2002 JEEP GRAND CHEROKEE lifter removal

REMOVAL
REMOVAL - CAMSHAFT BEARINGS.......31
REMOVAL - CAMSHAFT................31
INSPECTION
INSPECTION - CAMSHAFT BEARINGS.....31
INSPECTION - CAMSHAFT..............31
INSTALLATION
INSTALLATION - CAMSHAFT BEARINGS . . . 32
INSTALLATION - CAMSHAFT............32
CONNECTING ROD BEARINGS
STANDARD PROCEDURE - FITTING
CONNECTING ROD BEARINGS..........33
CRANKSHAFT
DESCRIPTION.........................35
CRANKSHAFT MAIN BEARINGS
STANDARD PROCEDURE - FITTING
CRANKSHAFT MAIN BEARINGS..........36
REMOVAL.............................39
INSPECTION..........................40
INSTALLATION.........................40
CRANKSHAFT OIL SEAL - FRONT
REMOVAL.............................41
INSTALLATION.........................41
CRANKSHAFT OIL SEAL - REAR
REMOVAL.............................42
INSTALLATION.........................42
HYDRAULIC LIFTERS
DESCRIPTION.........................43
REMOVAL.............................43
CLEANING............................43
INSPECTION..........................43
INSTALLATION.........................43
PISTON & CONNECTING ROD
DESCRIPTION.........................44
STANDARD PROCEDURE - PISTON FITTING . 44
REMOVAL.............................45
INSTALLATION.........................46
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING.............................47
VIBRATION DAMPER
REMOVAL.............................49
INSTALLATION.........................49STRUCTURAL SUPPORT
REMOVAL.............................49
INSTALLATION.........................50
LUBRICATION
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL
PRESSURE..........................51
DIAGNOSIS AND TESTING - ENGINE OIL
LEAK...............................51
OIL
STANDARD PROCEDURE - ENGINE OIL
SERVICE............................53
OIL FILTER
REMOVAL.............................53
INSTALLATION.........................54
OIL PAN
DESCRIPTION.........................54
REMOVAL.............................54
INSTALLATION.........................55
ENGINE OIL PRESSURE SENSOR
DESCRIPTION.........................56
OPERATION...........................56
OIL PUMP
REMOVAL.............................56
INSTALLATION.........................57
INTAKE MANIFOLD
DESCRIPTION.........................57
DIAGNOSIS AND TESTING - INTAKE
MANIFOLD LEAKAGE..................57
REMOVAL.............................57
INSTALLATION.........................57
EXHAUST MANIFOLD
DESCRIPTION.........................58
REMOVAL.............................58
INSTALLATION.........................58
TIMING BELT / CHAIN COVER(S)
REMOVAL.............................58
INSTALLATION.........................58
TIMING BELT/CHAIN AND SPROCKETS
REMOVAL.............................60
INSTALLATION.........................60
ENGINE - 4.0L
DESCRIPTION
The 4.0 Liter (242 CID) six-cylinder engine is an
In-line, lightweight, overhead valve engine. This
engine is designed for unleaded fuel.
The engine cylinder head has dual quench-type
combustion chambers that create turbulence and fast
burning of the air/fuel mixture. This results in better
fuel economy.
The cylinders are numbered 1 through 6 from front
to rear. The firing order is 1-5-3-6-2-4 (Fig. 1).The crankshaft rotation is clockwise, when viewed
from the front of the engine. The crankshaft rotates
within seven main bearings. The camshaft rotates
within four bearings.
The engine Build Date Code is located on a
machined surface on the right side of the cylinder
block between the No.2 and No.3 cylinders (Fig. 2).
The digits of the code identify:
²1st DigitÐThe year (8 = 1998).
²2nd & 3rd DigitsÐThe month (01 - 12).
²4th & 5th DigitsÐThe engine type/fuel system/
compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1
compression ratio engine with a multi-point fuel
injection system).
