserve/overflow system provides a

q u ick m e t h od f or d e t er m in in g coola n t level w it h o u t

removing ra diator pressure cap. With engine not run-

n in g , open t h e cool a n t r ecov er y b ot t le ca p a n dr e m ove coola n t leve l in d ica t or d ipst ick t o obser ve

coolant level in coolan t recovery bott le. The coolan t

l ev el s h ou ld b e b e t w ee n AD D a n d F U L L m a r k s . I f

t h e cool a n t l ev el i s a t or b el ow t h e AD D m a r k , f il l

th e recovery bott le wit h a 50/50 mixture of an tifreeze

an d w at er ONE QU ART AT A TIME. R epeat this pro-

ce d u r e u n t i l t h e co o la n t le ve l is a t t h e F U L L m a r k .

COOLANT SERVICEF or cool in g s ys t em f lu sh a n d f il l m a i nt en a n ce

in t e r va ls , r e f e r t o Gr o u p 0, L u br ica t io n a n d Ma in t e -

nance.

COOLANT

DESCRIPTION

ETHYLENE-GLYCOL MIXTURES

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

ene-glycol.

The required ethylene-glycol (antifreeze) and water

mixture depends upon the climate and vehicle oper-

at ing conditions. The recommend ed mixtur e of 50/50

e t h y le n e-g ly col a n d w a t e r w il l p r ovid e p r ot e ct ion

against freezing to -37 deg. C (-35 deg. F). The anti-

freeze concentration must always be a m in im u m o f44 percent, year-round in all climates. If percentageis lower than 44 percent, engine parts may beeroded by cavitation, and cooling system com-ponents may be severely damaged by corrosion.M a x im u m p rot e ct i on a g a i n s t f r ee zi n g i s p rov id ed

w it h a 68 p er ce n t a n t i f r e ez e con ce n t r a t ion , w h ich

prevents freezing down to -67.7 deg. C (-90 deg. F). A

Fig. 25 Coolant Recovery Bottle Location

1 RADIATOR2 WASHER FLUID RESERVOIR

3 COOLANT OVERFLOW/RESERVOIR

4 FAN SHROUD (UPPER)

5 SCREW

6 INTERLOCKING PINS





23/44

h ig h er p er cen t a g e w il l f r e ez e a t a w a r m e r t e m p er a -

t u r e. Al so, a h i gh er p er ce nt a g e of a n t i f re ez e ca n

ca u s e t h e en g in e t o ov er h ea t b eca u s e t h e s peci fi c

h e a t o f a n t i f r e e z e is lo w e r t h a n t h a t o f w a t e r .

Use of 100 percent ethylene-glycol w ill cause for-

mation of addit ive deposits in the system, as the cor-

rosion inhibit ive a ddit ives in ethylene-glycol requirethe presence of water to dissolve. The deposits act as

in su la t ion , ca u sin g t e m p er a t u r e s t o r ise t o a s h ig h a s

149 d e g. C (300) d eg . F ). Th is t e m pe r a t u r e is h ot

en ou gh t o m el t pl a st i c a n d s of t en s ol der. Th e

in cr e a sed t e m pe r a t u r e ca n r e su lt in e n g in e d e t on a -

tion. In addition, 100 percent ethylene-glycol freezes

at 22 deg. C (-8 deg. F ).

PROPYLENE-GLYCOL MIXTURES

I t s o ve r a l l e f f e ct ive t e m p e r a t u r e r a n g e is sm a lle r

th a n t ha t of ethy lene-glycol. The freeze point of 50/50

propylene-glycol and water is -32 deg. C (-26 deg. F).

5 deg. C higher t ha n ethylene-glycols freeze point .The boiling point (protection aga inst summer boil-

over) of propylene-glycol is 125 deg. C (257 deg. F )

a t 96.5 k P a (14 p si), com p a r e d t o 128 d e g . C (263

deg. F) for ethylene-glycol. Use of propylene-glycol

can result in boil-over or freeze-up on a cooling sys-

tem designed for ethylene-glycol. P ropylene glycol

a l s o h a s p oor er h ea t t r a n s f er ch a r a c t er i st i cs t h a n

ethylene glycol. This can increase cylinder head tem-

peratures under certain conditions.

