Datasheet exj_7 Datasheet

XJ COOLING SYSTEM 7 - 1

COOLING SYSTEM

TABLE OF CONTENTS

page page

DESCRIPTION AND OPERATION

COOLING SYSTEM........................1

AUTOMATIC TRANSMISSION OIL COOLER.....2

COOLANT RESERVE/OVERFLOW SYSTEM .....2

COOLING SYSTEM FANS...................3

BLOCK HEATER ..........................4

THERMOSTAT............................4

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

RADIATOR PRESSURE CAP.................5

WATER PUMP ...........................6

HOSE CLAMPS...........................6

VISCOUS FAN DRIVE......................7

ELECTRIC COOLING FAN...................8

DIAGNOSIS AND TESTING

ON-BOARD DIAGNOSTICS (OBD) ............9

DRB SCAN TOOL .........................9

ACCESSORY DRIVE BELT DIAGNOSIS.........9

PRELIMINARY CHECKS ...................11

RADIATOR COOLANT FLOW CHECK .........17

COOLING SYSTEM—TESTING FOR LEAKS....17

VISCOUS FAN DRIVE.....................19

ELECTRIC COOLING FAN..................19

RADIATOR CAP-TO-FILLER NECK

SEAL—PRESSURE RELIEF CHECK.........20

RADIATOR CAP—PRESSURE TESTING.......20

COOLANT—LOW LEVEL AERATION .........21

DEAERATION ...........................21

SERVICE PROCEDURES

COOLANT—ROUTINE LEVEL CHECK.........21

COOLANT—ADDING ADDITIONAL...........21

COOLANT—LEVEL CHECK.................21

COOLING SYSTEM—DRAINING AND

FILLING ..............................21

COOLING SYSTEM—REVERSE FLUSHING ....22

REMOVAL AND INSTALLATION

TRANSMISSION OIL COOLERS .............23

COOLANT RESERVE TANK.................23

WATER PUMP ..........................24

THERMOSTAT...........................28

RADIATOR—2.5L........................29

RADIATOR—4.0L........................31

ELECTRIC COOLING FAN—2.5L ............33

ELECTRIC COOLING FAN—4.0L ............34

BLOCK HEATER .........................35

ENGINE ACCESSORY DRIVE BELTS..........35

COOLING SYSTEM FANS..................38

VISCOUS FAN DRIVE REMOVAL/

INSTALLATION.........................39

CLEANING AND INSPECTION

RADIATOR PRESSURE CAP................39

RADIATOR .............................39

WATER PUMP ..........................39

FAN BLADE.............................39

COOLING SYSTEM HOSES.................40

SPECIFICATIONS

BELT TENSION ..........................40

TORQUE SPECIFICATIONS.................40

SPECIAL TOOLS

COOLING ..............................40

DESCRIPTION AND OPERATION

COOLING SYSTEM

DESCRIPTION

The cooling system regulates engine operating tem­perature. It allows the engine to reach normal oper­ating temperature as quickly as possible, maintains
normal operating temperature and prevents over­heating.

The cooling system also provides a means of heat­ing 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 heavy duty cooling
package is available on most models. The package
consists of a radiator that has an increased number
of cooling fins. Vehicles equipped with a 2.5L/4.0L
engine and heavy duty cooling and/or air condition­ing also have an auxiliary electric cooling fan.

The cooling system consists of:

• A radiator

• Cooling fan (mechanical and/or electrical)

• Thermal viscous fan drive

7 - 2 COOLING SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

• Fan shroud

• Radiator pressure cap

• Thermostat

• Coolant reserve/overflow system

• Transmission oil cooler (if equipped with an

automatic transmission)

• Coolant

• Water pump

• Hoses and hose clamps

Cooling system circulation for 2.5L/4.0L models is

shown in (Fig. 1).

Transmission oil is cooled when it passes through
this separate cooler. In case of a leak in the internal
radiator mounted transmission oil cooler, engine 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 if the internal radiator
mounted transmission cooler is leaking.

An auxiliary air-to-oil transmission oil cooler is
available with most engine packages.

The auxiliary air-to-oil transmission oil cooler is
located in front of the radiator or A/C condenser (if
equipped) and behind the grill. It is mounted to the
front frame crossmember.

The auxiliary oil coolers on all models operate in
conjunction with the internal radiator mounted main
oil cooler. The transmission oil is routed through the
main cooler first, then the auxiliary cooler, before
returning to the transmission.

Fig. 1 Coolant Circulation—2.5L/4.0L Engines

1 – HEATER CORE
2 – TO COOLANT RESERVE/OVERFLOW TANK
3 – THERMOSTAT HOUSING
4 – RADIATOR
5 – WATER PUMP

AUTOMATIC TRANSMISSION OIL COOLER

DESCRIPTION

All models equipped with an automatic transmis­sion are equipped with a transmission oil cooler
mounted internally within the radiator tank. This
internal cooler is supplied as standard equipment on
all models equipped with an automatic transmission.

Fig. 2 Auxiliary Transmission Oil Cooler

1 – AUXILIARY TRANSMISSION OIL COOLER

COOLANT RESERVE/OVERFLOW SYSTEM

DESCRIPTION

The system works along with the radiator pressure
cap. This is done by using thermal expansion and
contraction of the coolant to keep the coolant free of
trapped air. It provides:

• A volume for coolant expansion and contraction.

• A convenient and safe method for checking/ad-

justing coolant level at atmospheric pressure. This is
done without removing the radiator pressure cap.

• Some reserve coolant to the radiator to cover

minor leaks and evaporation or boiling losses.

XJ COOLING SYSTEM 7 - 3

DESCRIPTION AND OPERATION (Continued)

The coolant reserve/overflow system consists of a
radiator mounted pressurized cap, a plastic reserve/
overflow tank (Fig. 3) (Fig. 4), a tube (hose) connect­ing the radiator and tank, and an overflow tube on
the side of the tank.

Fig. 3 Reserve/Overflow Tank—Except Right Hand

Drive

1 – COOLANT RESERVE/OVERFLOW TANK
2 – CLAMP
3 – MOUNTING BOLTS
4 – TUBE TO RADIATOR

OPERATION

As the engine cools, a vacuum is formed in the
cooling system of both the radiator and engine. Cool­ant will then be drawn from the coolant tank and
returned to a proper level in the radiator.

COOLING SYSTEM FANS

DESCRIPTION

All models are equipped with a viscous fan. This
thermal viscous fan drive is a torque-and-tempera­ture-sensitive clutch unit. It automatically increases
or decreases fan speed to provide proper engine cool­ing. Vehicles with a 2.5L/4.0L engine with air condi­tioning, or 4.0L with “max” cooling also have an
auxiliary electrical cooling fan.

Fig. 4 Reserve/Overflow Tank—With Right Hand

Drive

1 – CLAMP
2 – COOLANT RESERVE/OVERFLOW TANK
3 – MOUNTING BOLTS
4 – LOWER BRACKET
5 – TUBE TO RADIATOR

Fig. 5 Viscous Fan Drive and Fan Blade Assembly

1 – VISCOUS FAN DRIVE
2 – FAN BLADE ASSEMBLY

7 - 4 COOLING SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

BLOCK HEATER

DESCRIPTION

WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.

An optional engine block heater is available for all
models. The heater is equipped with a power cord.
The cord is attached to an engine compartment com­ponent with tie-straps. The heater warms the engine
providing easier engine starting and faster warm-up
in low temperatures. The heater is mounted in a core
hole of the engine cylinder block (in place of a freeze
plug) with the heating element immersed in engine
coolant.

BLOCK HEATER SPECIFICATIONS

• 2.5L 4-Cylinder Engine: 115 Volts 400 Watts

• 4.0L 6-Cylinder Engine: 120 Volts 600 Watts

THERMOSTAT

DESCRIPTION

CAUTION: Do not operate an engine without a ther­mostat, except for servicing or testing.

A pellet-type thermostat controls the operating
temperature of the engine by controlling the amount
of coolant flow to the radiator. On all engines the
thermostat is closed below 195°F (90°C). Above this
temperature, coolant is allowed to flow to the radia­tor. This provides quick engine warm-up and overall
temperature control.

An arrow plus the word UP is stamped on the
front flange next to the air bleed. The words TO
RAD are stamped on one arm of the thermostat.
They indicate the proper installed position.

The same thermostat is used for winter and sum­mer seasons. An engine should not be operated with­out a thermostat, except for servicing or testing.
Operating without a thermostat causes other prob­lems. These are: A ’check engine’ light and a DTC
will eventually be set, longer engine warm-up time,
unreliable warm-up performance, increased exhaust
emissions and crankcase condensation. This conden­sation can result in sludge formation.

Fig. 6 Engine Block Heater

1 – BLOCK HEATER
2 – CYLINDER BLOCK
3 – BLOCK HEATER POWER CORD

OPERATION

Connecting the power cord to a grounded 110-120
volt AC electrical outlet with a grounded, three-wire
extension cord activates the block heater.

Fig. 7 Thermostat and Housing

1 – LONG BOLT
2 – GASKET
3 – THERMOSTAT
4 – THERMOSTAT HOUSING
5 – SHORT BOLT

XJ COOLING SYSTEM 7 - 5

DESCRIPTION AND OPERATION (Continued)

RADIATOR

DESCRIPTION

CAUTION: Plastic tanks, while stronger than brass,
are subject to damage by impact, such as
wrenches.

Radiators for both engines are the cross flow type.
Plastic tanks are used on all radiators.

A rubber gasket seals radiator filler neck. This is
done to maintain vacuum during coolant cool-down
and to prevent leakage when system is under pres­sure.

Fig. 8 Cross Flow Radiator

1 – RADIATOR

RADIATOR PRESSURE CAP

DESCRIPTION

All radiators are equipped with a pressure cap.
This cap releases pressure at some point within a
range of 83-110 kPa (12-16 psi). The pressure relief
point (in pounds) is engraved on top of the cap (Fig.

9).

The cooling system will operate at pressures
slightly above atmospheric pressure. This results in a
higher coolant boiling point allowing increased radi­ator cooling capacity. The cap contains a spring­loaded pressure relief valve that opens when system
pressure reaches release range of 83-110 kPa (12-16
psi).

Fig. 9 Radiator Pressure Cap and Filler Neck—

Typical

1 – FILLER NECK SEAL
2 – VACUUM VENT VALVE
3 – PRESSURE RATING
4 – PRESSURE VALVE

OPERATION

A vent valve in the center of cap allows a small
coolant flow through cap when coolant is below boil­ing temperature. The valve is completely closed when
boiling point is reached. As the coolant cools, it con­tracts and creates a vacuum in the cooling system.
This causes the vacuum valve to open and coolant in
the reserve/overflow tank to be drawn through its
connecting hose into radiator. If the vacuum valve is
stuck shut, the radiator hoses will collapse on cool­down.

7 - 6 COOLING SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

WATER PUMP

DESCRIPTION

CAUTION: All engines are equipped with a reverse
(counter-clockwise) rotating water pump and vis­cous fan drive assembly. REVERSE is stamped or
imprinted on the cover of the viscous fan drive and
inner side of the fan. The letter R is stamped into
the back of the water pump impeller (Fig. 10).

