1988 JEEP CHEROKEE Service Repair Manual

manifold.
3) Remove EGR tube fittings from manifolds. Remove power
steering pump and A/C compressor and mounting brackets (if equipped).
4) Remove intake manifold bolts. Remove intake manifold. If
exhaust manifold requires removal, disconnect exhaust pipe from
manifold. Remove oxygen sensor (if equipped). Remove exhaust manifold.\
Installation
1) Install new gasket. Install exhaust manifold and loosely
install bolts. Install intake manifold. Tighten bolts to specification
in proper sequence. See Fig. 2.
2) Apply anti-seize to oxygen sensor threads prior to
installation. Reverse removal procedure for remaining components.
Tighten bolts to specification. Fill and purge cooling system. See
COOLING SYSTEM AIR PURGE under WATER PUMP in this article.
Fig. 2: Manifold Tightening Sequence (4.2L)
Courtesy of Chrysler Motors.
CYLINDER HEAD
Removal
1) Disconnect negative battery cable. Drain cooling system.
Disconnect hoses at thermostat housing. Remove intake and exhaust
manifolds. See the following:
* INTAKE & EXHAUST MANIFOLD (4.0L) .
* INTAKE & EXHAUST MANIFOLD (4.2L) .
2) Disconnect and mark all hoses and electrical connections
at cylinder head. Disconnect and mark spark plug wires. Remove spark
plugs. Remove valve cover bolts.
3) Remove the rocker arms and the push rods. Remove cylinder
head bolts. Remove cylinder head. See ROCKER ARMS & BRIDGE.
Inspection
Inspect cylinder head for cracks or damage. Using
straightedge, check cylinder head for warpage in several areas. Repair

or replace cylinder head if warpage exceeds .002" (.05 mm) per each 6"\
(152 mm) or damage exists.
Installation
1) Ensure all gasket surfaces are clean. Clean carbon from
combustion chambers and tops of pistons. Apply sealant to both sides
of new cylinder head gasket. Install new gasket with the word "TOP"
upward. Ensure all holes are aligned.
2) Install cylinder head. Apply sealing compound to threads
of cylinder head bolt No. 11 prior to installation. See Fig. 3.
Install head bolts.
3) Tighten all bolts in sequence (except No. 11) to 110 ft.
lbs. (149 N.m) on 4.0L or 85 ft. lbs. (115 N.m) on 4.2L models.
Tighten No. 11 head bolt to 100 ft. lbs. (136 N.m) on 4.0L or 75 ft.
lbs. (136 N.m) on 4.2L. See Fig. 3.
4) Reverse removal procedure for remaining components.
Install valve cover and new gasket. Tighten bolts to specification.
5) Refill and purge cooling system. See COOLING SYSTEM AIR
PURGE under WATER PUMP in this article.
Fig. 3: Cylinder Head Bolt Tightening Sequence
Courtesy of Chrysler Motors.
Valve Arrangement
E-I-I-E-I-E-E-I-E-I-I-E (Front-to-rear).
ROCKER ARMS & BRIDGE
Removal
1) Remove PCV valve hose at valve cover. Remove cruise
control servo (if equipped). Remove valve cover. Alternately loosen
each rocker arm bolt one turn at a time.
2) Remove rocker arm assemblies and push rods. Mark
components for reassembly. Components must be installed in original
location.
Installation
Reverse removal procedure. Install rocker arm components in
original location. Install valve cover and new gasket. Tighten bolts
to specification.
Valve Guide
Valve guides are not replaceable. If clearance is excessive,
valve guides must be reamed to accommodate oversized stem valves.

