1993 DODGE TRUCK engine overheat

0
- 32
LUBRICATION
AND
MAINTENANCE

•

Fig.
5 Parking Brake Ratio Lever Lubrication (2) Note any indication of brake overheating,
wheel dragging or the vehicle pulling to one side.
(3) Evaluate any performance complaints received
from the owner/operator. (4) Repair the brake system as necessary (refer to
Group 5—Brakes for additional information and ser­
vice procedures).

BODY
COMPONENT
MECHANISMS
LUBRICATION REQUIREMENTS
All operating mechanisms and linkages should be
lubricated when necessary. This will maintain ease of operation and provide protection against rust and
excessive wear. The door weatherstrip seals should
be lubricated to prolong their life as well as to im­ prove door sealing.

LUBRICANT SPECIFICATIONS
All applicable exterior and interior vehicle operat­
ing mechanisms should be:
• Inspected • Cleaned
• All the pivoting/sliding contact areas on the mech­ anisms should then be lubricated.
MOPAR®Multi-Mileage Lubricant or an equiva­
lent, should be used to lubricate the mechanisms.
The door weatherstrip seals should be lubricated
with silicone lubricant spray. Refer to the Body Lu­
bricant Specifications chart below for additional lu­
bricant applications.

LUBRICATION
(1) When necessary, lubricate the cab and cargo
box operating mechanisms with the specified lubri­
cants.

(2) Apply silicone lubricant to a cloth and wipe it
on door seals to avoid over-spray that can soil pas­
senger clothing. (3) Before applying lubricant, the component
should be wiped clean. After lubrication, any excess
lubricant should be removed.
(4) The hood latch, latch release mechanism, latch
striker and safety latch should be lubricated periodi­
cally.
(5) The door lock cylinders should be lubricated 2
times each year (preferably autumn and spring): • Spray a small amount of lock cylinder lubricant di­
rectly into the lock cylinder
• Apply a small amount to the key and insert it into
the lock cylinder • Rotate it to the locked position and then back to
the unlocked position several times
• Remove the key. Wipe the lubricant from it with a
clean cloth to avoid soiling of clothing.

TIRES
RECOMMENDED MAINTENANCE
The condition of the tires should be inspected. The
inflation pressures tested/corrected at the same time as the engine oil is changed and the oil filter is re­
placed.
The tires/wheels should be rotated periodically to
ensure even tread wear. The tires/wheels should be
rotated at the first 12 000 km (7,500-miles) interval.
Thereafter, at each 24 000 km (15,000-miles) inter­
val.
INSPECTION
Inspect the tires for excessive wear, damage. Test
the tires for the recommended inflation pressure and adjust the pressure accordingly. Refer to the tire in­
flation pressure decal located on the left door face. Also to Group 22—Tires And Wheels for tire pres­sure charts, tire replacement, and treadwear indica­

tors.

ROTATION
Tires/wheels should be rotated according to the rec­
ommended interval. The first tire/wheel rotation is
the most important for establishing the prevention of uneven tread wear. After rotation, adjust the tire in­
flation pressure to the air pressure recommended on
the decal located on the left door face.
Refer to Group 22—Tires And Wheels for the rec­
ommended method of tire/wheel rotation.

HEADLAMPS

MAINTENANCE SCHEDULE
Every six months check the headlamp beams to en­
sure that the headlamp beams are correctly posi­
tioned.

AIM
ADJUSTMENT
Refer to Group 8L—Lamps for headlamp aim ad­
justment procedures.

FRONT
SUSPENSION
AND
AXLE
2 - 19

DRAIN
AND
REFILL

(1) Drive the vehicle until the gear lubricant
reaches normal operating temperature. (2) Raise and support the vehicle.
(3) Remove the lubricant fill hole plug from the
differential housing cover.
(4) Remove the differential housing cover. Allow
the original lubricant to completely drain from the
housing and axle shaft tubes.
(5) With standard differential, clean the differen­
tial and the housing cavity with a flushing oil (or light engine oil). This will remove the residual lubri­cant and foreign matter. Do not use water, steam,
kerosene or gasoline for flushing. (6) Scrape the residual gasket from the housing
and cover mating surfaces. Clean the mating sur­
faces with mineral spirits. Install a new cover gas­ ket. Apply a bead of MOPAR® Silicone Rubber Sealant on the housing cover (Fig. 2). Allow the
sealant to cure for a few minutes.

