tow DODGE TRUCK 1993 Service Owner's Guide

•

CLUTCH
6 - 3 Check condition of the clutch before installation. A
warped cover or diaphragm spring will cause grab and incomplete release or engagement.
Be careful when handling the cover and disc. Im­
pact can distort the cover, diaphragm spring, release
fingers and the hub of the clutch disc.
Use an alignment tool when positioning the disc on
the flywheel. The tool prevents accidental misalign­ ment which could result in cover distortion and disc
damage.
A frequent cause of clutch cover distortion (and
consequent misalignment) is improper bolt tighten­
ing. To avoid warping the cover, tighten the bolts al­
ternately (in a diagonal pattern) and evenly (2-3
threads at a time) to specified torque.
Clutch
Housing
Misalignment And Runout Clutch housing alignment is important to proper
operation. The housing bore maintains alignment be­
tween the crankshaft and transmission input shaft.
Misalignment can cause noise, incomplete clutch
release and chatter. It can also result in premature
wear of the pilot bearing, cover release fingers and
clutch disc. In severe cases, misalignment can also cause premature wear of the transmission input
shaft and bearing.
Housing face misalignment is generally caused by
incorrect seating on the engine or transmission, loose
housing bolts, missing alignment dowels or housing damage. Infrequently, misalignment may also be
caused by housing mounting surfaces that are not
parallel. If housing misalignment is suspected, housing bore
and face runout can be checked with a dial indicator
as described in the following two procedures:

MEASURING
CLUTCH HOUSING BORE
RUNOUT
(1) Remove the clutch housing and strut.
(2) Remove the clutch cover and disc.
(3) Replace one of the flywheel bolts with a 7/16-20
threaded rod that is 10 in. (25.4 cm) long (Fig. 1).
The rod will be used to mount the dial indicator.
(4) Remove the release fork from the clutch hous­
ing. (5) Reinstall the clutch housing. Tighten the hous­
ing bolts nearest the alignment dowels first. (6) Mount the dial indicator on the threaded rod
and position the indicator plunger on the surface of
the clutch housing bore (Fig. 2).
(7) Rotate the crankshaft until the indicator
plunger is at the top center of the housing bore. Zero the indicator at this point.
(8) Rotate the crankshaft and record the indicator
readings at eight points (45° apart) around the bore (Fig. 3). Repeat the measurement at least twice for
accuracy. (9) Subtract each reading from the one 180° oppo­
site to determine magnitude and direction of runout.
Refer to Figure 3 and following example.
Bore runout example: 0.000 - (-0.007) = 0.007 in. + 0.002 - (-0.010) = 0.012 in.
+ 0.004 - (-0.005) = 0.009 in.
-0.001 -
(
+ 0.001) = -0.002 in. (= 0.002 inch)
In the above example, the largest difference is
0.012 in. and is called the total indicator reading
(TIR).
This means that the housing bore is offset
from the crankshaft centerline by 0.006 in. (which is 1/2 of 0.012 in.).
On gas engines, the acceptable maximum TIR for
housing bore runout is 0.010 inch. If measured TIR is more than 0.010 in. (as in the example), bore runout
will have to be corrected with offset dowels. Offset dowels are available in 0.007, 0.014 and 0.021 in.
sizes for this purpose (Fig. 4). Refer to Correcting
Housing Bore Runout for dowel installation.
On diesel engines, the acceptable maximum
TIR for housing bore runout is 0.015 inch. How­
ever, unlike gas engines, offset dowels are not available to correct runout on diesel engines. If
bore runout exceeds the stated maximum on a diesel engine, it may be necessary to replace ei­
ther the clutch housing, or transmission adapter
plate.