9 - 2 ENGINE - 4.0LWJ

REMOVAL
REMOVAL - CAMSHAFT BEARINGS
The camshaft rotates within four steel-shelled,
babbitt-lined bearings that are pressed into the cyl-
inder block and then line reamed. The camshaft
bearing bores and bearing diameters are not the
same size. They are stepped down in 0.254 mm
(0.010 inch) increments from the front bearing (larg-
est) to the rear bearing (smallest). This permits eas-
ier removal and installation of the camshaft. The
camshaft bearings are pressure lubricated. Camshaft
end play is maintained by the thrust plate.
(1) Remove the camshaft (Refer to 9 - ENGINE/
ENGINE BLOCK/CAMSHAFT & BEARINGS (IN
BLOCK) - REMOVAL).
NOTE: It is not advisable to attempt to replace cam-
shaft bearings unless special removal and installa-
tion tools are available, such as recommended tool
8544 Camshaft Bushing Remover Installer.
(2) Using Special tool 8544 Camshaft Bushing
Remover Installer, remove the camshaft bearings.
REMOVAL - CAMSHAFT
WARNING: THE COOLANT IN A RECENTLY OPER-
ATED ENGINE IS HOT AND PRESSURIZED.RELEASE THE PRESSURE BEFORE REMOVING
THE DRAIN COCK, CAP AND DRAIN PLUGS.
(1) Disconnect negative cable from battery.
(2) Drain the cooling system (Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
(3) Remove the radiator (Refer to 7 - COOLING/
ENGINE/RADIATOR - REMOVAL) and condenser
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/A/C CONDENSER - REMOVAL), if
equipped with A/C.
(4) Remove the engine cylinder head cover (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - REMOVAL).
(5) Remove the rocker arms, bridges and pivots
(Refer to 9 - ENGINE/CYLINDER HEAD/ROCKER
ARM / ADJUSTER ASSY - REMOVAL).
(6) Remove the push rods.
(7) Remove the engine cylinder head and gasket
(Refer to 9 - ENGINE/CYLINDER HEAD - REMOV-
AL).
(8) Remove the hydraulic valve tappets from the
engine cylinder block (Refer to 9 - ENGINE/ENGINE
BLOCK/HYDRAULIC LIFTERS (CAM IN BLOCK) -
REMOVAL).
(9) Remove the vibration damper (Refer to 9 -
ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
REMOVAL).
(10) Remove the timing case cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(11) Rotate the crankshaft until the crankshaft
sprocket timing mark is aligned on centerline with
the camshaft sprocket timing mark (Fig. 32).
(12) Remove the timing chain and sprockets (Refer
to 9 - ENGINE/VALVE TIMING/TIMING BELT/
CHAIN AND SPROCKETS - REMOVAL).
(13) Remove the front bumper and/or grille, as
required.
(14) Remove the two thrust plate retaining screws,
thrust plate and camshaft (Fig. 31).
INSPECTION
INSPECTION - CAMSHAFT BEARINGS
(1) Inspect the bearing journals for uneven wear
pattern or finish.
(2) Inspect the bearings for wear.
INSPECTION - CAMSHAFT
(1) Inspect the cam lobes for wear.
(2) Inspect the camshaft position sensor drive gear
for wear.
(3) If the camshaft appears to have been rubbing
against the thrust washer, examine the oil pressure
Fig. 30 CamshaftÐTypical
1 - CAMSHAFT
2 - LOBES
3 - BEARING JOURNAL
WJENGINE - 4.0L 9 - 31
CAMSHAFT & BEARINGS (Continued)

relief holes in the rear cam journal. The oil pressure
relief holes must be free of debris.
INSTALLATION
INSTALLATION - CAMSHAFT BEARINGS
CAUTION: Make sure outside diameter of number 1
bearing is clean. Make sure that the bearing is
properly installed in the engine block, align the oil
hole in the bearing with the oil gallery in the bear-
ing bore. Failure to do so will cause inadequate oil
supply for the sprockets and timing chain.
(1) Using recommended special tool 8544 Cam-
shaft Bearing Remover/Installer, install new cam-
shaft bearings.