SEALING

SURFACE
CONTOUR
OF
BEAD
BEAD

THICKNESS

6.35mm
(1/4")
J9302-30

Fig.
2 Sealant On
Housing
Cover

Install the housing cover within 5 minutes af­
ter applying the sealant. If not installed the seal­ ant must be removed and another bead applied.
(7) Install the cover on the differential with the

bolts.
Install the identification tag. Tighten the cover
bolts to 47 Nnn (35 ft. lbs.) torque.

CAUTION:
Overfilling the
differential
can result in
the lubricant
foaming
and overheating.
(8) Refill the differential housing with the speci­
fied quantity of MOPAR® Hypoid Gear Lubricant.
(9) Install the fill hole plug and tighten to 34 N#m
(25 ft. lbs.) torque.
(10) Road test the vehicle.
PINION
SHAFT
SEAL

REMOVAL
(1) Raise and support the vehicle.
(2) Mark the U-joint, pinion yoke, and pinion shaft
for reference.
(3) Disconnect the drive shaft from the pinion
yoke. Secure the drive shaft in an upright position to prevent damage to the rear U-joint.
(4) Remove the pinion yoke nut and washer. Use
Remover C-452 and Wrench C-3281 to remove the
pinion yoke (Fig. 3).
(5) Mark the positions of the yoke and pinion gear
for installation alignment reference.

SPECIAL
TOOL
C-3281

SPECIAL
TOOL
C-452
J9102-31

Fig.
3
Pinion
Yoke
Removal

(6) Use Remover C-748 to remove the pinion gear
seal (Fig. 4).
PINION
SEAL

SPECIAL
TOOL
C-748

Fig.
4
Pinion
Seal
Removal
J9203-55

FRONT
SUSPENSION
AND
AXLE
2 - 51

LUBRICANT

Multi-purpose API GL 5 quality hypoid gear lubri­
cant should be used for Model 60 axles. MOPAR Hy­
poid Gear Lubricant conforms to these specifications and is recommended.

CAUTION:
If a front axle is
submerged
in
water,
the
axle lubricant
must
be replaced immediately.

DRAIN AND REFILL
(1) Drive the vehicle until the gear lubricant
reaches normal operating temperature. (2) Raise and support the vehicle.
(3) Remove the lubricant fill hole plug from the
differential housing cover. (4) Remove the differential housing cover. Allow
the original lubricant to completely drain from the
housing and axle shaft tubes. (5) With standard differential, clean the differen­
tial and the housing cavity with a flushing oil (or light engine oil). This will remove the residual lubri­cant and foreign matter. Do not use water, steam,
kerosene or gasoline for flushing. (6) Scrape the residual gasket from the housing
and cover mating surfaces. Clean the mating sur­
faces with mineral spirits. Install a new cover gas­
ket. Apply a bead of MOPAR® Silicone Rubber Sealant on the housing cover (Fig. 2). Allow the
sealant to cure for a few minutes.

SEALING

SURFACE
CONTOUR
OF
BEAD
BEAD

THICKNESS

6.35mm (1/4
J9302-30

Fig.
2 Sealant On
Housing
Cover

Install the housing cover within 5 minutes af­
ter applying the sealant. If not installed the seal­ ant must be removed and another bead applied. (7) Install the cover on the differential with the

bolts.
Install the identification tag. Tighten the cover
bolts to 47 Nnn (35 ft. lbs.) torque.

CAUTION:
Overfilling the
differential
can result in
the lubricant
foaming
and overheating.
(8) Refill the differential housing with the speci­
fied quantity of MOPAR® Hypoid Gear Lubricant. (9) Install the fill hole plug and tighten to 34 N«m
(25 ft. lbs.) torque. (10) Road test the vehicle.

PINION
SHAFT
SEAL

REMOVAL (1) Raise and support the vehicle.
(2) Mark the drive shaft yoke and pinion yoke for
installation alignment reference.
(3) Remove the drive shaft from the yoke.
(4) Rotate the pinion gear three or four times.
(5) Remove the pinion yoke nut and washer. Use
Remover C-452 and Wrench C-3281 to remove the
pinion yoke (Fig. 3).
(6) Mark the positions of the yoke and pinion gear
for installation alignment reference.

SPECIAL
TOOL
C-3281

SPECIAL
TOOL
C-452
J9102-31

Fig.
3
Pinion
Yoke
Removal

(7) Use Remover C-748 to remove the pinion gear
seal (Fig. 4).