CORRECTING CLUTCH HOUSING BORE
RUNOUT
(GAS
ENGINE
ONLY)
On gas engine vehicles, clutch housing bore runout
is corrected with offset dowels. However, if bore
runout exceeds 0.015 in. TIR on a diesel equipped model, the clutch housing, or transmission adapter
plate may have to be replaced. Offset dowels are not available for diesel models.
The dial indicator reads positive when the plunger
moves inward (toward indicator) and negative when it moves outward (away from indicator). As a result,
the lowest or most negative reading determines the
direction of housing bore offset (runout).
In the sample readings shown in Figure 3 and in
step (7) above, the bore is offset toward the 0.010
inch reading. To correct this, remove the housing and
original dowels. Then install the new offset dowels in
the direction needed to center the bore with the crankshaft centerline.
In the example, TIR was 0.012 inch. The dowels
needed for correction would have an offset of 0.007
in. (Fig. 4).
Install the dowels with the slotted side facing out
so they can be turned with a screwdriver. Then in­
stall the housing, remount the dial indicator and
check bore runout again. Rotate the dowels until the
TIR is less than 0.010 in. if necessary.
If a TIR of 0.053 in. or greater is encountered, it
may be necessary to replace the clutch housing.

6 - 6
CLUTCH

1
Check
clutch
housing bolts.
Tighten
if loose. Be sure

housing
is
fully
seated on engine block.
2 Check
flywheel
condition.
Scuff sand
flywheel
face
to remove glaze. Clean surface
with
a wax and

grease
remover afterward. Replace
flywheel
if
severely scored, worn or cracked. Secure
flywheel

with
new bolts (if removed). Do not reuse old bolts.
Use
Lock and Seal on bolts.

3
Tighten clutch cover bolts 2-3 threads at a
time,
alter­
nately and evenly (in a diagonal
pattern)
to specified
torque. Failure to do so could warp the cover.
4 Check release fork. Replace fork if distorted or worn. Make sure ball stud and release bearing contact sur­

faces
are lubricated.

5
Check release fork pivot. Be sure pivot is tight and ball end is lubricated.
6 Transmission input
shaft
bearing
will
cause noise,
chatter,
or improper release if
damaged.
Check
con­

dition before installing transmission.
7 Inspect release bearing slide surface of trans,
front
bearing
retainer.
Surface should be smooth,
free
of

nicks,
scores.
Replace
retainer
if
necessary.
Lubricate slide surface before installing release bearing. 8 Check input shaft seal if clutch cover and
disc
were

oil covered. Replace seal if worn, or cut.
9 Do not replace release bearing
unless
actually
faulty.
Replace bearing only if seized, noisy, or damaged.
10 Check clutch cover diaphragm spring and release
fingers.
Replace cover if spring or fingers are bent, warped, broken, cracked. Do not tamper
with
fac­

tory
clutch spring setting. Clutch problems
will
result.
11 Check condition of clutch cover. Replace clutch cover if
plate
surface is deeply scored, warped, worn, or
cracked. Be sure cover is correct size and properly
aligned on
disc
and flywheel.
12 Inspect clutch
housing.
Be sure alignment dowels are in position and bolts are tight. Replace housing if
cracked, or damaged. If clutch problems ocurred,
check runout, to be sure housing is square
with

flywheel
and transmission input shaft.
13
Verify
that
housing
alignment dowels are in position before installing
housing.

14 Clean engine block surface before installing clutch
housing.
Dirt, grime can produce misalignment.
15 Make sure side of clutch
disc
marked
"flywheel
side"
is
toward flywheel.
16 Check
rear
main seal if clutch
disc
and cover
were
oil covered. Replace seal if necessary.
17 Check crankshaft flange (if
flywheel
is removed). Be sure flange is clean and
flywheel
bolt threads are
in
good
condition.
18 Check pilot bearing. Replace bearing if dam­
aged.
Lube
with
high temp. Grease before in­
stallation.
19 Check transmission input shaft. Clutch
disc
must slide
freely
on shaft splines. Lightly grease

splines
before installation. Replace shaft if

splines
or pilot bearing hub are damaged.
20 Check
flywheel
bolt torque. If bolts are loose, replace them. Use Mopar Lock and Seal to secure
new bolts.
21 Check clutch
disc
facing. Replace
disc
if facing is charred, scored, flaking off, or worn.
Also
check runout of new
disc.
Runout should not ex­
ceed 0.5 mm (0.02 in.).