A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
drive belt on all engines.

The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has a small hole to allow seep­age to escape. The water pump seals are lubricated
by the antifreeze in the coolant mixture. No addi­tional lubrication is necessary.

HOSE CLAMPS

DESCRIPTION

The cooling system utilizes both worm drive and
spring type hose clamps. If a spring type clamp
replacement is necessary, replace with the original
Mopart equipment spring type clamp.

CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only a original equipment clamp
with matching number or letter (Fig. 11).

Fig. 10 Reverse Rotating Water Pump—Typical

1 – R STAMPED INTO IMPELLER

Fig. 11 Spring Clamp Size Location

1 – SPRING CLAMP SIZE LOCATION

OPERATION

The worm type hose clamp uses a specified torque
value to maintain proper tension on a hose connec­tion.

The spring type hose clamp applies constant ten­sion on a hose connection. To remove a spring type
hose clamp, use Special Tool 6094 or equivalent, con­stant tension clamp pliers (Fig. 12) to compress the
hose clamp.

XJ COOLING SYSTEM 7 - 7

DESCRIPTION AND OPERATION (Continued)

A thermostatic bimetallic spring coil is located on
the front face of the viscous fan drive unit. A typical
viscous unit is shown in (Fig. 13). This spring coil
reacts to the temperature of the radiator discharge
air. It engages the viscous fan drive for higher fan
speed if the air temperature from the radiator rises
above a certain point. Until additional engine cooling
is necessary, the fan will remain at a reduced rpm
regardless of engine speed.

Vehicles equipped with 2.5L engines have what is
know as an hybrid cooling fan system. This means
that not only do they have a viscous fan but they also
have an electric fan as well. The hybrid viscous fan
drive has a low speed characteristic. This causes the
mechanical fan speeds to be very low 200–400 rpm

Fig. 12 Hose Clamp Tool

1 – HOSE CLAMP TOOL 6094
2 – HOSE CLAMP

range when not engaged allowing the engine to have
additional performance and horsepower gaines.

VISCOUS FAN DRIVE

DESCRIPTION

CAUTION: Engines equipped with poly–V drive
belts have reverse rotating fans and viscous fan
drives. They are marked with the word REVERSE to
designate their usage. Installation of the wrong fan
or viscous fan drive can result in engine overheat­ing.

The thermal viscous fan drive is a silicone-fluid­filled coupling used to connect the fan blades to
either the engine or the water pump shaft. The cou­pling allows the fan to be driven in a normal manner.
This is done at low engine speeds while limiting the
top speed of the fan to a predetermined maximum
level at higher engine speeds.

2.5L vehicles with A/C are equipped with a viscous
fan drive which is designed to “free wheel” during
most of the ambient conditions encountered by the
vehicle and will only engage during high heat loads
as seen in trailer towing or high ambient tempera­tures.

Fig. 13 Typical Viscous Fan Drive

1 – VISCOUS FAN DRIVE
2 – MOUNTING HUB
3 – THERMOSTATIC SPRING

OPERATION

Only when sufficient heat is present, will the vis­cous fan drive engage. This is when the air flowing
through the radiator core causes a reaction to the
bimetallic coil. It then increases fan speed to provide
the necessary additional engine cooling.

Once the engine has cooled, the radiator discharge
temperature will drop. The bimetallic coil again
reacts and the fan speed is reduced to the previous
disengaged speed.

7 - 8 COOLING SYSTEM XJ

DESCRIPTION AND OPERATION (Continued)

ELECTRIC COOLING FAN

DESCRIPTION

Vehicles equipped with a 2.5L/4.0L engine and air
conditioning and 4.0L vehicles equipped with the
“max” cooling package also have an electrical cooling
fan. The fan is controlled by the cooling fan relay,
which is located in the power distribution center
(PDC) (Fig. 15). For the location of relay within the
PDC, refer to the label on PDC cover.

The electric fan on the 2.5L engine equipped vehi­cles is considered the primary fan (low to moderate
ambient conditions) and is energized when the JTEC
receives input from the coolant temperature sensor
or the a/c system and supplies ground to the cooling
fan relay.

The cooling fan motor is protected by a 40 amp
maxi-fuse located in the PDC. The fan relay is pro­tected by a 15 amp fuse located in the junction block.

OPERATION

Electric cooling fan 2.5L: When air conditioning
is not requested, the electric fan will not come on
unless the coolant temperature is at least 103° C
(218° F), at which time the fan will come on and
remain on until the coolant temperature drops to 99°
C (210° F) or below. When air conditioning is
requested (including defroster operation), the fan will
cycle on and off in conjunction with the A/C compres­sor unless the coolant temperature is at least 97° C
(207° F), at which time the fan will come on and
remain on until the coolant temperature drops to 93°
C (199° F) or below. Then, the cycle fan operation
will resume. When the fan is scheduled to be on, the
powertrain control module (PCM) provides a ground
path for the fan relay. This ground is provided to the
cooling fan relay through pin C2 of PCM connector
C3. Battery voltage is then applied to the fan
through the relay. When the fan is scheduled to be
off, the PCM opens the ground path to the relay. This
will prevent the cooling fan from being energized.

1 – (LHD)
2 – (RHD)
3 – VISCOUS FAN SHROUD
4 – ELECTRIC FAN MODULE
5 – ISOLATOR

Fig. 14 Electric Cooling Fan

6 – RADIATOR
7 – LOWER CROSSMEMBER
8 – U-NUT
9 – UPPER CROSSMEMBER

XJ COOLING SYSTEM 7 - 9

DESCRIPTION AND OPERATION (Continued)

to Group 25, Emission Control Systems for proper
procedures)

ACCESSING DIAGNOSTIC TROUBLE CODES

To read DTC’s and to obtain cooling system data,
refer to Group 25, Emission Control Systems for
proper procedures.

DRB SCAN TOOL

For operation of the DRB scan tool, refer to the
appropriate Powertrain Diagnostic Procedures ser­vice manual.

ACCESSORY DRIVE BELT DIAGNOSIS

VISUAL DIAGNOSIS

When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 16), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) are not nor-

Fig. 15 Power Distribution Center (PDC)

1 – RIGHT FENDER
2 – BATTERY
3 – POWER DISTRIBUTION CENTER

mal. Any belt with cracks running along a rib must
be replaced (Fig. 16). Also replace the belt if it has
excessive wear, frayed cords or severe glazing.

Refer to the Accessory Drive Belt Diagnosis charts
for further belt diagnosis.

Electric cooling fan 4.0L: With or without A/C
request the electric fan will come on only when the
coolant temperature is at least 106° C (223° F), and
will remain on until the coolant temperature drops to
103° C (217° F) or below. Regardless of coolant tem­perature, When air conditioning system pressures
reach 2068.5 6 138 kPa (300 6 20 psi) the electric
fan will engage and continue to run until the A/C
system pressure drops to 1620.3 kPa (235 psi) mini­mum, then the electric fan will shut off.

DIAGNOSIS AND TESTING

ON-BOARD DIAGNOSTICS (OBD)

COOLING SYSTEM RELATED DIAGNOSTICS

The Powertrain Control Module (PCM) has been
programmed to monitor the certain following cooling
system components:

• If the engine has remained cool for too long a
period, such as with a stuck open thermostat, a Diag­nostic Trouble Code (DTC) can be set.

• If an open or shorted condition has developed in
the relay circuit controlling the electric radiator fan,
a Diagnostic Trouble Code (DTC) can be set.

If the problem is sensed in a monitored circuit
often enough to indicate an actual problem, a DTC is
stored. The DTC will be stored in the PCM memory
for eventual display to the service technician. (Refer

Fig. 16 Belt Wear Patterns

1 – NORMAL CRACKS BELT OK
2 – NOT NORMAL CRACKS REPLACE BELT

NOISE DIAGNOSIS

Noises generated by the accessory drive belt are
most noticeable at idle. Before replacing a belt to
resolve a noise condition, inspect all of the accessory
drive pulleys for alignment, glazing, or excessive end
play.

7 - 10 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

ACCESSORY DRIVE BELT DIAGNOSIS CHART

CONDITION POSSIBLE CAUSES CORRECTION

RIB CHUNKING (One or more ribs
has separated from belt body)

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

BELT SLIPS 1. Belt slipping because of

1. Foreign objects imbedded in
pulley grooves.

2. Installation damage 2. Replace belt

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

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

4. Sharp or jagged pulley groove
tips

5. Belt rubber deteriorated 5. Replace belt

insufficient tension

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

3. Driven component bearing failure
(seizure)

4. Belt glazed or hardened from
heat and excessive slippage

1. Remove foreign objects from
pulley grooves. Replace belt.

necessary

4. Replace pulley. Inspect belt.

1. Adjust tension (2.5L)

2. Replace belt and clean pulleys

3. Replace faulty component or
bearing

4. Replace belt.

LONGITUDAL BELT CRACKING 1. Belt has mistracked from pulley

groove

2. Pulley groove tip has worn away
rubber to tensile member

9GROOVE JUMPING”
(Belt does not maintain correct
position on pulley)

BELT BROKEN
(Note: Identify and correct problem
before new belt is installed)

1. Belt tension either too low or too
high

2. Pulley(s) not within design
tolerance

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

4. Pulley misalignment 4. Align component

5. Belt cordline is broken 5. Replace belt

1. Excessive tension 1. Replace belt and adjust tension

2. Tensile member damaged during
belt installation

3. Severe misalignment 3. Align pulley(s)

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

1. Replace belt

2. Replace belt

1. Adjust belt tension (2.5L)

2. Replace pulley(s)

grooves

to specification

2. Replace belt

and belt

XJ COOLING SYSTEM 7 - 11

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NOISE (Objectionable squeal,
squeak, or rumble is heard or felt
while drive belt is in operation)

TENSION SHEETING FABRIC
FAILURE
(Woven fabric on outside,
circumference of belt has cracked or
separated from body of belt)

CORD EDGE FAILURE
(Tensile member exposed at edges
of belt or separated from belt body)

1. Belt slippage 1. Adjust belt tension (2.5L)

2. Bearing noise 2. Locate and repair

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

4. Belt to pulley mismatch 4. Install correct belt

5. Driven component induced
vibration

6. System resonant frequency
induced vibration

1. Tension sheeting contacting
stationary object

2. Excessive heat causing woven
fabric to age

3. Tension sheeting splice has
fractured

1. Excessive tension 1. Adjust belt tension (2.5L)

2. Belt contacting stationary object 2. Replace belt

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

4. Insufficient adhesion between
tensile member and rubber matrix

5. Locate defective driven
component and repair

6. Vary belt tension within
specifications.

1. Correct rubbing condition

2. Replace belt

3. Replace belt

4. Replace belt and adjust tension
to specifications

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATING

Establish what driving conditions caused the com­plaint. Abnormal loads on the cooling system such as
the following may be the cause:

PROLONGED IDLE, VERY HIGH AMBIENT 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 rec-

ommended.