P ropylene-glycol/ethylene-glycol Mixtures can

cause the destabilization of various corrosion inhibi-

t o r s, ca u sin g d a m a g e t o t h e va r io u s co o lin g sy st e m

components. Also, once ethylene-glycol an d propy-lene-glycol based coolan ts are mixed in the vehicle,

conventional methods of determining freeze point will

n ot be a ccur a t e . B o t h t h e r e f r a ct ive in d ex a n d sp e-

cific gravity differ between ethylene glycol a nd propy-

lene glycol.

OPERATION

ETHYLENE-GLYCOL MIXTURES

Co ola n t f low s t h r o ug h t h e e n gin e block a bsor bin g

t h e h e a t f r o m t h e e n g in e , t h e n f lo w s t o t h e r a d ia t o r

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

heat from the coolant to the atmosphere. During coldw e a t h e r t h e e t h y le n e-g ly col coola n t p r even t s w a t e r

p r ese n t in t h e coolin g sy st e m f r om f r ee z in g w it h in

temperatures indicated by mixture rat io of coolant to

w a t e r .

COOLANT SELECTION AND ADDITIVESThe presence of aluminum components in the cool-

ing system requires str ict corrosion protection. Ma in-

t a i n cool a nt a t s peci fi ed l ev el w i t h a m ix tu r e of

ethylene-glycol based antifreeze and water. Daimler-

Chrysler Corpora tion recommends Mopar Antifreeze

or e q u iva le n t . I f coola n t becom e s con t a m in a t e d or

looses color, drain an d flush cooling syst em a nd fill

with correctly mixed solution.

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

COOLANT ADDING ADDITIONALDo not remove radiator cap to add coolant to

system. Wh e n a d d in g coola n t t o m a in t a in cor r e ctlevel, do so a t coolant reserve/overflow ta nk. Use a

50/50 mixture of ethylene glycol a ntifr eeze conta ining

Aluga rd 340-2 a n d l ow m i n er a l con t en t w a t e r.

Re m o ve r a d ia t o r ca p o n ly f o r t e st in g o r w h e n r e f i l l-

ing system after service. Removing cap unnecessarily

ca n ca u se lo ss o f co o la n t a n d a l lo w a ir t o e n t e r sy s-

tem, which produces corrosion.

COOLANT LEVEL CHECKThe cooling syst em is closed a nd designed to m ain-

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.

Remove ra diat or cap. The coolant level sh ould be

to top of radiator. I f not , and if coolant level in cool-

ant recovery bott le is at ADD mark, check for:

An air leak in coolan t reserve/overflow ta nk or

i t s h ose An a ir le a k in r a d ia t o r f i l le r n e ck

L e a k in p r e ssur e ca p se a l t o r a d ia t o r f i l le r n e ck

COOLING SYSTEM DRAINING AND FILLING

WARNING: DO NOT REMOVE CYLINDER BLOCKDRAIN PLUGS OR LOOSEN RADIATOR DRAIN-COCK WITH SYSTEM HOT AND UNDER PRESSURE.

SERIOUS BURNS FROM COOLANT CAN OCCUR.

D O N O T WASTE r e u sa ble coola n t . I f solu t ion is


DRAINING

NOTE: On the 4.7L engine the thermostat is an inletside thermostat. This means that the engine coolantwill not drain when the radiator drain petcock is

opened. It will be necessary to remove the thermo-stat housing and thermostat to allow the coolanttraped in the engine block to drain.

(1) Remove radiator pressure cap.

(2) Loosen radiator petcock.


SERVICE PROCEDURES (Continued)


24/44

(3) P l a c e a d r a i n p a n u n d er t h e t h e r m os t a t h ou s -

i n g, t h en r em ov e t h e t h er m os t a t h ou s in g a n d t h e r-

mostat (4.7L only).

(4) Re m ove cyl in de r block d r a in p lu g s. Re fe r t o

(Fig. 26) (Fig. 27).

REFILLINGCle a n cooling sy st e m p r ior t o r e fi ll in g. Re fe r t o

Cooling System Cleaning section of this group.

(1) I n st a l l cyl in de r block d r a in p lu g (s) s . Co a t t h e

t h r e a d s w it h Mo p a r Thread Seala nt with Teflon.

(2) Close radiator petcock.

(3) F il l coolin g sy st e m w it h a 50/50 m ixt u r e of

w a t e r a n d M o p a r Antifr eeze/Coola nt .

(4) F il l coola n t r e ser ve/over f low t a n k t o F U L L

mark on indicator st ick.