J9206-9

Fig. 8 Clutch Inspection Points

6
- 8
CLUTCH

IMPROPER CLUTCH
RELEASE

Condition
Found
Cause
Correction

1.
Clutch disc warped. New disc not checked for axial
runout before installation. Replace
disc.
Be sure runout of new

disc
is
less
than .5 mm (.020 in.).
2. Clutch disc binds on input shaft splines. a) Clutch disc hub splines

damaged
during installation.
b) Input shaft splines rough,
damaged.

c) Corrosion, rust formations on
splines
of disc and input shaft.
Clean,
smooth and lubricate disc
and shaft spines. Replace disc
and/or input shaft if splines are
severely damaged.
3. Clutch disc rusted to
flywheel
and/or pressure plate.
Occurs
in vehicles stored, or not
driven for extended periods
of
time.
Also
occurs
after
steam
cleaning if vehicle is not used for extended period.
Remove
clutch cover and
disc.
Sand
rusted surfaces clean
with
180 grit
paper. Replace disc cover, and

flywheel
if corrosion is severe.
4. Clutch disc facing sticks to flywheel.
Vacuum
may form in pockets over

rivet
heads in clutch
disc.
Occurs as
clutch cools down
after
use.
Drill
1/16 inch diameter hole
through rivets and scuff sand disc
facing
with
180J
9r>t
paper.
5. Clutch disc too thick.
Wrong
disc installed. Replace
disc.

6. Pilot bushing seized or loose. a) Bushing cocked during

installation.

b) Bushing defective.
c) Bushing not lubricated.
d) Clutch misalignment. a), b), c), d) Lubricate and install
new bushing. Check and
correct any misalignment.
7. Clutch
will
not disengage properly. a) Low clutch fluid level.
b) Clutch cover loose.
c) Wrong clutch
disc.

d)
Disc
bent, distorted during installation.
e) Clutch cover diaphragm spring bent or wraped during

transmission
instalation.
f) Clutch disc installed
backwards.

g)
Release fork bent or fork pivot
is
loose or damaged.
h) Clutch master or slave cylinder
fault.
a) Top off reservoir and check for

leaks.

b) Tighten bolts.

|
c) Install correct
disc.
d) Repalce
disc.

e) Replace cover.
f) Remove and reinstall disc correctly. Be sure disc side marked "to flywheel" is
actually toward flywheel.

g)
Replace
fork
and pivot if worn or damaged.
h) Replace master and slave cylinder as assembly.
J9006-22

6-12
CLUTCH

(c) Position indicator plunger about 1/4 inch from
outer edge of disc facing.
(d) Runout should not exceed 0.5 mm (0.020 in.).
Obtain another clutch disc if runout exceeds this
limit.
(2) Lubricate crankshaft pilot bearing with Mopar
high temperature bearing grease.
(3) Insert clutch alignment tool in clutch disc hub,
(4) Verify that clutch disc is positioned correctly.
Side of hub marked "Flywheel Side" should face fly­
wheel (Fig. 4). If disc is not marked, position raised side of disc hub toward clutch cover and transmis­
sion.
CLUTCH

DISC

"FLYWHEEL
SIDE"
STAMPED
ON

THIS
SURFACE

J9006-33
Fig. 4 Clutch Disc Position (Typical)
(5) Insert alignment tool in pilot bearing and posi­
tion disc on flywheel surface (Fig. 5).
(6) Position clutch cover over disc and onto fly­
wheel (Fig. 5).