INSTALLATION
(1) Apply a light coating of gear lubricant on the
lip of pinion seal. Install the new seal (Fig. 5) use In­
staller C-3719-A and Handle C-4735
(2) Align the installation reference marks and po­
sition the yoke on the pinion gear.
(3) Install the pinion yoke, washer, and nut on
shaft. Tighten the nut to 339-366 N-m (250-270 ft.
lbs.) torque (Fig. 6).
(4) Align the installation reference marks and at­
tach the drive shaft to the yoke. (5) Add API grade GL 5 hypoid gear lubricant to

3
- 6
REAR SUSPENSION
AND
AXLE

•

NUT PIPE
SOCKET
WRENCH
(DRIVER)

FLAT
THREADED
WASHER
ROD
J8917-20

Fig.
6
Spring
Eye
Bushing
Removal
(3) Align
the
bushing with
the
spring
eye and

tighten
the nut
located
at the
socket wrench
end of

the threaded
rod.
Tighten until
the
bushing
is
forced into
the
spring
eye.

The bushing must
be
centered
in the
spring

eye.
The
ends
of the
bushing must
be
flush
or
slightly recessed within
the end
surfaces
of the

spring
eye.
8ERW1GE DIAGNOSIS
INDEX
page

Driveline
Snap
8

Gear
and
Bearing Noise
7

General
Information
6
Limited
Slip
Differential
8
page
Low Speed Knock
.........................
8
Rear
Axle
Alignment
.......................
7

Tire
Noise
7
Vibration
8

GENERAL INFORMATION
Axle bearing problem conditions
are
usually caused
by: • Insufficient
or
incorrect lubricant
• Foreign matter/water contamination
• Incorrect bearing preload torque adjustment When serviced,
the
bearings must
be
cleaned thor­
oughly. They should
be
dried with lint-free shop tow­

els.
Never
dry
bearings with compressed
air.

This will overheat them
and
brinell
the
bearing surfaces. This will result
in
noisy operation after
repair. Axle gear problem conditions
are
usually
the
result

of:

• Insufficient lubrication
• Incorrect
or
contaminated lubricant
• Overloading (excessive engine torque)
• Incorrect clearance
or
backlash adjustment Insufficient lubrication
is
usually
the
result
of a

housing cover leak.
It can
also
be
from worn axle shaft
or
pinion gear seals. Check
for
cracks
or
porous
areas
in the
housing
or
tubes.
Using
the
wrong lubricant will cause overheating
and gear failure. Gear tooth cracking
and
bearing
spalling
are
indicators
of
this.
Axle component breakage
is
most often
the
result

of:

• Severe overloading
• Insufficient lubricant
• Incorrect lubricant • Improperly tightened components
Common causes
of
overloading
is
from full-throttle
acceleration. Overloading occurs when towing
heavier than normal loads. Component breakage
can
occur when
the
wheels
are
spun excessively. Insuffi­
cient
or
incorrect lubricants contribute
to
breakage
through overheating. Loose differential components can also cause breakage. Incorrect bearing preload
or
gear backlash will
not

result
in
component breakage. Mis-adjustment will
produce enough noise
to
cause service repair before
a

•

REAR
SUSPENSION
AND
AXLE
3 - 11 8 3/8 and 9 1/4
AXLE

INDEX

page
Axle Shaft, Seal
and
Bearing Service
......... 11
Complete Axle Removal/Installation
16

Differential
Service
16
Information
11

INFORMATION
The 8 3/8 and 9 1/4 axle (Fig. 1) housing consist of
a cast iron center section. They also have two steel
axle shaft tubes that are pressed into and welded to
the differential housing. The removable, stamped steel cover provides a
means for inspection and service without removing
the complete axle from the vehicle.

LUBRICANT
Multi-purpose, hypoid gear lubricant should be
used for 8 3/8 and 9 1/4 axles. The lubricant should
have MIL-L-2105C and API GL 5 quality specifica­

tions.
MOPAR® Hypoid Gear Lubricant conforms to
both of these specifications.
Refer to Group 0, Lubrication and Maintenance for
additional information.

CAUTION:
If a
rear axle
is
submerged
in
water,
the

axle lubricant must
be
replaced immediately.
DRAIN
AND
REFILL
(1) Drive the vehicle until the gear lubricant
reaches normal operating temperature.
(2) Raise and support the vehicle.
(3) Remove the lubricant fill hole plug from the
differential housing cover.
(4) Remove the differential housing cover. Allow
the original lubricant to completely drain from the
housing and axle shaft tubes. (5) With standard differential, clean the differen­
tial and the housing cavity with a flushing oil (or light engine oil). This will remove the residual lubri­
cant and foreign matter.Do not use water, steam,
kerosene or gasoline for flushing.

