CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
(12) Remove lower radiator hose from water pump.
Remove heater hose from water pump fitting.
(13) Remove four nuts or bolts (refer to the previ-
ous step #3).
(14) Remove the fan assembly and pulley (if fan is
installed at pump), or remove the pulley from the ve-
hicle.
(15) Remove the four pump mounting bolts (Fig. 9)
and remove pump from vehicle. Discard old gasket.
Note that one of the four bolts is longer than the
other bolts.
(16) If pump is to be replaced, the heater hose fit-
ting must be removed. Note position of fitting before
removal.
INSTALLATIONÐALL MODELS
(1) If pump is being replaced, install the heater
hose fitting to the pump. Use a sealant on the fitting
such as MoparŸ 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 for-
eign material. Inspect the cylinder block and water
pump mating surfaces for erosion or damage from
cavitation.
(3) Install the gasket and water pump (the gasket
is installed dry). Tighten mounting bolts to 30 Nzm
(22 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) If equipped with a water pump mounted fan,
install fan and four nuts to water pump hub. If notequipped with a water pump mounted fan, install
four pump hub bolts. Tighten bolts (or nuts) to 27
Nzm (20 ft. lbs.) torque.
(7) Position power steering pump bracket to en-
gine. Install bolts E, F and G (Fig. 7). Tighten bolts
FandGto38Nzm (28 ft. lbs.) torque. Tighten bolt E
to 27 Nzm (20 ft. lbs.) torque.
(8) Position power steering pump to mounting
bracket. Install pivot bolt B (Fig. 6) finger tight. In-
stall locknut C and adjustment bolt D (Figs. 6 or 7)
finger tight.
(9) Install two adjustment bolts A (Fig. 6) finger
tight.
(10) Install idler pulley.
CAUTION: When installing the serpentine engine
accessory drive belt, the belt MUST be routed cor-
rectly. If not, the engine may overheat due to the
water pump rotating in the wrong direction. Refer to
Figs. 10, 11, 12 or 13 for appropriate belt routing.
You may also refer to the Belt Routing Label in the ve-
hicle engine compartment.
(11) Position drive belt to pulleys.
(12) Tighten belt adjustment bolt D (Fig. 5) to the
proper tension. Refer to the Specifications section at
the end of this group for belt tension.
(13) Tighten bolts A (Fig. 5) to 27 Nzm (20 ft. lbs.)
torque.
Fig. 8 Hose Clamp ToolÐTypical
Fig. 9 Water Pump Remove/InstallÐTypical
7 - 12 COOLING SYSTEMJ
CAUTION: Do not operate an engine without a ther-
mostat, except for servicing or testing.
ON-BOARD DIAGNOSTICS
XJ and YJ models are equipped with On-Board Di-
agnostics for certain cooling system components. Re-
fer to On-Board Diagnostics (OBD) in the Diagnosis
section of this group for additional information. If the
powertrain control module (PCM) detects low engine
coolant temperature, it will record a Diagnostic Trou-
ble Code (DTC) in the PCM memory. The DTC num-
ber for low coolant temperature is 17. Do not change
a thermostat for lack of heat as indicated by the in-
strument panel gauge or heater performance unless a
DTC number 17 is present. Refer to the Diagnosis
section of this group for other probable causes. For
other DTC numbers, refer to On-Board Diagnostics
in the General Diagnosis section of group 14, Fuel
Systems.
The DTC can also be accessed through the DRB
scan tool. Refer to the appropriate Powertrain Diag-
nostic Procedures manual for diagnostic information
and operation of the DRB scan tool.
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
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 (NUM-
BER 6094) (FIG. 14). SNAP-ON CLAMP TOOL (NUM-
BER 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. 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. 15).
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. 16).
(b) Position thermostat in groove with arrow and
air bleed hole on outer flange pointing up.
(2) Install replacement gasket and thermostat
housing.
Fig. 14 Hose Clamp ToolÐTypical
Fig. 15 Thermostat Removal/Installation
7 - 14 COOLING SYSTEMJ
RADIATORS
GENERAL INFORMATION
All radiators are down flow types except XJ models
with 4.0L engines. Radiators in XJ models equipped
with the 4.0L six-cylinder engine, are the cross flow
type. Plastic tanks are used on all radiators.
CAUTION: Plastic tanks, while stronger than brass,
are subject to damage by impact, such as
wrenches.
If plastic tank has been damaged, plastic tank
and/or O-rings are available for service repair. Tank
replacement should be done by qualified personal
with proper equipment.
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.
RADIATOR REMOVAL/INSTALLATION
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS, RADIATOR CAP, 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 (NUM-
BER 6094) (FIG. 26). SNAP-ON CLAMP TOOL (NUM-
BER 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. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
XJ MODELS WITH 2.5L ENGINE
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Observe the previousWARNINGS.Remove ra-
diator cap.(3) Position drain pan under draincock. Open radi-
ator draincock. Drain radiator.
(4) Remove radiator upper and lower hose clamps
and hoses.
(5) Remove alignment dowel E-clip from radiator
lower mounting bracket (Fig. 27).
(6) Disconnect coolant reserve/overflow tank hose
from radiator.
