Engine JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

DESCRIPTION SPECIFICATION
Ring Side Clearance
Compression Rings 0.042 to 0.084 mm
(0.0017 to 0.0033 in.)
Oil Control Rings 0.06 to 0.21 mm
(0.0024 to 0.0083 in.)
Piston Ring Groove
Height
Compression Rings 1.530 to 1.555 mm
(0.0602 to 0.0612 in.)
Oil Control Ring 4.035 to 4.060 mm
(0.1589 to 0.1598 in.)
Piston Ring Groove
Diameter
No.1 Compression Ring 88.39 to 88.65 mm
(3.48 to 3.49 in.)
No.2 Compression Ring 87.63 to 87.88 mm
(3.45 to 3.46 in.)
Oil Control Ring 89.66 to 89.92 mm
(3.53 to 3.54 in.)
Piston Pin Bore Diameter 23.650 to 23.658 mm
(0.9312 to 0.9315 in.)
Piston Pin Diameter 23.637 to 23.640 mm
(0.9306 to 0.9307 in.)
Piston-to-Pin Clearance 0.0102 to 0.0208 mm
(0.0005 to 0.0009 in.)
Piston-to-Pin Connecting
Rod (Press Fit) 8.9 kN (2000 lbf.)
OIL PUMP
Gear-to-Body Clearance 0.051 to 0.102 mm
(Radial) (0.002 to 0.004 in.)
Gear-to-Body Clearance
(Radial) Preferred 0.051 mm (0.002 in.)
Gear End Clearance 0.051 to 0.152 mm
Plastigage (0.002 to 0.006 in.)
Gear End Clearance
Plastigage (Preferred) 0.051 mm (0.002 in.)
Gear End Clearance 0.1016 to 0.2032 mm
Feeler Gauge (0.004 to 0.008 in.)DESCRIPTION SPECIFICATION
Gear End Clearance
Feeler Gauge (Preferred) 0.1778 mm (0.007 in.)
Oil Pressure
At Idle Speed 89.6 kPa (13 psi)
At 1600 rpm & Higher 255 to 517 kPa
(37 to 75 psi)
Oil Pressure Relief 517 kPa (75 psi)
TORQUE - 4.0L ENGINE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
A/C CompressorÐBolts 28 Ð 250
Block HeaterÐNut 2 Ð 16
Camshaft SprocketÐBolt 68 50 Ð
Camshaft Thrust Plate to
Cylinder BlockÐScrews 24 18 Ð
Clutch Cover to FlywheelÐBolts 54 40 Ð
Coil Bracket to BlockÐBolts 22 Ð 192
Connecting RodÐNuts 45 33 Ð
Cylinder BlockÐDrain Plugs 34 25 Ð
Cylinder HeadÐBolts 135 100 Ð
Cylinder Head CoverÐBolts 10 Ð 85
Distributor ClampÐBolts 23 Ð 204
Engine MountsÐFront
Support Bracket Bolts 61 45 Ð
Support Cushion Bolts/Nuts 41 30 Ð
Support Cushion Bracket Bolts 54 40 Ð
Support Cushion Bracket Stud
Nuts41 30 Ð
Support Cushion Thru-Bolt 65 48 Ð
Engine MountsÐRear
Crossmember to Sill BoltsÐ
(Automatic) 41 30 Ð
Insulator Stud AssemblyÐNut 41 30 Ð
Support Cushion/
CrossmemberÐ
Nuts 22 Ð 192
Support Cushion/BracketÐNuts
(Manual) 75 55 Ð
WJENGINE - 4.0L 9 - 17
ENGINE - 4.0L (Continued)

DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Transmission Support Bracket
ÐBolt (Manual) 46 34 Ð
Transmission Support Bracket/
CushionÐBolt (4WD Auto) 75 55 Ð
Transmission Support Adaptor
BracketÐBolts (2WD Auto) 75 55 Ð
Exhaust Manifold/PipeÐNuts 27 20 Ð
Intake/Exhaust Manifold
Fasteners #1-5 33 24 Ð
Fasteners #6 and 7 14 Ð 126
