Page 1265 of 2199

(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)
Page 1266 of 2199

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)
Page 1267 of 2199

(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)
Page 1268 of 2199

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)
Page 1269 of 2199

(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)
Page 1270 of 2199

INSPECTION
Inspect the pivot surface area of each rocker arm.
Replace any that are scuffed, pitted, cracked or
excessively worn.
Inspect the valve stem tip contact surface of each
rocker arm and replace any rocker arm that is deeply
pitted.
Inspect each push rod end for excessive wear and
replace as required. If any push rod is excessively
worn because of lack of oil, replace it and inspect the
corresponding hydraulic tappet for excessive wear.
Inspect the push rods for straightness by rolling
them on a flat surface or by shining a light between
the push rod and the flat surface.
A wear pattern along the length of the push rod is
not normal. Inspect the engine cylinder head for
obstruction if this condition exists.
INSTALLATION
NOTE: This procedure can be done with the engine
in or out of the vehicle.
(1) Lubricate the ball ends of the push rods with
MopartEngine Oil Supplement, or equivalent and
install push rods in their original locations. Ensurethat the bottom end of each push rod is centered in
the tappet plunger cap seat.
(2) Using MopartEngine Oil Supplement, or
equivalent, lubricate the area of the rocker arm that
the pivot contacts. Install rocker arms, pivots and
bridge above each cylinder in their originally position
(Fig. 23).
(3) Loosely install the capscrews through each
bridge.
(4) At each bridge, tighten the capscrews alter-
nately, one turn at a time, to avoid damaging the
bridge. Tighten the capscrews to 28 N´m (21 ft. lbs.)
torque.
(5) Install the engine cylinder head cover (Refer to
9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
VALVE STEM SEALS
DESCRIPTION
The valve stem seals (Fig. 24) are made of rubber
and incorporate a garter spring to maintain consis-
tent lubrication control.
Fig. 22 Rocker Arm
1 - CAPSCREWS
2 - BRIDGE
3 - PIVOT ASSEMBLY
4 - PUSH RODS
5 - ROCKER ARMS
Fig. 23 Rocker Arm
1 - CAPSCREWS
2 - BRIDGE
3 - PIVOT ASSEMBLY
4 - PUSH RODS
5 - ROCKER ARMS
WJENGINE - 4.0L 9 - 27
ROCKER ARM / ADJUSTER ASSEMBLY (Continued)
Page 1271 of 2199

VALVE SPRINGS
DESCRIPTION
The valve springs (Fig. 25) are made of high
strength silicon chrome spring steel. The springs are
common for both intake and exhaust valves.
STANDARD PROCEDURE - VALVE SPRING
TENSION TEST
Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
Use a universal Valve Spring Tester and a torque
wrench to test each valve spring for the specified ten-
sion value (Fig. 26).
Replace valve springs that are not within specifica-
tions.
REMOVAL
NOTE: This procedure can be done with the engine
cylinder head installed on the block.
Inspect the valve stems, especially the grooves. An
Arkansas smooth stone should be used to remove
nicks and high spots.Each valve spring is held in place by a retainer
and a set of conical valve locks. The locks can be
removed only by compressing the valve spring.
(1) Remove the engine cylinder head cover (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - REMOVAL).
Fig. 24 Valve
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
Fig. 25 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. 26 Valve Spring Tester
1 - TORQUE WRENCH
2 - VALVE SPRING TESTER
9 - 28 ENGINE - 4.0LWJ
VALVE STEM SEALS (Continued)
Page 1272 of 2199

(2) Remove cap screws, bridge and pivot assem-
blies and rocker arms (Refer to 9 - ENGINE/CYLIN-
DER HEAD/ROCKER ARM / ADJUSTER ASSY -
REMOVAL) for access to each valve spring to be
removed.
(3) Remove push rods.Retain the push rods,
bridges, pivots and rocker arms in the same
order and position as removed.
(4) Inspect the springs and retainer for cracks and
possible signs of weakening.
(5) Remove the spark plug(s) adjacent to the cylin-
der(s) below the valve springs to be removed.
(6) Connect an air hose to the adapter and apply
air pressure slowly. Maintain at least 621 kPa (90
psi) of air pressure in the cylinder to hold the valves
against their seats. For vehicles equipped with an air
conditioner, use a flexible air adaptor when servicing
the No.1 cylinder.
(7) Tap the retainer or tip with a rawhide hammer
to loosen the lock from the retainer. Use Valve Spring
Compressor Tool MD-998772A to compress the spring
and remove the locks (Fig. 27).
(8) Remove valve spring and retainer (Fig. 27).
(9) Remove valve stem oil seals (Fig. 27). Note the
valve seals are different for intake and exhaust
valves. The top of each seal is marked either INT
(intake/black in color) or EXH (exhaust/brown in
color). DO NOT mix the seals.
INSTALLATION
NOTE: This procedure can be done with the engine
cylinder head installed on the block.
CAUTION: Install oil seals carefully to prevent dam-
age from the sharp edges of the valve spring lock
grove.
(1) Lightly push the valve seal over the valve stem
and valve guide boss. Be sure the seal is completely
seated on the valve guide boss.
(2) Install valve spring and retainer (Fig. 28).
(3) Compress the valve spring with Valve Spring
Compressor Tool MD-998772A and insert the valve
locks. Release the spring tension and remove the
tool. Tap the spring from side-to-side to ensure that
the spring is seated properly on the engine cylinder
head.(4) Release air pressure and disconnect the air
hose. Remove the adaptor from the spark plug hole
and install the spark plug.
(5) Repeat the procedures for each remaining valve
spring to be removed.
(6) Install the push rods. Ensure the bottom end of
each rod is centered in the plunger cap seat of the
hydraulic valve tappet.
(7) Install the rocker arms, pivots and bridge
(Refer to 9 - ENGINE/CYLINDER HEAD/ROCKER
ARM / ADJUSTER ASSY - INSTALLATION) at their
original location.
(8) Install the engine cylinder head cover (Refer to
9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
Fig. 27 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 - 29
VALVE SPRINGS (Continued)