2003 JEEP GRAND CHEROKEE Engine

Do not waste reusable coolant. If the solution is
clean, drain the 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. 37). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 38). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
CAUTION: When removing the radiator or A/C con-
denser for any reason, note the location of all radi-
ator-to-body and radiator-to-A/C condenser rubber
air seals (Fig. 39). These are used at the top, bot-
tom and sides of the radiator and A/C condenser.
To prevent overheating, these seals must be
installed to their original positions.
(1) Disconnect the negative battery cable at bat-
tery.
(2) Drain coolant from radiator (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(3) Do not attempt to remove fan/viscous fan drive
assembly from vehicle at this time.(4) Remove the front grill (Refer to 23 - BODY/EX-
TERIOR/GRILLE - REMOVAL).
(5) Remove two radiator mounting bolts (Fig. 41).
(6) Disconnect both transmission cooler lines from
radiator.
(7) Disconnect electric fan connector, then discon-
nect connector harness from shroud (Fig. 41).
(8) Disconnect the radiator upper and lower hoses
(Fig. 41).
Fig. 36 Cross Flow Radiator - Typical
1 - RADIATOR
Fig. 37 Hose Clamp Tool - Typical
1 - HOSE CLAMP TOOL 6094
2 - HOSE CLAMP
Fig. 38 Clamp Number/Letter Location - Typical
1 - TYPICAL CONSTANT TENSION HOSE CLAMP
2 - CLAMP NUMBER/LETTER LOCATION
3 - TYPICAL HOSE
WJENGINE 7 - 45
RADIATOR - 4.0L (Continued)

(9) Disconnect the overflow hose from radiator
(Fig. 41).
(10) Remove the air inlet duct at the grill.
(11) The lower part of radiator is equipped with
two alignment dowel pins (Fig. 40). They are located
on the bottom of radiator tank and fit into rubber
grommets. These rubber grommets are pressed into
the radiator lower crossmember.
WARNING: THE AIR CONDITIONING SYSTEM (IF
EQUIPPED) IS UNDER A CONSTANT PRESSURE
EVEN WITH THE ENGINE OFF. REFER TO REFRIG-
ERANT WARNINGS IN GROUP 24, HEATING AND
AIR CONDITIONING BEFORE HANDLING ANY AIR
CONDITIONING COMPONENT.
(12) If equipped with an auxiliary automatic trans-
mission oil cooler, use caution when removing radia-
tor. The oil cooler lines are routed through a rubber
air seal on the right side of radiator. Do not cut or
tear this seal.
(13) Gently lift up and remove radiator from vehi-
cle. Be careful not to scrape the radiator fins against
any other component. Also be careful not to disturb
the air conditioning condenser (if equipped).
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 con-
denser of debris.
Fig. 39 Air Seals - Typical
1 - AIR DAM
2 - RADIATOR
3 - AIR DAM
4 - A/C CONDENSER
5 - AIR SEAL
Fig. 40 Radiator Alignment Dowels
1 - RADIATOR
2 - ALIGNMENT DOWEL
3 - RADIATOR LOWER ISOLATOR
4 - RADIATOR LOWER CROSSMEMBER
Fig. 41 Radiator, Shroud and Electric Fan
1 - RADIATOR/SHROUD/FAN ASSEMBLY
2 - OVER FLOW HOSE
3 - ELECTRIC FAN CONNECTOR
4 - RADIATOR MOUNTING BOLT(S)
5 - CLAMP
7 - 46 ENGINEWJ
RADIATOR - 4.0L (Continued)

