2002 JEEP GRAND CHEROKEE 4.7l

CONDITION POSSIBLE CAUSES CORRECTION
17. Viscous fan drive not operating
properly.17. Check fan drive operation and replace as
necessary. (Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DIAGNOSIS AND TESTING).
18. Cylinder head gasket leaking. 18. Check for cylinder head gasket leaks.
(Refer to 7 - COOLING - DIAGNOSIS AND
TESTING). For repair, (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
19. Heater core leaking. 19. Check heater core for leaks. (Refer to 24
- HEATING & AIR CONDITIONING/
PLUMBING/HEATER CORE - REMOVAL).
Repair as necessary.
20. Hydraulic fan speed too low or
inopertive.20. Check for
DTC code.
Check fan operation speeds.
Refer to fan speed operation table.
Low power steering pump output. Refer to
power steering pump diagnosis - 4.7L engine.
TEMPERATURE GAUGE
READING IS
INCONSISTENT
(FLUCTUATES, CYCLES
OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly.1. A normal condition. No correction is
necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge and repair if
necessary. Refer to Group 8J, Instrument
cluster.
3. Gauge reading rises when vehicle
is brought to a stop after heavy use
(engine still running)3. A normal condition. No correction is
necessary. Gauge should return to normal
range after vehicle is driven.
4. Gauge reading high after
re-starting a warmed up (hot)
engine.4. A normal condition. No correction is
necessary. The gauge should return to
normal range after a few minutes of engine
operation.
5. Coolant level low in radiator (air
will build up in the cooling system
causing the thermostat to open late).5. Check and correct coolant leaks. (Refer to
7 - COOLING - DIAGNOSIS AND TESTING).
6. Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing a thermostat
to open late.6. (a) Check for cylinder head gasket leaks.
(Refer to 7 - COOLING - DIAGNOSIS AND
TESTING).
(b) Check for coolant in the engine oil.
Inspect for white steam emitting from the
exhaust system. Repair as necessary.
WJCOOLING 7 - 7
COOLING (Continued)

accessory drive belt (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - REMOVAL).
Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of top of thermostat housing.
CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub-
bles do not appear, internal combustion gas leakage
is not present.
DIAGNOSIS AND TESTING - COOLING SYSTEM
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.
STANDARD PROCEDURE
STANDARD PROCEDUREÐDRAINING COOLING
SYSTEM 4.7L ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS (Fig. 7) OR LOOSEN THE
RADIATOR DRAINCOCK WITH SYSTEM HOT AND
UNDER PRESSURE. SERIOUS BURNS FROM
COOLANT CAN OCCUR.
(1) DO NOT remove radiator cap first. With engine
cold, raise vehicle on a hoist and locate radiator
draincock.
NOTE: Radiator draincock is located on the left/
lower side of radiator facing to rear of vehicle.
(2) Attach one end of a hose to the draincock. Put
the other end into a clean container. Open draincock
and drain coolant from radiator. This will empty the
coolant reserve/overflow tank. The coolant does not
have to be removed from the tank unless the system
is being refilled with a fresh mixture. When tank is
empty, remove radiator cap and continue draining
cooling system.
STANDARD PROCEDURE - REFILLING
COOLING SYSTEM 4.7L ENGINE
(1) Tighten the radiator draincock and the cylinder
block drain plug(s) (if removed).
CAUTION: Failure to purge air from the cooling sys-
tem can result in an overheating condition and
severe engine damage.
(2) Remove the cooling system bleed plug from the
radiator upper hose inlet housing. (Fig. 8)Fill system
using a 50/50 mixture of ethylene-glycol antifreeze
and low mineral content water, until coolant begains
coming out of the cooling system bleed hole. Install
the cooling system bleed plug. Fill radiator to top and
install radiator cap. Add sufficient coolant to the
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.
When engine is cooling down, coolant will be drawn
into the radiator from the reserve/overflow tank.
(5) Add coolant to reserve/overflow tank as neces-
sary.Only add coolant to the reserve/overflow
tank when the engine is cold. Coolant level in a
warm engine will be higher due to thermal
expansion.To purge the cooling system of all air,
this heat up/cool down cycle (adding coolant to cold
engine) must be performed three times. Add neces-
sary coolant to raise tank level to the FULL mark
after each cool down period.
Fig. 7 Drain PlugÐ4.7L Engine
1 - CYLINDER BLOCK DRAIN PLUG
2 - EXHAUST MANIFOLD AND HEAT SHIELD
7 - 12 COOLINGWJ
COOLING (Continued)