(7) Remove radiator fan shroud mounting bolts
(Fig. 28). Push shroud back against front of engine.
(8) If equipped, disconnect and plug automatic
transmission fluid cooler lines.
(9) Remove radiator top mounting bolts (Fig. 28).
(10) Remove the radiator grille mounting screws.
Remove grille (Fig. 29).
(11) Remove the air conditioning condenser-to-ra-
diator mounting bolt. Use an open end wrench to re-
Fig. 26 Hose Clamp ToolÐTypical
Fig. 27 Radiator Remove/InstallÐXJ ModelsÐ2.5L
Engine
7 - 22 COOLING SYSTEMJ
move bottom bolts (Fig. 30).
(12) Lift radiator straight up and out of vehicle.
Take care not to damage radiator fins.
INSTALLATION
(1) Install radiator behind air conditioning con-
denser with bottom alignment dowel inserted into ra-
diator lower mounting bracket.
(2) Install E-clip to alignment dowel.(3) Tighten the four condenser-to-radiator mount-
ing bolts to 6.2 Nzm (55 in. lbs.) torque.
(4) Install radiator grille.
(5) Tighten radiator top mounting bolts to 6 Nzm
(55 in. lbs.) torque.
(6) If equipped, connect automatic transmission
fluid cooler lines to radiator.
(7) Install the radiator fan shroud. Connect the
coolant reserve/overflow tank hose.
(8) Connect radiator hoses and install hose clamps.
(9) Connect negative battery cable.
(10) Close the draincock.
(11) Fill cooling system with correct coolant.
(12) Install radiator cap.
(13) Check and adjust automatic transmission fluid
level (if equipped).
XJ MODELS WITH 4.0L ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
Fig. 28 Shroud Remove/InstallÐXJ Models With
2.5L Engine
Fig. 29 Grille Remove/InstallÐCherokee Models
With 2.5L Engine
Fig. 30 Condenser Mounting BoltsÐXJ Models With
2.5L Engine
JCOOLING SYSTEM 7 - 23
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 (NUM-
BER 6094) (FIG. 26). SNAP-ON CLAMP TOOL (NUM-
BER 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. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Observe the previousWARNINGS.
(3) Remove pressure cap.
(4) For access to radiator draincock, remove radia-
tor grille (Fig. 29).
(5) 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 radia-
tor.
(6) If equipped, disconnect electric cooling fan elec-
trical connector (Fig. 31).
(7) Remove electric fan mounting bolts. Lift fan
straight up and out of engine compartment.
(8) Remove the mechanical (non-electrical) fan
shroud mounting bolts. Lift shroud up until align-ment tabs at the bottom are clear of slots in bracket
at bottom of radiator (Fig. 32). Place shroud over me-
chanical fan.
(9) If equipped, disconnect and plug automatic
transmission fluid cooler lines. If equipped with re-
mote cooler, remove line to cooler from bracket at
bottom of radiator.
(10) 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 radiator upper crossmember bracket.
(13) Remove radiator upper crossmember.
(14) If equipped with air conditioning, separate ra-
diator from condenser by removing condenser-to-radi-
ator mounting brackets (Fig. 33).
(15) Lift radiator straight up and out of engine
compartment taking care not to damage fins.
INSTALLATION
The radiator has two alignment dowels. They are
located on the bottom tank and fit into rubber grom-
mets in the radiator lower crossmember.
(1) Lower radiator into engine compartment. Posi-
tion alignment dowels into grommets in radiator
lower crossmember (Fig. 34).
(2) If equipped with air conditioning, attach con-
denser to radiator with mounting brackets (Fig. 33).
(3) Install radiator upper crossmember.
(4) Install radiator upper crossmember bracket.
(5) Install hood latch striker.
(6) Connect radiator upper and lower hoses.
Fig. 31 Auxiliary FanÐRemove/Install
Fig. 32 Auxiliary Fan and Mechanical Fan
ShroudÐRemove/InstallÐTypical
7 - 24 COOLING SYSTEMJ
(7) If equipped, connect automatic transmission
fluid cooler lines. If equipped with remote cooler, at-
tach cooler line to bracket at bottom of radiator.
(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 4 Nzm (36 in. lbs.) torque.
(9) Connect electric cooling fan electrical connec-
tor.(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 4 Nzm (36 in. lbs.) torque (Fig. 32).
(11) Close radiator draincock.
(12) Install grille.
(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).
YJ MODELS
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. 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 (NUM-
BER 6094) (FIG. 26). SNAP-ON CLAMP TOOL (NUM-
BER 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. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Observe the previousWARNINGS.Remove
the radiator cap.
(3) Position drain pan under draincock. Open radi-
ator draincock and drain radiator.
(4) Remove radiator upper and lower hose clamps
and hoses.
(5) Disconnect coolant reserve/overflow tank hose
from radiator.
(6) Remove fan shroud bolts and push shroud back
onto fan (Fig. 35).
(7) If equipped, disconnect and plug automatic
transmission fluid cooler lines.
(8) Remove radiator attaching bolts.
(9) Lift radiator straight up and out of vehicle tak-
ing care not to damage radiator fins.