Fasteners #8-11 33 24 Ð
Flywheel to Converter
HousingÐBolts38 28 Ð
Flywheel to CrankshaftÐBolts 143 105 Ð
Front Cover to BlockÐBolts
1/4-20 7 Ð 60
5/16-18 22 Ð 192
Fuel RailÐBolts/Stud 12 Ð 108
GeneratorÐBolts 57 42 Ð
Generator Bracket to EngineÐ
Bolts47 35 Ð
Idler Pulley to Cylinder
HeadÐBolt47 35 Ð
Main Bearing CapÐBolts 108 80 Ð
Oil Filter 18 Ð 156
Oil Filter Connector to
Adaptor 47 35 Ð
Block 68 50 Ð
Adaptor Bolts 102 50 Ð
Oil GalleyÐPlug 41 30 Ð
Oil PanÐBolts
1/4-20 9.5 Ð 84
5/16-18 15 Ð 132
Oil PanÐDrain Plug 34 25 Ð
Oil Pump
Mounting Bolts 23 Ð 204
Cover Bolts 8 Ð 70
Rocker Arm Assembly to
Cylinder
HeadÐCapscrews 30 21 Ð
Spark Plugs 37 27 ÐDESCRIPTION N´m Ft. In.
Lbs. Lbs.
Starter MotorÐMounting Bolts 45 33 Ð
Thermostat HousingÐBolts 18 Ð 156
Throttle BodyÐBolts 10 Ð 90
Vibration DamperÐBolt 108 80 Ð
Water Pump to BlockÐBolts 23 17 Ð
AIR CLEANER ELEMENT
REMOVAL - 4.0L
(1) Unlatch four clips retaining air cleaner cover to
air cleaner housing (Fig. 6).
Fig. 6 Air Cleaner Assembly Ð4.0L Engine
1 - RESONATOR BOLTS
2 - CLAMPS
3 - AIR DUCT
4 - AIR CLEANER COVER
5 - CLIPS
6 - HOUSING
7 - HOUSING BOLTS (3)
8 - LOWER HOUSING NUTS (3)
9 - RESONATOR
9 - 18 ENGINE - 4.0LWJ
ENGINE - 4.0L (Continued)

(2) Lift cover up and position to the side.
(3) Remove air cleaner element.
INSTALLATION - 4.0L
(1) Clean inside of air cleaner housing before
installing new element.
(2) Install air cleaner element into housing.
(3) Latch clips and clamp cover down to secure. Be
sure air cleaner cover is properly seated to air
cleaner housing.
AIR CLEANER HOUSING
REMOVAL - 4.0L
(1) Disconnect air cleaner cover-to-air duct clamp
(Fig. 6).
(2) Disconnect air duct at housing.
(3)Each of the 3 air cleaner housing mount-
ing bolts is attached with 2 nuts (an upper nut
and lower nut). DO NOT REMOVE BOLTS. To
prevent stripping bolts, only remove lower
nuts. The lower housing nuts are located under
left front inner fender (Fig. 6).
(a) To gain access to lower nuts, raise vehicle.
(b) Remove clips retaining rubber inner fender
shield.
(c) Pry back shield enough to gain access to
lower nuts.
(d) Remove 3 nuts.
(e) Remove air cleaner assembly from vehicle.
(4) If resonator is to be removed, disconnect
breather tube at resonator, disconnect air duct clamp
at resonator (Fig. 6)and remove 1 resonator mount-
ing bolt. Remove resonator from throttle body by
loosening clamp (Fig. 7).
INSTALLATION - 4.0L
(1) Position air cleaner assembly to body and
install 3 nuts. Tighten nuts to 10 N´m (93 in. lbs.)
torque.To prevent excessive vibration transmit-
ted through housing, the nuts must be properly
torqued. Do not overtighten nuts.