CAUTION:
DO NOT
FLUSH
Sure-Grip differentials.

Sure-Grip
differentials
may be
cleaned only
by
wip­
ing
with
clean,
lint-free
cloths.
(6)
Scrape the residual sealant from the housing
and cover mating surfaces. Clean the mating sur­
faces with mineral spirits. Apply a bead of MOPAR® Silicone Rubber Sealant on the housing cover (Fig.

2).
Allow the sealant to cure for a few minutes.
page

Lubricant
11
Pinion Depth Measurement
and
Adjustment
with
Gauge
Set 20

Pinion
Seal
Replacement
14
Install the housing cover within 5 minutes af­
ter applying the sealant. If not installed, the sealant must be removed and another bead ap­
plied. (7) Install the cover on the differential. Install the
identification tag. Tighten the cover bolts to 47 N#m (35 ft. lbs.) torque.

CAUTION:
Overfilling
the
differential
can
result
in

the lubricant foaming
and
overheating.

(8) Refill the differential with the specified quan­
tity of MOPAR® Hypoid Gear Lubricant. With Sure- Grip differentials, add a container of MOPAR®
Hypoid Gear Lubricant Additive.
(9) Install the fill hole plug.
(10) Road test the vehicle.

AXLE
SHAFT, SEAL AND BEARING
SERVICE
CAUTION:
When rear axle service
is
necessary, both rear wheels must
be
raised
off the
surface
so

that
they
are
free
to
rotate.
Be
cautious when
the

tires
are
being rotated
by the
engine
or by
other
means.

CAUTION:
If
equipped
with
a
Sure-Grip
differential,

do
not
rotate
either
axle shaft unless both
are
prop­

erly
in-place. Rotation
of one
axle shaft without
the
other being installed
can
result
in
misalignment
of

the side gears/splines. This
will
necessitate side
gear
re-alignment before
the
axle shaft
can be in­

stalled.
AXLE SHAFT REMOVAL
(1) Raise and support the vehicle.
(2) Remove the wheel.
(3) Remove the brake drum.
(4) Clean all the foreign material from housing
cover area.
(5) Loosen the housing cover bolts. Drain the lubri­
cant from the housing. Remove the housing cover.

(6)
Rotate the differential case so the pinion mate
gear shaft lock screw is accessible. Remove the lock screw and the pinion mate gear shaft from the case (Fig. 3).

5
- 4
BRAKES

• (3) During road test, make normal and firm brake
stops in 25-40 mph (40-64 Km/h) range. Note faulty
brake operation such as pull, grab, drag, noise, low
pedal, etc.
(4) Inspect suspect brake components and refer to
problem diagnosis information for causes of various
brake conditions.

COMPONENT
INSPECTION
Fluid leak points and dragging brake units can usu­
ally be located without removing any components. The
area around a leak point will be wet with fluid. The
components at a dragging brake unit (wheel, tire, rotor)
will be quite warm or hot to the touch.
Other brake problem conditions will require compo­
nent removal for proper inspection. Raise the vehicle and remove the necessary wheels for better visual ac­

cess.

DIAGNOSING BRAKE
PROBLEMS

PEDAL FALLS
AWAY
A
brake pedal that falls away under steady foot
pressure is the result of a system leak. The leak
point could be at a brakeline, fitting, hose, or caliper. Internal leakage in the master cylinder caused by
worn or damaged piston cups, may also be the prob­ lem cause.
If leakage is severe, fluid will be evident at or around
the leaking component. However, internal leakage in
the master cylinder may not be physically evident. Re­ fer to the cylinder test procedure in this section.

LOW PEDAL
If a low pedal is experienced, pump the pedal sev­
eral times. If the pedal comes back up, worn lining
and worn rotors or drums are the likely causes.
A decrease in fluid level in the master cylinder res­
ervoirs may only be the result of normal lining wear.
Fluid level can be expected to decrease in proportion to wear. It is a result of the outward movement of
caliper and wheel cylinder pistons to compensate for
normal wear. Top off the reservoir fluid level and
check brake operation to verify proper brake action.
SPONGY PEDAL. A spongy pedal is most often caused by air in the sys­
tem. Thin brake drums or substandard brake lines and
hoses can also cause a spongy pedal. The proper course
of action is to bleed the system and replace thin drums and suspect quality brake lines and hoses.