Fig. 33 Condenser-to-Radiator Mounting
BracketsÐXJ with 4.0L Engine
Fig. 34 Radiator InstallationÐXJ Models with 4.0L
Engine
JCOOLING SYSTEM 7 - 25
INSTALLATION
(1) Install the radiator. Tighten the mounting bolts
to8Nzm (6 ft. lbs.) torque (Fig. 35).
(2) Close radiator draincock.
(3) Install fan shroud. Tighten mounting bolts to
16 Nzm (11 ft. lbs.) torque.
(4) If equipped, remove plugs and connect auto-
matic transmission fluid cooler lines.
(5) Connect radiator hoses and install hose clamps.
(6) Connect negative battery cable.
(7) Fill cooling system with correct coolant. Refer
to the Coolant section of this group.
(8) Connect reserve/overflow tank hose.
(9) Install radiator cap.
(10) Check and adjust automatic transmission fluid
level (if equipped).
COOLING SYSTEM HOSES
Rubber hoses route coolant to and from the radia-
tor, intake manifold and heater core. All XJ models
equipped with air conditioning have a coolant control
valve. This is located in-line with the heater core in-
let and outlet hoses. It controls coolant flow to the
heater core when the air conditioning system is in
operation.
Radiator lower hoses are spring-reinforced to pre-
vent collapse from water pump suction at moderate
and high engine speeds.
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 (NUM-
BER 6094) (FIG. 36). SNAP-ON CLAMP TOOL (NUM-
BER 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. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
Inspect the hoses at regular intervals. Replace
hoses that are cracked, feel brittle when squeezed, or
swell excessively when the system is pressurized.
For all vehicles: In areas where specific routing
clamps are not provided, be sure that hoses are posi-
tioned with sufficient clearance. Check clearance
from exhaust manifolds and pipe, fan blades, drive
belts and sway bars. Improperly positioned hoses can
be damaged, resulting in coolant loss and engine
overheating.
Ordinary worm gear type hose clamps (when
equipped) can be removed with a straight screw-
driver or a hex socket.To prevent damage to
hoses or clamps, the hose clamps should be
tightened to 4 Nzm (34 in. lbs.) torque. Do not
over tighten hose clamps.
When performing a hose inspection, inspect the ra-
diator lower hose for proper position and condition of
the internal spring.
COOLING SYSTEM FANS
All models are equipped with a mechanical temper-
ature controlled fan. The viscous fan drive is a
torque-and-temperature-sensitive clutch unit. It auto-
matically increases or decreases fan speed to provide
proper engine cooling. XJ models equipped with a
4.0L engine may also have an auxiliary electrical
fan. This is with models that have air conditioning
and/or heavy duty cooling.
VISCOUS FAN DRIVE OPERATION
The viscous fan drive (Fig. 37) is a silicone-fluid-
filled coupling. On some engines it connects the fan
assembly to the fan/water pump pulley. The coupling
allows the fan to be driven in a normal manner. This
is done at low engine speeds while limiting the top
Fig. 35 RadiatorÐRemove/InstallÐYJ Models
Fig. 36 Hose Clamp ToolÐTypical
7 - 26 COOLING SYSTEMJ
and torque convertor may not require reconditioning.
Refer to Group 21 for automatic transmission servic-
ing.
AIR-TO-OIL COOLER
An auxiliary air-to-oil transmission oil cooler is
available with most engine packages.
On XJ and YJ models, the cooler is located in front
of the radiator or A/C condenser (if equipped) and be-
hind the grill (Figs. 42 or 43). 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 re-
turning to the transmission.
REMOVAL/INSTALLATIONÐXJ MODELS
(1) Remove the grill. Refer to Group 23, Body.
(2) Place a drain pan below the transmission oil
cooler.
(3) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Fig. 42).
(4) Remove the two oil cooler mounting bolts (Fig.
42).
(5) Remove the oil cooler from vehicle.
(6) Reverse the preceding operation for installa-
tion. Tighten the two clamps 2 Nzm (15 in. lbs.)
torque.
REMOVAL/INSTALLATIONÐYJ MODELS
(1) Remove fan shroud and radiator. Refer to
Group 7, Cooling for procedures.
(2) Remove the air conditioning filter/drier mount-
ing bolts.
CAUTION: Before proceeding with the next step, be
sure to wear safety glasses. The A/C system is un-
der pressure even with the system off.
(3) Remove the A/C condenser mounting bolts (Fig.
44).
(4) Carefully tilt the A/C condenser rearward for
access to the auxiliary transmission oil cooler.
(5) Place a drain pan below the oil cooler.
(6) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Fig. 43).
(7) Remove the two oil cooler mounting bolts (Fig.
43).
(8) Remove the oil cooler from vehicle.
(9) Reverse the preceding operation for installation.
Tighten the two clamps 2 Nzm (15 in. lbs.) torque.
Fig. 42 Auxiliary Air-To-Oil CoolerÐYJ Models
Fig. 43 Auxiliary Air-To-Oil CoolerÐXJ Models
Fig. 44 Condenser Mounting BoltsÐYJ Models
7 - 30 COOLING SYSTEMJ