(2) If resonator was removed: Install resonator and
bolts. Tighten bolts to 4 N´m (35 in. lbs.) torque.
Tighten clamp at throttle body to 4 N´m (35 in. lbs.)
torque.
(3) Position fender liner and install clips.
(4) Connect air duct at housing (Fig. 6).
(5) Tighten air duct clamp.
CYLINDER HEAD
DESCRIPTION
The cylinder head is made of cast iron containing
twelve valves made of chrome plated heat resistant
steel, valve stem seals, springs, retainers and keep-
ers. The cylinder head and valve seats can be resur-
faced for service purposes.
The valve guides are integral to the cylinder head,
They are not replaceable. However, they are service-
able.
The cylinder head uses dual quench-type design
combustion chambers which cause turbulence in the
cylinders allowing faster burning of the air/fuel mix-
ture, resulting in better fuel economy (Fig. 8).
REMOVAL
NOTE: This procedure can be done with the engine
in or out of the vehicle.
(1) Disconnect the battery negative cable.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAIN COCK WITH THE SYSTEM HOT AND PRES-
SURIZED BECAUSE SERIOUS BURNS FROM THE
COOLANT CAN OCCUR.
Fig. 7 RESONATOR CLAMP - 4.0L
1 - RESONATOR
2 - AIR DUCT
3 - CLAMP
WJENGINE - 4.0L 9 - 19
AIR CLEANER ELEMENT (Continued)

(2) Drain the coolant (Refer to 7 - COOLING -
STANDARD PROCEDURE) and disconnect the hoses
at the engine thermostat housing and the water
pump inlet. DO NOT waste reusable coolant. If the
solution is clean and is being drained only to service
the engine or cooling system, drain the coolant into a
clean container for reuse.
(3) Remove the air cleaner assembly (Refer to 9 -
ENGINE/AIR INTAKE SYSTEM/AIR CLEANER
HOUSING - REMOVAL).
(4) Remove the cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(5) Remove the capscrews, bridge and pivot assem-
blies and rocker arms (Refer to 9 - ENGINE/CYLIN-
DER HEAD/ROCKER ARM / ADJUSTER ASSY -
REMOVAL).
(6) Remove the push rods.Retain the push rods,
bridges, pivots and rocker arms in the same
order as removed.
(7) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(8) Remove the A/C compressor mounting bolts
and secure the compressor to the side.
(9) Remove the power steering pump and bracket
from the intake manifold and water pump. Set the
pump and bracket aside. DO NOT disconnect the
hoses.
(10) Perform the Fuel System Pressure Release
procedure. (Refer to 14 - FUEL SYSTEM/FUEL
DELIVERY - STANDARD PROCEDURE).
(11) Disconnect the fuel supply line at the fuel rail.(12) Remove the intake and exhaust manifolds
from the engine cylinder head (Refer to 9 - ENGINE/
MANIFOLDS/INTAKE MANIFOLD - REMOVAL).
(13) Remove the coil rail (Refer to 8 - ELECTRI-
CAL/IGNITION CONTROL/COIL RAIL - REMOV-
AL).
(14) Remove spark plugs (Refer to 8 - ELECTRI-
CAL/IGNITION CONTROL/SPARK PLUG - REMOV-
AL).
(15) Disconnect the temperature sending unit wire
connector.
(16) Remove the engine cylinder head bolts. Bolt
No.14 cannot be removed until the head is moved for-
ward (Fig. 9). Pull bolt No.14 out as far as it will go
and then suspend the bolt in this position (tape
around the bolt).
(17) Remove the engine cylinder head and gasket
(Fig. 9).
(18) If this was the first time the bolts were
removed, put a paint dab on the top of the bolt. If the
bolts have a paint dab on the top of the bolt or it
isn't known if they were used before, discard the
bolts.
