engine overheat DODGE TRUCK 1993 Service User Guide

•
COOLING SYSTEM 7-13
DIESEL COOLING SYSTEM DIAGNOSIS-CONTINUED

CONDITION
AND
CHECKS
DIAGNOSIS

COOLANT
LOSS
PAST
PRESSURE
CAP
TOP
SEAL,

VISIBLE
ON
RADIATOR
FILLER
NECK.
(1)
With
normal gauge reading. (1) a — Pressure cap not installed
tightly.

b — Pressure cap top seal leaks.

c
— Pressure cap diaphragm bowed.

d
— Damaged
radiator
filler
neck.
e — Pressure cap top seal out of position.
(2)
With
high or low gauge reading on new vehicle. (2) a — Kinked coolant reserve system hose.
(2)
With
high or low gauge reading on new vehicle.
b — Coolant reserve system
tank
plastic
tube
plugged.

c
— Pressure cap seal out of position.

DETONATION
OR
PREIGNITION.
NOT
CAUSED
BY
IGNI­

TION OR
ENGINE
CONDITIONS.

(1)
Check engine coolant
freeze
point.
If the
tester
does
not
regis­
(1) a — Adjust coolant solution to
50/50
water

ter a reading or if the reading is below 50°F, inspect
ethyl­
ethylene-glycol
mixture.

ene-glycol/
water
ratio.
A 100
percent
solution of
ethylene-
b — If 100
percent
ethylene-glycol
solution is found
glycol
in
the
system
causes
the engine
to
run
hotter
and
possi­
in system,
clean
and flush system
before

bly overheat.
replacing
with
50/50
mixture
of

ethylene-glycol
and
water.

COOLING
SYSTEM
HOSES
COLLAPSE
ON
COOLDOWN.
(1) Inspect pressure cap
vent
valve. (1) a — Gasket swell can
prevent
valve
from
opening.
b — Replace pressure cap.
(2) Coolant reserve
tank
hose plugged or kinked. (2) Repair as necessary.
(3) Inside of pressure cap plugged. (3) Clean cap or
replace
if necessary.

COOLING
SYSTEM
SUSPECTED
AS
CAUSE
OF
INADE­
QUATE
AIR CONDITIONING
SYSTEM
PERFORMANCE.

(1) Inspect for plugged
radiator
and/or condenser. (D Clean
with
low pressure
water
from
fan side.
(2) Inspect for
missing
air
seals
in the
recirculating
air path. (2) Repair
as
necessary.

EXCESSIVE
FAN
NOISE

(1)
Inspect for loose or
bent
fan blades. (1) Replace fan.
(2) Inspect clearance
between
fan and
adjacent
part.
(2) Repair or
replace
as necessary.
(3) Inspect
radiator
and condenser for incoming air obstructions. (3) Clean air path
with
low pressure
water
from
fan side.
(4) Inspect
viscous
fan drive. (4) Replace if
viscous
drive
does not
operate
properly.

HEAT
ODOR

(1)
Was
temperature
gauge reading high? (1) If
YES,
refer
to
GAUGE
READING
HIGH.
If
NO,
refer
to
steps

2, 3, and 4.
(2) Are all
heat
shields in place? (2) If
YES,
refer
to steps 3 and 4. If NO,
repair
as
required.

(3)
Is
the air side of the
heat
exchanger plugged? (3) Clean as necessary.
(4) Engine running rich causing
catalytic
converter
to overheat. (4) Repair
as
necessary.

POOR
DRIVEABILITY.
SUSPECT
THERMOSTAT FAILED
IN OPEN POSITION.

(1)
Thermostat stuck in open position? 01 Replace thermostat. ._ _0 .
Jy
107-24

7 - 18
COOLING
SYSTEM

• (9) Relax tension from automatic belt tensioner

(Figs.
4 or 5). Install drive belt.

CAUTION:
When
installing
the
serpentine
accessory

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

gine
may
overheat
due to
water
pump
rotating
in

wrong
direction.
Refer
to
(Figs,
i, 10 or 11) for
cor­
rect
belt
routing.
The
correct
belt with
correct

length
must
be
used.