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.
INSTALLATION
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals (Fig. 39) are
properly fastened to their original positions. These
are used at the top, bottom and sides of the radia-
tor and A/C condenser. To prevent overheating,
these seals must be installed to their original posi-
tions.
(1) Equipped with air conditioning: Gently lower
the radiator into the vehicle. Guide the two radiator
alignment dowels through the holes in the rubber air
seals first and then through the A/C support brackets
(Fig. 40). Continue to guide the alignment dowels
into the rubber grommets located in lower radiator
crossmember. The holes in the L-shaped brackets
(located on bottom of A/C condenser) must be posi-
tioned between bottom of rubber air seals and top of
rubber grommets.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator (Fig. 41).
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator (Fig. 41).
(4) Connect both transmission cooler lines at the
radiator (Fig. 41).
(5) Install both radiator mounting bolts (Fig. 41).
(6) Install air inlet duct at grill.
(7) Attach electric fan harness to shroud, then con-
nect harness to connector (Fig. 41).
(8) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(9) Install the fan/viscous fan drive assembly to
the water pump.
(10) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(11) Be sure of at least 25 mm (1.0 inch) between
tips of fan blades and fan shroud.
(12) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(13) Connect battery cable at battery.
(14) Start and warm engine. Check for leaks.
RADIATOR FAN MOTOR
DIAGNOSIS AND TESTINGÐELECTRIC
COOLING FAN
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 25 - EMISSIONS CONTROL - DESCRIP-
TION).
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
okay, refer to ELECTRICAL for cooling fan and relay
circuit schematic.
WATER PUMP - 4.7L
DESCRIPTION
DESCRIPTIONÐWATER PUMP
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
single serpentine drive belt.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary.
Both heater hoses are connected to fittings on the
timing chain front cover. The water pump is also
mounted directly to the timing chain cover and is
equipped with a non serviceable integral pulley (Fig.
42).
DESCRIPTIONÐWATER PUMP BYPASS
The 4.7L engine uses an internal water/coolant
bypass system. The design uses galleries in the tim-
ing chain cover to circulate coolant during engine
warm-up preventing the coolant from flowing
through the radiator. The thermostat uses a stub
shaft located at the rear of the thermostat (Fig. 43)
to control flow through the bypass gallery.
OPERATION
OPERATIONÐWATER PUMP
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
WJENGINE 7 - 47
RADIATOR - 4.0L (Continued)

radiator core, cooling system hoses and heater core,
this coolant absorbs the heat generated when the
engine is running. The pump is driven by the engine
crankshaft via a drive belt.
OPERATIONÐWATER PUMP BYPASS
When the thermostat is in the closed position the
bypass gallery is not obstructed allowing 100% flow.
When the thermostat is in the open position the stub
shaft enters the bypass gallery obstructing bypass
coolant flow by 50%. This design allows the coolant
to reach operating temperature quickly when cold,
while adding extra cooling during normal tempera-
ture operation.
DIAGNOSIS AND TESTINGÐWATER PUMP
LOOSE IMPELLER - 4.0L and 4.7L
NOTE: Due to the design of the 4.0L and 4.7L
engine water pumps, testing the pump for a loose
impeller must be done by verifying coolant flow in
the radiator. To accomplish this refer to the follow-
ing procedure.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.(1) Drain coolant until the first row of cores is vis-
ible in the radiator (Refer to 7 - COOLING - STAN-
DARD PROCEDURE) 4.7L Engine or (Refer to 7 -
COOLING - STANDARD PROCEDURE) 4.0L
Engine.
(2) Leaving the radiator cap off, start the engine.
Run engine until thermostat opens.
(3) While looking into the radiator through the
radiator fill neck, raise engine rpm to 2000 RPM.
Observe the flow of coolant from the first row of
cores.
(4) If there is no flow or very little flow visable,
replace the water pump.
INSPECTING FOR INLET RESTRICTIONS
Inadequate heater performance may be caused by
a metal casting restriction in the heater hose inlet.
DO NOT WASTE reusable coolant. If solution is
clean, drain the coolant into a clean container for
reuse.
Fig. 42 Water Pump and Timing Chain Cover
1 - INTEGRAL WATER PUMP PULLEY
2 - TIMING CHAIN COVER
3 - THERMOSTAT HOUSING
4 - HEATER HOSE FITTINGS
5 - WATER PUMP
Fig. 43 Water/Coolant Bypass Flow and Thermostat
1 - FROM HEATER
2 - FROM RADIATOR
3 - TO WATER PUMP
4 - ENGINE BYPASS
5 - THERMOSTAT
7 - 48 ENGINEWJ
WATER PUMP - 4.7L (Continued)