(19) Stuff clean lint free shop towels into the cyl-
inder bores.
NOTE: If the valves, springs, or seals are to be
inspected/replaced at this time, (Refer to 9 -
ENGINE/CYLINDER HEAD/INTAKE/EXHAUST
VALVES & SEATS - STANDARD PROCEDURE) for
proper inspection procedures.
Fig. 8 Cylinder Head 4.0L Engine
1 - CYLINDER HEAD BOLTS
2 - CYLINDER HEAD GASKET
3 - CYLINDER HEAD
Fig. 9 Engine Cylinder
1 - CYLINDER HEAD BOLTS
2 - CYLINDER HEAD GASKET
3 - CYLINDER HEAD
9 - 20 ENGINE - 4.0LWJ
CYLINDER HEAD (Continued)

CLEANING
Thoroughly clean the engine cylinder head and cyl-
inder block mating surfaces. Clean the intake and
engine exhaust manifold and engine cylinder head
mating surfaces. Remove all gasket material and car-
bon.
Check to ensure that no coolant or foreign material
has fallen into the tappet bore area.
Remove the carbon deposits from the combustion
chambers and top of the pistons.
INSPECTION
Use a straightedge and feeler gauge to check the
flatness of the engine cylinder head and block mating
surfaces.
INSTALLATION
NOTE: This procedure can be done with the engine
in or out of the vehicle.
The engine cylinder head gasket is a composition
gasket. The gasket is to be installed DRY.DO NOT
use a gasket sealing compound on the gasket.
If the engine cylinder head is to be replaced and
the original valves used, measure the valve stem
diameter. Only standard size valves can be used with
a service replacement engine cylinder head unless
the replacement head valve stem guide bores are
reamed to accommodate oversize valve stems.
Remove all carbon buildup and reface the valves.
(1) Remove the shop towels from the cylinder
bores. Coat the bores with clean engine oil.
(2) Position the engine cylinder head gasket (with
the numbers facing up) using the alignment dowels
in the cylinder block, to position the gasket.
CAUTION: Engine cylinder head bolts should be
reused only once. Replace the head bolts if they
were used before or if they have a paint dab on the
top of the bolt.
(3) With bolt No.14 held in place (tape around
bolt), install the engine cylinder head over the same
dowels used to locate the gasket. Remove the tape
from bolt No.14.
(4) Coat the threads of stud bolt No.11 with Loc-
tite 592 sealant, or equivalent.
(5) Tighten the engine cylinder head bolts in
sequence according to the following procedure (Fig.
10).
CAUTION: During the final tightening sequence,
bolt No.11 will be tightened to a lower torque than
the rest of the bolts. DO NOT overtighten bolt
No.11.(a) Tighten all bolts in sequence (1 through 14)
to 30 N´m (22 ft. lbs.) torque.
(b) Tighten all bolts in sequence (1 through 14)
to 61 N´m (45 ft. lbs.) torque.
(c) Check all bolts to verify they are set to 61
N´m (45 ft. lbs.) torque.
(d) Tighten bolts in sequence:
²Bolts 1 through 10 to 149 N´m (110 ft. lbs.)
torque.
²Bolt 11 to 135 N´m (100 ft. lbs.) torque.
²Bolts 12 through 14 to 149 N´m (110 ft. lbs.)
torque.
CYLINDER HEAD BOLTS
POSITION DESCRIPTION
1,4,5,12,13 1/2 in.-13 BOLT
8,9 1/2 in.-13 BOLT WITH DOWEL
POINT
2,3,6,7,10,11,14 1/2 in.-13 WITH 7/16 in.-14 STUD
END
All bolts are 12 point drives for rocker cover clearance
(e) Check all bolts in sequence to verify the cor-
rect torque.
(f) If not already done, clean and mark each bolt
with a dab of paint after tightening. Should you
encounter bolts which were painted in an earlier
service operation, replace them.