*IF
VEHICLE
IS NOT
EQUIPPED
WITH
POWER
STEERING,
THIS
WILL
BE
AN
IDLER
PULLEY.
J9307-26
Fig.
9 Belt Routing—3.9U5.2L/5.9L
LDC-Gas
Engine

AUTOMATIC
TENSIONER
AUTOMATIC

TENSIONER

J9307-56

Fig.
11 Belt Routing—5.9L
HDC-Gas
Engine—Without
A/C (10) Position fan shroud and fan blade/viscous fan
drive assembly to vehicle as a complete unit. (11) Install fan shroud.
(12) Install fan blade/viscous fan drive assembly to
water pump shaft.
(13) Fill cooling system. Refer to Refilling Cooling
System in this group. (14) Connect negative battery cable.
(15) Start and warm the engine. Check for leaks.

WATER
PUMPS—5.9L
DIESEL
The diesel engine water pump draws coolant from
radiator outlet and circulates it through engine,
heater core and back to radiator inlet. The crank­ shaft pulley drives the water pump via a serpentine
drive belt (Fig. 12). An automatic belt tensioner (Fig. 12) is used to prevent the belt from slipping.
REMOVAL (1) Disconnect the negative battery cable at bat­
tery. (2) Drain cooling system. Refer to Draining Cool­
ing System in this section.
(3) Remove the accessory drive belt. Refer to the
Engine Accessory Drive Belt section of this group. (4) Remove water pump mounting bolts (Fig. 13).
(5) Clean water pump sealing surface on cylinder
block.
J9307-55

Fig.
10 Belt Routing—5.9L
HDC-Gas
Engine-With

A/C
INSTALLATION

(1) Install new O-ring seal in groove on water
pump (Fig. 14). (2) Install water pump. Tighten mounting bolts to
24 N-m (18 ft. lbs.) torque.

7 - 22
COOLING
SYSTEM

•

Fig.
23 Bracket
Bolts—5.9L
HDC-Gas Engine
(2) Install bypass hose to engine.
(3) Secure both hose clamps.
(4) Install generator-A/C mounting bracket assem­
bly to engine. Tighten bolts (number 1 and 2 Fig. 17)
to 54 Nnn (40 ft. lbs.) torque. Tighten bracket mount­ ing bolts (Figs. 22 or 23) to 40 N-m (30 ft. lbs.)
torque.
(5) Install a new O-ring to the heater hose coolant
return tube (Figs. 20 or 21). Coat the new O-ring
with antifreeze before installation. (6) Install coolant return tube and its mounting
bolt to engine (Figs. 20 or 21). (7) Connect throttle body control cables.
(8) Install oil dipstick mounting bolt.
(9) 3.9L/5.2L/5.9L LDC-Gas: Install idler pulley.
Tighten bolt to 54 Nnn (40 ft. lbs.) torque. 5.9L HDC-Gas: Install automatic belt tensioner
assembly to mounting bracket. A dowel pin is located
on back of tensioner (Fig. 24). Align this to dowel
hole (Fig. 25) in tensioner mounting bracket. Tighten
bolt to 41 N-m (30 ft. lbs.). (10) Install drive belt. Refer to Belt Removal/In­
stallation in the Engine Accessory Drive Belt section
of this group.

CAUTION:
When installing
the
serpentine
accessory

drive belt,
the
belt must
be
routed correctly.
If not,

the engine
may
overheat
due to the
water pump
ro­

tating
in the
wrong direction. Refer
to
Belt Schemat­
ics
in the
Engine
Accessory
Drive Belt section
of

this
group
for
correct belt routing.
The
correct belt

with the
correct length must
be
used.

(11) Install air cleaner assembly.
BELT TENSIONER
DOWEL PIN
J9307-63

Fig.
24 Tensioner
Dowel
Pin—5.9L
HDC-Gas Engine Fig.
25 Tensioner
Mounting
Bracket
Dowel

Hote—5.9L
HDC-Gas Engine

(12) Install upper radiator hose to radiator.
(13) Connect throttle cable to clip at radiator fan
shroud.
(14) Connect wiring harness to A/C compressor. (15) Fill cooling system. Refer to Refilling Cooling
System in this group.
(16) Start and warm the engine. Check for leaks.