CLUTCH COVER AND DISC CLUTCH DISC
ALIGNMENT TOOL

FLYWHEEL.
J9106-18

Fig. 5 Clutch Disc And
Cower
Alignment/installation (7) Align and hold clutch cover in position and in­
stall cover bolts finger tight.
(8) Tighten cover bolts evenly and a few threads at
a time. Cover bolts must be tightened evenly and
to specified torque to avoid distorting cover.
• Tighten 5/16 in. diameter bolts to 23 N-m (17 ft.
lbs.)
• Tighten 3/8 in. diameter bolts to 41 N-m (30 ft.

lbs.).
(9) Remove release lever and release bearing from
clutch housing. Apply Mopar high temperature bear­
ing grease to bore of release bearing, release lever
contact surfaces and release lever pivot stud (Fig. 6).
CLUTCH

HOUSING

COAT

RELEASE

FORK
PIVOT
BALL STUD

WITH

HIGH
TEMP.
GREASE

RELEASE
FORK

(HIGH
TEMP.
GREASE)
LUBE
POINTS

(HIGH
TEMP.
GREASE)
APPLY
LIGHT
COAT

HIGH
TEMP. GREASE
TO RELEASE BEARING
BORE
LUBE
POINTS

J9106-19
Fig. 6 Clutch Release Component Lubrication
Points
(10) Apply light coat of Mopar high temperature
bearing grease to splines of transmission input shaft and to release bearing slide surface of transmission
front bearing retainer (Fig. 7). Do not overlubri- cate shaft splines. Grease contamination of disc
will result. (11) Install release lever and bearing in clutch
housing.
(12) Install clutch housing (Figs. 8 and 9). Be sure
housing is properly seated on alignment dowels be­ fore tightening housing bolts.
(13) Install transmission/transfer case.
(14) Check fluid level in clutch master cylinder. transmission and
CLUTCH HOUSING REMOVAL

(1) Raise vehicle and remove
transfer case if equipped. (2) Remove clutch housing bolts and remove hous­
ing from engine (Figs. 8 and 9). (3) Clean housing mounting surface of engine
block with wax and grease remover.

6
- 14
CLUTCH

(9) Install transmission. Also install transfer case
on 4-wheel drive models.
Fig.
10
Clutch
Release
Fork
And Bearing

PILOT BEARING REPLACEMENT
(1) Remove transmission and clutch housing.
(2) Remove clutch cover and disc.
(3) Remove pilot bearing. Use blind hole puller
tools such as those included in Snap-On set CG40CB
to remove bearing. (4) Clean bearing bore with solvent and wipe dry
with shop towel. (5) Install new bearing with clutch alignment tool
(Fig. 11). Keep bearing straight during installation.
Do not allow bearing to become cocked. Tap bearing
into place until flush with edge of bearing bore. Do
not recess bearing.

BEARING SEAL
MUST
FACE

J9206-8

Fig.
11 Typical Method Of Installing Pilot Bearing (6) Lubricate bearing with Mopar high tempera­
ture grease, or an equivalent quality grease.
(7) Install clutch cover and disc.
(8) Install clutch housing, transmission and trans­
fer case on 4-wheel drive models.

CLUTCH LINKAGE SERVICE
The clutch master cylinder, remote reservoir,
slave cylinder and connecting lines are all ser­
viced as an assembly. These components cannot
be serviced separately. The linkage cylinders and connecting lines are sealed units. They are
prefilled with fluid during manufacture and
must not be disassembled nor disconnected.

LINKAGE REMOVAL
(1) Raise vehicle.
(2) On diesel models, remove slave cylinder shield
from clutch housing (Fig. 12).
Fig.
12
Slave
Cylinder
Shield—Diesel
Models

(3) Remove nuts attaching slave cylinder to studs
on clutch housing flange.
(4) Remove slave cylinder from clutch housing
(Fig. 13). (5) Disengage slave cylinder fluid line from under-
vehicle retainer clips. (6) Lower vehicle.
(7) On diesel models, disconnect clutch pedal inter­
lock switch wires.
(8) Carefully remove locating clip from clutch mas­
ter cylinder mounting bracket (Fig. 14). (9) Remove retaining ring, flat washer and wave
washer that attach clutch master cylinder push rod
to clutch pedal (Fig. 14).