(5) S t a r t a n d oper a t e en gi ne u nt i l t h er m os t a t

opens (upper radiator hose warm to touch).(6) I f n e ce ssa r y , a d d a 50/50 w a t e r a n d Mop a r

Antifreeze/Coolant mixture to the coolan t reserve/

overflow tank. This is done to maintain coolant level

be t w e e n t h e F U L L a n d AD D m a r k s. T h e le ve l in t h e

reserve/overflow t a nk ma y drop below the ADD ma rk

after three or four warm-up and cool-down cycles.

COOLING SYSTEM CLEANING/REVERSEFLUSHING

CLEANINGD r a i n cool in g s y s t em a n d r ef il l w i t h w a t er. R u n

e n g in e w it h r a d ia t o r ca p in st a l le d u n t i l u p p e r r a d ia -t or h os e i s h ot . S t o p e ng in e a n d d r a i n w a t e r f r om

sy st e m . I f w a t e r is d ir t y , f i l l sy st e m w it h w a t e r , r u n

e ng in e a n d d r a i n s y s t e m. R ep ea t u n t il w a t er d r a i n s

clean.

REVERSE FLUSHINGReverse 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-

a n t f lo w . I t is u su a lly o n ly n e ce ssa r y w it h ve r y d ir t y

systems with evidence of partial plugging.

REVERSE FLUSHING RADIATORD iscon n e ct r a d ia t o r h ose s f r om r a d ia t or in le t a n d

ou t let . At t a ch a se ct ion of r a d ia t o r h o se t o r a d ia t o r

bot t o m ou t let f it t in g a n d in ser t f lush in g g u n . Co n -

n ect a w a t e r s up pl y h os e a n d a i r s upp ly h os e t o

flushing gun.

CAUTION: Internal radiator pressure must not

exceed 138 kPa (20 psi) as damage to radiator mayresult.

Allo w r a d ia t o r t o f i l l w it h w a t e r . W h e n r a d ia t o r is

f il le d, a p pl y a i r i n s h or t b la s t s . A ll ow r a d i a t or t o

r e f i l l be t w e e n bla st s . Co n t in u e t h is r e ve r se f lu sh in g

u n t i l c le a n w a t e r f lo w s o u t t h r o u g h r e a r o f r a d ia t o r

coolin g t u be p a ssa g e s. Ha ve r a d ia t o r clea n e d m or e

extensively by a radiator repair shop.

REVERSE FLUSHING ENGINEDrain cooling system. Remove thermostat housing

a n d t h e r m o st a t . I n st a l l t h e r m o st a t h o u sin g . D isco n -

n ect r a d i a t or u pp er h os e f r om r a d i a t or a n d a t t a ch

flushing gun to hose. Disconnect radiator lower hose

Fig. 26 Cylinder Block Drain Plug5.2L/5.9LEnginesTypical

1 BLOCK DRAIN PLUG

Fig. 27 Cylinder Block Drain Plug4.7L EngineTypical

1 CYLINDER BLOCK DRAIN PLUG

2 EXHAUST MANIFOLD AND HEAT SHIELD




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f rom w a t e r p u m p a n d a t t a c h a l ea d -a w a y h os e t o

w a t e r p u m p in le t f i t t in g .

CAUTION: On vehicles equipped with a heaterwater control valve, be sure heater control valve isclosed (heat off). This will prevent coolant flow withscale and other deposits from entering heater core.

Co n n e ct w a t e r su p p ly h o se a n d a ir su p p ly h o se t o

f lush in g g u n . Allow e n gin e t o f il l w it h w a t e r. Wh e n

e ng in e i s f il led , a p pl y a i r i n s h or t b la s t s , a l l ow i n g

system to fill between air blasts. Continue until clean

w a t e r f lo w s t h r o u g h t h e le a d a w a y h o se .

Re m o ve le a d a w a y h o se , f lu sh in g g u n , w a t e r su p -

p ly h os e a n d a i r s u pp ly h os e. R em ov e t h e rm os t a t

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

housing with a replacement gasket. Refer to Thermo-

sta t Replacement. C onnect ra diat or hoses. Refill cool-

in g sy st e m w it h cor r e ct a n t i f r e ez e/w a t e r m ixt u r e .

Refer to Refilling the Cooling System.

CHEMICAL CLEANINGI n som e in st a n ces, u se a r a d ia t or clea n e r (Mop a r

Ra d ia t or K lee n or e q u iva le n t ) be for e f lush in g. Th is

w il l so f t e n sca le a n d o t h e r d e p o sit s a n d a id f lu sh in g

operation.