THERMOSTAT
GENERAL
INFORMATION
The thermostat on all gas powered engines is lo­
cated beneath the thermostat housing at the front of
the intake manifold (Fig. 26). The thermostat has an air bleed notch.
The thermostat of the 5.9L diesel engine is located
in the thermostat housing at front of cylinder head.
This is on exhaust manifold side of engine (Fig. 27). The thermostat is a wax pellet driven, reverse pop­
pet choke type. The wax pellet is located in a sealed container at the spring end of the thermostat. When
heated, the pellet expands, overcoming closing spring

•

COOLING
SYSTEM
7 - 25

Fig.
31 Thermostat Position
CAUTION; Housing must
be
tightened
evenly and

thermostat must
be
centered into recessed groove in
intake manifold. If not, it may
result
in a
cracked
housing,
damaged intake manifold threads
or
cool­
ant
leak.
(6) Install upper radiator hose to thermostat hous­
ing. (7) Air conditioned vehicles: (a) Install generator. Tighten bolts to 41 N-m (30
ft. lbs.). (b) Install support bracket (generator mounting
bracket-to-intake manifold) (Fig. 28). Tighten bolts
to 54 N-m (40 ft. lbs.) torque.

CAUTION:
When installing
the
serpentine accessory
drive belt,
the
belt must
be
routed correctly.
If not,

the engine
may overheat due to the
water pump
ro­
tating in the
wrong direction. Refer
to
Belt Schemat­
ics
in the
Engine
Accessory
Drive Belt section
of

this group
for
correct engine belt routing.
The
cor­ rect belt with
the
correct length must
be
used.

(8) Fill cooling system. Refer to Refilling Cooling
System in this Group. (9) Connect negative battery cable to battery.
(10) Start and warm engine. Check for leaks.

THERMOSTAT OPERATIONr-5.9L DIESEL
ENGINE

The thermostat controls the operating temperature
of the engine by controlling the amount of coolant
flow to the radiator. When coolant temperature is be­ low 83°C (181°F), the thermostat is closed. Coolant is
routed back to the water pump inlet through the by­
pass (Fig. 32).

Fig.
32 Thermostat Operation—5.9L
Diesel
When coolant temperature reaches 83°C (181°F),
the thermostat begins to open allowing coolant flow
to the radiator. This provides quick engine warm-up and overall temperature control. The thermostat is
designed to provide a minimum engine operating
temperature of 83°C (181°F) and to be fully open for maximum coolant flow at approximately 95°C (203°F). Above 95°C (203°F), coolant temperature is
controlled by the radiator, fan and ambient tempera­

ture.

The thermostat is equipped with three air bleeds
on the flange. The air bleeds will vent air when the system is filled. It also acts as a check valve to block
the flow of coolant during engine operation.
REMOVAL-DIESEL

WARNING:
DO NOT
LOOSEN
THE
RADIATOR
DRAINCOCK
WITH
THE
SYSTEM
HOT
AND
PRES­

SURIZED.
SERIOUS
BURNS
FROM
THE
COOLANT

CAN
OCCUR.

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

use.
(1) Disconnect negative battery cable from battery.
(2) Remove accessory drive belt. Refer to Belt Re­
moval/Installation in the Engine Accessory Drive
Belt section in this group.
(3) Drain cooling system until coolant level is be­
low thermostat. Refer to Draining Cooling System in
this section.
(4) Remove radiator hose clamp and hose from
thermostat housing. Special Clamp Tool number 6094 (Fig. 29) may be used to remove the constant
tension clamps.
(5) Loosen generator pivot bolt.

