1993 DODGE TRUCK Service Repair Manual

7 - 34
COOLING SYSTEM

•
WARNING;
DO NOT
REMOVE
THE
CYLINDER
BLOCK DRAIN PLUGS
OR
LOOSEN
THE
RADIATOR
DRAINCOCK
WITH
THE
SYSTEM
HOT AND
UNDER

PRESSURE.
SERIOUS BURNS FROM COOLANT
CAN OCCUR.

(2) Drain the cooling system. Refer to Draining
Cooling System in this group. (3) Remove hose clamps and hoses from radiator.
Remove coolant reserve/overflow tank hose from ra­ diator filler neck nipple.
(4) Remove fan shroud retaining clips. The shroud
has two tabs that fit into clips in the bottom of the radiator. Lift the shroud up and position it back onto
the engine (Fig. 46).
Fig. 46 Radiator and Fan
Shroud—5.9L
Diesel Engine
(5) Remove radiator top mounting brackets. The
brackets fit over support dowels on the radiator inlet
tank (Fig. 46).
(6) The bottom of the radiator has two dowels that
fit into holes in the lower support panel. Taking care not to damage radiator cooling fins or tubes, lift ra­
diator straight up out of engine compartment
INSTALLATION (1) Position shroud rearward on engine.
(2) Lower radiator into position. The dowels on the
bottom of the radiator fit into alignment holes in the lower support panel.
(3) Install top mounting brackets. Tighten mount­
ing bolts to 23 N*m (17 in. lbs.) torque. (4) Connect radiator hoses. Install hose clamps.
(5) Position fan shroud on radiator flange. Install
retaining clips. (6) Place heater controls in full heat position.
(7) Fill cooling system with coolant. Refer to Refill­
ing Cooling System in this group.
(8) Operate engine until it reaches normal temper­
ature. Check cooling system. RADIATOR DRAINCOCK SERVICE
The radiator draincock is replaceable. Unscrew the
draincock in a clockwise direction and remove from
radiator. Install replacement draincock.

COOLING SYSTEM HOSES
Rubber hoses route coolant to and from the radia­
tor, intake manifold and heater core. Radiator lower
hoses are spring-reinforced to prevent collapse from
water pump suction at moderate and high engine speeds. Inspect the hoses at regular intervals. Replace
hoses that are cracked, feel brittle when squeezed or swell excessively when system is pressurized. The
use of molded replacement hoses is recommended.
When performing a hose inspection, inspect radiator lower hose for proper position and condition of spring.

RADIATOR

J9207-35

Fig. 47 Radiator Hoses—Typical
HOSE CLAMPS Constant tension hose clamps are used on some
cooling system hoses. The clamp size is identified by a letter stamped on the tongue. Special Clamp Tool
number 6094 (Fig. 48) may be used to remove the
constant tension clamps.
Ordinary worm gear type hose clamps (when
equipped) can be removed with a straight screw­
driver or a hex socket. To prevent damage to
hoses or clamps, the hose clamps should be
tightened to 4 N«m (34 in. lbs.) torque. Do not
over tighten hose clamps.

•

COOLING
SYSTEM
7 - 35

HOSE
CLAMP TOOL
6094
HOSE

CLAMP

J9207-36
Fig.
48
Hose
damp Tool

TRANSMISSION
OIL
COOLER—EXCEPT DIESEL
The automatic transmission oil is cooled when it
passes through a cooler in the radiator lower tank (Fig. 49 and 50).

h*-TRANSMISSION

- OIL
COOLER

FRONT
OF
VEHICLE
AUTOMATIC

TRANSMISSION
PRESSURE
LINE
6 AND
8
CYLINDER ENGINE

RETURN
LINE
RY402

Fig.
49 Top View of
Transmission
Oil
Cooling
Circuit—Except Diesel—Typical

COOLING
TUBE (CUT-A-WAY)