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

7 - 2
COOLING
SYSTEM

•

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

CYLINDER
HEAD
RR07B52

Fig.
2
Cooling
System
Routing—5.9L (V-8 Gas)—Typical All vehicles are equipped with either a 3.9L (V-6),
a 5.2L (V-8), a 5.9L (LDC-gas V-8), a 5.9L (HDC-gas
V-8) or a 5.9L (in-line 6 cylinder diesel) engine.
As coolant temperature reaches approximately

220°F,
the engine idle speed is increased by the pow-
ertrain control module (PCM) to provide increased
cooling system performance. The PCM was formerly
referred to as the engine controller or SBEC.

COOLING
SYSTEM
COMPONENTS—EXCEPT

DIESEL
ENGINE
The cooling system consists of:
• A down-flow radiator
• Thermal viscous fan drive
• Fan shroud
• Radiator pressure cap
• Thermostat
• Coolant reserve/overflow system
• Transmission oil cooler (automatic transmission)
• Coolant
• Water pump (to circulate coolant)
• Hoses and hose clamps Coolant flow circuits for 3.9L (V-6) and 5.2L (V-8)
engines with water cooled intake manifolds are
shown in figure 1. Coolant flow circuits for 5.9L (V-8 Gas) engines
with water cooled intake manifolds are shown in fig­ ure 2.
COOLING
SYSTEM
COMPONENTS-DIESEL

ENGINE
Coolant flow circuits for 5.9L (diesel) engines with
water cooled intake manifolds are shown in figure 3. The cooling system (Fig. 3) consists of: a cross-flow
radiator, engine driven cooling fan, thermal viscous
fan drive, fan shroud, radiator pressure cap, thermo­ stat, coolant reserve/overflow system, transmission
oil cooler (if equipped with an automatic transmis­
sion),
coolant, water pump, hoses and hose clamps.

SYSTEM
COOLANT ROUTING-DIESEL ENGINE
Coolant is drawn from radiator into the water
pump. Water pump output is directed to the engine oil cooler cavity of the cylinder block (Fig. 4). From the oil cooler cavity, the coolant circulates
around each cylinder. It then crosses to the lift pump
side of engine where it flows up into cylinder head
through openings in top of cylinder block (Fig. 4). Coolant flows past the valve bridges (Fig. 5), to ex­
haust manifold side of engine, to thermostat. As cool­ ant flows toward the thermostat, it provides cooling
for the injector nozzle.
When thermostat is closed (engine is below operating
temperature), coolant flows through bypass passage to
water pump inlet (Fig. 6). Once operating temperature is reached, the thermostat opens and blocks the bypass
passage. Coolant then flows to the radiator inlet.

DIAGNOSIS

PRELIMINARY
CHECKS

ENGINE COOLING SYSTEM OVERHEATING Establish what driving conditions caused the com­
plaint. Abnormal loads on the cooling system such as
the following may be the cause:

1.
PROLONGED IDLE, VERY HIGH AMBI­
ENT TEMPERATURE, SLIGHT TAIL WIND AT
IDLE, SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED OR STEEP GRADES.
Driving techniques that avoid overheating are:
• Idle with A/C off when temperature gauge is at
end of normal range. * Increasing engine speed for more air flow is recom­
mended.

2.
TRAILER TOWING: Consult Trailer Towing section of owners manual.
Do not exceed limits.

3.
AIR CONDITIONING; ADD-ON OR AFTER
MARKET: A maximum cooling package should have been or­
dered with vehicle if add-on or after market A/C is
SYMPTOM AND ACTION

SYMPTOM
installed. If not, maximum cooling system compo­
nents should be installed for model involved per
manufacturer's specifications.