(6) Install the spark plugs (Refer to 8 - ELECTRI-
CAL/IGNITION CONTROL/SPARK PLUG - INSTAL-
LATION).
(7) Connect the temperature sending unit wire
connector.
(8) Install the ignition coil rail (Refer to 8 - ELEC-
TRICAL/IGNITION CONTROL/COIL RAIL -
INSTALLATION).
(9) Install the intake and exhaust manifolds (Refer
to 9 - ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION).
(10) Install the fuel line.
(11) Attach the power steering pump and bracket.
Fig. 10 Engine Cylinder Head Bolt Tightening
Sequence
WJENGINE - 4.0L 9 - 21
CYLINDER HEAD (Continued)

(12) Install the push rods, rocker arms, pivots and
bridges in the order they were removed (Refer to 9 -
ENGINE/CYLINDER HEAD/ROCKER ARM /
ADJUSTER ASSY - INSTALLATION).
(13) Install the engine cylinder head cover (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - INSTALLATION).
(14) Attach the air conditioner compressor mount-
ing bracket to the engine cylinder head and block.
Tighten the bolts to 40 N´m (30 ft. lbs.) torque.
(15) Attach the air conditioning compressor to the
bracket. Tighten the bolts to 27 N´m (20 ft. lbs.)
torque.
CAUTION: The serpentine drive belt must be routed
correctly. Incorrect routing can cause the water
pump to turn in the opposite direction causing the
engine to overheat.
(16) Install the serpentine drive belt. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(17) Install the air cleaner and ducting.
(18) Connect the hoses to the engine thermostat
housing and fill the cooling system to the specified
level (Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(19) The automatic transmission throttle linkage
and cable must be adjusted after completing the
engine cylinder head installation (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - AW4/
THROTTLE VALVE CABLE - ADJUSTMENTS).
(20) Install the temperature sending unit and con-
nect the wire connector.
(21) If equipped with air conditioning, install A/C
compressor (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/A/C COMPRESSOR -
INSTALLATION) and charge A/C system (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE).
(22) Connect negative cable to battery.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN DIRECT
LINE WITH THE FAN. DO NOT PUT HANDS NEAR
THE PULLEYS, BELTS OR FAN. DO NOT WEAR
LOOSE CLOTHING.
(23) Operate the engine with the radiator cap off.
Inspect for leaks and continue operating the engine
until the engine thermostat opens. Add coolant, if
required.CYLINDER HEAD COVER(S)
DESCRIPTION
The cylinder head cover (Fig. 11) is made of
stamped steel and incorporates the Crankcase Venti-
lation (CCV) Hoses and the oil fill opening.
REMOVAL
The cylinder head cover is isolated from the cylin-
der head via grommets and a reusable molded rubber
gasket. The grommet and limiter are retained in the
cylinder head cover.
(1) Disconnect negative cable from battery.
(2) Disconnect the Crankcase Ventilation (CCV)
vacuum hose from engine cylinder head cover.
(3) Disconnect the fresh air inlet hose from the
engine cylinder head cover.
(4) Disconnect the accelerator, transmission, and
speed (if equipped) control cables from the throttle
body (Fig. 12).
(5) Remove the three bolts that fasten the control
cable bracket to the intake manifold.
(6) Remove control cables from cylinder head cover
clip.
(7) Position control cables and bracket away from
cylinder head cover secure with tie straps.
(8) Remove the engine cylinder head cover mount-
ing bolts.
(9) Remove the engine cylinder head cover and
gasket.
Fig. 11 Cylinder Head Cover
9 - 22 ENGINE - 4.0LWJ
CYLINDER HEAD (Continued)

CLEANING
Remove any original sealer from the cover sealing
surface of the engine cylinder head and clean the
surface using a fabric cleaner.
Remove all residue from the sealing surface using
a clean, dry cloth.
INSPECTION
Inspect the engine cylinder head cover for cracks.
Replace the cover, if cracked.