WARNING: DO NOT 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
decrease the level below the heater hose inlet. On
4.7L engines this requires complete draining.
(2) Remove the heater hose.
(3) Inspect the inlet for metal casting flash or
other restrictions.
NOTE: On 4.0L engines remove the pump from the
engine before removing restriction to prevent con-
tamination of the coolant with debris. . On 4.7L
engine remove the fitting from the timing chain
cover, If the restriction is in the timing chain cover,
remove the timing chain cover.
REMOVAL
The water pump on 4.7L engines is bolted directly
to the engine timing chain case/cover.
A gasket is used as a seal between the water pump
and timing chain case/cover.
The water pump can be removed without discharg-
ing the air conditioning system (if equipped).
(1) Disconnect negative battery cable from battery.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE). 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). SNAP-ON CLAMP TOOL (NUMBER HPC-20)
MAY BE USED FOR LARGER CLAMPS. ALWAYS
WEAR SAFETY GLASSES WHEN SERVICING CON-
STANT 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.
(3) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(4) Remove lower radiator hose clamp and remove
lower hose at water pump.
(5) Remove seven water pump mounting bolts and
one stud bolt.CAUTION: Do not pry water pump at timing chain
case/cover. The machined surfaces may be dam-
aged resulting in leaks.
(6) Remove water pump and gasket. Discard gas-
ket.
CLEANING
Clean the gasket mating surface. Use caution not
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.
INSTALLATION
(1) Clean gasket mating surfaces.
(2) Using a new gasket, position water pump and
install mounting bolts as shown. (Fig. 44). Tighten
water pump mounting bolts to 54 N´m (40 ft. lbs.)
torque.
(3) Spin water pump to be sure that pump impel-
ler does not rub against timing chain case/cover.
(4) Connect radiator lower hose to water pump.
(5) Install accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
Fig. 44 Water Pump Installation
1 - WATER PUMP
2 - TIMING CHAIN COVER
WJENGINE 7 - 49
WATER PUMP - 4.7L (Continued)

CAUTION: When installing the serpentine accessory
drive belt, belt must be routed correctly. If not,
engine may overheat due to water pump rotating in
wrong direction.
(6) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(7) Connect negative battery cable.
(8) Start and warm the engine. Check for leaks.
WATER PUMP - 4.0L
DESCRIPTION
CAUTION: All 4.0L 6-cylinder engines are equipped
with a reverse (counterclockwise) rotating water
pump and thermal 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. Engines from previous model years,
depending upon application, may have been
equipped with a forward (clockwise) rotating water
pump. Installation of the wrong water pump or vis-
cous fan drive will cause engine over heating.
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
single serpentine drive belt.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary (Fig. 45).
DIAGNOSIS AND TESTINGÐWATER PUMP
LOOSE IMPELLER - 4.0L and 4.7L
NOTE: Due to the design of the 4.0L and 4.7L
engine water pumps, testing the pump for a loose
impeller must be done by verifying coolant flow in
the radiator. To accomplish this refer to the follow-
ing procedure.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Drain coolant until the first row of cores is vis-
ible in the radiator (Refer to 7 - COOLING - STAN-
DARD PROCEDURE) 4.7L Engine or (Refer to 7 -
COOLING - STANDARD PROCEDURE) 4.0L
Engine.(2) Leaving the radiator cap off, start the engine.
Run engine until thermostat opens.
(3) While looking into the radiator through the
radiator fill neck, raise engine rpm to 2000 RPM.
Observe the flow of coolant from the first row of
cores.
(4) If there is no flow or very little flow visable,
replace the water pump.
INSPECTING FOR INLET RESTRICTIONS
Inadequate heater performance may be caused by
a metal casting restriction in the heater hose inlet.
DO NOT WASTE reusable coolant. If solution is
clean, drain the coolant into a clean container for
reuse.
WARNING: DO NOT 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
decrease the level below the heater hose inlet. On
4.7L engines this requires complete draining.
(2) Remove the heater hose.
(3) Inspect the inlet for metal casting flash or
other restrictions.
Fig. 45 Water Pump
1 - HEATER HOSE FITTING BORE
2 - WATER PUMP
3 - WATER PUMP HUB
7 - 50 ENGINEWJ
WATER PUMP - 4.7L (Continued)

