2002 JEEP GRAND CHEROKEE Lubrication

(12) Install the oil pan and gasket (Refer to 9 -
ENGINE/LUBRICATION/OIL PAN - INSTALLA-
TION).
(13) Lower the vehicle.
(14) Install the engine cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - INSTALLATION),
push rods, rocker arms, bridges, pivots and engine
cylinder head cover(Refer to 9 - ENGINE/CYLINDER
HEAD/CYLINDER HEAD COVER(S) - INSTALLA-
TION).
(15) Fill the crankcase with engine oil.
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING
(1) Carefully clean the carbon from all ring
grooves. Oil drain openings in the oil ring groove and
pin boss must be clear. DO NOT remove metal from
the grooves or lands. This will change ring-to-groove
clearances and will damage the ring-to-land seating.
(2) Be sure the piston ring grooves are free of
nicks and burrs.
(3) Measure the ring side clearance with a feeler
gauge fitted snugly between the ring land and ring
(Fig. 62) (Fig. 63). Rotate the ring in the groove. It
must move freely around circumference of the groove.
RING SIDE CLEARANCE CHART
ITEM SPECIFICATION
Top Compression Ring 0.042 - 0.084 mm
(0.0017 - 0.0033 in.)
Second Compression
Ring0.042 - 0.084 mm
(0.0017 - 0.0033 in.)
Oil Control Ring 0.06 - 0.21 mm
(0.0024 - 0.0083 in.)
(4) Place ring in the cylinder bore and push down
with inverted piston to position near lower end of the
ring travel. Measure ring gap with a feeler gauge fit-
ting snugly between ring ends (Fig. 64).
RING GAP MEASUREMENT CHART
ITEM SPECIFICATION
Top Compression Ring 0.229 - 0.610 mm
(0.0090 - 0.0240 in.)
Second Compression
Ring0.483 - 0.965 mm
(0.0190 - 0.080 in.)
Oil Control Ring 0.254 - 1.500 mm
(0.010 - 0.060 in.)
Fig. 62 Piston Dimensions
Fig. 63 Ring Side Clearance Measurement
1 - FEELER GAUGE
WJENGINE - 4.0L 9 - 47
PISTON & CONNECTING ROD (Continued)

NOTE: Before the engine or the transmission can
be removed the engine bending braces must be
removed.
(1) Raise and support vehicle.
NOTE: Both left and right side bending braces are
removed the sameway. Only the right side is
shown.
NOTE: The exhaust does not require removal to
preform this procedure.
(2) Remove the exhaust hanger bracket retaining
bolt.
(3) Remove locknut and transmission bending
brace bar.
(4) Remove engine-to-bending brace retaining bolt,
bending brace bar and cross bar.
INSTALLATION
NOTE: DO NOT tighten the retaining hardware until
all bending braces are in place.
(1) Position the cross brace into the engine-to-
transmission brace, then position the engine-to-trans-
mission brace and install retaining bolt.
(2) Position the transmission bending brace onto
through brace and install new locknut.
(3) Position exhaust hanger and transmission
brace, install retaining bolt (Fig. 72).
(4) Tighten engine-to-transmission brace retaining
bolt (Fig. 71)to 40 N´m (30 ft. lbs.).
(5) Tighten transmission brace retaining bolts (Fig.
72)to 40 N´m (30 ft. lbs.), then tighten transmission
brace retaining lock nuts (Fig. 72) to 108 N´m (80 ft.
lbs.).
LUBRICATION
DESCRIPTION
A gearÐtype positive displacement pump is
mounted at the underside of the block opposite the
No. 4 main bearing.
OPERATION
The pump draws oil through the screen and inlet
tube from the sump at the rear of the oil pan. The oil
is driven between the drive and idler gears and
pump body, then forced through the outlet to the
block. An oil gallery in the block channels the oil to
the inlet side of the full flow oil filter. After passing
through the filter element, the oil passes from the
center outlet of the filter through an oil gallery thatchannels the oil up to the main gallery which
extends the entire length of the block.
Galleries extend downward from the main oil gal-
lery to the upper shell of each main bearing. The
Fig. 71 Engine-to-Transmission Bending Braces
1 - ENGINE-TO-TRANSMISSION BENDING BRACE
2 - CROSS BRACE
3 - ENGINE-TO-TRANSMISSION BENDING BRACE RETAINING
BOLT
Fig. 72 Transmission Bending Braces and Exhaust
Hanger
1 - TRANSMISSION BENDING BRACE RETAINING BOLT
2 - ENGINE-TO-TRANSMISSION BENDING BRACE
3 - LOCKNUT
4 - TRANSMISSION BRACE
5 - EXHAUST HANGER
9 - 50 ENGINE - 4.0LWJ
STRUCTURAL SUPPORT (Continued)