TRAILER TOWING:

Consult Trailer Towing section of owners manual.
Do not exceed limits.

AIR CONDITIONING; ADD-ON OR AFTER MARKET:

A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo­nents should be installed for model involved per
manufacturer’s specifications.

RECENT SERVICE OR ACCIDENT REPAIR:

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

rotating in wrong direction due to belt not correctly
routed

• Reconditioned radiator or cooling system refill-

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

NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com­plaint, refer to following Cooling System Diagnosis
charts.

These charts are to be used as a quick-reference
only. Refer to the group text for information.

7 - 12 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

COOLING SYSTEM DIAGNOSIS CHART

CONDITION POSSIBLE CAUSES CORRECTION

TEMPERATURE GAUGE READS
LOW

TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM

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

2. Is the temperature sending unit
connected?

3. Is the temperature gauge
operating OK?

4. Coolant level low in cold ambient
temperatures accompanied with
poor heater performance.

5. Improper operation of internal
heater doors or heater controls.

1. Trailer is being towed, a steep
hill is being climbed, vehicle is
operated in slow moving traffic, or
engine is being idled with very high
ambient (outside) temperatures and
the air conditioning is on. Higher
altitudes could aggravate these
conditions.

1. Refer to Group 25, Emission
Systems for On-Board Diagnostics
and DTC information. Replace
thermostat if necessary.

2. Check the temperature sensor
connector. Refer to Group 8E.
Repair connector if necessary.

3. Check gauge operation. Refer to
Group 8E. Repair as necessary.

4. Check coolant level in the coolant
reserve/overflow tank and the
radiator. Inspect system for leaks.
Repair leaks as necessary. Refer to
the Coolant section of the manual
text for WARNINGS and
CAUTIONS associated with
removing the radiator cap.

5. Inspect heater and repair as
necessary. Refer to Group 24,
Heating and Air Conditioning for
procedures.

1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and attempt to drive the
vehicle without any of the previous
conditions. Observe the temperature
gauge. The gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause for overheating
and repair. Refer to Possible
Causes (2-20).

2. Is the temperature gauge reading
correctly?

3. Is the temperature warning
illuminating unnecessarily?

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

5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following Step 6.

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

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

4. Check for coolant leaks and
repair as necessary. Refer to
Testing Cooling System for Leaks in
this Group.

5. Tighten cap

XJ COOLING SYSTEM 7 - 13

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM (CONTINUED)

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

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

7. Coolant level low in radiator but

not in coolant reserve/overflow
tank. This means the radiator is not
drawing coolant from the coolant
reserve/overflow tank as the engine
cools

8. Incorrect coolant concentration 8. Check coolant. Refer to Coolant

9. Coolant not flowing through

system

10. Radiator or A/C condenser fins

are dirty or clogged.

11. Radiator core is corroded or

plugged.

12. Aftermarket A/C installed

without proper radiator.

13. Fuel or ignition system

problems.

14. Dragging brakes. 14. Check and correct as

15. Bug screen or cardboard is

being used, reducing airflow.

16. Thermostat partially or

completely shut.

7. (a) Check condition of radiator
cap and cap seals. Refer to
Radiator Cap in this Group. Replace
cap if necessary.

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

(c) Check condition of the hose from
the radiator to the coolant tank. It
should fit tight at both ends without
any kinks or tears. Replace hose if
necessary.

(d) Check coolant reserve/overflow
tank and tanks hoses for blockage.
Repair as necessary.

section in this Group for correct
coolant/water mixture ratio.

9. Check for coolant flow at radiator
filler neck with some coolant
removed, engine warm and
thermostat open. Coolant should be
observed flowing through radiator. If
flow is not observed, determine area
of obstruction and repair as
necessary.

10. Remove insects and debris.
Refer to Radiator Cleaning in this
Group.

11. Have radiator re-cored or
replaced.

12. Install proper radiator.

13. Refer to Fuel and Ignition
System Groups for diagnosis.

necessary. Refer to Group 5,
Brakes for correct procedures.

15. Remove bug screen or
cardboard.

16. Check thermostat operation and
replace as necessary. Refer to
Thermostats in this Group.

7 - 14 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM (CONTINUED)

TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC)

17. Viscous fan drive not operating

properly.

18. Electric cooling fan not

operating properly (vehicles
equipped with 2.5L/4.0L and air
conditioning

19. Cylinder head gasket leaking. 19. Check for cylinder head gasket

20. Heater core leaking. 20. Check heater core for leaks.

1. On vehicles equipped with an

electric fan, the gauge may cycle
up and down. This is due to the
cycling of the electric radiator fan.

2. During cold weather operation,

with the heater blower in the high
position, the gauge reading may
drop slightly.

3. Temperature gauge or engine

mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.

4. Gauge reading rises when

vehicle is brought to a stop after
heavy use (engine still running)

5. Gauge reading high after

re-starting a warmed up (hot)
engine.

6. Coolant level low in radiator (air

will build up in the cooling system
causing the thermostat to open
late).

7. Cylinder head gasket leaking

allowing exhaust gas to enter
cooling system causing a
thermostat to open late.

17. Check fan drive operation and
replace as necessary. Refer to
Viscous Fan Drive in this Group.

18. Check electric fan operation and
repair as necessary. Refer to
Electric Cooling Fan in this Group.

leaks. Refer to Cooling System­Testing For Leaks in this Group. For
repair, refer to Group 9, Engines.

Refer to Group 24, Heating and Air
Conditioning. Repair as necessary.

1. This is a normal condition. No
correction is necessary unless the
gauge cycles into the red (overheat)
zone. Refer to Electric Cooling Fan
Diagnosis and Testing in this group.

2. A normal condition. No correction
is necessary.

3. Check operation of gauge and
repair if necessary. Refer to Group
8E, Instrument Panel and Gauges.

4. A normal condition. No correction
is necessary. Gauge should return
to normal range after vehicle is
driven.

5. A normal condition. No correction
is necessary. The gauge should
return to normal range after a few
minutes of engine operation.

6. Check and correct coolant leaks.
Refer to Cooling System-Testing for
leaks in this group.

7. (a) Check for cylinder head
gasket leaks. Refer to Cooling
System-Testing for Leaks in this
group.

(b) Check for coolant in the engine
oil. Inspect for white steam emitting
from the exhaust system. Repair as
necessary.

XJ COOLING SYSTEM 7 - 15

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC)
(CONTINUED)

PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK

COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE READING
HIGH OR HOT

8. Water pump impeller loose on

shaft.

9. Loose accessory drive belt.

(water pump slipping)

10. Air leak on the suction side of

the water pump allows air to build
up in cooling system causing
thermostat to open late.

1. Pressure relief valve in radiator

cap is defective.

1. Coolant leaks in radiator, cooling

system hoses, water pump or
engine.

8. Check water pump and replace
as necessary. Refer to water Pumps
in this group.

9. Refer to Accessory Drive Belts in
this group. Check and correct as
necessary.

10. Locate leak and repair as
necessary.

1. Check condition of radiator cap
and cap seals. Refer to Radiator
Caps in this group. Replace cap as
necessary.

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

DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH

HOSE OR HOSES COLLAPSE
WHILE ENGINE IS RUNNING

ELECTRIC RADIATOR FAN RUNS
ALL OF THE TIME (2.5L/4.0L
MODELS EQUIPPED WITH A/C
AND 4.0L MODELS EQUIPPED
WITH MAX COOLING)

1. engine overheating. 1. Check reason for overheating
and repair as necessary.

2. Freeze point of coolant not

correct. Mixture is too rich or too
lean.

1. Vacuum created in cooling

system on engine cool-down is not
being relieved through coolant
reserve/overflow system.

1. Fan relay, powertrain control

module (PCM) or coolant
temperature sensor defective.

2. Check coolant concentration.
Refer to the Coolant section of this
group and adjust ratio as required.

1. (a) Radiator cap relief valve
stuck. Refer to Radiator Cap in this
group. Replace if necessary

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

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

(d) Reserve/overflow tank is
internally blocked or plugged. Check
for blockage and repair as
necessary.

1. Refer to Electric Cooling Fan
Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.

7 - 16 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

ELECTRIC RADIATOR FAN WILL
NOT RUN AT ALL. GAUGE
READING HIGH OR HOT
(2.5L/4.0L MODELS EQUIPPED
WITH A/C AND 4.0L MODELS
EQUIPPED WITH MAX COOLING)

NOISY VISCOUS FAN/DRIVE 1. Fan blades loose. 1. Replace fan blade assembly.

1. Blown Fuse in Power Distribution

Center (PDC)

2. Fan relay, powertrain control

module (PCM) or coolant
temperature sensor defective.

3. Fan Motor Defective 3. Refer to Electric Cooling Fan

2. Fan blades striking a surrounding

object.

3. Air obstructions at radiator or air

conditioning condenser.

4. Thermal viscous fan drive has

defective bearing.

5. A certain amount of fan noise

may be evident on models
equipped with a thermal viscous fan
drive. Some of this noise is normal.

1. Determine reason for blown fuse
and repair as necessary.

2. Refer to Electric Cooling Fan
Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.

Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.

Refer to Cooling System Fans in
this Group

2. Locate point of fan blade contact
and repair as necessary.

3. Remove obstructions and/or
clean debris or insects from radiator
or A/C condenser.

4. Replace fan drive. Bearing is not
serviceable. Refer to Viscous Fan
Drive in this group.

5. Refer to Viscous Fan Drive in this
group for an explanation of normal
fan noise.

INADEQUATE HEATER
PERFORMANCE. THERMOSTAT
FAILED IN OPEN POSITION

1. Has a Diagnostic trouble Code

(DTC) been set?

2. Coolant level low 2. Refer to Cooling System-Testing

3. Obstructions in heater hose/

fittings

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

5. Water pump is not pumping

water to/through the heater core.
When the engine is fully warmed
up, both heater hoses should be
hot to the touch. If only one of the
hoses is hot, the water pump may
not be operating correctly or the
heater core may be plugged.
Accessory drive belt may be
slipping causing poor water pump
operation.

1. Refer to Group 25, Emissions for
correct procedures and replace
thermostat if necessary

For Leaks in this group.

3. Remove heater hoses at both
ends and check for obstructions

necessary

5. Refer to Water Pump in this
group. If a slipping belt is detected,
refer to Accessory Drive Belts in this
group. If heater core obstruction is
detected, refer to Group 24, Heating
and Air Conditioning.

XJ COOLING SYSTEM 7 - 17

DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

STEAM IS COMING FROM THE
FRONT OF VEHICLE NEAR THE
GRILL AREA WHEN WEATHER IS
WET, ENGINE IS WARMED UP
AND RUNNING, AND VEHICLE IS
STATIONARY. TEMPERATURE
GAUGE IS IN NORMAL RANGE

COOLANT COLOR 1. Coolant color is not necessarily

COOLANT LEVEL CHANGES IN
COOLANT RESERVE/OVERFLOW
TANK. TEMPERATURE GAUGE IS
IN NORMAL RANGE

1. During wet weather, moisture

(snow, ice or rain condensation) on
the radiator will evaporate when the
thermostat opens. This opening
allows heated water into the
radiator. When the moisture
contacts the hot radiator, steam
may be emitted. This usually occurs
in cold weather with no fan or
airflow to blow it away.

an indication of adequate corrosion
or temperature protection. Do not
rely on coolant color for determining
condition of coolant.

