1995 JEEP CHEROKEE engine

INSPECTING FOR INLET RESTRICTIONS
Inadequate heater performance may be caused by a
metal casting restriction in the water pump heater
hose inlet.
DO NOT WASTE reusable coolant. If solution is
clean, drain 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 THE COOL-
ANT CAN OCCUR.
(1) Drain sufficient coolant from the radiator to de-
crease the level below the water pump heater hose
inlet.
(2) Remove the heater hose.
(3) Inspect the inlet for metal casting flash or
other restrictions.
Remove the pump from engine before remov-
ing restriction to prevent contamination of the
coolant with debris. Refer to Water Pump Re-
moval.
WATER PUMPSÐREMOVAL/INSTALLATION
REMOVALÐALL MODELS
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 vibra-
tion.The water pump on all models can be removed
without discharging the air conditioning system (if
equipped).
CAUTION: All engines have a reverse (counter-
clockwise) rotating water pump. The letter R is
stamped into the back of the water pump impeller
(Fig. 1) 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.
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 re-
use.
(1) Disconnect negative battery cable at battery.
(2) Drain the cooling system. Refer to Draining
Cooling System in this group.
(3)XJ models with 4.0L 6-cylinder engine
equipped with A/C or heavy duty cooling sys-
tem:
Loosen (but do not remove at this time) the four
water pump pulley-to-water pump hub mounting
bolts (Fig. 3).
XJ models with 4.0L 6-cylinder engine with-
out A/C or heavy duty cooling system; or any
2.5L 4-cylinder engines; or any YJ models:
Loosen (but do not remove at this time) the four
fan hub-to-water pump pulley mounting nuts (Fig. 4).
Fig. 2 Impeller TestÐTypical
Fig. 3 Water Pump Pulley Bolts
7 - 14 COOLING SYSTEM SERVICE PROCEDURESJ

The engine accessory drive belt must be removed
prior to removing the fan (if installed at pump) or
fan pulley.
(4) Remove engine drive belt as follows:
(a) Loosen two rear power steering pump mount-
ing bolts A (Fig. 5).
(b) Loosen upper pump pivot bolt B and lower
lock nut C (Figs. 6 or 7).
(c) Loosen pump adjusting bolt D (Fig. 5) until
belt can be removed.(d) Remove belt.
(5) Check condition of all pulleys.
(6) The power steering pump must be removed
from its cast mounting bracket to gain access to bolt
E. Bracket mounting bolt E is located behind the
power steering pump (Fig. 7).
(7) Remove two bolts A (Fig. 5).
(8) Remove locknut C and belt adjustment bolt D
(Figs. 6 or 7).
(9) Remove bolt B (Fig. 6). Position power steering
pump to the side. Hold pump in position with wire.
Do not disconnect hydraulic lines from pump.
(10) Remove bolts E, F and G (Fig. 7) and remove
pump mounting bracket.
Fig. 4 Fan Mounting Nuts
Fig. 5 P.S. Pump Rear Mounting BoltsÐTypical
Fig. 6 P.S. Pump Front Mounting Bolt/LocknutÐ
Typical
Fig. 7 Bracket Mounting BoltsÐTypical
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 15

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 silicone
bead on the gasket should be facing the water pump.
Also, 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 not
equipped 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 F
andGto38Nzm (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
figures 11, 12, 13 or 14 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.
(14) Tighten pivot bolt B (Fig. 6) to 27 Nzm (20 ft.
lbs.) torque.
(15) Tighten locknut C (Fig. 6) to 27 Nzm (20 ft.
lbs.) torque.
(16) After the power steering pump has been tight-
ened, recheck belt tension.
(17) Fill cooling system with coolant and check for
leaks. Refer to Refilling Cooling System in this
group.(18) Connect battery cable to battery.
(19) Start and warm the engine. Check for leaks.
THERMOSTAT
DESCRIPTION AND OPERATION
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 195ÉF (90ÉC). Above this
Fig. 11 YJ Models with 4.0L Engine, and XJ Models
with 2.5L 4-Cylinder EngineÐWith A/C
Fig. 12 YJ Models With 2.5L or 4.0L Engine, and XJ
Models with 2.5L EngineÐWithout A/C
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 17