CAUTION: Follow manufacturers instructions whenusing these products.

REMOVAL AND INSTALLATION

COOLANT RESERVE/OVERFLOW TANK

NOTE: The coolant reservoir/overflow tank is inte-geral to the upper fan shroud. Refer to Fan Shroud

in this section for proper removal/installation proce-dures.

WATER PUMP 5. 2L/5. 9L ENGINES

REMOVALTh e w a t e r pu m p ca n b e r em ov ed a n d i ns t a ll ed

w it h o u t d isch a r g in g t h e a ir con d it ion in g sy st e m (if

equipped).

(1) Disconnect battery negative cable.

(2) D r a i n cool in g s y s t em . R ef er t o C ool in g S y s -

t e m D r a in in g a n d F il l in g in t h is g r o u p .

(3) D o n ot w a s t e r eu s a b le cool a n t . I f s ol u t ion i s


WARNING: CONSTANT TENSION HOSE CLAMPS

ARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLYTOOLS DESIGNED FOR SERVICING THIS TYPE OF

CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (Fig. 38). SNAP-ON CLAMP TOOL (NUMBERHPC-20) MAY BE USED FOR LARGER CLAMPS.ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-ING CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into thetongue of constant tension clamps (Fig. 39). Ifreplacement is necessary, use only an originalequipment clamp with matching number or letter.

(4) Remove upper radiator hose clamp and hose at

radiator.

(5) Th e t h er m a l v is cou s f a n d ri ve i s a t t a c hed

(t h r ea d e d) t o t h e w a t er p um p h u b s h a f t (F i g. 29).

Re m ove f a n /viscou s f a n d r ive a ssem bly f r om w a t e r

p u m p by t u r n in g m ou n t in g n u t cou n t e r clock w ise a s

vie w e d f r o m f r o n t . T h r e a d s o n visco u s f a n d r ive a r e

RIGHT HAND. A S n a p -O n 36 M M F a n Wr en ch(number SP 346 from Sna p-On Cummins Diesel Tool

Set number 2017DS P ) an d Special Tool 6958 S pan-

n er Wr en ch w i t h Ad a p t er P i n s 8346 ca n b e u s ed .

P la ce Sp e cia l Tool 6958 Sp a n n e r Wr e n ch on t o t h e

w a t e r p u m p p u lle y w it h Ad a p t e r Pin s 8346 in se r t e d

into the holes on the pulley (Fig. 28) to prevent pul-

ley from rotating. Do not at tempt to remove fan/vis-

cou s f a n d r ive a sse m bly f r om ve hicle a t t h is t im e .

Fig. 28 Viscous Fan Drive Removal / Installation1 SPECIAL TOOL 6958 SPANNER WRENCH WITH ADAPTER

PINS 8346

2 FAN




26/44

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

f a n bla d e a ssem bly (F ig . 29) fr om t h e r m a l viscou s

f a n d r ive.

(7) R em ov e f a n s h r ou d a t t a ch i ng h a r d w a r e (t w o

bolts at bottom-two clips at top).

(8) Re m ove f a n sh r ou d a n d f a n bla d e/viscou s f a n

drive assembly from vehicle as a complete unit .

(9) Af t er r e m ovin g f a n bla d e/viscou s f a n d r ive

assembly, do not pla ce t h e r m a l viscou s f a n d r ive in

h or iz on t a l p osit ion . I f s t o re d h or iz on t a l ly, s i licon efluid in viscous fan drive could drain into its bearing

a sse m bly a n d co n t a m in a t e lu br ica n t .

(10) Remove a ccessory drive belt as follows: The

drive belt is equipped with a spring loaded automatic

tensioner (Fig. 30). Relax tension from belt by rotat-

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

30). When all belt tension has been relaxed, remove

accessory drive belt .

(11) Remove lower ra diator h ose clamp an d remove

lo w e r h o se a t w a t e r p u m p .

(12) Re m ove h e a t e r h ose cla m p a n d h e a t e r h ose

from heater hose coolant return tube.

(13) L oos en h ea t e r h os e cool a n t r et u rn t u bemounting bolt (Fig. 31) and remove tube from water

pump. Discard the old tube O-ring.

(14) Remove seven water pump mounting bolts.

(15) L o os en cl a m p a t w a t e r p um p e nd of b y pa s s

h os e (F i g. 29). S l ip b y pa s s h os e f r om w a t er p um 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.

INSTALLATION(1) Cle a n g a sk e t m a t in g su r f a ce s.