1. Level changes are to be

expected as coolant volume
fluctuates with engine temperature.
If the level in the tank was between
the FULL and ADD marks at normal
operating temperature, the level
should return to within that range
after operation at elevated
temperatures.

1. Occasional steam emitting from
this area is normal. No repair is
necessary.

1. Refer to Coolant in this group for
coolant concentration information.
Adjust coolant mixture as
necessary.

1. A normal condition. No repair is
necessary.

RADIATOR COOLANT FLOW CHECK

The following procedure will determine if coolant is

flowing through the cooling system.

If engine is cold, idle engine until normal operating
temperature is reached. Then feel the upper radiator
hose. If hose is hot, the thermostat is open and water
is circulating through cooling system.

COOLING SYSTEM—TESTING FOR LEAKS

ULTRAVIOLET LIGHT METHOD

All Jeep models have a leak detection additive
added to the cooling system before they leave the fac­tory. The additive is highly visible under ultraviolet
light (black light). If the factory original coolant has
been drained, pour one ounce of additive into the
cooling system. The additive is available through the
part’s department. Place the heater control unit in
HEAT position. Start and operate the engine until
the radiator upper hose is warm to the touch. Aim
the commercially available black light tool at the
components to be checked. If leaks are present, the
black light will cause the additive to glow a bright
green color.

The black light can be used along with a pressure
tester to determine if any external leaks exist (Fig.

17).

Fig. 17 Leak Detection Using Black Light—Typical

1 – TYPICAL BLACK LIGHT TOOL

7 - 18 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

PRESSURE TESTER METHOD

The engine should be at the normal operating tem­perature. Recheck the system cold if the cause of
coolant loss is not located during warm engine exam­ination.

WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.

Carefully remove the radiator pressure cap from
the filler neck and check the coolant level. Push
down on the cap to disengage it from the stop tabs.
Wipe the inner part of the filler neck and examine
the lower inside sealing seat for nicks, cracks, paint,
dirt and solder residue. Inspect the reserve/overflow
tank tube for internal obstructions. Insert a wire
through the tube to be sure it is not obstructed.

Inspect the cams on the outside part of the filler
neck. If the cams are bent, seating of pressure cap
valve and tester seal will be affected. Replace cap if
cams are bent.

Attach pressure tester 7700 (or an equivalent) to
the radiator filler neck (Fig. 18).

• Drops Slowly: Shows a small leak or seepage is
occurring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect the radiator,
hoses, gasket edges and heater. Seal any small leak
holes with a Sealer Lubricant or equivalent. Repair
leak holes and reinspect the system with pressure
applied.

• Drops Quickly: Shows that a serious leakage is
occurring. Examine the system for serious external
leakage. If no leaks are visible, inspect for internal
leakage. Large radiator leak holes should be repaired
by a reputable radiator repair shop.

INTERNAL LEAKAGE INSPECTION

Remove the engine oil pan drain plug and drain a
small amount of engine oil. Coolant, being heavier
than engine oil, will drain first. Another way of test­ing is to operate the engine and check for water glob­ules on the engine oil dipstick. Also inspect the
automatic transmission oil dipstick for water glob­ules. Inspect the automatic transmission fluid cooler
for leakage. Operate the engine without the pressure
cap on the radiator until thermostat opens.

Attach a pressure tester to the filler neck. If pres­sure builds up quickly, a leak exists as a result of a
faulty cylinder head gasket or crack in the engine.
Repair as necessary.

Fig. 18 Pressurizing System—Typical

1 – TYPICAL COOLING SYSTEM PRESSURE TESTER

Operate the tester pump to apply 124 kPa (18 psi)
pressure to the system. If the hoses enlarge exces­sively or bulge while testing, replace as necessary.
Observe the gauge pointer and determine the condi­tion of the cooling system according to the following
criteria:

• Holds Steady: If the pointer remains steady for
two minutes, there are no serious coolant leaks in
the system. However, there could be an internal leak
that does not appear with normal system test pres­sure. Inspect for interior leakage or do the Internal
Leakage Test. Do this if it is certain that coolant is
being lost and no leaks can be detected.

WARNING: DO NOT ALLOW PRESSURE TO
EXCEED 124 KPA (18 PSI). TURN THE ENGINE OFF.
TO RELEASE THE PRESSURE, ROCK THE TESTER
FROM SIDE TO SIDE. WHEN REMOVING THE
TESTER, DO NOT TURN THE TESTER MORE THAN
1/2 TURN IF THE SYSTEM IS UNDER PRESSURE.

If there is no immediate pressure increase, pump
the pressure tester until the indicated pressure is
within the system range. Vibration of the gauge
pointer indicates compression or combustion leakage
into the cooling system.

WARNING: DO NOT DISCONNECT THE SPARK
PLUG WIRES WHILE THE ENGINE IS OPERATING.

CAUTION: Do not operate the engine with a spark
plug shorted for more than a minute. The catalytic
converter may be damaged.

Isolate the compression leak by shorting each
spark plug to the cylinder block. The gauge pointer
should stop or decrease vibration when spark plug
for leaking cylinder is shorted. This happens because
of the absence of combustion pressure.

XJ COOLING SYSTEM 7 - 19

DIAGNOSIS AND TESTING (Continued)

COMBUSTION LEAKAGE TEST (WITHOUT PRESSURE TESTER)

DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.

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.

Drain sufficient coolant to allow for thermostat
removal. Refer to Thermostat Replacement. Discon­nect the water pump drive belt.

Disconnect the upper radiator hose from the ther­mostat housing. Remove the housing and thermostat.
Install the thermostat housing.

Add coolant to the radiator to bring the level to
within 6.3 mm (1/4 in) of the top of the thermostat
housing.

CAUTION: Avoid overheating. Do not operate the
engine for an excessive period of time. Open the
draincock immediately after the test to eliminate
boil over of coolant.

Start the engine and accelerate rapidly three times
(to approximately 3000 rpm) while observing the
coolant. If internal engine combustion gases are leak­ing into the cooling system, bubbles will appear in
the coolant. If bubbles do not appear, there is no
internal combustion gas leakage.

105°C (0°-to-220° F). Insert thermometer through the
hole in the shroud. Be sure that there is adequate
clearance from the fan blades.

(3) Connect a tachometer and an engine ignition
timing light (timing light is to be used as a strobe
light).

(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator (or air con­ditioner condenser). Use tape at the top to secure the
plastic and be sure that the air flow is blocked.

(5) Be sure that the air conditioner (if equipped) is
turned off.

WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.

(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88° C (190° F).
Fan drive engagement should have started to occur
at between 74° to 82° C (165° to 180° F). Engage­ment is distinguishable by a definite increase in fan
flow noise (roaring). The timing light also will indi­cate an increase in the speed of the fan.

(7) When the air temperature reaches 88° C (190°
F), remove the plastic sheet. Fan drive disengage-
ment should have started to occur at between 57° to
79° C (135° to 175° F). A definite decrease of fan
flow noise (roaring) should be noticed. If not, replace
the defective viscous fan drive unit.

VISCOUS FAN DRIVE

LEAKS

Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.

TESTING

If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.

For the following test, the cooling system must be
in good condition. It also will ensure against exces­sively high coolant temperature.

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

(1) Drill a 3.18-mm (1/8-in) diameter hole in the
top center of the fan shroud.

(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18°-to-

ELECTRIC COOLING FAN

ELECTRIC COOLING FAN AND RELAY DIAGNOSIS

NOTE: Refer to Electrical Group 8W for electric
cooling fan and relay circuit schematic.

The powertrain control module (PCM) will enter a
diagnostic trouble code (DTC) in memory if it detects
a problem in the auxiliary cooling fan relay or circuit.
Refer to Group 25, Emission Control Systems for cor­rect DTC retrieval procedures.

If the electric cooling fan is inoperative, check the
15A fuse in the junction block and the 40A fuse in
the Power Distribution Center (PDC) with a 12 volt
test lamp or DVOM. Refer to the inside of the PDC
cover for the exact location of the fuse. If fuses are
o.k., refer to Group 8W for electric cooling fan and
relay circuit schematic.

7 - 20 COOLING SYSTEM XJ

DIAGNOSIS AND TESTING (Continued)

RADIATOR CAP-TO-FILLER NECK SEAL—
PRESSURE RELIEF CHECK

With radiator cap installed on filler neck, remove
coolant reserve/ overflow tank hose from nipple on
filler neck. Connect a hand operated vacuum pump
to nipple. Operate pump until a reading of 47-to-61
kPa (14- to-18 in. Hg) appears on gauge. If the read­ing stays steady, or drops slightly and then remains
steady, the pressure valve seal is good. Replace radi­ator cap if reading does not hold.

WARNING: THE WARNING WORDS -DO NOT OPEN
HOT- ON THE RADIATOR PRESSURE CAP (Fig. 19)
ARE A SAFETY PRECAUTION. WHEN HOT, PRES­SURE BUILDS UP IN COOLING SYSTEM. TO PRE­VENT SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM
IS HOT AND/OR UNDER PRESSURE.

There is no need to remove the radiator cap

except for the following purposes:

(1) To check and adjust antifreeze freeze point.
(2) To refill system with new antifreeze.
(3) For conducting service procedures.
(4) When checking for vacuum leaks.

WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT AT LEAST 15 MINUTES BEFORE REMOVING
RADIATOR CAP. WITH A RAG, SQUEEZE RADIATOR
UPPER HOSE TO CHECK IF SYSTEM IS UNDER
PRESSURE. PLACE A RAG OVER THE CAP AND
WITHOUT PUSHING DOWN, ROTATE CAP
COUNTER-CLOCKWISE TO THE FIRST STOP.
ALLOW FLUID TO ESCAPE THROUGH OVERFLOW
HOSE INTO COOLANT RESERVE/OVERFLOW
TANK. SQUEEZE RADIATOR UPPER HOSE TO
DETERMINE WHEN PRESSURE HAS BEEN
RELEASED. WHEN COOLANT AND STEAM STOP
BEING PUSHED INTO TANK AND SYSTEM PRES­SURE DROPS, REMOVE RADIATOR CAP COM­PLETELY.

RADIATOR CAP—PRESSURE TESTING

Remove cap from radiator. Be sure that sealing
surfaces are clean. Moisten rubber gasket with water
and install the cap on pressure tester (tool 7700 or
an equivalent) (Fig. 20).