DRAIN
COCK
HOSE

CLAMP
HOSE
TO

COOLER
LINE
HOSE
TO

COOLER
LINE

RY401

Fig.
50 Automatic
Transmission
Oil Cooler—Except
Diesel—
Typical

In case of a leak in the transmission oil cooler, en­
gine coolant may become mixed with transmission
fluid or transmission fluid may enter engine cooling system. Both cooling system and transmission should
be drained and inspected in the event cooler is leak­ ing.
REPLACING
OIL
COOLER
IN
BOTTOM
TANK

Remove radiator. Refer to Radiator removal in this
group. The servicing should be performed by a qual­
ified repair facility.
Once the repaired or replacement radiator has been
installed, fill the cooling system and inspect for

leaks.
Refer to Refilling Cooling System and Testing Cooling System For Leaks sections in this group. If
the transmission operates properly after repairing
the leak, drain the transmission and remove the
transmission oil pan. Inspect for sludge and/or rust. Inspect for a dirty or plugged inlet filter. If none of
these conditions are found, the transmission and
torque convertor may not require reconditioning. Re­
fer to Group 21 for automatic transmission servicing.

1RANSMISSI0N
OIL
COOLER-DIESEL
The transmission oil cooler is mounted to a bracket
on the turbocharger side of the engine (Fig. 51).

TRANSMISSION
OIL
COOLER
Fig.
51 Automatic
Transmission
Oil Cooler—5.9L

Diesel
REMOVAL

In case of a leak in the transmission oil cooler, en­
gine coolant may become mixed with transmission
fluid or transmission fluid may enter engine cooling system. Both cooling system and transmission should
be drained and inspected in the event cooler is leak­ ing. (1) Disconnect negative battery cable at battery.
(2) Drain cooling system. Refer to Draining Cool­
ing System. (3) Disconnect coolant lines from cooler.
(4) Disconnect transmission oil lines from cooler.
Plug cooler lines to prevent oil leakage. (5) Remove oil cooler mounting straps.
(6) Lift oil cooler off of mounting bracket.

INSTALLATION
(1) Position oil cooler on bracket.
(2) Install mounting straps.
(3) Connect transmission oil lines to cooler.

7 - 36
COOLING
SYSTEM

• (4) Connect coolant hoses to cooler.

(5)
Connect battery cable to battery.

(6)
Fill cooling system. Refer to Refilling Cooling
System in this section. (7) Check transmission oil level and fill as neces­
sary.

TRANSMISSION
OIL/TO-AIR
COOLER
Oil to air transmission coolers are mounted ahead
of the radiator and operate in conjunction with the
main cooler (Figs, 52 or 53). The transmission oil is
routed through the main cooler first, then the auxil­ iary cooler, before returning to the transmission.
FRONT
OIL-TO-AIR
COOLER

RADIATOR
RADIATOR GRILL SUPPORT RETURN JO

_
TRANSMISSION

*
PRESSURE

(FROM BOTTOM COOLER)
VIEW
IN
CIRCLE J9007-75 Fig.
52
Transmission
Oil-to-Air Cooler—Except

Diesel—
Typical

AUXILIARY
OIL TO AIR
COOLER
J9107-73
Fig.
53
Transmission
Oil-to-Air
Cooler—Diesel

Engine—Typical
COOLING
SYSTEM FAN—GAS ENGINES

Also refer to Viscous Fan Drive in this group for
additional information.
REMOVAL (1) Disconnect negative battery cable from battery.
(2) Remove throttle cable at top of fan shroud.
(3) Unsnap coolant reserve/overflow tank from fan
shroud and lay aside. The tank is held to shroud
with T-shaped slots. Do not disconnect hose or drain
coolant from tank.
(4) The thermal Viscous Fan Drive/Fan Blade As­
sembly is attached (threaded) to water pump hub
shaft (Fig. 54). Remove fan blade/viscous fan drive
assembly from water pump by turning mounting nut
counterclockwise as viewed from front. Threads on
viscous fan drive are RIGHT HAND. A Snap-On 36
MM Fan Wrench (number SP346 from Snap-On Cummins Diesel Tool Set number 2017DSP) can be
used. Place a bar or screwdriver between water pump
pulley bolts (Fig. 54) to prevent pulley from rotating. Do not attempt to remove fan/viscous fan drive as­
sembly from vehicle at this time.
FAN BLADE