HARD PEDAL
OR
HIGH
PEDAL
EFFORT
A hard pedal or high pedal effort may be due to
lining that is water soaked, contaminated, glazed, or
badly worn. The power booster or check valve could also be faulty. On diesel engine models, high pedal effort may be
the result of a low vacuum condition. If the booster and check valve are OK, the problem may be related
to a vacuum pump hose, hose connection, hose fit­
ting, pump diaphragm, or drive gear. Vacuum pump output can be checked with a standard vacuum
gauge. Vacuum output should range from 8.5 to 25 inches vacuum. If vacuum pump output is within

limits,
check the power booster and check valve as
described in this section.

BRAKE DRAG
Brake drag occurs when the lining is in constant
contact with the rotor or drum. Drag can occur at
one wheel, all wheels, fronts only, or rears only. It is a product of incomplete brakeshoe release. Drag can
be minor or severe enough to overheat the linings,
rotors and drums.
Brake drag can also effect fuel economy. If undetec­
ted, minor brake drag can be misdiagnosed as an en­ gine or transmission/torque converter problem.
Minor drag will usually cause slight surface charring
of the lining. It can also generate hard spots in rotors and drums from the overheat-cool down process. In most

cases,
the rotors, drums, wheels and tires are quite
warm to the touch after the vehicle is stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and drums to the point of replacement. The wheels, tires and brake components will be extremely hot. In se­
vere cases, the lining may generate smoke as it chars
from overheating.
Some common causes of brake drag are:
• seized or improperly adjusted parking brake cables
• loose/worn wheel bearing
• seized caliper or wheel cylinder piston
• caliper binding on corroded bushings or rusted
slide surfaces
• loose caliper mounting bracket
• drum brakeshoes binding on worn or damaged sup­
port plates
• misassembled components. If brake drag occurs at all wheels, the problem may
be related to a blocked master cylinder return port, or faulty power booster that binds and does not release.

BRAKE FADE
Brake fade is a product of overheating caused by
brake drag. However, brake overheating and subse­ quent fade can also be caused by riding the brake
pedal, making repeated high deceleration stops in a short time span, or constant braking on steep moun­
tain roads. Refer to the Brake Drag information in
this section for additional causes.

PEDAL
PULSA
TION
Pedal pulsation is caused by components that are
loose, out of round, or worn beyond tolerance limits.

•

BRAKES
5 - 5 Disc brake rotors with excessive lateral runout or
thickness variation, or out of round brake drums are
the primary causes of pulsation. Other causes are loose
wheel bearings or calipers and worn, damaged tires.

PULL A
front pull condition could be the result of con­
taminated lining in one caliper, seized caliper piston,
binding caliper, loose caliper, loose or corroded slide

pins,
improper brakeshoes, or a damaged rotor.
A worn, damaged wheel bearing or suspension compo­
nent are further causes of pull. A damaged front tire (bruised, ply separation) can also cause pull.
A common and frequently misdiagnosed pull condi­
tion is where direction of pull changes after a few
stops.
The cause is a combination of brake drag fol­
lowed by fade at one of the brake units.
As the dragging brake overheats, efficiency is so
reduced that fade occurs. Since the opposite brake
unit is still functioning normally, its braking effect is
magnified. This causes pull to switch direction in fa­
vor of the normally functioning brake unit.
When diagnosing a change in pull condition, re­
member that pull will return to the original direction
if the dragging brake unit is allowed to cool down (and is not seriously damaged).

REAR BRAKE GRAB
OR
PULL
Rear grab or pull is usually caused by an improperly
adjusted or seized parking brake cable, contaminated
lining, bent or binding shoes and support plates, or im­
properly assembled components. This is particularly
true when only one rear wheel is involved. However,
when both rear wheels are affected, the master cylinder or proportioning valve could be at fault.

BRAKES
DO NOT
HOLD
AFTER
DRIVING
THROUGH
DEEP
WATER
PUDDLES

This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by driv­
ing with the brakes very lightly applied for a few min­

utes.
However, if the lining is thoroughly wet and dirty,
disassembly and cleaning will be necessary.