VALVE SPRING
Valve springs can be removed without removing cylinder head.
Valve Spring Installed
For 4.0L the Valve Spring Installed Height Specification is
1.625 inches or 41.29 mm. For the 4.2L the information is not
available from manufacturer.
HYDRAULIC VALVE LIFTER
Removal
Remove cylinder head. See CYLINDER HEAD. Using Lifter
Remover/Installer (J-21884), remove lifter. Mark lifter location for
reassembly reference. Replace lifters as an assembly if damaged.
Internal components cannot be interchanged.
Inspection
Inspect lifter and camshaft mating surfaces for wear. Check
cylinder block lifter bore diameter. Lifter bore diameter should be
within .9055-.9065" (22.999-23.025 mm). Replace parts as necessary.
Installation
Soak lifter assembly in engine oil prior to installation.
Reverse removal procedure for installation. Install lifter in original
location.
ENGINE FRONT COVER
Removal
1) Disconnect negative battery cable. Remove drive belts, fan
and hub assembly. Remove pulley from vibration damper. Remove
vibration damper retaining bolt and washer.
2) Using Puller (J-21719-01), remove vibration damper and
key. Remove alternator and A/C compressor bracket (if equipped).
Remove oil pan-to-front cover bolts. Remove cover-to-block retaining
bolts. Remove front cover.
3) Cut oil pan gasket tabs even with face of cylinder block.
Remove tabs. Remove gasket from oil pan. Pry crankshaft oil seal from
cover.
Installation
1) Ensure all gasket surfaces are clean. Ensure oil slinger
is installed on crankshaft. Apply sealing compound on both sides of
front cover gasket. Install gasket on cylinder block. Replace front
section of oil pan seal with similar section fabricated from new seal.
2) Coat seal with RTV sealant and place in position. Apply
sealant to the joint area of oil pan and cylinder block. Apply engine
oil on seal-to-oil pan contact areas.
3) Place front cover on cylinder block. Place Front Cover
Seal Installer (J-22248) in front cover seal area. Install all
retaining bolts. Tighten bolts to specification.
4) Install front cover oil seal. See FRONT COVER OIL SEAL in
this article. Remove front cover seal installer. Reverse removal
procedure for remaining components. Lubricate vibration damper
retaining bolt with oil prior to installation. Tighten bolts to
specification.
FRONT COVER OIL SEAL
1) Remove vibration damper. Pry seal from front cover. Use

care not to damage seal area. Position new seal on Front Cover Seal
Installer (J-22248) with lip facing outward.
2) Apply sealant to seal outer diameter. Lightly coat
crankshaft with oil. Place front cover seal installer on front of
crankshaft. Tap seal into front cover. Lightly coat seal contact area
of vibration damper with oil.
3) Install key in crankshaft (if removed). Install vibration\
damper. Lubricate vibration damper bolt with oil. Install retaining
bolt and washer. Tighten to specification.
TIMING CHAIN & SPROCKET
Removal
1) Drain cooling system. Remove radiator. Remove engine front
cover. See ENGINE FRONT COVER in this article. Remove oil slinger.
Rotate crankshaft until timing marks on sprockets are aligned. See
Fig. 4 .
2) Remove camshaft sprocket bolt. Remove timing chain and
both sprockets as an assembly.
Installation
Install timing chain and sprockets. Ensure timing marks are
aligned. See Fig. 4. Install camshaft sprocket bolt. Tighten bolts to
specification. Install new front cover oil seal. Reverse removal
procedure for remaining components.
Fig. 4: Timing Chain & Sprocket Alignment
Courtesy of Chrysler Motors.
CAMSHAFT

Removal
1) Drain cooling system. Remove radiator. Discharge A/C
system if necessary. Remove A/C condenser and receiver assembly (if
equipped). Remove fuel pump (if equipped with mechanical pump),
ignition wires and distributor.
2) Remove cylinder head. See CYLINDER HEAD in this article.
Remove hydraulic lifters. Using Lifter Remover/Installer (J-21884),
remove lifters. Mark lifter location for reassembly reference.
3) Remove engine front cover. See ENGINE FRONT COVER in this
article. Remove timing chain and sprockets. Remove front bumper and
grille (if necessary). Carefully remove camshaft.
Inspection
Inspect camshaft for flaking, lobe wear or worn bearing
journals. Replace if not within specification. See ENGINE
SPECIFICATIONS tables.
Installation
Lubricate camshaft and install into place. Use care not to
damage camshaft bearings. Reverse removal procedure to complete
installation. Tighten bolts to specification.
Camshaft Bearing
Replace camshaft bearings using camshaft bearing
remover/installer. Ensure oil holes are aligned after installation.
OIL PAN
See OIL PAN REMOVAL at end of ENGINE section.
PISTON & ROD
NOTE: Mark piston cylinder location for reassembly reference.
Install pistons in original cylinder location.
Removal
1) Remove cylinder head. See CYLINDER HEAD in this article.
Remove oil pan. See OIL PAN REMOVAL at end of ENGINE section. Remove
ridge or deposits from cylinder bore.
2) Mark connecting rod and piston for cylinder
identification. Remove bearing cap. Remove piston and rod assembly.
CAUTION: Arrows on top of piston must point toward front of engine.
Oil squirt holes in connecting rod must face camshaft side
of engine.
Installation
1) Ensure ring end gap and side clearance are within
specification. See ENGINE SPECIFICATIONS tables. Install rings on
piston. Position ring end gaps at specified areas. See Fig. 5. Ring
gaps may vary 20 degrees from positions illustrated.