Fig. 19 Radiator Pressure Cap

1 – FILLER NECK SEAL
2 – VACUUM VENT VALVE
3 – PRESSURE RATING
4 – PRESSURE VALVE

Fig. 20 Pressure Testing Radiator Pressure

Cap—Typical

1 – PRESSURE CAP
2 – TYPICAL COOLING SYSTEM PRESSURE TESTER

XJ COOLING SYSTEM 7 - 21

DIAGNOSIS AND TESTING (Continued)

Operate the tester pump and observe the gauge
pointer at its highest point. The cap release pressure
should be 83-to-110 kPa (12-to-16 psi). The cap is sat­isfactory when the pressure holds steady. It is also
good if it holds pressure within the 83-to-110 kPa
(12-to-16 psi) range for 30 seconds or more. If the
pointer drops quickly, replace the cap.

CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks, which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.

CAP INSPECTION

Visually inspect the pressure valve gasket on the
cap. Replace cap if the gasket is swollen, torn or
worn. Inspect the area around radiator filler neck for
white deposits that indicate a leaking cap.

COOLANT—LOW LEVEL AERATION

If the coolant level in radiator drops below top of
radiator core tubes, air will enter cooling system.

Low coolant level can cause thermostat pellet to be
suspended in air instead of coolant. This will cause
thermostat to open later, which in turn causes higher
coolant temperature. Air trapped in cooling system
also reduces amount of coolant circulating in heater
core resulting in low heat output.

DEAERATION

As the engine operates, any air trapped in cooling
system gathers under the radiator cap. The next time
the engine is operated, thermal expansion of coolant
will push any trapped air past radiator cap into the
coolant reserve/overflow tank. Here it escapes to the
atmosphere into the tank. When the engine cools
down the coolant, it will be drawn from the reserve/
overflow tank into the radiator to replace any
removed air.

The coolant reserve/overflow system provides a
quick visual method for determining coolant level
without removing radiator pressure cap. With engine
cold and not running, observe coolant level in
reserve/overflow tank. The coolant level should be
between ADD and FULL marks.

COOLANT—ADDING ADDITIONAL

Do not remove radiator cap to add coolant to
system. When adding coolant to maintain correct

level, do so at coolant reserve/overflow tank. Use a
50/50 mixture of ethylene-glycol antifreeze containing
Alugard 340-2 y and low mineral content water.
Remove radiator cap only for testing or when refill­ing system after service. Removing cap unnecessarily
can cause loss of coolant and allow air to enter sys­tem, which produces corrosion.

COOLANT—LEVEL CHECK

The cooling system is closed and designed to main­tain coolant level to top of radiator.

WARNING: DO NOT OPEN RADIATOR DRAINCOCK
WITH ENGINE RUNNING OR WHILE ENGINE IS HOT
AND COOLING SYSTEM IS UNDER PRESSURE.

When vehicle servicing requires a coolant level
check in radiator, drain several ounces of coolant
from radiator drain cock. Do this while observing
coolant reserve/overflow system tank. The coolant
level in reserve/overflow tank should drop slightly. If
not, inspect for a leak between radiator and coolant
reserve/overflow system connection. Remove radiator
cap. The coolant level should be to top of radiator. If
not and if coolant level in reserve/overflow tank is at
ADD mark, check for:

• An air leak in coolant reserve/overflow tank or

its hose

• An air leak in radiator filler neck

• Leak in pressure cap seal to radiator filler neck

COOLING SYSTEM—DRAINING AND FILLING

DRAINING

SERVICE PROCEDURES

COOLANT—ROUTINE LEVEL CHECK

NOTE: Do not remove radiator cap for routine
coolant level inspections. The coolant level can be
checked at coolant reserve/overflow tank.

WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.

DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.

(1) Remove radiator pressure cap.

7 - 22 COOLING SYSTEM XJ

SERVICE PROCEDURES (Continued)

(2) For access to radiator draincock (Fig. 21),
remove radiator grille mounting screws and remove
grill. Refer to Group 23, Body for correct procedure.

Fig. 21 Radiator Petcock—2.5L/4.0L (LHD/RHD)

1 – RADIATOR PETCOCK

(3) Attach one end of a 24 inch long X 1/4 inch ID
hose to the radiator draincock. Put the other end into
a clean container. Open draincock and drain coolant
from radiator.

(4) Drain coolant from engine by removing the
drain plug and coolant temperature sensor on left
side of block.

REFILLING

(1) Tighten the radiator petcock and the cylinder
block drain plug(s).

(2) Install grille.

(3) Fill system using a 50/50 mixture of water and
antifreeze as described in the Coolant section of this
group. Fill radiator to top and install radiator cap.
Add sufficient coolant to reserve/overflow tank to
raise level to FULL mark.

(4) With heater control unit in the HEAT position,
operate engine with radiator cap in place.

(5) After engine has reached normal operating
temperature, shut engine off and allow it to cool.

(6) Add coolant to reserve/overflow tank as neces­sary. Only add coolant when the engine is cold.

Coolant level in a warm engine will be higher
due to thermal expansion.

COOLING SYSTEM—REVERSE FLUSHING

CAUTION: The cooling system normally operates at
97-to-124 kPa (14- to-18 psi) pressure. Exceeding
this pressure may damage the radiator or hoses.

Reverse flushing of the cooling system is the forc­ing of water through the cooling system. This is done
using air pressure in the opposite direction of normal
coolant flow. It is usually only necessary with very
dirty systems with evidence of partial plugging.

CHEMICAL CLEANING

If visual inspection indicates the formation of
sludge or scaly deposits, use a radiator cleaner
(Mopar Radiator Kleen or equivalent) before flushing.
This will soften scale and other deposits and aid the
flushing operation.

CAUTION: Be sure instructions on the container
are followed.

REVERSE FLUSHING RADIATOR

Disconnect the radiator hoses from the radiator fit­tings. Attach a section of radiator hose to the radia­tor bottom outlet fitting and insert the flushing gun.
Connect a water supply hose and air supply hose to
the flushing gun.

CAUTION: The cooling system normally operates at
97-to-124 kPa (14- to-18 psi) pressure. Exceeding
this pressure may damage the radiator or hoses.

Allow the radiator to fill with water. When radiator
is filled, apply air in short blasts allowing radiator to
refill between blasts. Continue this reverse flushing
until clean water flows out through rear of radiator
cooling tube passages. For more information, refer to
operating instructions supplied with flushing equip­ment. Have radiator cleaned more extensively by a
radiator repair shop.

REVERSE FLUSHING ENGINE

Drain the cooling system. Remove the thermostat
housing and thermostat. Install the thermostat hous­ing. Disconnect the radiator upper hose from the
radiator and attach the flushing gun to the hose. Dis­connect the radiator lower hose from the water
pump. Attach a lead away hose to the water pump
inlet fitting.

CAUTION: Be sure that the heater control valve is
closed (heat off). This is done to prevent coolant
flow with scale and other deposits from entering
the heater core.

Connect the water supply hose and air supply hose
to the flushing gun. Allow the engine to fill with
water. When the engine is filled, apply air in short
blasts, allowing the system to fill between air blasts.
Continue until clean water flows through the lead
away hose. For more information, refer to operating
instructions supplied with flushing equipment.

XJ COOLING SYSTEM 7 - 23

SERVICE PROCEDURES (Continued)

Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo­stat housing and install thermostat. Install the ther­mostat housing with a replacement gasket. Refer to
Thermostat Replacement. Connect the radiator
hoses. Refill the cooling system with the correct anti­freeze/water mixture.

REMOVAL AND INSTALLATION

TRANSMISSION OIL COOLERS

WATER-TO-OIL COOLER

The internal transmission oil cooler located within
the radiator is not serviceable. If it requires service,
the radiator must be replaced.

Once the repaired or replacement radiator has been
installed, fill the cooling system and inspect for leaks.
Refer to the 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. Refer to Group 21 for
automatic transmission servicing.

1 – AIR CONDITIONING CONDENSER
2 – HOSE CLAMPS (2)
3 – AUXILIARY AUTOMATIC TRANSMISSION OIL COOLER
4 – MOUNTING BOLT
5 – MOUNTING BOLT

(2) Remove the tank mounting bolts and remove

tank (Fig. 23) (Fig. 24).

Fig. 22 Auxiliary Air-To-Oil Cooler

AIR-TO-OIL COOLER

REMOVAL

(1) Remove the grill mounting screws and remove
the grill. Refer to Group 23, Body for procedures.

(2) Place a drain pan below the transmission oil
cooler.

(3) Remove the two constant tension clamps at oil
cooler inlet and outlet tubes.

Remove the two oil cooler mounting bolts (Fig.

(4)

22).

(5) Remove the oil cooler from vehicle.

INSTALLATION

(1) Position and secure oil cooler to vehicle.
Tighten mounting bolts to 8 N·m (72 in. lbs.) torque.

(2) Secure inlet and outlet tubes with constant
tension clamps.

Install the grill.

(3) Start engine and check transmission fluid level.
Add fluid if necessary.

COOLANT RESERVE TANK

REMOVAL

(1) Remove the tube clamp at the tank and remove
tube.

Fig. 23 Reserve/Overflow Tank—Except Right Hand

Drive

1 – COOLANT RESERVE/OVERFLOW TANK
2 – CLAMP
3 – MOUNTING BOLTS
4 – TUBE TO RADIATOR

7 - 24 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 25 Reverse Rotating Water Pump—Typical

Fig. 24 Reserve/Overflow Tank—With Right Hand

Drive

1 – CLAMP
2 – COOLANT RESERVE/OVERFLOW TANK
3 – MOUNTING BOLTS
4 – LOWER BRACKET
5 – TUBE TO RADIATOR

INSTALLATION

(1) Position tank and tighten to 2 N·m (17 in. lbs.)
torque.

(2) Position tube and secure clamp.

WATER PUMP

1 – R STAMPED INTO IMPELLER

The water pump impeller is pressed on the rear of
the pump shaft and bearing assembly. The water
pump is serviced only as a complete assembly.

WARNING: DO NOT REMOVE THE BLOCK DRAIN
PLUG(S) OR LOOSEN RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.

DO NOT WASTE reusable coolant. If the solution
is clean, drain coolant into a clean container for
reuse.

CAUTION: If the water pump is replaced because of
mechanical damage, the fan blades and viscous fan
drive should also be inspected. These components
could have been damaged due to excessive vibra­tion.

The water pump can be removed without discharg-

ing the air conditioning system (if equipped).

CAUTION: All engines have a reverse (counter­clockwise) rotating water pump. The letter R is
stamped into the back of the water pump impeller
(Fig. 25) to identify. Engines from previous model
years, depending upon application, may be
equipped with a forward (clockwise) rotating water
pump. Installation of the wrong water pump will
cause engine over heating.

REMOVAL-2.5L ENGINE (LHD/RHD)

(1) Disconnect battery negative cable.

(2) Drain cooling system. Refer to Cooling System­Draining and Filling in this group.

(3) Remove upper radiator hose.

(4) Loosen (but do not remove at this time) the
four fan hub-to-water pump pulley mounting nuts
(Fig. 26).

(5) Remove accessory drive belt. (Refer to Acces­sory Drive Belt, Removal and Installation in this
group)

(6) Disconnect electric cooling fan connector (if
equipped).

(7) Unbolt fan shroud.

(8) Remove the four fan hub-to-water pump pulley
nuts and remove fan and shroud together.