INSTALLATION - CAMSHAFT
(1) Lubricate the camshaft with MopartEngine
Oil Supplement, or equivalent.
(2) Carefully install the camshaft to prevent dam-
age to the camshaft bearings.
(3) Position thrust plate and install retaining
screws. Tighten screws to 24 N´m (18 ft. lbs.).
(4) Lubricate the camshaft with Mopartengine oil
supplement, or equivalent.
(5) Install the camshaft sprocket, crankshaft
sprocket and timing chain (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - INSTALLATION).
(6) Tighten the camshaft sprocket bolt and washer
to 68 N´m (50 ft. lbs.).
(7) To verify correct installation of the timing
chain, turn the crankshaft two full revolutions then
position the camshaft sprocket timing mark as shown
in (Fig. 33).
(8) Install the timing case cover with a replace-
ment oil seal (Fig. 34). (Refer to 9 - ENGINE/VALVE
TIMING/TIMING BELT / CHAIN COVER(S) -
INSTALLATION).
(9) Install the vibration damper (Fig. 34) (Refer to
9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - INSTALLATION).
(10) Install the hydraulic valve tappets (Refer to 9
- ENGINE/ENGINE BLOCK/HYDRAULIC LIFTERS
(CAM IN BLOCK) - INSTALLATION).
(11) Install the cylinder head gasket with the
numbers facing up.
(12) Install the cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - INSTALLATION).
(13) Install the push rods.
(14) Install the rocker arms and pivot and bridge
assemblies (Refer to 9 - ENGINE/CYLINDER HEAD/
ROCKER ARM / ADJUSTER ASSY - INSTALLA-
TION).
(15) Install the engine cylinder head cover (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - INSTALLATION).
Fig. 31 Camshaft Removal
1 - CAMSHAFT
2 - CRANKSHAFT
Fig. 32 Crankshaft / Camshaft Sprocket Timing Mark
Alignment
1 - CAMSHAFT SPROCKET
2 - TIMING MARKS
3 - CRANKSHAFT SPROCKET
9 - 32 ENGINE - 4.0LWJ
CAMSHAFT & BEARINGS (Continued)

HYDRAULIC LIFTERS
DESCRIPTION
Valve lash is controlled by hydraulic tappets
located inside the cylinder block, in tappet bores
above the camshaft.
REMOVAL
NOTE: Retain all the components in the same order
as removed.
(1) Remove the engine cylinder head(Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(2) Remove the push rods.
(3) Remove the tappets through the push rod open-
ings in the cylinder block with a Hydraulic Valve
Tappet Removal/Installation Tool (Fig. 53).
CLEANING
Clean each tappet assembly in cleaning solvent to
remove all varnish, gum and sludge deposits.
INSPECTION
Inspect for indications of scuffing on the side and
base of each tappet body.
Inspect each tappet base for concave wear with a
straightedge positioned across the base. If the base is
concave, the corresponding lobe on the camshaft is
also worn. Replace the camshaft and tappets.
After cleaning and inspection, test each tappet for
specified leak-down rate tolerance to ensure zero-lash
operation (Fig. 54).
Swing the weighted arm of the hydraulic valve tap-
pet tester away from the ram of the Leak-Down
Tester.
(1) Place a 7.925-7.950 mm (0.312-0.313 inch)
diameter ball bearing on the plunger cap of the tap-
pet.(2) Lift the ram and position the tappet (with the
ball bearing) inside the tester cup.
(3) Lower the ram, then adjust the nose of the ram
until it contacts the ball bearing. DO NOT tighten
the hex nut on the ram.
(4) Fill the tester cup with hydraulic valve tappet
test oil until the tappet is completely submerged.
(5) Swing the weighted arm onto the push rod and
pump the tappet plunger up and down to remove air.
When the air bubbles cease, swing the weighted arm
away and allow the plunger to rise to the normal
position.
(6) Adjust the nose of the ram to align the pointer
with the SET mark on the scale of the tester and
tighten the hex nut.