NOTE: On 4.0L engines remove the pump from the
engine before removing restriction to prevent con-
tamination of the coolant with debris. . On 4.7L
engine remove the fitting from the timing chain
cover, If the restriction is in the timing chain cover,
remove the timing chain cover.
REMOVAL
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 impeller is pressed on the rear of
the pump shaft and bearing assembly. The water
pump is serviced only as a complete assembly.
NOTE: The water pump can be replaced without
discharging the A/C system.
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.
(1) Disconnect negative battery cable at battery.
(2) Drain the cooling system (Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
(3) The thermal viscous fan drive is attached
(threaded) to the water pump hub shaft. Remove fan/
viscous fan drive assembly from water pump by turn-
ing mounting nut counterclockwise as viewed from
front. Threads on viscous fan drive areRIGHT
HANDDo not attempt to remove fan/viscous fan
drive assembly from vehicle at this time.
(4) If water pump is being replaced, do not unbolt
fan blade assembly from thermal viscous fan drive.
(5) Remove fan shroud-to-radiator nuts (Fig. 46).
Do not attempt to remove fan shroud at this time.
(6) Remove fan shroud and fan blade/viscous fan
drive assembly from vehicle as a complete unit.
(7) After removing fan blade/viscous fan drive
assembly,do notplace 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.
Loosen but do not remove the water pump pulley
mounting bolts.Remove accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - REMOV-
AL).
Remove the water pump pulley.
(8) Remove the idler pulley (located over the water
pump).
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. 47) SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 48). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
(9) Remove lower radiator hose from water pump.
Remove heater hose from water pump fitting.
(10) Remove the five pump mounting bolts (Fig.
49) and remove pump from vehicle. Discard old gas-
ket. Note that one of the five bolts is longer than the
other bolts.
(11) If pump is to be replaced, the heater hose fit-
ting must be removed. Note position of fitting before
removal.
Fig. 46 Fan Shroud Mounting
1 - SHROUD FASTENERS
2 - DRAIN COCK
3 - RADIATOR FAN SHROUD
4 - SHROUD FASTENERS
WJENGINE 7 - 51
WATER PUMP - 4.0L (Continued)

CLEANING
Clean the gasket mating surface. Use caution not
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.
INSTALLATION
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.
(1) If pump is being replaced, install the heater
hose fitting to the pump. Use a sealant on the fitting
such as MopartThread 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 sili-
cone bead on the gasket should be facing the water
pump. Also, the gasket is installed dry. Tighten
mounting bolts to 30 N´m (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. Tighten bolts 28 N´m (250 in. lbs.).
Install the idler pulley. Tighten the bolt 47 N´m (35
ft. lbs.).
Fig. 47 Hose Clamp Tool - Typical
1 - HOSE CLAMP TOOL 6094
2 - HOSE CLAMP
Fig. 48 Clamp - Typical
1 - TYPICAL CONSTANT TENSION HOSE CLAMP
2 - CLAMP NUMBER/LETTER LOCATION
3 - TYPICAL HOSE
Fig. 49 Water Pump Remove/Install - Typical
1 - HEATER HOSE FITTING
2 - PUMP GASKET
3 - WATER PUMP
4 - LONG BOLT
5 - BOLTS (4) SHORT
7 - 52 ENGINEWJ
WATER PUMP - 4.0L (Continued)