XJ COOLING SYSTEM 7 - 25

REMOVAL AND INSTALLATION (Continued)

CAUTION: After removing fan blade/viscous fan
drive assembly, do not place thermal viscous fan
drive in horizontal position. If stored horizontally,
silicone fluid in viscous fan drive could drain into
its bearing assembly and contaminate lubricant.

(9) Remove power steering pump and bracket (Fig.

27), refer to Group 19 Steering for correct procedure.
(10) Remove lower radiator hose from water pump.

Remove heater hose from water pump pipe.

(11) Remove the four pump mounting bolts (Fig.

28) and remove pump from vehicle. Discard old gas-

ket. Note that one of the four bolts is longer than the
other bolts.

(12) If pump is to be replaced, the heater hose fit-

ting must be removed. Note position of fitting before
removal.

Fig. 27 Power Steering Pump Attachment-2.5L

1 – INTAKE MANIFOLD
2 – PUMP ASSEMBLY 2.5L
3 – PUMP BRACKET

Fig. 26 Fan Mounting Nuts

1 – THERMAL VISCOUS FAN DRIVE
2 – (4) FAN BLADE-TO-VISCOUS DRIVE BOLTS
3 – (4) FAN HUB-TO-PUMP PULLEY STUDS
4 – WATER PUMP
5 – WATER PUMP PULLEY
6 – FAN BLADE
7 – (4) FAN HUB-TO-PUMP PULLEY NUTS

INSTALLATION-2.5L ENGINE (LHD/RHD)

(1) If pump is being replaced, install the heater

hose pipe to the pump. Use a sealant on the fitting
such as Mopart Thread Sealant With Teflon. Refer to
the directions on the package.

(2) Clean the gasket mating surfaces. If the origi-

nal pump is used, remove any deposits or other for­eign material. Inspect the cylinder block and water

Fig. 28 Water Pump Remove/Install—Typical

1 – HEATER HOSE FITTING
2 – UPPER VENT HOLE
3 – PUMP GASKET
4 – WATER PUMP
5 – LOWER VENT HOLE
6 – LONG BOLT
7 – BOLTS (3) SHORT

7 - 26 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

pump mating surfaces for erosion or damage from
cavitation.

(3) Install the gasket and water pump. The sili-

cone bead on the gasket should be facing the water
pump. Also, the gasket is installed dry. Tighten
mounting bolts to 23 N·m (17 ft. lbs.) torque. Rotate
the shaft by hand to be sure it turns freely.

(4) Connect the radiator and heater hoses to the

water pump.

(5) Install power steering pump and bracket. Refer

to Group 19, Steering.

(6) Position water pump pulley to water pump

hub.

(7) Install shroud and fan together and install four

nuts to water pump hub studs. Tighten nuts to 27
N·m (20 ft. lbs.) torque.

(8) Install and tighten upper fan shroud nuts to 4

N·m (31 in. lbs.).

(9) Connect electric fan connector (if equipped).

CAUTION: When installing the accessory drive belt,
the belt MUST be routed correctly. If not, the engine
may overheat due to the water pump rotating in the
wrong direction. Refer to the Belt Removal and
Installation in this group for appropriate belt rout­ing. You may also refer to the Belt Routing Label in
the vehicle engine compartment.

(10) Install and tension accessory drive belt, refer

to Accessory Drive Belt removal and installation in
this group.

(11) Install upper radiator hose.
(12) Fill cooling system with coolant and check for

leaks. Refer to Refilling Cooling System in this
group.

(13) Connect battery negative cable.
(14) Start and warm the engine. Check for leaks.

REMOVAL-4.0L ENGINE (LHD/RHD)

(1) Disconnect battery negative cable.
(2) Drain the cooling system. (Refer to Cooling

System-Draining and Filling in this group.)

(3) Disconnect electric cooling fan connector.
(4) Remove electric cooling fan/shroud assembly (if

equipped).

(5) Remove viscous fan shroud bolts (2).
(6) Loosen (but do not remove at this time) the

four water pump pulley-to-water pump hub mounting
bolts (Fig. 29) and the four viscous fan to idler pulley
nuts.

NOTE: The accessory drive belt must be removed
prior to removing the fan (if installed at pump) or
fan pulley.

(7) Remove accessory drive belt (refer to Accessory

Drive Belt, Removal and Installation in this group)

1 – WATER PUMP HUB
2 – BOLTS (4)
3 – PUMP PULLEY

(8) Remove the four viscous fan to idler pulley

nuts and remove the fan and shroud together.

CAUTION: After removing fan blade/viscous fan
drive assembly, do not place thermal viscous fan
drive in horizontal position. If stored horizontally,
silicone fluid in viscous fan drive could drain into
its bearing assembly and contaminate lubricant.

(9) Remove the four water pump pulley bolts and

remove the pulley.

(10) Remove power steering pump and bracket

(Fig. 30), refer to Group 19 Steering.

(11) Remove lower radiator hose from water pump.

Remove heater hose from water pump fitting.

(12) Remove the four pump mounting bolts (Fig.

31) and remove pump from vehicle. Discard old gas­ket. Note that one of the four bolts is longer than the
other bolts.

(13) If pump is to be replaced, the heater hose fit­ting must be removed. Note position of fitting before
removal.

INSTALLATION-4.0L ENGINE (LHD/RHD)

(1) If pump is being replaced, install the heater
hose fitting to the pump. Use a sealant on the fitting
such as Mopart Thread Sealant With Teflon. Refer to
the directions on the package.

(2) Clean the gasket mating surfaces. If the origi­nal pump is used, remove any deposits or other for­eign material. Inspect the cylinder block and water
pump mating surfaces for erosion or damage from
cavitation.

(3) Install the gasket and water pump. The sili­cone bead on the gasket should be facing the water

Fig. 29 Water Pump Pulley Bolts

XJ COOLING SYSTEM 7 - 27

REMOVAL AND INSTALLATION (Continued)

Fig. 30 Power Steering Pump Attachment-4.0L

1 – PUMP ASSEMBLY
2 – PUMP BRACKET

pump. Also, the gasket is installed dry. Tighten
mounting bolts to 23 N·m (17 ft. lbs.) torque. Rotate
the shaft by hand to be sure it turns freely.

(4) Connect the radiator and heater hoses to the

water pump.

(5) Position water pump pulley to water pump

hub.

(6) Install four pump pulley bolts. Tighten bolts (or

nuts) to 27 N·m (20 ft. lbs.) torque.

(7) Install power steering pump. Refer to Group

19, Steering for proper procedure and torque values.

(8) Install the viscous fan and shroud together.
Install the four fan to idler pulley nuts and tighten
to 27 N·m (20 ft. lbs.).

CAUTION: When installing the accessory drive belt,
the belt MUST be routed correctly. If not, the engine
may overheat due to the water pump rotating in the
wrong direction. Refer to the Belt Removal and
Installation in this group for appropriate belt rout­ing. You may also refer to the Belt Routing Label in
the vehicle engine compartment.

(9) Install and tighten viscous fan shroud bolts to
4 N·m (31 in. lbs.).

(10) Install and tension the accessory drive belt,
refer to Accessory Drive Belt removal and installa­tion in this group.

(11) Install the electric cooling fan/shroud assy.

(12) Install and tighten electric fan shroud bolts to
4 N·m (31 in. lbs.). Connect fan connector.

Fig. 31 Water Pump Remove/Install—Typical

1 – HEATER HOSE FITTING
2 – UPPER VENT HOLE
3 – PUMP GASKET
4 – WATER PUMP
5 – LOWER VENT HOLE
6 – LONG BOLT
7 – BOLTS (3) SHORT

7 - 28 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

(13) Fill cooling system with coolant and check for
leaks. Refer to Refilling Cooling System in this
group.

(14) Connect battery negative cable.

(15) Start and warm the engine. Check for leaks.

THERMOSTAT

REMOVAL

WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES­SURIZED. 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
reuse.

(1) Drain the coolant from the radiator until the
level is below the thermostat housing.

WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (Fig. 12). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC­ING CONSTANT TENSION CLAMPS.

Fig. 32 Thermostat Removal/Installation

1 – LONG BOLT
2 – GASKET
3 – THERMOSTAT
4 – THERMOSTAT HOUSING
5 – SHORT BOLT

CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 11). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.

(2) Remove radiator upper hose and heater hose at
thermostat housing.

(3) Disconnect wiring connector at engine coolant
temperature sensor.

(4) Remove thermostat housing mounting bolts,
thermostat housing, gasket and thermostat (Fig. 32).
Discard old gasket.

(5) Clean the gasket mating surfaces.

INSTALLATION

(1) Install the replacement thermostat so that the
pellet, which is encircled by a coil spring, faces the
engine. All thermostats are marked on the outer
flange to indicate the proper installed position.

(a) Observe the recess groove in the engine cyl-

inder head (Fig. 33).

(b) Position thermostat into this groove with
arrow and air bleed hole on outer flange pointing
up.

Fig. 33 Thermostat Recess

1 – GROOVE

(2) Install replacement gasket and thermostat

housing.

XJ COOLING SYSTEM 7 - 29

REMOVAL AND INSTALLATION (Continued)

CAUTION: Tightening the thermostat housing
unevenly or with the thermostat out of its recess
may result in a cracked housing.

(3) Tighten the housing bolts to 20 N·m (15 ft. lbs.)

torque.

(4) Install hoses to thermostat housing.
(5) Install electrical connector to coolant tempera-

ture sensor.

(6) Be sure that the radiator draincock is tightly

closed. Fill the cooling system to the correct level
with the required coolant mixture. Refer to Refilling
Cooling System in this group.

(7) Start and warm the engine. Check for leaks.

RADIATOR—2.5L

WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES­SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.

DO NOT WASTE reusable coolant. If solution is

clean, drain coolant into a clean container for reuse.

WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (Fig. 12). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC­ING CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 11). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.

REMOVAL

(1) Disconnect battery negative cable.
(2) Observe the previous WARNINGS.
(3) Remove radiator pressure cap.
(4) For access to radiator draincock, remove radia-

tor grill mounting screws and remove grill. Refer to
Group 23, Body for procedures.

(5) Attach one end of a 24 inch long X 1/4 inch ID

hose to the radiator petcock (Fig. 34). Put the other
end into a clean container. Open petcock and drain
radiator.

(6) Detach power steering fluid reservoir from fan

shroud and lay aside.

(7) Disconnect electric cooling fan electrical con-

nector, if equipped.

Fig. 34 Radiator Petcock—Typical

1 – RADIATOR PETCOCK

(8) Disconnect CRS hose from radiator filler neck

and remove from shroud retaining loops.

(9) Remove the four (4) viscous fan/drive assembly
nuts from the water pump pulley and remove fan/
drive assy.

(10) Remove the four (4) fan shroud to core sup­port mounting screws.

(11) Remove the electric fan (if equipped) and
shroud assembly from the vehicle (Fig. 36).

(12) Remove radiator upper crossmember (Fig. 36).

(13) If equipped with air conditioning, separate
radiator from condenser by removing condenser-to-ra­diator mounting brackets (Fig. 35).

