1995 JEEP CHEROKEE Compressor

(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.
(4) Use an Arkansas 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.
VALVE CLEANING
Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
Clean all grime and gasket material from the en-
gine cylinder head machined gasket surface.
INSPECTION
Inspect for cracks in the combustion chambers and
valve ports.
Inspect for cracks on the exhaust seat.
Inspect for cracks in the gasket surface at each
coolant passage.
Inspect valves for burned, cracked or warped
heads.
Inspect for scuffed or bent valve stems.
Replace valves displaying any damage.
VALVE REFACING
(1) Use a valve refacing machine to reface the in-
take and exhaust valves to the specified angle.
(2) After refacing, a margin of at least 0.787 mm
(0.031 inch) must remain (Fig. 8). If the margin is
less than 0.787 mm (0.031 inch), the valve must be
replaced.
VALVE SEAT REFACING
(1) Install a pilot of the correct size in the valve
guide bore. Reface the valve seat to the specified an-
gle 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.
(3) Control valve seat runout to a maximum of
0.0635 mm (0.0025 in.)Ð(Fig. 9).
VALVE STEM OIL SEAL REPLACEMENT
Valve stem oil seals are installed on each valve
stem to prevent rocker arm lubricating oil from en-
tering the combustion chamber through the valve
guide bores. One seal is marked INT (intake valve)
and the other is marked EXH (exhaust valve).
Replace the oil seals whenever valve service is per-
formed or if the seals have deteriorated.
VALVE GUIDES
The valve guides are an integral part of the engine
cylinder head and are not replaceable.
When the valve stem guide clearance is excessive,
the valve guide bores must be reamed oversize. Ser-
vice valves with oversize stems are available in 0.076
mm (0.003 inch) and 0.381 mm (0.015 inch) incre-
ments.
Corresponding oversize valve stem seals are also
available and must be used with valves having 0.381
mm (0.015 inch) oversize stems, 0.076mm (.003in.)
oversize stems do not require oversize seals.
If the valve guides are reamed oversize, the
valve seats must be ground to ensure that the
valve seat is concentric to the valve guide.
VALVE STEM-TO-GUIDE CLEARANCE
MEASUREMENT
Valve stem-to-guide clearance may be measured by
either of the following two methods.
Fig. 8 Valve Facing Margin
Fig. 9 Measurement of Valve Seat Runout
9 - 28 2.5L ENGINEJ

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. 10).
(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. 11).
(2) Correct clearance is 0.025-0.0762 mm (0.001-
0.003 inch). If indicated movement exceeds the spec-
ification ream the valve guide to accommodate an
oversize valve stem.
Valve seats must be ground after reaming the
valve guides to ensure that the valve seat is
concentric to the valve guide.
VALVE SPRING TENSION TEST
Use a Universal Valve Spring Tester and a torque
wrench to test each valve spring for the specified ten-
sion value (Fig. 12).
Replace valve springs that are not within specifica-
tions.
INSTALLATION
(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. If the 0.381 mm (0.015 inch) over-
size valve stems are used, oversize oil seals are re-
quired.
(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
Fig. 10 Measurement of Valve Guide Bore Diameter
Fig. 11 Measurement of Lateral Movement Of Valve
Stem
Fig. 12 Valve Spring Tester
J2.5L ENGINE 9 - 29