temperature, coolant is allowed to flow to the radia-
tor. This provides quick engine warmup and overall
temperature control.
An arrow plus the wordUPis stamped on the
front flange next to the air bleed. The wordsTO
RADare stamped on one arm of the thermostat.
They indicate the proper installed position.
The same thermostat is used for winter and sum-
mer seasons. An engine should not be operated with-
out a thermostat, except for servicing or testing.
Operating without a thermostat causes other prob-
lems. These are: longer engine warmup time, unreli-
able warmup performance, increased exhaust
emissions and crankcase condensation. This conden-
sation can result in sludge formation.
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 (NUMBER
6094) (FIG. 15). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS. AL-
WAYS WEAR SAFETY GLASSES WHEN SERVICING
CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 16). If re-
placement is necessary, use only an original equip-
ment 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. 17).
Discard old gasket.
(5) Clean the gasket mating surfaces.
Fig. 13 XJ Models with 4.0L 6-Cylinder EngineÐ
Without A/C
Fig. 14 XJ Models With 4.0L 6-Cylinder EngineÐ
With A/C
7 - 18 COOLING SYSTEM SERVICE PROCEDURESJ

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 cylin-
der head (Fig. 18).
(b) Position thermostat into this groove with ar-
row and air bleed hole on outer flange pointing up.
(2) Install replacement gasket and thermostat
housing.
CAUTION: Tightening the thermostat housing un-
evenly or with the thermostat out of its recess may
result in a cracked housing.(3) Tighten the housing bolts to 20 Nzm (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.
Fig. 15 Hose Clamp ToolÐTypical
Fig. 16 Clamp Number/Letter Location
Fig. 17 Thermostat Removal/Installation
Fig. 18 Thermostat Recess
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 19

COOLANT
GENERAL INFORMATION
The cooling system is designed around the coolant.
Coolant flows through the engine water jackets ab-
sorbing heat produced during engine operation. The
coolant carries heat to the radiator and heater core.
Here it is transferred to the ambient air passing
through the radiator and heater core fins. The cool-
ant also removes heat from the automatic transmis-
sion fluid in vehicles equipped with an automatic
transmission.
COOLANT PERFORMANCE
The required ethylene-glycol (antifreeze) and water
mixture depends upon climate and vehicle operating
conditions. The coolant performance of various mix-
tures follows:
Pure Water-Water can absorb more heat than a
mixture of water and ethylene-glycol. This is for pur-
pose of heat transfer only. Water also freezes at a
higher temperature and allows corrosion.
100 percent Ethylene-Glycol-The corrosion in-
hibiting additives in ethylene-glycol need the pres-
ence of water to dissolve. Without water, additives
form deposits in system. These act as insulation
causing temperature to rise to as high as 149ÉC
(300ÉF). This temperature is hot enough to melt plas-
tic and soften solder. The increased temperature can
result in engine detonation. In addition, 100 percent
ethylene-glycol freezes at -22ÉC (-8ÉF).
50/50 Ethylene-Glycol and Water-Is the recom-
mended mixture, it provides protection against freez-
ing to -37ÉC (-35ÉF). The antifreeze concentration
must alwaysbe a minimum of 44 percent, year-
round in all climates. If percentage is lower, engine
parts may be eroded by cavitation. Maximum protec-
tion against freezing is provided with a 68 percent
antifreeze concentration, which prevents freezing
down to -67.7ÉC (-90ÉF). A higher percentage will
freeze at a warmer temperature. Also, a higher per-
centage of antifreeze can cause the engine to over-
heat because specific heat of antifreeze is lower than
that of water.
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
COOLANT SELECTION-ADDITIVES
Coolant should be maintained at the specified level
with a mixture of ethylene glycol-based antifreeze
and low mineral content water. Only use an anti-
freeze containing ALUGARD 340-2 Ÿ.CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
COOLANT SERVICE
It is recommended that the cooling system be
drained and flushed at 84,000 kilometers (52,500
miles), or 3 years, whichever occurs first. Then every
two years, or 48,000 kilometers (30,000 miles),
whichever occurs first.
COOLANT LEVEL CHECKÐROUTINE
Do not remove radiator cap for routine cool-
ant level inspections. The coolant level can be
checked at coolant reserve/overflow tank.
The coolant reserve/overflow system provides a
quick visual method for determining coolant level
without removing radiator pressure cap. With engine
idling and at normal operating temperature, observe
coolant level in reserve/overflow tank. The coolant
level should be between ADD and FULL marks.
ADDING ADDITIONAL COOLANTÐROUTINE
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 Ÿ and low mineral content water. Re-
move 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-SERVICE
The cooling system is closed and designed to main-
tain 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:
²An air leak in coolant reserve/overflow tank or its
hose
²An air leak in radiator filler neck
²Leak in pressure cap seal to radiator filler neck
LOW COOLANT LEVEL-AERATION
If the coolant level in radiator drops below top of
radiator core tubes, air will enter cooling system.
7 - 20 COOLING SYSTEM SERVICE PROCEDURESJ

