1994 JEEP CHEROKEE radiator

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

speed of the fan to a predetermined maximum level
at higher engine speeds. A bimetallic spring coil is
located on the front face. This spring coil reacts to
the temperature of the radiator discharge air. It en-
gages 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 nec-
essary, the fan will remain at a reduced rpm regard-
less of engine speed.
Only when sufficient heat is present, will the vis-
cous fan drive engage. This is when the air flowing
through the radiator core causes a reaction from 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 re-
acts and the fan speed is reduced to the previous dis-
engaged speed.
CAUTION: Engines equipped with serpentine 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 overheat-
ing.
VISCOUS FAN DRIVE TEST
The cooling system must be in good condition. This
is checked prior to performing the following test. It
also will ensure against excessively high coolant
temperature.
CAUTION: 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 -18É-to-
105ÉC (0É-to-220É 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 con-
ditioner 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 DI-
RECT 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 with
the timing light (strobe light) aimed at the fan
blades. Within ten minutes the air temperature (in-
dicated on the dial thermometer) should be 88É C
(190É F). Satisfactory operation of the fan drive re-
quires that it engage before or at 88É C (190É F). En-
gagement is distinguishable by a definite increase in
flow noise. The timing light also will indicate an in-
crease in the speed of the fan.
(7) When the air temperature reaches 88É C (190É
F), remove the plastic sheet. Satisfactory operation of
the viscous fan requires the air temperature to drop
20É F (11É C) or more. A definite decrease of audible-
fan-air-flow-noise should be noticed. Replace defec-
tive fan assemblies.
VISCOUS FAN DRIVE REPLACEMENT
REMOVAL
Some engines have the mechanical fan/viscous fan
drive assembly mounted directly to the water pump
hub (Fig. 38). It may also be mounted to a hub/bear-
ing attached to an aluminum bracket on the right
front side of engine (Fig. 39).
(1) Loosen but do not remove at this time, the four
fan hub mounting nuts (Figs. 38 or 39).
(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 as-
sembly.
Fig. 37 Viscous Fan DriveÐTypical
JCOOLING SYSTEM 7 - 27

through the relay. When coolant temperature is be-
low 88ÉC (190ÉF), the PCM opens the ground path to
the relay. This will prevent the cooling fan from be-
ing energized.
Whenever the air conditioning is used, the PCM
engages the auxiliary cooling fan. It provides a
ground path to the cooling fan relay.
DIAGNOSIS
The powertrain control module (PCM) will enter a
diagnostic trouble code (DTC) number 35 in memory
if it detects a problem in the auxiliary cooling fan re-
lay or circuit. This will be read as a flashing signal
at the instrument panel mounted Malfunction Indica-
tor Lamp (formerly referred to as the Check Engine
Lamp). Refer to On-Board Diagnostics in Group 14,
Fuel Systems for information on accessing a DTC.
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
The auxiliary fan is attached to the radiator upper
crossmember behind the radiator.
(1) Remove the fan retaining bolts from radiator
upper crossmember (Fig. 41).
(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 Nzm (31 in.
lbs.) torque.
(3) Connect auxiliary cooling fan electrical connec-
tor.
TRANSMISSION OIL COOLERS
WATER-TO-OIL COOLER
All models equipped with an automatic transmis-
sion are equipped with a transmission oil cooler
mounted internally within the radiator tank. This in-
ternal cooler is supplied as standard equipment on
all models equipped with an automatic transmission.
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.
Also refer to the section on Transmission Air-to-Oil
Coolers. This auxiliary air-to-oil cooler is an option
on most engine packages.
REPLACING WATER-TO-OIL COOLER IN
RADIATOR SIDE TANK
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 re-
pairing 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
Fig. 40 PDCÐXJ Models
Fig. 41 Auxiliary FanÐRemove/Install
JCOOLING SYSTEM 7 - 29

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

ENGINE BLOCK HEATER
GENERAL INFORMATION
DESCRIPTION AND OPERATION
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 com-
ponent 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. Connect the power cord to a grounded 110-
120 volt AC electrical outlet with a grounded, three-
wire extension cord.
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
BLOCK HEATER SPECIFICATIONS
²2.5L Engine: 115 Volts 400 Watts
²4.0L Engine: 120 Volts 600 Watts
REMOVAL
Refer to correct illustration (Figures 11, 12 or 13)
when servicing block heater.
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.
(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 (Figs.
11, 12 or 13).
(4) Remove block heater from cylinder block.
INSTALLATION
(1) Thoroughly clean the engine core hole and the
block heater seat.
(2) Insert block heater assembly into core hole
with element loop pointingUp.
(3) Seat block heater flush against block face.
Tighten mounting screw to 3.6 Nzm (32 in. lbs.)
torque.
(4) Fill cooling system with coolant. Pressurize sys-
tem and inspect for leaks.
(5) Plug power cord into block heater. Route cord
away from moving parts, linkages and exhaust sys-
tem components. Secure cord in place with tie-straps.
Fig. 11 Heater and CordÐXJ with 2.5L Engine
Fig. 12 Heater and CordÐXJ with 4.0L Engine
Fig. 13 Heater and CordÐYJ Models
JCOOLING SYSTEM 7 - 37

The camshaft position sensor is located in the dis-
tributor on all engines (Fig. 9).
Refer to figure 9 for an exploded view of the dis-
tributor.
(1) Disconnect the negative battery cable at bat-
tery.
(2) On XJ models equipped with A/C, remove the
electrical cooling fan and shroud assembly from the
radiator. This will provide room to turn the engine
with a socket and ratchet using the vibration damper
bolt.
(3) Scribe a mark on the distributor housing. Do
this below the left side of (past) the number one
spark plug cable post of the distributor cap. This will
be used as a reference for #1 cylinder firing position
(Fig. 14).
(4) Remove the distributor cap from distributor (2
screws).
(5) Turn the engine in a clockwise direction until
the rotor is approaching the scribe mark on the dis-
tributor housing. Then slowly turn the engine until
the timing mark on the crankshaft vibration damper
lines up with zero on the front cover timing scale
(Fig. 15).
The timing mark is on the edge of the vibra-
tion damper closest to the engine front cover.
(6) Align the trailing edge of the rotor blade with
the scribe mark on the distributor housing (Fig. 16).
(7) Remove the distributor holddown bolt and
clamp.
(8) Remove the distributor from the engine by lift-
ing straight up. Remove and discard old distributor-
to-engine block gasket. Note that the rotor willrotate slightly in a counterclockwise direction while
lifting up the distributor. Note this position after re-
moval.
INSTALLATIONÐ4.0L ENGINE
(1) Clean the distributor mounting area of the cyl-
inder block.
(2) Install a replacement distributor-to-engine
block gasket.
(3) Using a flat blade screwdriver, turn the oil
pump gear shaft. Do this until the slot is slightly
past the 11 o'clock position (Fig. 17).
Fig. 13 Distributor Rotor PositionÐ2.5L EngineFig. 14 Mark Distributor Housing
Fig. 15 Align Timing Marks
JIGNITION SYSTEMS 8D - 25