oil on the vibration damper hub contact surface of
the seal.
(9) Apply Mopar Silicone Rubber Adhesive Sealant
to the keyway in the crankshaft and insert the key.
With the key inserted in the keyway in the crank-
shaft, install the vibration damper, washer and bolt.
Lubricate and tighten the bolt to 108 Nzm (80 ft. lbs.)
torque.
(10) Install the serpentine belt and tighten to the
specified tension (refer to Group 7, Cooling Systems
for the proper specifications and procedures).
(11) Install the radiator shroud.
(12) Connect negative cable to battery.
TIMING CASE COVER
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove the vibration damper (Fig. 4).
(3) Remove the fan and hub assembly and remove
the fan shroud.
(4) Remove the accessory drive brackets that are
attached to the timing case cover.
(5) Remove the A/C compressor (if equipped) and
generator bracket assembly from the engine cylinder
head and move to one side.
(6) Remove the oil pan-to-timing case cover bolts
and timing case cover-to-cylinder block bolts.
(7) Remove the timing case cover and gasket from
the engine.
(8) Pry the crankshaft oil seal from the front of the
timing case cover (Fig. 4).
CLEANING
Clean the timing case cover, oil pan and cylinder
block gasket surfaces.
INSTALLATION
(1) Install a new crankshaft oil seal in the timing
case cover. The open end of the seal should be toward
the inside of the cover. Support the cover at the sealarea while installing the seal. Force it into position
with Seal Installation Tool 6139.
(2) Position the gasket on the cylinder block.
(3) Position the timing case cover on the oil pan
gasket and the cylinder block.
(4) Insert Timing Case Cover Alignment and Seal
Installation Tool 6139 in the crankshaft opening in
the cover (Fig. 5).
(5) Install the timing case cover-to-cylinder block
and the oil pan-to-timing case cover bolts.
(6) Tighten the 1/4 inch cover-to-block bolts to 7
Nzm (60 in. lbs.) torque. Tighten the 5/16 inch front
cover-to-block bolts to 22 Nzm (192 in. lbs.) torque.
Tighten the oil pan-to-cover 1/4 inch bolts to 14 Nzm
(120 in. lbs.) torque. Tighten the oil pan-to-cover 5/16
inch bolts to 18 Nzm (156 in. lbs.) torque.
(7) Remove the cover alignment tool.
(8) Apply a light film of engine oil on the vibration
damper hub contact surface of the seal.
(9) Apply Mopar Silicone Rubber Adhesive Sealant
to the keyway in the crankshaft and insert the key.
With the key inserted in the keyway in the crank-
shaft, install the vibration damper, washer and bolt.
Lubricate and tighten the bolt to 108 Nzm (80 ft. lbs.)
torque.
(10) Install the A/C compressor (if equipped) and
generator bracket assembly.
(11) Install the engine fan and hub assembly and
shroud.
(12) Install the serpentine drive belt and tighten to
obtain the specified tension.
(13) Connect negative cable to battery.
TIMING CHAIN AND SPROCKETS
The timing chain tensioner reduces noise and pro-
longs timing chain life. In addition, it compensates
for slack in a worn or stretched chain and maintains
the correct valve timing.
Fig. 4 Timing Case Cover Components
Fig. 5 Timing Case Cover Alignment and Seal
Installation Tool 6139
J2.5L ENGINE 9 - 31