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 re-
moved air.
DRAINING COOLING SYSTEM
ALL MODELSÐEXCEPT XJ WITH 4.0L
6-CYLINDER ENGINE
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.
DO NOT remove the radiator cap when draining
the coolant from the reserve/overflow tank. Open the
radiator draincock and when the tank is empty, re-
move the radiator cap. The coolant does not have to
be removed from the tank unless the system is being
refilled with a fresh mixture.
(1) Drain the coolant from the radiator by loosen-
ing the draincock.
(2) Drain coolant from engine as follows:
(a) On 2.5L 4-cylinder engines (all models) by re-
moving drain plug at left rear side of block.
(b) On 4.0L 6-cylinder engines by removing the
drain plug or coolant temperature sensor on the
left side of the block (Fig. 19).
XJ MODELS WITH 4.0L 6-CYLINDER ENGINE
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.(2) For access to radiator draincock, remove radia-
tor grille mounting screws and remove grill. Refer to
Group 23, Body for procedures.
(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 (Fig. 19).
REFILLING COOLING SYSTEM
YJ MODELS
(1) Remove draining hose. Tighten the radiator
draincock and the cylinder block drain plug(s).
(2) Fill system using a 50/50 mixture of water and
antifreeze. This is described in the Coolant section of
this group. Fill the radiator to the top and install the
radiator cap. Add sufficient coolant to the reserve/
overflow tank to raise the level to the FULL mark.
(3) Operate the engine with both the radiator cap
and reserve/overflow tank cap in place. After the en-
gine has reached the normal operating temperature,
shut the engine off and allow it to cool.
(4) Add coolant to the 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.
XJ MODELS
(1) Tighten the radiator draincock and the cylinder
block drain plug(s). If removed, install coolant tem-
perature sensor (4.0L 6-cylinder engine).
(2) Fill system using a 50/50 mixture of water and
antifreeze as described in the Coolant section of this
Fig. 19 Draining CoolantÐ4.0L 6-Cylinder Engine
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 21

group. Fill radiator to top and install radiator cap.
Add sufficient coolant to reserve/overflow tank to
raise level to FULL mark.
(3) With heater control unit in the HEAT position,
operate engine with radiator cap in place.
(4) After engine has reached normal operating
temperature, shut engine off and allow it to cool.
(5) Add coolant to reserve/overflow tank as neces-
sary.Only add coolant when the engine is cold.
Coolant level in a warm engine will be higher
due to thermal expansion.
COOLING SYSTEM CLEANING/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.
CLEANING
Drain cooling system and refill with water. Run en-
gine with radiator cap installed until upper radiator
hose is hot. Stop engine and drain water from sys-
tem. If water is dirty, fill system with water, run en-
gine and drain system. Repeat until water drains
clean.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forc-
ing 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.
REVERSE FLUSHING RADIATOR
Disconnect the radiator hoses from the radiator fit-
tings. Attach a section of radiator hose to the radia-
tor 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 equip-
ment. 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 hous-
ing. Disconnect the radiator upper hose from the ra-
diator 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: On XJ models, 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 wa-
ter. 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.
Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo-
stat housing and install thermostat. Install the ther-
mostat housing with a replacement gasket. Refer to
Thermostat Replacement. Connect the radiator
hoses. Refill the cooling system with the correct an-
tifreeze/water mixture.
CHEMICAL CLEANING
In some instances, use a radiator cleaner (Mopar
Radiator Kleen or equivalent) before flushing. This
will soften scale and other deposits and aid the flush-
ing operation.
CAUTION: Be sure instructions on the container are
followed.
TESTING COOLING SYSTEM FOR LEAKS
ULTRAVIOLET LIGHT METHOD
All Jeep models have a leak detection additive
added to the cooling system before they leave the fac-
tory. 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.
20).
PRESSURE TESTER METHOD
The engine should be at the normal operating tem-
perature. Recheck the system cold if the cause of
coolant loss is not located during warm engine exam-
ination.
7 - 22 COOLING SYSTEM SERVICE PROCEDURESJ