(7) Slowly swing the weighted arm onto the push
rod.
(8) Rotate the cup by turning the handle at the
base of the tester clockwise one revolution every 2
seconds.
(9) Observe the leak-down time interval from the
instant the pointer aligns with the START mark on
the scale until the pointer aligns with the 0.125
mark. A normally functioning tappet will require
20-110 seconds to leak-down. Discard tappets with
leak-down time interval not within this specification.
INSTALLATION
Retain all the components in the same order as
removed.
Fig. 53 HYDRAULIC VALVE TAPPET REMOVAL -
4.0L
1 - HYDRAULIC TAPPET REMOVAL TOOL
2 - CYLINDER BLOCK
Fig. 54 Leak-Down Tester
1 - POINTER
2 - WEIGHTED ARM
3 - RAM
4 - CUP
5 - HANDLE
6 - PUSH ROD
WJENGINE - 4.0L 9 - 43

It is not necessary to charge the tappets with
engine oil. They will charge themselves within a very
short period of engine operation.
(1) Dip each tappet in MopartEngine Oil Supple-
ment, or equivalent.
(2) Use Hydraulic Valve Tappet Removal/Installa-
tion Tool to install each tappet in the same bore from
where it was originally removed.
(3) Install the cylinder head (Refer to 9 - ENGINE/
CYLINDER HEAD - INSTALLATION).
(4) Install the push rods in their original locations.
(5) Install the rocker arms and bridge and pivot
assemblies at their original locations. Loosely install
the capscrews at each bridge.
(6) Tighten the capscrews alternately, one turn at
a time, to avoid damaging the bridges. Tighten the
capscrews to 28 N´m (21 ft. lbs.) torque.
(7)
Pour the remaining MopartEngine Oil Supple-
ment, or equivalent over the entire valve actuating
assembly. The MopartEngine Oil Supplement, or equiv-
alent must remain with the engine oil for at least 1 609
km (1,000 miles). The oil supplement need not be
drained until the next scheduled oil change.
(8) Install the cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
PISTON & CONNECTING ROD
DESCRIPTION
The pistons (Fig. 55) are made of a high strength
aluminum alloy, the piston skirts are coated with a
solid lubricant (Molykote) to reduce friction and pro-
vide scuff resistance. The connecting rods are made
of cast iron.
STANDARD PROCEDURE - PISTON FITTING
(1) To correctly select the proper size piston, a cyl-
inder bore gauge, capable of reading in 0.003 mm
(.0001 in.) INCREMENTS is required. If a bore
gauge is not available, do not use an inside microme-
ter.
(2) Measure the inside diameter of the cylinder
bore at a point 49.5 mm (1-15/16 inches) below top of
bore. Start perpendicular (across or at 90 degrees) to
the axis of the crankshaft at point A and then take
an additional bore reading 90 degrees to that at point
B (Fig. 57).
(3) The coated pistons will be serviced with the
piston pin and connecting rod pre-assembled.The
coated piston connecting rod assembly can be
used to service previous built engines and
MUST be replaced as complete sets.Tin coated
pistons should not be used as replacements for coated
pistons.
(4) The coating material is applied to the piston
after the final piston machining process. Measuring
the outside diameter of a coated piston will not pro-
vide accurate results (Fig. 56). Therefore measuring
the inside diameter of the cylinder bore with a dial
Bore Gauge isMANDATORY. To correctly select the
proper size piston, a cylinder bore gauge capable of
reading in 0.003 mm (.0001 in.) increments is
required.
(5) Piston installation into the cylinder bore
requires slightly more pressure than that required
for non-coated pistons. The bonded coating on the
piston will give the appearance of a line-to-line fit
with the cylinder bore.
Fig. 55 Piston and Connecting Rod Assembly
Fig. 56 Moly Coated Piston
1 - MOLY COATED
2 - MOLY COATED
9 - 44 ENGINE - 4.0LWJ
HYDRAULIC LIFTERS (Continued)