tor in the Component Removal/Installation section of
Group 8D, Ignition Systems.
(14) Install the distributor and ignition wires. Re-
fer to Distributor in the Component Removal/Instal-
lation section of Group 8D, Ignition Systems.
(15) Install the radiator or radiator and condenser,
if equipped with A/C.
(16) Fill the cooling system.
(17) Connect negative cable to battery.
CAMSHAFT PIN REPLACEMENT
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAIN COCK WITH THE SYSTEM HOT AND PRES-
SURIZED BECAUSE SERIOUS BURNS FROM COOL-
ANT CAN OCCUR.
(1) Disconnect negative cable from battery.
(2) Drain the radiator. DO NOT waste reusable
coolant. Drain the coolant into a clean container.
(3) Remove the fan and shroud.
(4) Disconnect the radiator overflow tube, radiator
hoses, automatic transmission fluid cooler pipes (if
equipped).
(5) Remove the radiator.
(6) If equipped with air conditioning:
CAUTION: DO NOT loosen or disconnect any air
conditioner system fittings. Move the condenser
and receiver/drier aside as a complete assembly.
(a) Remove the A/C compressor serpentine drive
belt idler pulley.
(b) Disconnect and remove the generator.
(c) Remove the A/C condenser attaching bolts
and move the condenser and receiver/drier assem-
bly up and out of the way.
(7) Remove the serpentine drive belt.
(8) Remove the crankshaft vibration damper.
(9) Remove the timing case cover. Clean the gasket
material from the cover.
(10) Rotate crankshaft until the crankshaft
sprocket timing mark is closest to and on the center
line with the camshaft sprocket timing mark (Fig.
12).
(11) Remove camshaft sprocket retaining bolt.
(12) Remove the crankshaft oil slinger.
(13) Remove the sprockets and chain as an assem-
bly (Fig. 13).
CAUTION: The following procedural step must be
accomplished to prevent the camshaft from damag-
ing the rear camshaft plug during pin installation.
(14) Inspect the damaged camshaft pin.(15) If the pin is a spring-type pin, remove the bro-
ken pin by inserting a self-tapping screw into the pin
and carefully pulling the pin from the camshaft.
(16) If the pin is a dowel-type pin, center-punch it.
Ensure the exact center is located when center-
punching the pin.
CAUTION: Cover the opened oil pan area to prevent
metal chips from entering the pan.
(17) Drill into the pin center witha4mm(5/32
inch) drill bit.
(18) Insert a self-tapping screw into the drilled pin
and carefully pull the pin from the camshaft.
CAMSHAFT BEARINGS
The camshaft rotates within four steel-shelled, bab-
bitt-lined bearings that are pressed into the cylinder
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) in-
crements from the front bearing (largest) to the rear
Fig. 12 Timing Chain Alignment
Fig. 13 Camshaft and Crankshaft Sprocket and
Chain
9 - 34 2.5L ENGINEJ

bearing (smallest). This permits easier removal and
installation of the camshaft. The camshaft bearings
are pressure lubricated.
It is not advisable to attempt to replace cam-
shaft bearings unless special removal and in-
stallation tools are available.
Camshaft end play is maintained by the load
placed on the camshaft by the oil pump and distrib-
utor drive gear. The helical cut of the gear holds the
camshaft sprocket thrust face against the cylinder
block face.
INSTALLATION
(1) Clean the camshaft pin hole.
(2) Compress the center of the replacement spring
pin with vise grips.
(3) Carefully drive the pin into the camshaft pin
hole until it is seated.
(4) Install the camshaft sprocket, crankshaft
sprocket and timing chain with the timing marks
aligned (Fig. 12).
(5) To verify correct installation of the timing
chain, turn the crankshaft to position the camshaft
sprocket timing mark as shown in Fig. 14. Count the
number of chain pins between the timing marks of
both sprockets. There must be 20 pins.
(6) Install the crankshaft oil slinger.
(7) Tighten the camshaft sprocket bolt to 108 Nzm
(80 ft. lbs.) torque.
(8) Check the valve timing.
(9) Coat both sides of the replacement timing case
cover gasket with gasket sealer. Applya3mm(1/8
inch) bead of Mopar Silicone Rubber Adhesive Seal-ant, or equivalent to the joint formed at the timing
case cover and cylinder block.
(10) Position the timing case cover on the oil pan
gasket and the cylinder block.
(11) Place Timing Case Cover Alignment and Seal
Installation Tool 6139 in the crankshaft opening of
the cover (Fig. 15).
(12) Install the timing case cover-to-cylinder block
bolts. Install the oil pan-to-timing case cover bolts.
(13) Tighten the 1/4 inch cover-to-block bolts to 7
Nzm (60 in. lbs.) torque. Tighten the 5/16 inch front
cover-to-block bolts to 22 Nzm (192 in. lbs.) torque.
Tighten the oil pan-to-cover 1/4 inch bolts to 14 Nzm
(120 in. lbs.) torque. Tighten the oil pan-to-cover 5/16
inch bolts to 18 Nzm (156 in. lbs.) torque.
(14) Remove the cover alignment tool and install a
replacement oil seal into the cover.
(15) Install the vibration damper on the crank-
shaft.
(16) Lubricate and tighten the damper bolt to 108
Nzm (80 ft. lbs.) torque.
(17) If equipped with air conditioning:
(a) Install the A/C compressor serpentine drive
belt idler pulley.
(b) Install the generator.
(c) Install the A/C condenser and receiver/drier
assembly.
(18) Install the serpentine drive belt on the pulleys
and tighten (refer to Group 7, Cooling System for the
specifications and procedures).
(19) Install the radiator. Connect the radiator
hoses and automatic transmission fluid cooler pipes,
if equipped. Fill the cooling system.
(20) Install the fan and shroud.
(21) Connect negative cable to battery.
Fig. 14 Verify CrankshaftÐCamshaft Installation
Fig. 15 Timing Case Cover Alignment and Seal
Installation Tool 6139
J2.5L ENGINE 9 - 35