7 - 30
COOLING
SYSTEM

•

COOLING
SYSTEM

Fig.
39
Pressure
Testing
Cooling
System—Typical bulges while testing, replace as necessary. Observe
gauge pointer and determine condition of cooling sys­
tem according to following criteria:
Holds Steady: If pointer remains steady for two
minutes, serious coolant leaks are not present in sys­
tem. However, there could be an internal leak that does not appear with normal system test pressure. If
it is certain that coolant is being lost and leaks can­
not be detected, inspect for interior leakage or per­
form Internal Leakage Test.
Drops Slowly: Indicates a small leak or seepage is
occurring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect radiator,

hoses,
gasket edges and heater. Seal small leak holes
with a Sealer Lubricant (or equivalent). Repair leak
holes and inspect system again with pressure ap­
plied.
Drops Quickly: Indicates that serious leakage is
occurring. Examine system for external leakage. If
leaks are not visible, inspect for internal leakage.
Large radiator leak holes should be repaired by a
reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION Remove engine oil pan drain plug and drain a
small amount of engine oil. If coolant is present in
the pan, it will drain first because it is heavier than
oil.
An alternative method is to operate engine for a
short period to churn the oil. After this is done, re­
move engine dipstick and inspect for water globules.
Also inspect transmission dipstick for water globules and transmission fluid cooler for leakage.

WARNING:
WITH
PRESSURE TESTER TOOL
7700
INSTALLED
ON
RADIATOR,
DO
NOT ALLOW
PRES­

SURE
TO
EXCEED
110 KPA (20
PSI). PRESSURE

WILL
BUILD
UP
QUICKLY
IF A
COMBUSTION LEAK

IS
PRESENT.
TO
RELEASE
PRESSURE,
ROCK

TESTER
FROM SIDE
TO
SIDE. WHEN REMOVING

TESTER,
DO NOT
TURN TESTER MORE THAN
1/2

TURN
IF
SYSTEM
IS
UNDER
PRESSURE.
Operate engine without pressure cap on radiator
until thermostat opens. Attach a Pressure Tester to
filler neck. If pressure builds up quickly it indicates a combustion leak exists. This is usually the result of
a cylinder head gasket leak or crack in engine. Re­
pair as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi). Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter, do not remove spark plug cables or short
out cylinders (non-diesel engines) to isolate compres­
sion leak.
If the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an ab­ normal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head
gasket, cracked engine cylinder block or cylinder
head. A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail­ able Block Leak Check tool. Follow manufacturers
instructions when using this product.
COMBUSTION LEAKAGE TEST-WITHOUT
PRESSURE TESTER DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.

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

COCK
WITH
SYSTEM
HOT AND
UNDER PRES­

SURE.
SERIOUS BURNS FROM COOLANT
CAN

OCCUR.

Drain sufficient coolant to allow thermostat re­
moval. Refer to Thermostat Replacement. Disconnect
water pump drive belt. Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of top of thermostat housing.

CAUTION:
Avoid
overheating.
Do not
operate
en­

gine
for an
excessive
period
of
time.
Open
drain-

cock
immediately
after
test
to
eliminate
boil
over.

Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases% are leaking into
cooling system, bubbles will appear in coolant. If
bubbles do not appear, internal combustion gas leak­ age is not present.

COOLANT
RESERVE/0WERFL0W
SYSTEM
The coolant reserve/overflow system (Fig. 40 or 41)
works in conjunction with the radiator pressure cap.

7 - 38
COOLING
SYSTEM

•
WARNING:
DO NOT
ATTEMPT
TO
BEND
OR

STRAIGHTEN
FAN
BLADES
IF
NOT WITHIN
SPECI­
FICATIONS.

(4) Inspect fan assembly for cracks, bends, loose
rivets or broken welds. Replace fan if any damage is
found.
CAUTION; If the fan
blade assembly
is
replaced
be­

cause
of
mechanical damage,
the fan
pulley
and

viscous
fan
drive should also
be
inspected.
These
components
could have been damaged
due to ex­
cessive
vibration.
INSTALLATION
(1) Install fan blade assembly to viscous fan drive.
Tighten mounting bolts.
(2) Position the fan shroud and fan blade/viscous
fan drive to the vehicle as an assembly.
(3) Install viscous fan drive assembly on fan hub
shaft. Tighten mounting nut to 57 N*m (42 ft. lbs.)
torque.
(4) Install fan shroud bolts.
(5) Install battery cable to battery.