ASSEMBLY

THREADED NUT WATER
PUMP

PULLEY
PULLEY
BOLTS
WATER PUMP
THREADED SHAFT
(WATER PUMP HUB)
VISCOUS
FAN DRIVE CRANKSHAFT
PULLEY
J9307-32

Fig.
54 Fan
Blade/Viscous
Fan
Drive—Gas
Engines
Do not unbolt fan blade assembly (Fig. 54) from
viscous fan drive at this time.
(5) Remove fan shroud attaching hardware (two
bolts at bottom-two clips at top). (6) Remove fan shroud and fan blade/viscous fan
drive assembly as a complete unit from vehicle.
After removing fan blade/viscous fan drive assem­
bly, do not place viscous fan drive in horizontal po­ sition. If stored horizontally, silicone fluid in the
viscous fan drive could drain into its bearing assem­
bly and contaminate lubricant.

•

COOLING
SYSTEM
7 - 37
CAUTION:
Do not
remove
water
pump pulley-to-wa­

ter
pump
bolts
(Fig. 54), This
pulley
is
under spring
tension.

(7) Remove four bolts securing fan blade assembly
to viscous fan drive (Fig. 54).
INSPECTION The fan cannot be repaired. If fan is damaged, it
must be replaced. Inspect fan as follows:
(1) Remove fan blade and viscous fan drive as an
assembly from the engine. Refer to preceding Re­
moval procedure.
(2) Remove fan blade assembly from viscous fan
drive unit (four bolts).
(3) Lay fan on a flat surface with leading edge fac­
ing down. With tip of blade touching flat surface, re­
place fan if clearance between opposite blade and surface is greater than 2.0 mm (.090 inch). Rocking
motion of opposite blades should not exceed 2.0 mm (.090 inch). Test all blades in this manner.

WARNING:
DO NOT
ATTEMPT
TO
BEND
OR
STRAIGHTEN
FAN
BLADES
IF 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 fan
blade assembly
is
replaced
be­

cause
of
mechanical damage,
water
pump
and
vis­

cous
fan
drive should
also
be
inspected. These

components
could have been damaged
due to ex­

cessive
vibration.

INSTALLATION (1) Install fan blade assembly to viscous fan drive.
Tighten bolts (Fig. 48) to 23 N*m (17 ft. lbs.) torque. (2) Position fan shroud and fan blade/viscous fan
drive assembly to vehicle as a complete unit.
(3) Install fan shroud.
(4) Install fan blade/viscous fan drive assembly to
water pump shaft (Fig. 54). (5) Install coolant reserve/overflow tank to fan
shroud. Snaps into position.
(6) Install throttle cable to fan shroud.
(7) Connect negative battery cable.

COOLING
SYSTEM
FAN-DIESEL ENGINE

REMOVAL (1) Disconnect negative battery cable from battery.
(2) Remove the fan shroud mounting bolts. Posi­
tion fan shroud towards engine.

CAUTION:
Do not
remove
the fan
puHey bolts. This pulley
is
under spring tension.
(3) The thermal viscous fan drive/fan blade assem­
bly is attached (threaded) to the fan hub shaft (Fig.
55).
Remove the fan blade/fan drive assembly from
fan pulley by turning the mounting nut clockwise (as
viewed from front). Threads on the viscous fan drive are LEFT HAND. A Snap-On 36 MM Fan Wrench
(number SP346 from Snap-On Cummins Diesel Tool
Set number 2017DSP) can be used. Place a bar or
screwdriver between the fan pulley bolts to prevent
pulley from rotating.