Fig. 5: Positioning Piston Ring Gaps
Courtesy of Chrysler Motors
2) Lubricate piston assembly and cylinder block. Install
piston assembly. Arrows on top of piston must face toward front of
engine and connecting rod oil squirt hole should face camshaft side of

engine.
3) Install bearings. Check oil clearance and connecting rod
side play clearance. Reverse removal procedure for remaining
components. Tighten bolts to specification.
Fitting Pistons
1) Determine cylinder taper, wear and out-of-roundness and
piston clearance. For cylinder specifications, see CYLINDER, PISTON &
ROD SPECIFICATIONS table. If taper or out-of-roundness are not within
specification, hone or bore cylinders for installation of new pistons.
2) Measure piston at right angle of the piston pin at the
center line of the pin. Compare reading to cylinder bore to determine
clearance. Mark fitted piston for cylinder location.
CYLINDER, PISTON & ROD SPECIFICATIONS TABLE









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Application In. (mm)
Connecting Rod
Crankshaft Bore ................ 2.2080-2.2085 (56.083-56.095)
Pin Bore ......................... .9288-.9298 (23.591-23.616)
Cylinder Bore
Diameter
4.0L ......................... 3.8751-3.8775 (98.427-98.488)
4.2L ......................... 3.7501-3.7533 (95.252-95.334)
Out-of-Round ...................................... .001 (.02)
Taper ............................................. .001 (.02)
Piston Pin Bore Diameter ........... .9308-.9313 (23.642-23.655)
Piston Pin Diameter ................ .9304-.9309 (23.632-23.644)
Piston-to-Cylinder Clearance ..... .0009-.0017 (.022-.043)









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PISTON PIN
NOTE: Note direction of arrows on piston and oil squirt hole in
connecting rod location prior to removal.
Removal
Position piston on Support (J-21872-1), Pin Pilot (J-21872-2\
)
and Driver (J-21872-3) on an arbor press. See Fig. 6. Note location of
piston pin through gauge window. Press piston pin from piston.
NOTE: Piston and pin must be at standard room temperature when
measuring fit. Piston pin should gravity-fall through the
piston at room temperature. Piston pin cannot be reused
after removal.
Inspection
Measure piston pin diameter, piston bore and connecting rod
bores. Replace components if not within specification. See CYLINDER,
PISTON & ROD SPECIFICATIONS table.
NOTE: Rod must be positioned on the piston so the oil squirt hole
faces the camshaft side of the engine when piston is
installed with arrow toward the front of the engine.
Installation
1) Insert pin pilot through piston and connecting rod. Place
assembly on support. Insert piston pin through the upper piston pin
bore and into connecting rod pin bore. See Fig. 6.

Fig. 6: Piston Pin Removal & Installation
Courtesy of Chrysler Motors.
2) Position driver inside pin. Using arbor press, press pin
through rod and piston bores until pilot indexes with mark on support.
Remove piston and connecting rod. Pin should be centered in rod
 .
0312" (.792 mm).
3) Piston pin installation requires a 2000 lb. (906 kg) pres\
s
fit. Replace connecting rod if noticeably less effort is encountered.