VISCOUS
FAN
DRIVE
The thermal viscous fan drive (Figs. 54 or 55) con­
sists of the viscous fan drive clutch and a thermo­
static spring coil mounted on its front face (Fig. 56).
The viscous fan drive clutch is a silicone-fluid-filled coupling connecting fan blade assembly to water
pump shaft. The coupling allows fan to be driven in a normal manner at low engine speeds. It will limit top
speed of fan to a predetermined maximum level at
higher engine speeds.
The thermostatic spring coil (Fig. 56) reacts to the
temperature of radiator discharge air. It engages drive clutch for higher fan speed if air temperature
from radiator rises above a certain point. Until addi­
tional engine cooling is necessary, fan will remain at a reduced rpm regardless of engine speed. Only when
sufficient heat is present in the air, will the viscous
fan drive clutch engage. This air flowing through ra­ diator core will cause a reaction to thermostatic spring coil. Fan speed will then increase to provide
necessary additional engine cooling.
MOUNTING
NUT

TO WATER PUMP
Fig.
56
Viscous
Fan Drive CAUTION; If
viscous
fan
drive
is
replaced because
of mechanical damage, cooling
fan
blades should

also
be
inspected. Inspect
for
fatigue cracks, loose
blades
or
loose rivets
that
could have resulted
from

excessive
vibration. Replace
fan
blade assembly
if

any
of
these conditions
are
found.
Also
inspect
wa­
ter
pump bearing
and
shaft assembly
for any re­
lated
damage
due to a
viscous
drive malfunction.

Regardless of increased engine speed, once the fan
has reached its maximum operating speed, it will not
rotate any faster. When the necessary engine cooling
has been accomplished causing a reduction in tem­ perature of radiator discharge air, the spring coil again reacts. This will cause fan speed to be reduced
to its previous disengaged speed.
TESTING VISCOUS FAN DRIVE In case of engine overheating, inspect thermal vis­
cous fan drive for proper operation. Observe move­
ment of thermostatic spring coil and shaft. Lift end
of thermostatic spring up and out of retaining slot in
fan drive (Fig. 57). Rotate spring counterclockwise until a stop is felt. The gap between end of coil and
retaining clip should be approximately 12 mm (0.5 inch) (Fig. 58). Replace unit if shaft does not rotate
with coil. After testing, install end of coil in slot of retaining clip.

REMOVAUINSTALLA
TION For removal and installation procedures, refer to
Cooling System Fans in this group.

ENGINE ACCESSORY DRIVE BELTS

INDEX

page

Automatic Belt Tensioner
45
Belt Diagnosis
40

Belt Removal/Installation
. 40
page

Belt Schematics
40
Belt Tension
40

General
Information
40

GENERAL
INFORMATION
All vehicles are available with either
a
3.9L (V-6),
a 5.2L (V-8),
a
5.9L (gas V-8) or
a
5.9L (in-line 6 cyl­
inder diesel) engine. The accessory drive components
are
operated
by a

single, crankshaft driven, serpentine drive belt on all
engines. An automatic belt tensioner
is
used to main­
tain correct belt tension
at all
times. Refer
to
Auto­ matic Belt Tensioner proceeding
in
this group.

BELT DIAGNOSIS SERPENTINE DRIVE BELT DIAGNOSIS-ALL
ENGINES
When diagnosing serpentine drive belts, small
cracks that run across ribbed surface of belt from rib
to rib (Fig. 1), are considered normal. These are not
a

reason
to
replace belt. However, cracks running along
a rib (not
across)
are not
normal.
Any
belt
with cracks running along
a rib
must
be
replaced (Fig.
1).
Also replace belt
if it has
excessive wear,
frayed cords
or
severe glazing.
Refer to the Serpentine Drive Belt Diagnosis charts
for further belt diagnosis. Also refer
to
Automatic Belt Tensioner proceeding
in
this group.

BELT SCHEMATICS
The following belt routing schematics
are
pub­
lished from
the
latest information available
at the

time
of
publication.
If
anything differs between
these schematics
and the
Belt Routing Label,
use
the
schematics
on
Belt Routing Label. This
label
is
located
in
the engine compartment.