THREADED
Fig.
55 Fan
Blades/Viscous
Fan Drive-5.9L
Diesel
(4) Remove the fan shroud and the fan blade/vis­
cous drive as an assembly from vehicle.
(5) Remove fan blade-to-viscous fan drive mount­
ing bolts.
Inspect the fan for cracks, loose rivets, loose or
bent fan blades.
INSPECTION The fan cannot be repaired. If the fan is damaged,
it must be replaced. Inspect the fan as follows:
(1) Remove fan blade and thermal viscous fan
drive assembly from engine. Refer to the preceding
Removal procedure.
(2) Remove fan blade assembly from thermal vis­
cous fan drive unit (four bolts). (3) Lay fan on a flat surface with leading edge fac­
ing down. With tip of blade touching flat surface, re­
place fan if clearance between opposite blade and surface is greater than 2.0 mm (.090 inch). Rocking
motion of opposite blades should not exceed 2.0 mm (.090 inch). Test all blades in this manner.

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.

Fig.
57
Disconnecting
End of Thermostatic Fig. 58 Testing
Spring
and Shaft Rotation-Typical

Spring—Typical

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).

•

COOLING
SYSTEM
7 - 41 SERPENTINE DRIVE BELT DIAGNOSIS-EXCEPT DIESEL ENGINE

Condition
Possible
Cause
Correction

RIB
CHUNKING

(ONE
OR
MORE
RIBS

HAS
SEPARATED

FROM
BELT
BODY)
(1)
Foreign objects imbedded in
pulley
grooves.

(2) Installation damage. (1) Remove foreign objects from
pulley
grooves.
Replace belt.
(2) Replace belt.

RIB
OR
BELT
WEAR
(1)
Put ley
(s)
misaligned. (1) Align pulley(s).
(2) Abrasive environment. (2) Clean pulley(s). Replace

belt
if
necessary.

(3)
Rusted
pulley(s). (3) Clean rust from pulley(s).
(4)
Sharp
or jagged pulley groove tips. (4) Replace pulley.
(5) Rubber deteriorated. (5) Replace belt.

LONGITUDINAL

BELT
CRACKING
(CRACKS
BETWEEN

TWO
RIBS)
(1) Belt has mistracked from pulley

groove.

(2) Pulley groove tip
has
worn away rubber to tensile member. (1) Replace belt.
(2) Replace belt.

BELT
SLIPS
(1) Belt
slipping
because of
insufficient tension. (1) Adjust tension.
(2) Belt or pulley subjected to
substance
(belt
dressing,
oil,
ethylene glycol)
that
has
reduced
friction. (2) Replace
belt
and clean pulleys.
(3) Driven component bearing failure. (3) Replace faulty component bearing.

(4)
Belt glazed and hardened from heat and
excessive
slippage.
(4) Replace belt.

"GROOVE
JUMPING"

(BELT
DOES
NOT

MAINTAIN
CORRECT
POSITION
ON

PULLEY)
(1)
Belt tension
either
too

high
or too low.
(2) Pulley(s) not within design tolerance. (1) Adjust
belt
tension.
(2) Replace pulley(s).
(3) Foreign object(s) in
grooves.
(3) Remove foreign objects from

grooves.

(4) Pulley misalignment. (4)
Align
pulley(s).
(5) Belt cordline is broken. (5) Replace belt.

BELT
BROKEN

(NOTE:
IDENTIFY

AND
CORRECT
PROBLEM
BEFORE

NEW
BELT
IS
INSTALLED)
(1)
Excessive
tension.
(2) Tensile members damaged during
belt
installation.
(3) Severe misalignment. (1) Replace
belt
and adjust tension
to specification.
(2) Replace belt.
(3) Align pulley(s).

(4)
Bracket, pulley, or bearing failure. (4) Replace defective component and
belt.

NOISE

(OBJECTIONAL

SQUEAL,
SQUEAK,

bR
RUMBLE
IS
HEARD
OR
FELT

WHILE
DRIVE
BELT
IS
IN
OPERATION)
(1)
Belt
slippage.

(2) Bearing noise.
(3) Belt misalignment.
(4) Beit-to-pulley mismatch. (1) Adjust belt.
(2) Locate and repair.
(3)
Align
belt/pulley(s).
(4) Install correct belt. E8907-143