crankshaft is drilled internally to pass oil from the
main bearing journals (except number 4 main bear-
ing journal) to the connecting rod journals. Each con-
necting rod bearing cap has a small squirt hole, oil
passes through the squirt hole and is thrown off as
the rod rotates. This oil throwoff lubricates the cam-
shaft lobes, distributor drive gear, cylinder walls, and
piston pins.
The hydraulic valve tappets receive oil directly
from the main oil gallery. Oil is provided to the cam-
shaft bearing through galleries. The front camshaft
bearing journal passes oil through the camshaft
sprocket to the timing chain. Oil drains back to the
oil pan under the number one main bearing cap.
The oil supply for the rocker arms and bridged
pivot assemblies is provided by the hydraulic valve
tappets which pass oil through hollow push rods to a
hole in the corresponding rocker arm. Oil from the
rocker arm lubricates the valve train components,
then passes down through the push rod guide holes
in the cylinder head past the valve tappet area, and
returns to the oil pan (Fig. 73).
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL
PRESSURE
(1) Disconnect connector and remove oil pressure
sending unit.
(2) Install Oil Pressure Line and Gauge Tool
C-3292 or equivalent. Start engine and record pres-
sure. (Refer to 9 - ENGINE - SPECIFICATIONS) for
the correct pressures.
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24km (15 miles), and
repeat inspection.If the oil leak source is not pos-itively identified at this time, proceed with the air
leak detection test method.
Air Leak Detection Test Method
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the CCV valve from the cylinder head
cover. Cap or plug the CCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service informa-
tion procedures.
(5) If the leakage occurs at the rear oil seal area,
INSPECTION FOR REAR SEAL AREA LEAKS .
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps.
Install the CCV valve and breather cap hose.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
camshaft bore cup plugs oil galley pipe plugs, oil
filter runoff, and main bearing cap to cylinder
block mating surfaces.
(4) If no leaks are detected, pressurize the crank-
case as outlined in the, Inspection (Engine oil Leaks
in general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
WJENGINE - 4.0L 9 - 51
LUBRICATION (Continued)

Fig. 73 Oil Lubrication SystemÐ4.0L Engine
1 - CAM/CRANK MAIN GALLERY (7)
2 - TAPPET GALLERY
3 - TAPPET GALLERY
4 - CAMSHAFT BEARING5 - NUMBER 1 CAMSHFT BEARING JOURNAL
6 - CAMSHAFT SPROCKET
7 - TAPPET GALLERY
9 - 52 ENGINE - 4.0LWJ
LUBRICATION (Continued)

(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled.
OIL
STANDARD PROCEDURE - ENGINE OIL
SERVICE
ENGINE OIL CHANGE
Change engine oil at mileage and time intervals
described in Maintenance Schedules.
Run engine until achieving normal operating tem-
perature.
(1) Position the vehicle on a level surface and turn
engine off.
(2) Hoist and support vehicle on safety stands.
(3) Remove oil fill cap.
(4) Place a suitable drain pan under crankcase
drain.
(5) Remove drain plug from crankcase and allow
oil to drain into pan. Inspect drain plug threads for
stretching or other damage. Replace drain plug if
damaged.
(6) Install drain plug in crankcase.
(7) Replace engine oil filter. (Refer to 9 - ENGINE/
LUBRICATION/OIL FILTER - REMOVAL).
(8) Lower vehicle and fill crankcase with specified
type of engine oil (Refer to LUBRICATION & MAIN-
TENANCE/FLUID TYPES - DESCRIPTION) and
amount of engine oil (Refer to LUBRICATION &
MAINTENANCE - SPECIFICATIONS).
(9) Install oil fill cap.
(10) Start engine and inspect for leaks.
(11) Stop engine and inspect oil level. Refer to
CRANKCASE OIL LEVEL INSPECTION .
USED ENGINE OIL DISPOSAL
Care should be exercised when disposing used
engine oil after it has been drained from a vehicle
engine.
CRANKCASE OIL LEVEL INSPECTION
CAUTION: Do not overfill crankcase with engine oil,
oil foaming and oil pressure loss can result.
The engine oil level indicator (Dipstick) is located
at the right rear of the 4.0L engine. Inspect engine
oil level approximately every 800 kilometers (500
miles). Unless the engine has exhibited loss of oil
pressure, run the engine for about five minutes
before checking oil level. Checking engine oil level on
a cold engine is not accurate.
To ensure proper lubrication of an engine, the
engine oil must be maintained at an acceptable level.
The acceptable levels are indicated between the ADD
and SAFE marks on the engine oil dipstick (Fig. 74).
(1) Position vehicle on level surface.
(2) With engine OFF, allow approximately ten min-
utes for oil to settle to bottom of crankcase, remove
engine oil dipstick.
(3) Wipe dipstick clean.
(4) Install dipstick and verify it is seated in the
tube.
(5) Remove dipstick, with handle held above the
tip, take oil level reading (Fig. 74).
(6) Add oil only if level is below the ADD mark on
dipstick.
OIL FILTER
REMOVAL
CAUTION: Do not use oil filter with metric threads.
The proper oil filter has SAE type 3/4 X 16 threads.
An oil filter with metric threads can result in oil
leaks and engine failure.
Fig. 74 Engine Oil DipstickÐ4.0L Engine
1 - DIPSTICK
2 - ADD
3 - SAFE
WJENGINE - 4.0L 9 - 53
LUBRICATION (Continued)