(14) Disconnect upper and lower radiator hoses.

(15) If equipped, disconnect and plug automatic
transmission fluid cooler lines. Quick Connect Fitting
Release Tool 6935 may be needed. If equipped with
remote transmission cooler, remove line to cooler
from bracket at bottom of radiator.

(16) Lift radiator straight up and out of engine
compartment taking care not to damage fins.

(17) If radiator is to be replaced, be sure to remove
and transfer any components not included with
replacement radiator.

INSTALLATION

The radiator is supplied with two alignment dowels
(Fig. 41). They are located on the bottom tank and fit
into rubber grommets in the radiator lower cross­member.

7 - 30 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

(1) Lower radiator into engine compartment. Posi­tion alignment dowels into rubber grommets in radi­ator lower crossmember (Fig. 41).

(2) If equipped with air conditioning, attach con­denser to radiator with mounting brackets (Fig. 35).

(3) Install radiator upper crossmember and four
mounting bolts.

(4) Install radiator upper crossmember-to-isolator
nuts. Tighten nuts to 10 N·m (86 in. lbs.) torque. If
isolator-to-radiator nuts had been removed, tighten
them to 5 N·m (47 in. lbs.) torque.

(5) Connect radiator upper and lower hoses.

(6) If equipped, connect automatic transmission
fluid cooler lines. If equipped with remote cooler,
attach cooler line to bracket at bottom of radiator.

(7) Install electric fan (if equipped) and shroud
assembly.. Insert alignment tabs at bottom of fan
shroud into slots in bracket at bottom of radiator.
Tighten mounting bolts to 3 N·m (31 in. lbs.) torque.

(8) Connect electric cooling fan electrical connector.

Fig. 35 Condenser-to-Radiator Mounting Brackets

1 – CONDENSER TO RADIATOR MOUNTING BRACKETS

(9) Install power steering reservoir to fan shroud.

(10) Install grill.

(11) Connect battery negative cable.

Fig. 36 Radiator Removal/Installation—2.5L Engines

1 – ELECTRIC FAN/SHROUD ASSEMBLY
2 – UPPER CROSSMEMBER
3 – ISOLATOR

4 – RADIATOR
5 – LOWER CROSSMEMBER
6 – U-NUT

XJ COOLING SYSTEM 7 - 31

REMOVAL AND INSTALLATION (Continued)

CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 11). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.

REMOVAL

(1) Disconnect battery negative cable.

(2) Observe the previous WARNINGS.

(3) Remove radiator pressure cap.

(4) For access to radiator draincock, remove radia­tor grill mounting screws and remove grill. Refer to
Group 23, Body for procedures.

(5) Attach one end of a 24 inch long X 1/4 inch ID
hose to the radiator petcock (Fig. 38). Put the other
end into a clean container. Open petcock and drain
radiator.

(6) Disconnect electric cooling fan electrical con­nector, if equipped.

Fig. 37 Radiator Alignment Dowels—Typical

1 – ALIGNMENT DOWEL
2 – RADIATOR
3 – AIR CONDITIONING CONDENSER
4 – GROMMET

(12) Fill cooling system with correct coolant. Refer

to the Coolant section of this group.

(13) Install pressure cap.
(14) Check and adjust automatic transmission

fluid level (if equipped).

(15) Start engine and visually check for leaks.

RADIATOR—4.0L

WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES­SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.

DO NOT WASTE reusable coolant. If solution is

clean, drain coolant into a clean container for reuse.

WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER

6094) (Fig. 12). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC­ING CONSTANT TENSION CLAMPS.

Fig. 38 Radiator Petcock—Typical

1 – RADIATOR PETCOCK

(7) If equipped, remove two electric cooling fan
mounting bolts. Lift cooling fan straight up until
alignment tabs at the bottom are clear of slots in
bracket at bottom of radiator (Fig. 39).

(8) Remove the two mechanical (non-electrical) fan
shroud mounting bolts. Lift shroud straight up until
alignment tabs at the bottom are clear of slots in
bracket at bottom of radiator (Fig. 39). Place shroud
over mechanical fan.

(9) If equipped, disconnect and plug automatic
transmission fluid cooler lines. Quick Connect Fitting
Release Tool 6935 may be needed. If equipped with
remote transmission cooler, remove line to cooler
from bracket at bottom of radiator.

7 - 32 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 39 Radiator Removal/Installation—4.0L Engines

1 – (LHD)
2 – (RHD)
3 – VISCOUS FAN SHROUD
4 – ELECTRIC FAN MODULE
5 – ISOLATOR

(10) Disconnect radiator upper and lower hoses

clamps. Disconnect radiator upper and lower hoses.

(11) Mark the position of the hood latch striker on
the radiator crossmember and remove hood latch
striker.

(12) Remove two radiator upper crossmember to
isolator nuts (Fig. 39).

(13) Remove four radiator upper crossmember
bolts and remove upper crossmember.

(14) If equipped with air conditioning, separate
radiator from condenser by removing condenser-to-ra­diator mounting brackets (Fig. 40).

(15) Lift radiator straight up and out of engine
compartment taking care not to damage fins.

INSTALLATION

The radiator is supplied with two alignment dowels
(Fig. 41). They are located on the bottom tank and fit
into rubber grommets in the radiator lower cross­member.

6 – RADIATOR
7 – LOWER CROSSMEMBER
8 – U-NUT
9 – UPPER CROSSMEMBER

(1) Lower radiator into engine compartment. Posi­tion alignment dowels into rubber grommets in radi­ator lower crossmember (Fig. 41)

(2) If equipped with air conditioning, attach con­denser to radiator with mounting brackets (Fig. 40).

(3) Install radiator upper crossmember and four
mounting bolts.

(4) Install radiator upper crossmember-to-isolator
nuts. Tighten nuts to 10 N·m (86 in. lbs.) torque. If
isolator-to-radiator nuts had been removed, tighten
them to 5 N·m (47 in. lbs.) torque.

(5) Install hood latch striker. Note previously
marked position.

(6) Connect radiator upper and lower hoses.

(7) If equipped, connect automatic transmission
fluid cooler lines. Refer to Group 21, Transmissions
for procedures. If equipped with remote cooler, attach
cooler line to bracket at bottom of radiator.

XJ COOLING SYSTEM 7 - 33

REMOVAL AND INSTALLATION (Continued)

(8) Install electric cooling fan (if equipped). Insert
alignment tabs at bottom of fan shroud into slots in
bracket at bottom of radiator. Tighten mounting bolts
to 3 N·m (31 in. lbs.) torque.

(9) Connect electric cooling fan electrical connector.

(10) Install mechanical cooling fan shroud. Insert
alignment tabs at bottom of shroud into slots in
bracket at bottom of radiator. Tighten mounting bolts
to 3 N·m (31 in. lbs.) torque.

(11) Close radiator draincock.

(12) Install grill.

(13) Connect negative battery cable.

(14) Fill cooling system with correct coolant. Refer
to the Coolant section of this group.

(15) Install pressure cap.

(16) Check and adjust automatic transmission
fluid level (if equipped).

ELECTRIC COOLING FAN—2.5L

The electric fan module is only to be serviced as an
assembly.

Fig. 40 Condenser to Radiator Mounting Brackets—

4.0L Engine

1 – CONDENSER TO RADIATOR MOUNTING BRACKETS

REMOVAL

(1) Disconnect battery negative cable.

(2) Disconnect CRS hose from radiator filler neck
and pull through (remove) the shroud retaining
loops.

(3) Detach power steering reservoir from fan
shroud and lay aside.

(4) Remove the four viscous fan/drive assembly
mounting nuts from the water pump studs and
remove viscous fan assembly.

(5) Disconnect cooling fan electrical connector.

(6) Remove the four upper fan shroud to radiator
crossmember mounting screws (Fig. 42).

(7) Lift fan and shroud assy. from vehicle

(8) Detach fan harness from shroud.

(9) Remove four fan module to shroud phillips
head screws (Fig. 43) and remove module from
shroud.

Fig. 41 Radiator Alignment Dowels—Typical

1 – ALIGNMENT DOWEL
2 – RADIATOR
3 – AIR CONDITIONING CONDENSER
4 – GROMMET

INSTALLATION

(1) Position fan module in shroud so that the har­ness exits the motor at the 12 o’clock postion (Fig.

43).

(2) Install and tighten fan module to shroud
screws to 3 N·m (31 in. lbs.).

(3) Route fan harness through the shroud and
attach to shroud at correct position.

(4) Lower fan and shroud assembly into place,
making sure the shroud alignment tabs rest in their
corresponding lower radiator slots.

(5) Install upper fan shroud screws and tighten to
3 N·m (31 in. lbs.).

7 - 34 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 42 Fan Shroud Removal/Installation

1 – ELECTRIC FAN/SHROUD ASSEMBLY
2 – UPPER CROSSMEMBER
3 – ISOLATOR

Fig. 43 Fan Module Orientation and Mounting

1 – FAN MOTOR HARNESS AT 12 O’CLOCK POSITION
2 – MOUNTING SCREWS (4)
3 – FAN CONNECTOR

4 – RADIATOR
5 – LOWER CROSSMEMBER
6 – U-NUT

(6) Connect fan electrical connector.

(7) Install power steering reservoir to shoud.

(8) Install viscous fan drive assy. to water pump
hub and tighten nuts to 27 N·m (20 ft. lbs.)

(9) Connect battery negative cable.

ELECTRIC COOLING FAN—4.0L

REMOVAL

The auxiliary cooling fan is attached to the radia­tor upper crossmember behind the radiator.

(1) Remove the two fan mounting bolts from radi­ator upper crossmember (Fig. 44).

(2) Disconnect the electric fan connector.

(3) Lift fan straight up and out of vehicle.

INSTALLATION

(1) Align lower retaining tabs of fan shroud with
slots in bracket at bottom of radiator. Push fan down
into position.

(2) Tighten the mounting bolts to 4 N·m (31 in.
lbs.) torque.

XJ COOLING SYSTEM 7 - 35

REMOVAL AND INSTALLATION (Continued)

(2) Insert block heater assembly into core hole
with element loop pointing Up.

(3) Seat block heater flush against block face.
Tighten mounting screw to 3.6 N·m (32 in. lbs.)
torque.

(4) Fill cooling system with coolant. Pressurize
system and inspect for leaks.

(5) Plug power cord into block heater. Route cord
away from moving parts, linkages and exhaust sys­tem components. Secure cord in place with tie-straps.

Fig. 44 Auxiliary Cooling Fan—Remove/Install—

Typical

1 – ELECTRIC COOLING FAN
2 – MOUNTING BOLT
3 – ELECTRIC COOLING FAN CONNECTOR
4 – MOUNTING BOLT

(3) Connect auxiliary cooling fan electrical connec-

tor.

BLOCK HEATER

REMOVAL

Refer to correct illustration (Fig. 45) (Fig. 46) when

servicing block heater.

WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES­SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.

DO NOT WASTE reusable coolant. If solution is

clean, drain coolant into a clean container for reuse.

(1) Drain coolant from radiator and engine cylin-

der block.