BRAKE NOISE

Squeak/Squeal
Brake squeak or squeal may be due to linings that
are wet or contaminated with brake fluid, grease, or oil. Glazed linings and rotors with hard spots can also con­
tribute to squeak. Dirt and foreign material embedded in the brake lining can also cause squeak/squeal.
A very loud squeak or squeal is frequently a sign of
severely worn brake lining. If the lining has worn
through to the brakeshoes in spots, metal-to-metal con­
tact occurs. If the condition is allowed to continue, ro­ tors can become so scored that replacement is necessary.
Thump/Clunk

Thumping or clunk noises during braking are fre­
quently not caused by brake components. In many

cases,
such noises are caused by loose or damaged steering, suspension, or engine components. How­
ever, calipers that bind on the slide pins, or slide sur­

faces,
can generate a thump or clunk noise. Worn
out, improperly adjusted, or improperly assembled
rear brakeshoes can also produce a thump noise.

Chatter
Brake chatter is usually caused by loose or worn
components, or glazed/burnt lining. Rotors with hard
spots can also contribute to chatter. Additional
causes of chatter are out of tolerance rotors, brake
lining not securely attached to the shoes, loose wheel
bearings and contaminated brake lining.
Brakelining Contamination Brakelining contamination is usually a product of
leaking calipers or wheel cylinders, driving through
deep water puddles, or lining that has become cov­
ered with grease and grit during repair.
Wheel and
Tire
Problems Some conditions attributed to brake components
may actually be caused by a wheel or tire problem.
A damaged wheel can cause shudder, vibration and
pull. A worn or damaged tire can also cause pull.
Severely worn tires with very little tread left can
produce a grab-like condition as the tire loses and re­ covers traction. Flat-spotted tires can cause vibration and wheel
tramp and generate shudder during brake operation. A tire with internal damage such as a severe
bruise or ply separation can cause pull and vibration.

MASTER
CYLINDER/POWER BOOSTER TEST
(1) Start engine and check booster vacuum hose
connections. Hissing noise indicates a vacuum leak. Correct any leaks before proceeding. (2) Stop engine and shift transmission into Neu­
tral (3) Pump brake pedal until all vacuum reserve in
booster is depleted. (4) Press and hold brake pedal under light foot
pressure. (a) If pedal holds firm, proceed to step (5).
(b) If pedal does not hold firm and falls away,
master cylinder is faulty (internal leakage). (5) Start engine and note pedal action. (a) If pedal falls away slightly under light foot
pressure then holds firm, proceed to step (6). (b) If pedal is effort is high, or no pedal action is
discernible, power booster or vacuum check valve is
faulty. Install known good check valve and repeat steps (2) through (5).

COOLING SYSTEM

CONTENTS page

DIAGNOSIS
... 4

ENGINE
ACCESSORY
DRIVE BELTS
40

ENGINE
BLOCK HEATERS
48

GENERAL
INFORMATION
Throughout this group, references are made to partic­
ular vehicle models by alphabetical designation or by
the particular vehicle nameplate. A chart showing a
breakdown of alphabetical designations is included in
the Introduction section at the beginning of this man­
ual.
5.9L gas powered engines will be' referred to as ei­
ther: LDC (Light Duty Cycle) or HDC (Heavy Duty
Cycle).

COOLING
SYSTEM
The cooling system regulates engine operating tem­
perature. It allows the engine to reach normal oper-
page

SERVICE
PROCEDURES
15

SPECIFICATIONS
; 49
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre­
vents overheating.
The cooling system also provides a means of heat­
ing the passenger compartment and cooling the auto­
matic transmission fluid (if equipped). The cooling system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
An optional factory installed maximum duty cool­
ing package is available on most models. This pack­ age will provide additional cooling capacity for
vehicles used under extreme conditions such as
trailer towing in high ambient temperatures.
NOTE: HEATER
COOLANT FLOW
CIRCUIT
IS
ALWAYS

OPEN
EXCEPT
WHEN
IN MAX. A/C
OR
OFF
MODES
HEATER
INTAKE MANIFOLD
COOLANT FLOW "METERED" FROM REAR
TO

FRONT
AND
BELOW EXHAUST
HEAT
CROSSOVER
SHUT
OFF
VALVE

A/C
ONLY COOLANT FLOW
-
PUMP
TO

CYLINDER BLOCK,
UP
THROUGH CYLINDER HEADS
TO
INTAKE MANIFOLD WATER
BOX TO
RADIATOR-TO PUMP

•BYPASS
THERMOSTAT CLOSED-HIGH FLOW
THERMOSTAT OPEN
- LOW
FLOW
J9207-18

Fig.
1
Cooling
System
Routing—3.9U5.2L Engine—Typical