The original dark grey gasket material should
NOT be removed. If sections of the gasket material
are missing or are compressed, replace the engine
cylinder head cover. However, sections with minor
damage such as small cracks, cuts or chips may be
repaired with a hand held applicator. The new mate-
rial must be smoothed over to maintain gasket
height. Allow the gasket material to cure prior to
engine cylinder head cover installation.
INSTALLATION
The cylinder head cover is isolated from the cylin-
der head via grommets and a reusable molded rubber
gasket. The grommet and limiter are retained in the
cylinder head cover.
(1) If a replacement cover is installed, transfer the
CCV valve grommet and oil filler cap from the origi-
nal cover to the replacement cover.
(2) Install cylinder head cover and gasket (Fig. 13).
Tighten the mounting bolts to 10 N´m (85 in. lbs.)
torque.
(3) Connect the CCV hoses.(4) Install control cables and bracket on intake
manifold and tighten bolts to 8.7 N´m (77 in. lbs.)
torque.
(5) Connect control cables to throttle body linkage.
(6) Snap control cables into cylinder head cover
clip.
(7) Connect negative cable to battery.
INTAKE/EXHAUST VALVES &
SEATS
DESCRIPTION
The valves are made of heat resistant steel and
have chrome plated stems to prevent scuffing. All
valves use three bead locks to promote valve rotation
(Fig. 14).
STANDARD PROCEDURE - VALVE SERVICE
VALVE REFACING
Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
(1) Use a valve refacing machine to reface the
intake and exhaust valves to the specified angle.
(2) After refacing, a margin of at least 0.787 mm
(0.031 inch) must remain (Fig. 15). If the margin is
less than 0.787 mm (0.031 inch), the valve must be
replaced.
VALVE SEAT REFACING
Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
(1) Install a pilot of the correct size in the valve
guide bore. Reface the valve seat to the specified
angle with a good dressing stone. Remove only
enough metal to provide a smooth finish.
(2) Use tapered stones to obtain the specified seat
width when required.
Fig. 12 Engine Cylinder Head Cover
1 - TRANS CONTROL CABLE
2 - ACCELERATOR CABLE
3 - CONTROL CABLE BRACKET
4 - CYLINDER HEAD COVER
Fig. 13 Cylinder Head Cover Gasket Locator Pins at
#8
WJENGINE - 4.0L 9 - 23
CYLINDER HEAD COVER(S) (Continued)

(3) Control valve seat runout to a maximum of
0.0635 mm (0.0025 in.) (Fig. 16).
VALVE STEM-TO-GUIDE CLEARANCE
MEASUREMENT
PREFERRED METHOD
(1) Remove the valve from the head.
(2) Clean the valve stem guide bore with solvent
and a bristle brush.
(3) Insert a telescoping gauge into the valve stem
guide bore approximately 9.525 mm (.375 inch) from
the valve spring side of the head (Fig. 17).
(4) Remove and measure telescoping gauge with a
micrometer.
(5) Repeat the measurement with contacts length-
wise to engine cylinder head.
(6) Compare the crosswise to lengthwise measure-
ments to determine out-of-roundness. If the measure-
ments differ by more than 0.0635 mm (0.0025 in.),
ream the guide bore to accommodate an oversize
valve stem.
(7) Compare the measured valve guide bore diam-
eter with specifications (7.95-7.97 mm or 0.313-0.314
inch). If the measurement differs from specification
by more than 0.076 mm (0.003 inch), ream the guide
bore to accommodate an oversize valve stem.
ALTERNATIVE METHOD
(1) Use a dial indicator to measure the lateral
movement of the valve stem (stem-to-guide clear-
ance). This must be done with the valve installed in
its guide and just off the valve seat (Fig. 18).
(2) Correct clearance is 0.025-0.0762 mm
(0.001-0.003 inch). If indicated movement exceeds the
specification ream the valve guide to accommodate
an oversize valve stem.