(2) Unplug power cord from block heater.
(3) Loosen screw in center of block heater (Fig. 45)

(Fig. 46).

(4) Remove block heater from cylinder block.

INSTALLATION

(1) Thoroughly clean the engine core hole and the

block heater seat.

Fig. 45 Heater and Cord— 2.5L 4-Cylinder Engine

1 – POWER CORD LOCATION
2 – BLOCK HEATER

ENGINE ACCESSORY DRIVE BELTS

Fig. 46 Heater and Cord—4.0L 6-Cylinder Engine

1 – POWER CORD LOCATION
2 – BLOCK HEATER

Correct drive belt tension is required to ensure
optimum performance of the belt driven engine acces­sories. There are different types of adjustment
gauges for checking either a serpentine or a V-type
belt. Refer to the instructions supplied with the

7 - 36 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

gauge. Use the correct gauge when checking belt ten­sion. Place gauge in the middle of the section of belt
being tested (between two pulleys) to check tension.
Do not allow the gauge (or gauge adapter) to contact
anything but the belt.

BELT SCHEMATICS

The belt routing schematics are published from the
latest information available at the time of publica­tion. If anything differs between these schemat-

ics and the Belt Routing Label, use the
schematics on Belt Routing Label. This label is

located in the engine compartment.

Refer to (Fig. 47) (Fig. 48) (Fig. 49) (Fig. 50) for
proper belt routing on vehicles with conventional left
hand drive. Refer to (Fig. 51) (Fig. 52) for proper belt
routing on vehicles with right hand drive (RHD). Or,
refer to the Belt Routing Label located in the vehicle
engine compartment.

Fig. 48 Models with 2.5L Engine—Without A/C

Fig. 47 Models with 2.5L Engine—With A/C

BELT REPLACEMENT OR ADJUSTMENT—LEFT
HAND DRIVE

Belt tension is adjusted at the power steering
pump bracket and idler pulley assembly.

(1) Disconnect negative battery cable from battery.

(2) Loosen idler pulley bolt at the power steering
bracket (Fig. 53).

(3) Loosen adjusting bolt until belt can be removed
from pulleys.

(4) Remove belt.

Fig. 49 Models with 4.0L Engine—Without A/C—

Except RHD

INSTALLATION

(1) Check condition of all pulleys.

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 rotating in the wrong direction. Refer to (Fig.

47) (Fig. 48) (Fig. 49) (Fig. 50) for correct belt rout­ing.

XJ COOLING SYSTEM 7 - 37

REMOVAL AND INSTALLATION (Continued)

Fig. 50 Models With 4.0L Engine—With A/C—Except

RHD

Fig. 51 Models With 4.0L Engine—With A/C—With

RHD

(2) Install new belt.

(3) Using serpentine belt tension gauge, tighten
adjusting bolt until belt reaches proper tension. Refer
to Belt Tension at the rear of this section for proper
belt tension.

(4) After belt is tensioned correctly, tighten idler
pulley bolt to 47 N·m (35 ft. lbs.)

(5) After idler pulley has been tightened into posi­tion, recheck belt tension. Adjust if necessary.

BELT REPLACEMENT OR ADJUSTMENT—RIGHT
HAND DRIVE (4.0L)

(1) Disconnect negative battery cable from battery.

(2) Loosen lower alternator mounting bolt and nut.

Fig. 52 Models With 4.0L Engine—Without A/C—

With RHD

Fig. 53 Power Steering Pump Bracket and Idler

Pulley

1 – ADJUSTING BOLT
2 – IDLER PULLEY BOLT

(3) Loosen upper alternator mounting nut.
(4)

Loosen adjusting bolt at upper alternator bracket

(Fig. 54) until belt can be removed from pulleys.

(5) Remove belt.

INSTALLATION

(1) Check condition of all pulleys.

7 - 38 COOLING SYSTEM XJ

REMOVAL AND INSTALLATION (Continued)

Fig. 54 Generator Belt Tension Adjust Bracket

1 – TENSION ADJUSTMENT BOLT
2 – UPPER ALTERNATOR NUT

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 rotating in the wrong direction. Refer to (Fig.

51) (Fig. 52) for correct belt routing.

Fig. 55 Water Pump Mounted Cooling Fan

1 – THERMAL VISCOUS FAN DRIVE
2 – (4) FAN BLADE-TO-VISCOUS DRIVE BOLTS
3 – (4) FAN HUB-TO-PUMP PULLEY STUDS
4 – WATER PUMP
5 – WATER PUMP PULLEY
6 – FAN BLADE
7 – (4) FAN HUB-TO-PUMP PULLEY NUTS

(2) Install new belt.

(3) Using serpentine belt tension gauge, tighten
adjusting bolt until belt reaches proper tension. Refer
to Belt Tension at the rear of this section for proper
belt tension.

(4) Tighten alternator upper and lower mounting
bolts.

(5) After generator and adjust bracket have been
tightened into position, recheck belt tension. Adjust if
necessary.

COOLING SYSTEM FANS

REMOVAL

Some engines have the mechanical fan/viscous fan
drive assembly mounted directly to the water pump
hub (Fig. 55). It may also be mounted to a hub/bear­ing attached to an aluminum bracket on the right
front side of engine (Fig. 56).

(1) Loosen but do not remove at this time, the four
fan hub mounting nuts (Fig. 55) (Fig. 56).

(2) Remove accessory serpentine drive belt. Refer
to Belt Service in the Engine Accessory Drive Belt
section of this group.

(3) Some models with certain engines may require
the removal of the fan shroud to remove the viscous
fan drive. The fan shroud and fan blade/viscous fan

drive should be removed from the vehicle as one
assembly.

(4) Remove four fan hub mounting nuts (Fig. 55)
(Fig. 56) and remove fan/viscous fan drive assembly
from vehicle.

(5) After removing fan blade/viscous fan drive
assembly, do not place thermal viscous fan drive in
horizontal position. If stored horizontally, silicone
fluid in viscous fan drive could drain into its bearing
assembly and contaminate lubricant.

INSTALLATION

(1) Assemble fan blade to viscous fan drive.
Tighten mounting bolts to 27 N·m (20 ft. lbs.) torque.

(2) Position mounting flange of fan blade/viscous
fan drive assembly onto hub. Install four nuts and
tighten to 24 N·m (18 ft. lbs.) torque. Tighten the
first two nuts 180 degrees apart. Then tighten last
two nuts.

CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction. Refer to appropriate
Engine Accessory Drive Belt Schematic in this
group for correct belt routing.

XJ COOLING SYSTEM 7 - 39

REMOVAL AND INSTALLATION (Continued)

RADIATOR

CLEANING

Clean radiator fins With the engine cold, apply cold
water and compressed air to the back (engine side) of
the radiator to flush the radiator and/or A/C con­denser of debris.

INSPECTION

The radiator cooling fins should be checked for
damage or deterioration. Inspect cooling fins to make
sure they are not bent or crushed, these areas result
in reduced heat exchange causing the cooling system
to operate at higher temperatures. Inspect the plastic
end tanks for cracks, damage or leaks.

Inspect the radiator neck for damage or distortion.

WATER PUMP

CLEANING

Clean the gasket mating surface. Use caution not

Fig. 56 Bracket Mounted Cooling Fan

1 – WATER PUMP (2.5L ENGINE)
2 – HUB/BEARING (4.0L ENGINE)
3 – PULLEY NUTS
4 – PULLEY
5 – BRACKET

(3) Install accessory drive belts. Tension belts to
specifications. Refer to the Specifications section at
the end of this group.

VISCOUS FAN DRIVE REMOVAL/INSTALLATION

Refer to Cooling System Fan for removal and
installation procedures of the viscous drive unit.

Viscous Fan Drive Fluid Pump Out Requirement:

After installing a new viscous fan drive, bring the
engine speed up to approximately 2000 rpm and hold
for approximately two minutes. This will ensure
proper fluid distribution within the drive.

to damage the gasket sealing surface.

INSPECTION

Inspect the water pump assembly for cracks in the
housing, Water leaks from shaft seal, Loose or rough
turning bearing or Impeller rubbing either the pump
body or timing chain case/cover.

FAN BLADE

CLEANING

Clean the fan blades using a mild soap and water.
Do not use an abrasive to clean the blades.

INSPECTION

WARNING: DO NOT ATTEMPT TO BEND OR
STRAIGHTEN FAN BLADES IF FAN IS NOT WITHIN
SPECIFICATIONS.

CLEANING AND INSPECTION

RADIATOR PRESSURE CAP

CLEANING

Clean the radiator pressure cap using a mild soap

and water only.

INSPECTION

Visually inspect the pressure valve gasket on the
cap. Replace cap if the gasket is swollen, torn or
worn. Inspect the area around radiator filler neck for
white deposits that indicate a leaking cap.

CAUTION: If fan blade assembly is replaced
because of mechanical damage, water pump and
viscous fan drive should also be inspected. These
components could have been damaged due to
excessive vibration.

(1) Remove fan blade assembly from viscous fan

drive unit (four bolts).

(2) Lay fan on a flat surface with leading edge fac­ing down. With tip of blade touching flat surface,
replace 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 - 40 COOLING SYSTEM XJ

CLEANING AND INSPECTION (Continued)

(3) Inspect fan assembly for cracks, bends, loose
rivets or broken welds. Replace fan if any damage is
found.

COOLING SYSTEM HOSES

INSPECTION

Inspect the hoses at regular intervals. Replace
hoses that are cracked, feel brittle when squeezed or
swell excessively when the system is pressurized.
The use of molded replacement hoses is recom­mended. When performing a hose inspection, inspect
the radiator lower hose for proper position and con­dition of the spring.

SPECIFICATIONS

BELT TENSION

Belt tension must be adjusted. Refer to the follow­ing Belt Tension chart for specifications.

DESCRIPTION N·f Lbs. ft.

New Serpentine Belt* 800-900 180-200
Used Serpentine Belt 623-712 140-160

* Belt is considered new if it has been used 15

minetes or less.

DESCRIPTION N·m Ft. In.

Lbs. Lbs.

Water Pump or Hub
Bearing—Nuts

Water Pump—Bolts 23 17 —

27 20 —

SPECIAL TOOLS

COOLING

Hose Clamp Tool—6094

TORQUE SPECIFICATIONS

DESCRIPTION N·m Ft. In.

Lbs. Lbs.

Trans. Auxiliary Oil
Cooler—Screws

Block Heater—Screw 4 — 20
Condenser-to-Radiator—

Bolts
Electric Cooling Fan—Bolts 3 — 31
Fan Blade Assy to Viscous

Fan Drive—Bolts 24 18 —
Fan Shroud—Bolts 3 — 31
Isolator-to-Crossmember—

Nuts
Isolator-to-Radiator—Nuts 5 — 47
Radiator—Bolts

4.0L Engine 8 — 70

2.5L Engine 6 — 55
Thermostat Housing—Bolts 20 15 —
Viscous Fan Drive Assy. to

2—18

6—55

10 — 86

Cooling System Pressure Tester—7700A

3/8” Quick Connect Release Tool—6935