BELT TENSION

ALL
ENGINES
Correct accessory drive belt tension
is
required
to

be sure
of
optimum performance
of
belt driven
en­
gine accessories.
If
specified tension
is not
main­
tained, belt slippage may cause; engine overheating, lack
of
power steering assist, loss
of
air conditioning
capacity, reduced generator output rate and greatly
reduced belt life.
It
is
not necessary
to
adjust belt tension on any en­
gine.
All
engines
are
equipped with
an
automatic
belt tensioner. The tensioner maintains correct belt tension
at all
times. For other tensioner information
NORMAL CRACKS
BELT
OK
NOT NORMAL CRACKS

REPLACE
BELT
J9007-44

Fig. 1 Serpentine Accessory Drive Belt Wear Patterns
and removal/installation procedures, refer
to
Auto­
matic Belt Tensioner proceeding
in
this group.
Due

to use
of
this belt tensioner, do not attempt
to
use
a

belt tension gauge
on
any engine.

BELT REMOVAL/INSTALLATION

Caution:
Do not
attempt
to
check belt tension with
a
belt
tension gauge
on
vehicles equipped with
an
automatic belt tensioner. Refer
to
Automatic Belt

Tensioner
in
this
group.

3.9L/5,2U5*9L
LDC-GAS ENGINES

REMOVAL
Drive belts
on
these engines
are
equipped with
a

spring loaded automatic belt tensioner (Fig.
7).
This
belt tensioner will
be
used on
all
belt configurations, such
as
with
or
without power steering
or
air condi­
tioning.
For
more information, refer
to
Automatic Belt Tensioner, proceeding
in
this group.
(1) Attach
a
socket/wrench
to
pulley mounting bolt
of automatic tensioner (Fig.
7).

•

*IF VEHICLE IS NOT EQUIPPED
WITH
POWER

STEERING,
THIS
WILL
BE
AN
IDLER PULLEY.
J9307-26
Fig.
2 Beit
Routing
- 3.9U5.2L/5.9L
LDC-Gas
Engine

AUTOMATIC TENSIONER

J9307-55
Fig.
3 Beit Routing—5.9L HDC-Gas Engine—With
A/C

(2)
Rotate tensioner assembly clockwise (as viewed
from front) until tension has been relieved from belt.
(3) Remove belt from idler pulley first.

(4)
Remove belt from vehicle.

INSTALLATION

CAUTION:
When
installing
serpentine accessory

drive
belt, belt
must
be
routed
correctly.
If not, en­
gine
may
overheat
due to
water
pump
rotating in
COOLING
SYSTEM
7 - 43

AUTOMATIC TENSIONER

J9307-56

Fig.
4 Belt Routing—5.9L
HDC-Gas
Engine—Without A/C

'POWER STEERING PUMP IS
NOT
BELT DRIVEN
Fig.
5 Belt Routing-5.9L Diesel-With A/C
wrong
direction. Refer
to
(Fig.
2) for
correct engine
belt routing.
The
correct belt with correct length

must
be
used.

(1) Position drive belt over all pulleys except idler
pulley. This pulley is located between generator and
A/C compressor.
(2) Attach a socket/wrench to pulley mounting bolt
of automatic tensioner (Fig. 7).

7 - 44
COOLING
SYSTEM

•

Fig.
6 Belt Routing-5.9L Diesel-Without A/C
Fig.
7 Belt Tensioner-3.9L/5.2U5.9L
LDC-Gas
Engine
(3)
Rotate socket/wrench clockwise. Place belt over
idler pulley. Let tensioner rotate back into place. Re­
move wrench. Be sure belt is properly seated on all
pulleys.

(4)
Check belt indexing marks. Refer to the pro­
ceeding Automatic Belt Tensioner for more belt in­
formation. 5.9L
HDC-GAS
ENGINE

REMOVAL
Drive belts are equipped with a spring loaded au­
tomatic belt tensioner (Fig. 8). This belt tensioner
will be used on all belt configurations, such as with or without power steering or air conditioning. For
more information, refer to Automatic Belt Tensioner,
proceeding in this group.