ENGINE - 4.7L
TABLE OF CONTENTS
page page
ENGINE - 4.7L
DESCRIPTIONÐ4.7L ENGINE.............63
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION...........64
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - PERFORMANCE...........65
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - MECHANICAL.............66
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - LUBRICATION.............67
DIAGNOSIS AND TESTING - CYLINDER
COMPRESSION PRESSURE.............68
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE......69
STANDARD PROCEDURE
STANDARD PROCEDURE - REPAIR
DAMAGED OR WORN THREADS.........70
STANDARD PROCEDURE - FORM-IN-
PLACE GASKETS AND SEALERS.........70
STANDARD PROCEDURE - ENGINE
GASKET SURFACE PREPARATION........70
STANDARD PROCEDURE - ENGINE CORE
AND OIL GALLERY PLUGS..............71
REMOVAL.............................71
INSTALLATION.........................73
SPECIFICATIONS
4.7L ENGINE.........................74
SPECIFICATIONS - 4.7L H.O. ENGINE.....77
TORQUE............................79
SPECIAL TOOLS
4.7L ENGINE.........................80
AIR CLEANER ELEMENT
REMOVAL - 4.7L........................83
INSTALLATION - 4.7L....................83
AIR CLEANER HOUSING
REMOVAL - 4.7L........................84
INSTALLATION - 4.7L....................84
CYLINDER HEAD - LEFT
DESCRIPTION
DESCRIPTION - CYLINDER HEAD........84
DESCRIPTION - VALVE GUIDES..........84
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - HYDRAULIC
LASH ADJUSTER.....................84
DIAGNOSIS AND TESTINGÐCYLINDER
HEAD GASKET.......................85
REMOVAL.............................85
CLEANING............................86
INSPECTION..........................87INSTALLATION.........................87
CAMSHAFT(S) - LEFT
DESCRIPTION.........................88
REMOVAL.............................89
INSTALLATION.........................90
CYLINDER HEAD COVER(S) - LEFT
DESCRIPTION.........................93
REMOVAL - LEFT SIDE..................93
CLEANING............................93
INSTALLATIONÐLEFT SIDE...............93
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION.........................94
STANDARD PROCEDUREÐREFACING......94
REMOVAL.............................94
INSTALLATION.........................95
ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION.........................96
REMOVAL.............................96
INSTALLATION.........................96
VALVE SPRINGS
DESCRIPTION.........................97
VALVE STEM SEALS
DESCRIPTION.........................97
CYLINDER HEAD - RIGHT
DESCRIPTION
DESCRIPTION - CYLINDER HEAD........97
DESCRIPTION - VALVE GUIDES..........97
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐCYLINDER
HEAD GASKET.......................97
DIAGNOSIS AND TESTING - HYDRAULIC
LASH ADJUSTER.....................98
REMOVAL.............................98
CLEANING............................99
INSPECTION..........................99
INSTALLATION.........................99
CAMSHAFT(S) - RIGHT
DESCRIPTION........................100
REMOVAL............................100
INSTALLATION........................102
CYLINDER HEAD COVER(S) - RIGHT
DESCRIPTION........................104
REMOVAL - RIGHT SIDE................104
CLEANING...........................104
INSTALLATION - RIGHT SIDE.............104
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION........................104
STANDARD PROCEDUREÐREFACING.....105
REMOVAL............................105
INSTALLATION........................106
WJENGINE - 4.7L 9 - 61

ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION........................107
REMOVAL............................107
INSTALLATION........................107
VALVE SPRINGS
DESCRIPTION........................108
VALVE STEM SEALS
DESCRIPTION........................108
ENGINE BLOCK
DESCRIPTION........................108
STANDARD PROCEDUREÐCYLINDER BORE
HONING...........................108
CLEANING...........................109
INSPECTION.........................109
CONNECTING ROD BEARINGS
STANDARD PROCEDURE - CONNECTING
ROD BEARING FITTING...............109
CRANKSHAFT
DESCRIPTION........................111
STANDARD PROCEDURE - MEASURING
CRANKSHAFT END PLAY..............111
REMOVAL............................112
INSPECTION..........................112
INSTALLATION........................112
CRANKSHAFT MAIN BEARINGS
STANDARD PROCEDUREÐCRANKSHAFT
MAIN BEARING - FITTING..............114
INSPECTION..........................115
CRANKSHAFT OIL SEAL - FRONT
REMOVAL............................115
INSTALLATION........................116
CRANKSHAFT OIL SEAL - REAR
REMOVAL............................117
INSTALLATION........................117
FLEX PLATE
REMOVAL............................118
INSTALLATION........................118
PISTON & CONNECTING ROD
DESCRIPTION........................118
STANDARD PROCEDUREÐPISTON FITTING . 118
REMOVAL............................118
CLEANING...........................119
INSPECTION..........................119
INSTALLATION........................120
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING............................121
VIBRATION DAMPER
REMOVAL............................122
INSTALLATION........................123
STRUCTURAL COVER
DESCRIPTION........................124
OPERATION..........................124
REMOVAL............................124
INSTALLATION........................124
FRONT MOUNT
REMOVAL............................124INSTALLATION........................125
REAR MOUNT
REMOVAL............................125
INSTALLATION........................126
LUBRICATION
DESCRIPTION........................126
OPERATION..........................126
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐENGINE OIL
PRESSURE.........................128
DIAGNOSIS AND TESTINGÐREAR SEAL
AREA LEAKS........................128
DIAGNOSIS AND TESTINGÐENGINE OIL
LEAK..............................129
OIL
STANDARD PROCEDURE - ENGINE OIL....130
OIL FILTER
REMOVAL............................131
INSTALLATION........................132
OIL PAN
DESCRIPTION........................132
REMOVAL............................132
CLEANING...........................132
INSPECTION.........................132
INSTALLATION........................132
OIL PRESSURE SENSOR/SWITCH
DESCRIPTION........................133
OPERATION..........................133
REMOVAL............................133
INSTALLATION........................133
OIL PUMP
REMOVAL............................134
DISASSEMBLY........................134
CLEANING...........................134
INSPECTION.........................134
ASSEMBLY...........................135
INSTALLATION........................135
INTAKE MANIFOLD
DESCRIPTION........................136
DIAGNOSIS AND TESTINGÐINTAKE
MANIFOLD LEAKAGE.................136
REMOVAL............................136
CLEANING...........................137
INSPECTION.........................137
INSTALLATION........................137
EXHAUST MANIFOLD - LEFT
DESCRIPTION........................138
REMOVAL............................138
CLEANING...........................138
INSPECTION.........................138
INSTALLATION........................138
EXHAUST MANIFOLD - RIGHT
DESCRIPTION........................139
REMOVAL............................139
CLEANING...........................140
INSPECTION.........................141
INSTALLATION........................141
9 - 62 ENGINE - 4.7LWJ

CONDITION POSSIBLE CAUSE CORRECTION
1. ENGINE MISSES ON
ACCELERATION1. Spark plugs dirty or incorrectly
gapped.1. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG -
CLEANING).
2. Dirt in fuel system. 2. Clean fuel system.
3. Burned, warped or pitted valves. 3. Replcae as necessary.
4. Faulty coil. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION COIL -
REMOVAL).
1. ENGINE MISSES AT HIGH
SPEED1. Spark plugs dirty or incorrectly
gapped.1. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG -
CLEANING).
2. Faulty coil. 2. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION COIL -
REMOVAL).
3. Dirt or water in fuel system. 3. Clean system and replace fuel filter.
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - MECHANICAL
CONDITION POSSIBLE CAUSES CORRECTIONS
NOISY VALVES 1. High or low oil level in crankcase. 1. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
2. Thin or diluted oil. 2. Change oil and filter.
3. Low oil pressure. 3. Check oil pump, if Ok, check rod
and main bearings for excessive wear.
4. Dirt in lash adjusters. 4. Replace as necessary.
5. Worn rocker arms. 5. Replace as necessary.
6. Worn lash adjusters 6. Replace as necessary.
7. Worn valve guides. 7. (Refer to 9 - ENGINE/CYLINDER
HEAD/INTAKE/EXHAUST VALVES &
SEATS - STANDARD PROCEDURE).
8. Excessive runout of valve seats
on valve faces.8. Service valves and valve seats.
(Refer to 9 - ENGINE/CYLINDER
HEAD/INTAKE/EXHAUST VALVES &
SEATS - STANDARD PROCEDURE).
CONNECTING ROD NOISE 1. Insufficient oil supply. 1. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
2. Low oil pressure. 2. Check oil pump, if Ok, check rod
and main bearings for excessive wear.
3. Thin or diluted oil. 3. Change oil and filter.
4. Excessive bearing clearance. 4. Replace as necessary.
5. Connecting rod journal out-of-
round.5. Service or replace crankshaft.
6. Misaligned connecting rods. 6. Replace bent connecting rods.
9 - 66 ENGINE - 4.7LWJ
ENGINE - 4.7L (Continued)