STANDARD PROCEDURE - DRAINING COOLING
SYSTEM - 4.0L 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.
(1) DO NOT remove radiator cap first. With engine
cold, raise vehicle on a hoist and locate radiator
draincock.
NOTE: Radiator draincock is located on the right/
lower side of radiator facing to rear of vehicle.
(2) Attach one end of a hose to the draincock. Put
the other end into a clean container. Open draincock
and drain coolant from radiator. This will empty the
coolant reserve/overflow tank. The coolant does not
have to be removed from the tank unless the system
is being refilled with a fresh mixture. When tank is
empty, remove radiator cap and continue draining
cooling system.
To drain the engine of coolant, remove the cylinder
block drain plug located on the side of cylinder block
(Fig. 9).
STANDARD PROCEDURE - REFILLING
COOLING SYSTEM - 4.0L ENGINE
(1) Tighten the radiator draincock and the cylinder
block drain plug(s) (if removed).
(2) Fill system using a 50/50 mixture of ethylene-
glycol antifreeze and low mineral content water. Fill
radiator to top and install radiator cap. Add suffi-
cient coolant to the 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.
When engine is cooling down, coolant will be drawn
into the radiator from the reserve/overflow tank.
(5) Add coolant to reserve/overflow tank as neces-
sary.Only add coolant to the reserve/overflow
tank when the engine is cold. Coolant level in a
warm engine will be higher due to thermal
expansion.To purge the cooling system of all air,
this heat up/cool down cycle (adding coolant to cold
engine) must be performed three times. Add neces-
sary coolant to raise tank level to the FULL mark
after each cool down period.
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (glycol base coolant with
Fig. 8 Cooling System Bleed Plug - 4.7L
1 - COOLING SYSTEM BLEED PLUG
Fig. 9 Drain PlugÐ4.0L Engine
1 - COOLANT TEMPERATURE SENSOR
2 - BLOCK DRAIN PLUG
WJCOOLING 7 - 13
COOLING (Continued)

corrosion inhibitors called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain to obtain a
freeze point of -37ÉC (-35ÉF). If it loses color or
becomes contaminated, drain, flush, and replace with
fresh properly mixed coolant solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
STANDARD PROCEDURE - 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 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.
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 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 (Refer to 7 - COOLING -
STANDARD PROCEDURE). Remove the thermostat
housing and thermostat. Install the thermostat hous-
ing. Disconnect the radiator upper hose from the
radiator and attach the flushing gun to the hose. Dis-
connect 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.
Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo-
stat housing (Refer to 7 - COOLING/ENGINE/EN-
GINE COOLANT THERMOSTAT - REMOVAL).
Install the thermostat and housing with a replace-
ment gasket (Refer to 7 - COOLING/ENGINE/EN-
GINE COOLANT THERMOSTAT -
INSTALLATION). Connect the radiator hoses. Refill
the cooling system with the correct antifreeze/water
mixture (Refer to 7 - COOLING - STANDARD PRO-
CEDURE).
SPECIFICATIONS
TORQUE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Automatic Belt Tensioner to
Mounting
BracketÐBolt
4.0L 28 Ð 250
4.7L 41 30 Ð
Automatic Belt Tensioner
PulleyÐ
Bolt
(4.7L) 61 45 Ð
Block HeaterÐBolt
7 - 14 COOLINGWJ
COOLING (Continued)

DESCRIPTION N´m Ft. In.
Lbs. Lbs.
4.0L 4 Ð 32
4.7L 2 Ð 17
Fan Blade Assy. to Viscous
DriveÐ
Bolts 4.0L 23 Ð 200
Generator MountingÐBolts
4.0L57 42 Ð
Radiator Upper Isolator to
CrossmemberÐNuts 3 Ð 20
Radiator Upper Isolator to
RadiatorÐ
Nuts 4 Ð 36
Radiator BraceÐBolts 10 Ð 90
Thermostat HousingÐBolts
4.0L 22 16 Ð
4.7L 13 Ð 115
Upper Radiator Crossmember
to
BodyÐBolts 10 Ð 90
Water PumpÐBolts
4.0L 23 17 Ð
4.7L 54 40 Ð
Water Pump Pulley to Water
PumpÐ
Bolts 4.0L 28 Ð 250
High Pressure Inlet Hose to
Hydraulic Fan DriveÐ1/2 inch
Fitting49 36 Ð
High Pressure Outlet Hose to
Steering GearÐ3/8 inch
Fitting29 21.5 Ð
Fan Shroud to Radiator
Mounting Bolts6Ð50SPECIAL TOOLS
COOLING
Pliers 6094
Pressure Tester 7700±A
WJCOOLING 7 - 15
COOLING (Continued)