Fig. 14 VALVE AND KEEPER CONFIGURATION 4.0L
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
Fig. 15 Valve Facing
1 - VALVE MARGIN
2 - NO MARGIN
Fig. 16 Measurement of Valve Seat Runout
1 - DIAL INDICATOR
9 - 24 ENGINE - 4.0LWJ
INTAKE/EXHAUST VALVES & SEATS (Continued)

NOTE: Valve seats must be ground after reaming
the valve guides to ensure that the valve seat is
concentric to the valve guide.
REMOVAL
NOTE: This procedure is done with the engine cyl-
inder head removed from the block.(1) Remove the engine cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL) from the
cylinder block.
(2) Use Valve Spring Compressor Tool
MD-998772A and compress each valve spring.
(3) Remove the valve locks, retainers, springs and
valve stem oil seals. Discard the oil seals (Fig. 19).
(4) Use a smooth stone or a jewelers file to remove
any burrs on the top of the valve stem, especially
around the groove for the locks.
(5) Remove the valves, and place them in a rack in
the same order as removed.
INSTALLATION
NOTE: This procedure is done with the engine cyl-
inder head removed from the block.
(1) Thoroughly clean the valve stems and the valve
guide bores.
(2) Lightly lubricate the stem.
(3) Install the valve in the original valve guide
bore.
(4) Install the replacement valve stem oil seals on
the valve stems (Fig. 20). If the 0.381 mm (0.015
inch) oversize valve stems are used, oversize oil seals
are required.
Fig. 17 Measurement of Valve Guide Bore Diameter
1 - GAUGE
2 - 9.525 MM (3/8 INCH)
3 - VALVE STEM GUIDE
4 - CYLINDER HEAD
Fig. 18 Measurement of Lateral Movement Of Valve
Stem
1 - DIAL INDICATOR
Fig. 19 Valve and Valve Components
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
WJENGINE - 4.0L 9 - 25
INTAKE/EXHAUST VALVES & SEATS (Continued)

(5) Position the valve spring and retainer on the
engine cylinder head and compress the valve spring
with Valve Spring Compressor Tool MD-998772A.
(6) Install the valve locks and release the tool.
(7) Tap the valve spring from side to side with a
hammer to ensure that the spring is properly seated
at the engine cylinder head. Also tap the top of the
retainer to seat the valve locks.
(8) Install the engine cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - INSTALLATION).
ROCKER ARM / ADJUSTER
ASSEMBLY
DESCRIPTION
The rocker arms are made of stamped steel and
have a operational ratio of 1.6:1 (Fig. 21).
OPERATION
When the push rods are forced upward by the cam-
shaft lobes the push rod presses upward on the
rocker arms, the rocker arms pivot, forcing down-
ward pressure on the valves forcing the valves to
move downward and off from their seats.
REMOVAL
NOTE: This procedure can be done with the engine
in or out of the vehicle.
(1) Remove the cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(2) Check for rocker arm bridges which are caus-
ing misalignment of the rocker arm to valve tip area.
(3) Remove the capscrews at each bridge and pivot
assembly (Fig. 22). Alternately loosen the capscrews
one turn at a time to avoid damaging the bridges.
(4) Remove the bridges, pivots and corresponding
pairs of rocker arms (Fig. 22). Place them on a bench
in the same order as removed.
(5) Remove the push rods and place them on a
bench in the same order as removed.
CLEANING
Clean all the components with cleaning solvent.
Use compressed air to blow out the oil passages in
the rocker arms and push rods.
Fig. 20 Valve and Valve Components
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
Fig. 21 Rocker ArmsÐTypical
1 - CAPSCREWS
2 - BRIDGE
3 - PIVOT ASSEMBLY
4 - PUSH RODS
5 - ROCKER ARMS
9 - 26 ENGINE - 4.0LWJ
INTAKE/EXHAUST VALVES & SEATS (Continued)