(2) U s in g a n ew g a s ket , i ns t a ll w a t e r pu m p t o

e ng in e a s f ol low s : G u i d e w a t e r p um p n i pp le i n t o

by pa ss h ose a s p u m p is be in g in st a l led . I n st a l l w a t e r

p u m p bolt s . Tig h t en w a t e r p u m p m o un t in g bolt s t o

40 Nm (30 ft . lbs.) torque.

(3) Posit ion bypass hose clamp to bypass hose.

(4) Sp in w a t e r p u m p t o be su r e t h a t p u m p im p e l-

ler does not rub aga inst t iming chain case/cover.

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

return tube (Fig. 31). Coat the new O-ring with anti-

freeze before insta llat ion.

(6) I n s t a l l cool a n t r et u r n t u b e a n d i t s m ou n t in g

b ol t t o e ng in e (F i g. 31). B e s u re t h e s lot i n t u b e

bracket is bottomed to mounting bolt . This will prop-

erly posit ion return tube.(7) Co n n ect r a d ia t o r low e r h ose t o w a t e r p u m p .

(8) Connect heater hose and hose clamp to coolant

r e t u r n t u be.

(9) Rela x t e n sion f r om belt t e n sion e r (F ig . 30).

Install accessory drive belt .

Fig. 29 Fan Blade and Viscous Fan Drive5.2L/5.9LEngines

1 WATER PUMP BYPASS HOSE


3 VISCOUS FAN DRIVE


Fig. 30 Automatic Belt Tensioner Assembly5.2L/5.9L Engines

1 IDLER PULLEY

2 TENSIONER

3 FAN BLADE


REMOVAL AND INSTALLATION (Continued)


27/44

CAUTION: When installing the serpentine acces-sory drive belt, the belt must be routed correctly. Ifnot, engine may overheat due to water pump rotat-

ing in wrong direction. Refer to (Fig. 32) for correctbelt routing. The correct belt with correct lengthmust be used.

(10) P osit ion fa n shroud a nd fan blade/viscous fan

drive assembly to vehicle as a complete unit .

(11) Install fan shroud.

(12) Inst all fan blade/viscous fan drive a ssembly to

w a t e r p u mp s h a f t .

(13) Fill cooling system. Refer to C ooling S ystem

D r a in in g a n d Re f i l l in g in t h is g r o u p .

(14) Connect battery negative cable.

(15) St a r t a n d w a r m t h e e n g in e . Ch e ck f o r le a k s.

WATER PUMP 4.7L ENGINESThe water pump on 4.7L engines is bolted directly

to t he engine timin g cha in case/cover.

A g a sk et is u sed a s a se a l bet w e e n t h e w a t e r p u m p

a nd timin g chain case/cover.

If wa ter pump is replaced because of bearing/sha ft

damage, or leaking shaft seal, the mechanical cooling

f a n a sse m bly sh ou ld a lso be in spe ct e d . I n sp ect f or

fat igue cracks, loose blades, or loose rivets tha t could

ha ve resulted from excessive vibrat ion. R eplace fan if

any of these conditions are found. Also check condi-tion of the therma l viscous fan drive. Refer to Viscous

F a n D r ive in t h is g r o u p .

The water pump can be removed without discharg-

ing the air conditioning system (if equipped).

REMOVAL(1) Disconnect negative battery cable from battery.

(2) D r a in cooling sy st e m . Re f er t o D r a in in g Co ol-

in g Sy st e m in t h is g r o u p .

D o n o t w a st e r e u sa ble coola n t . I f solu t ion is clea n ,

drain coolant into a clean container for reuse.

(3) Th e t h er m a l v is cou s f a n d ri ve i s a t t a c hed

(t h r e a d e d ) t o t h e w a t e r p u m p h u b sh a f t . Re m ove f a n /viscous fan drive assembly from water pump by turn-

in g m ou n t in g n u t cou n t e r clock w ise a s view e d f r om

f ron t . Th r ea d s on v is cou s f a n d r iv e a r e RIGHTHAND. Using special tool spanner wrench 6958 witha d a p t e r p in s 8346 a n d a su it a ble f a n w r e n ch lo o se n

the fan drive (Fig. 33). Do not at tempt to remove fan/

viscous fan drive assembly from vehicle at this t ime.

Fig. 31 Coolant Return Tube5.2L/5.9L EnginesTypical

1 COOLANT RETURN TUBE

07 cooling system

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