4.
RECENT SERVICE OR ACCIDENT RE­
PAIR:
Determine if any recent service has been performed
on vehicle that may effect cooling system. This may

be:

• Engine adjustments (incorrect timing)
• Slipping engine accessory drive belt(s) • Brakes (possibly dragging)
• Changed parts. Incorrect water pump or pump ro­
tating in wrong direction due to belt not correctly
routed
• Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
If investigation reveals none of the above as a
cause for an engine overheating complaint, refer to
the following Symptom and Action chart:
PRELIMINARY FIRST) ACTION
Blinking Engine Temperature
Warning Light or High Gauge indication - Without Coolant Loss
Normal during temporary operation
with
heavy load, towing
a
trailer,
high
outdoor temperatures, and/or on
a
steep
Loss
grade.

Coolant Loss
Hot Vehicle (Not Engine) Heat Damage,
Hot Carpet, Seat,
Hot
Catalytic
Converter,
Smoke, Burnt Odor
Hot Engine Crackling Noise Hot Smell
Severe Local Hot Spots
Coolant Color
Coolant Reserve Bottle Level Changes
Coolant Not Returning To Radiator
Improper refilling procedures
can
result
in
trapped air
in
the
system.
Subsequent
operation
of the
pressure cap and coolant reserve system
will
deaereate
the

cooling
system.
A low
coolant
level
will
then result
in the
Coolant Reserve
Tank. Add coolant.
If
condition persists,
refer
to
System
Diagnosis.

Check
heat shielding, exhaust
system,
engine emission controls, ignition
timing, engine misfiring.

A
moderate amount
of
sound from heating
metal
can
be
expected
with
any

vehicle. However,
a
crackling sound from
trie
thermostat
housing,
a hot
smell and/or severe local
hot
spots on
an
engine can indicate blocked coolant

passages,
bad castina, core sand deposits and subsequent blockage,
cracked cylinder block
or
head,
or
blown cylinder head gasket. Usually
accompanied
with
coolant
loss.

Coolant
color is
not
necessarily
an
indication
of
adequate
temperature
or

corrosion
protection.
Level changes
are to be
expected as coolant volume fluctuates
with
engine
temperature.
If the
level
in the
bottle
is
between
the
Maximum and Minimum
marks
at
normal engine operating temperature,
the
level
should
return
to

within
that
range
after
operation
at
elevated temperatures.

Coolant
will
not
return
to the
radiator
if the
radiator cap vent valve does
not

function,
if
an
air
leak destroys vacuum,
or if the
overflow
passage
is
blocked
or
restricted. Inspect
all
portions
of the
overflow
passage,
pressure

cap,
filler
neck nipple, hose, and
passages
within
the
bottle
for
vacuum leak
only. Coolant
return
failure
will
be
evident
by a low
level
in the
radiator.
Reserve
bottle
level
should increase during heat-up.

J9207-31

7 - 6
COOLING
SYSTEM

• COOLING SYSTEM DIAGNOSIS (EXCEPT DIESEL)—CONTINUED
Condition and Checks
Diagnosis

(7) Other possible
causes.
(7) a — If
symptom
occurs
during high speed operation inspect for

plugged
air
inlet
side of the radiator or condenser,

plugged
radiator core tubes, add on A/C package
without
proper radiator, engine not operating
within
specifications,

dragging
brakes,
trailer
towing or
hill
climbing, or an insect screen.
b — If
symptom
occurs
during high or low
speed
operation inspect for: thermostat being stuck
partially
open if ambient

temperature
is
below
70°F
and
the vehicle
has
high

mileage,
plugged
air
inlet
side of the radiator or
condenser, add on
A/C
with
incorrect radiator.

c
— If
symptom
occurs
during low
speed
operation only, inspect the radiator fan drive. Repair as necessary.