ACCESSORY DRIVE
TABLE OF CONTENTS
page page
BELT TENSIONERS
REMOVAL
REMOVALÐ4.7L ENGINE...............16
REMOVALÐ4.0L ENGINE...............16
INSTALLATION
INSTALLATIONÐ4.7L ENGINE...........16
INSTALLATIONÐ4.0L ENGINE...........17
DRIVE BELTS - 4.0L
DIAGNOSIS AND TESTING ± SERPENTINE
DRIVE BELT.........................17REMOVALÐ4.0L ENGINE.................19
INSTALLATIONÐ4.0L ENGINE.............19
DRIVE BELTS - 4.7L
DIAGNOSIS AND TESTING ± SERPENTINE
DRIVE BELT.........................20
REMOVAL - 4.7L ENGINE.................22
INSTALLATION - 4.7L ENGINE.............23
BELT TENSIONERS
REMOVAL
REMOVALÐ4.7L ENGINE
(1) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove tensioner assembly from engine front
cover (Fig. 1).
WARNING: BECAUSE OF HIGH SPRING TENSION,
DO NOT ATTEMPT TO DISASSEMBLE AUTOMATIC
TENSIONER. UNIT IS SERVICED AS AN ASSEMBLY
(EXCEPT FOR PULLEY ON TENSIONER).
(3) Remove pulley bolt. Remove pulley from ten-
sioner.
REMOVALÐ4.0L ENGINE
(1) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove tensioner assembly from mounting
bracket (Fig. 2).
WARNING: BECAUSE OF HIGH SPRING TENSION,
DO NOT ATTEMPT TO DISASSEMBLE AUTOMATIC
TENSIONER. UNIT IS SERVICED AS AN ASSEMBLY.
INSTALLATION
INSTALLATIONÐ4.7L ENGINE
(1) Install pulley and pulley bolt to tensioner.
Tighten bolt to 61 N´m (45 ft. lbs.) torque.
(2) An indexing slot is located on back of tensioner.
Align this slot to the head of the bolt on the front
cover. Install the mounting bolt. Tighten bolt to 41
N´m (30 ft. lbs.).
Fig. 1 Automatic Belt Tensioner
1 - TIMING CHAIN COVER
2 - BOLT TORQUE TO 41 N´m (30 FT LBS)
3 - AUTOMATIC BELT TENSIONER
7 - 16 ACCESSORY DRIVEWJ

(2) Install new belt (Fig. 4). Route the belt around
all pulleys except the idler pulley. Rotate the ten-
sioner arm until it contacts its stop position. Route
the belt around the idler and slowly let the tensioner
rotate into the belt. Make sure the belt is seated onto
all pulleys.
(3) With the drive belt installed, inspect the belt
wear indicator (Fig. 5). On 4.0L Engines, the indica-
tor mark must be between the minimum and maxi-
mum marks. If the measurement exceedes this
specification replace the serpentine accessory drive
belt.DRIVE BELTS - 4.7L
DIAGNOSIS AND TESTING ± SERPENTINE
DRIVE BELT
When diagnosing serpentine drive belts, small
cracks that run across ribbed surface of belt from rib
to rib (Fig. 6), are considered normal. These are not a
reason to replace belt. However, cracks running along
a rib (not across) arenotnormal. Any belt with
cracks running along a rib must be replaced (Fig. 6).
Also replace belt if it has excessive wear, frayed cords
or severe glazing.
Refer to SERPENTINE DRIVE BELT DIAGNOSIS
CHART for further belt diagnosis.
Fig. 5 Accessory Drive Belt Wear Indicator
1 - INDICATOR MARK
2 - MINIMUM TENSION MARK
3 - MAXIMUM TENSION MARK
Fig. 6 Serpentine Accessory Drive Belt Wear
Patterns
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
7 - 20 ACCESSORY DRIVEWJ
DRIVE BELTS - 4.0L (Continued)

SERPENTINE DRIVE BELT DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
RIB CHUNKING (ONE OR MORE
RIBS HAS SEPARATED FROM
BELT BODY)1. Foreign objects imbedded in pulley
grooves.1. Remove foreign objects from
pulley grooves. Replace belt.
2. Installation damage. 2. Replace belt.
RIB OR BELT WEAR 1. Pulley(s) misaligned. 1. Align pulley(s).
2. Abrasive environment. 2. Clean pulley(s). Replace belt if
necessary.
3. Rusted pulley(s). 3. Clean rust from pulley(s).
4. Sharp or jagged pulley groove tips. 4. Replace pulley.
5. Rubber deteriorated. 5. Replace belt.
LONGITUDINAL BELT
CRACKING (CRACKS BETWEEN
TWO RIBS)1. Belt has mistracked from pulley
groove.1. Replace belt.
2. Pulley groove tip has worn away
rubber to tensile member.2. Replace belt.
BELT SLIPS 1. Belt slipping because of insufficient
tension.1. Replace automatic belt tensioner.
2. Belt routed 2. Verify belt routing.
incorrectly
3. Incorrect belt. 3. Replace belt.
4. Belt or pulley subjected to
substance (belt dressing, oil ethylene
glycol) that has reduced friction.4. Replace belt and clean pulleys.
5. Driven component bearing failure. 5. Replace faulty component
bearing.
6. Belt glazed and hardened from
heat and excessive slippage.6. Replace belt.
ªGROOVE JUMPING9(BELT
DOES NOT MAINTAIN CORRECT
POSITION ON PULLEY)1. Belt tension either too high or too
low.1. Replace automatic belt tensioner.
2. Belt routed 2. Verify belt routing.
incorrectly.
3. Incorrect belt. 3. Replace belt.
4. Pulley(s) not within design
tolerance.4. Replace pulley(s).
5. Foreign object(s) in grooves. 5. Remove foreign objects from
grooves.
6. Pulley misalignment. 6. Check and replace.
7. Belt cord line is broken. 7. Replace belt.
WJACCESSORY DRIVE 7 - 21
DRIVE BELTS - 4.7L (Continued)