Fig.
8 Belt Tensioner—5.9L
HDC-Gas Engine

(1) Attach a socket/wrench to pulley mounting bolt
of automatic tensioner (Fig. 8). (The threads on this
bolt are left hand).
(2) Relax the tension from the belt by rotating the
tensioner counterclockwise (as viewed from front) (Fig. 8). When all belt tension has been relaxed, re­
move belt from tensioner pulley first and other pul­ leys last.

INSTALLATION

CAUTION:
When installing serpentine
accessory

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

wrong
direction. Refer
to
(Figs.
3 or 4) for
correct
engine
belt routing.
The
correct belt with correct length must
t^e
used.

CAUTION:
if the
pulley
is to be
removed from
the

tensioner,
its
mounting bolt
has left
hand threads.

(1) Position drive belt over all pulleys except ten­
sioner pulley. (2) Attach a socket/wrench to pulley mounting bolt
of automatic tensioner (Fig. 8).

•

COOLING
SYSTEM
7 - 45 (3) Rotate socket/wrench counterclockwise. Install
belt over tensioner pulley. Let tensioner rotate back into place. Remove wrench. Be sure belt is properly
seated on all pulleys.

5«9L
DIESEL ENGINE

REMOVAL
Drive belts on diesel engines are equipped with a
spring loaded automatic belt tensioner (Fig. 9). Fig­
ure 9 displays the tensioner for vehicles without air conditioning.
This belt tensioner will be used on all belt config­
urations, such as with or without air conditioning.
For more information, refer to Automatic Belt Ten­ sioner, proceeding in this group.
Fig.
9 Belt Tensioner—5.9L
Diesel
Engine—Typical
(1) A 3/8 inch square hole is provided in the auto­
matic belt tensioner (Fig. 9). Attach a 3/8 inch drive-
long handle ratchet to this hole.
(2) Rotate ratchet and tensioner assembly counter­
clockwise (as viewed from front) until tension has
been relieved from belt.
(3) Remove belt from water pump pulley first.
(4) Remove belt from vehicle.

INSTALLATION

CAUTION:
When installing serpentine
accessory

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

gine
may
overheat
due to
water pump rotating
in

wrong
direction. Refer
to
(Figs.
5 or 6) for
correct

engine
belt routing.
The
correct belt with correct
length
must
be
used.

(1) Position drive belt over all pulleys except wa­
ter pump pulley. (2) Attach a 3/8 inch ratchet to tensioner.
(3) Rotate ratchet and belt tensioner counterclock­

wise.
Place belt over water pump pulley. Let ten­ sioner rotate back into place. Remove ratchet. Be
sure belt is properly seated on all pulleys.

AUTOMATIC
BELT
TENSIONER
Drive belts on all engines are equipped with a
spring loaded automatic belt tensioner (Figs. 10, 11
or 12). This belt tensioner will be used with all belt configurations, such as with or without power steer­
ing or air conditioning.

Caution:
Do not
attempt
to
check belt tension with

a
belt tension
gauge
on
vehicles equipped with
an

automatic
belt tensioner. Fig.
10 Belt Tensioner—3.9U5.2U5.9L
LDC-Gas
Engine
On 3.9L/5.2L and 5.9L LDC-gas engines, the ten­
sioner is equipped with an indexing arrow (Fig. 13)
on back of tensioner and an indexing mark on ten­
sioner housing. If a new belt is being installed, arrow
must be within approximately 3 mm (1/8 in.) of in­ dexing mark (Point B—Fig. 13). Belt is considered
new if it has been used 15 minutes or less. If this
specification cannot be met, check for:
• The wrong belt being installed (incorrect length/
width)
• Worn bearings on an engine accessory (A/C com­
pressor, power steering pump, water pump, idler pul­ ley or generator)
• A pulley on an engine accessory being loose
• Misalignment of an engine accessory
• Belt incorrectly routed. Refer to (Figs. 2, 3 or 4) On 3.9L/5.2L and 5.9L LDC-gas engines, a used
belt should be replaced if tensioner indexing arrow
has moved beyond point A (Fig. 13).