TEMPERATURE
GAUGE
READS
HOT.
PRESSURE
CAP
VENTS
RESULTING
IN
STEAM
AND
COOLANT
TRANSFER
TO

COOLANT
RESERVE
TANK.
(1) Coolant
level
low in radiator and coolant reserve tank. (1) a —
Fill
cooling
system
and vent trapped air.
b — Inspect for leaks. Repair as necessary.

c
—
Ensure
that
pressure cap
is
completely shut and
seals.

d
— If
level
is low in radiator but normal in the coolant reserve tank, check the
filler
cap to coolant reserve
bottle

connection and pressure cap seal.
(2) Test coolant
freeze
point. (2) Adjust coolant to
50/50
mix of
anti-freeze
and
water.
Refer to

Coolant
section in this group.
(3)
Ensure
coolant
is
flowing through system. (3) a — With the coolant
level
low and the thermostat open, check
for coolant flow through the radiator at the
filler
neck.
b — If a
metal
cracking
sound
is heard, inspect for core sand restricting coolant flow through the
water
jacket
and/or a

faulty
cylinder head casting.
(4) Thermostat stuck in the
closed
position
(prevalent
in cold ambient temperatures). (4) Replace thermostat if found to be stuck in
closed
position.
Refer
to the Thermostat Testing section in this group.
(5) Cylinder head gasket leak. (5) Inspect for leaking cylinder head gasket
with
a commercially
available Block Leak Tester.
J9007-57

•

COOLING
SYSTEM
7-11 DIESEL COOLING SYSTEM DIAGNOSIS-CONTINUED
Condition and Chocks
Diagnosis

(7) Other possible
causes.
(7) a — If
symptom
occurs
during high speed operation inspect for

plugged
air
inlet
side of the radiator or condenser,

plugged
radiator core tubes, add on
A/C
package without
proper radiator, engine not operating
within
specifications,

dragging
brakes,
trailer
towing or
hill
climbing, or an insect screen.
b — If
symptom
occurs
during
high
or low speed operation inspect for: thermostat being stuck
partially
open if ambient

temperature
is
below 70°F
and
the vehicle
has
high

mileage,
plugged
air
inlet
side of the radiator or
condenser, add on
A/C
with
incorrect radiator.

c
— If
symptom
occurs
during low
speed
operation only, inspect the radiator fan drive. Repair
as
necessary.

TEMPERATURE
GAUGE
READS
HOT.
PRESSURE
CAP VENTS
RESULTING
IN
STEAM
AND COOLANT
TRANSFER
TO

COOLANT
RESERVE
TANK.

(1)
Coolant
level
low in radiator and coolant reserve tank. (1) a —
Fill
cooling
system
and vent trapped air.
b — Inspect for leaks. Repair as necessary.

c
—
Ensure
that
pressure cap
is
completely shut and
seals.

d
— If
level
is low in radiator but normal in the coolant reserve tank, check the
filler
cap to coolant reserve
bottle
connection and pressure cap seal.
(2) Test coolant
freeze
point. (2) Adjust coolant to 50/50 mix of
anti-freeze
and
water.
Refer to

Coolant
section
in this group.
(3)
Ensure
coolant
is
flowing through system. (3) a — With the coolant
level
low and the thermostat open, check
for coolant flow through the radiator at the
filler
neck.
b — If a
metal
cracking
sound
is
heard, inspect for core sand restricting coolant flow through the
water
jacket
and/or a

faulty
cylinder head casting.
(4) Thermostat stuck in the
closed
position (prevalent in cold ambient temperatures). (4) Replace thermostat if found to be stuck in
closed
position. Refer
to the Thermostat Testing section in this group.
(5) Cylinder head gasket leak. (5) Inspect for leaking cylinder head
gasket
with
a commercially
available Block Leak Tester.
J9007-57