ings for normal wear patterns, scoring, grooving, fa-
tigue and pitting (Fig. 5). Replace any bearing that
shows abnormal wear.
Inspect the connecting rod journals for signs of
scoring, nicks and burrs.
CONNECTING RODS
Misaligned or bent connecting rods can cause ab-
normal wear on pistons, piston rings, cylinder walls,
connecting rod bearings and crankshaft connecting
rod journals. If wear patterns or damage to any of
these components indicate the probability of a mis-
aligned connecting rod, inspect it for correct rod
alignment. Replace misaligned, bent or twisted con-
necting rods.BEARING-TO-JOURNAL CLEARANCE
(1) Wipe the oil from the connecting rod journal.
(2) Use short rubber hose sections over rod bolts
during installation.
(3) Lubricate the upper bearing insert and install
in connecting rod.
(4) Use piston ring compressor to install the rod
and piston assemblies. The oil squirt holes in the
rods must face the camshaft. The arrow on the piston
crown should point to the front of the engine (Fig. 6).
Verify that the oil squirt holes in the rods face the
camshaft and that the arrows on the pistons face the
front of the engine.
Fig. 2 Removal of Connecting Rod and Piston
Assembly
Fig. 3 Connecting Rod Bearing Inspection
Fig. 4 Locking Tab Inspection
Fig. 5 Scoring Caused by Insufficient Lubrication or
by Damaged Crankshaft Pin Journal
Fig. 6 Rod and Piston Assembly Installation
9 - 40 2.5L ENGINEJ

(9) The top compression ring (the scraping edge is
gray in color) has a chamfer on the TOP of the inside
edge (Fig. 16). This ring may also have 1 dot located
on the top surface.
(10) Using a ring installer, install the top ring with
the chamfer facing up (Fig. 17). The dot will be fac-
ing up.
(11) Position the gaps on the piston (Fig. 18):
²Oil spacer - Gap on center line of piston pin bore.
²Oil rails - Gap 180É apart on centerline of piston
skirt.
²No. 2 Compression ring - Gap 180É from top oil
rail gap.
²No. 1 Compression ring - Gap 180É from No. 2
compression ring gap.
CLEANING
Clean the cylinder bores thoroughly. Apply a light
film of clean engine oil to the bores with a clean lint-
free cloth.
INSTALLATION
(1) Install the piston rings on the pistons if re-
moved.
(2) Lubricate the piston and rings with clean en-
gine oil.
CAUTION: Ensure that connecting rod bolts do not
scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose slipped over the con-
necting rod bolts will provide protection during in-
stallation.
(3) Use a piston ring compressor to install the con-
necting rod and piston assemblies through the top of
the cylinder bores (Fig. 19).
(4) Ensure the arrow on the piston top points to
the front of the engine (Fig. 19).
(5) Raise the vehicle.
Each bearing insert is fitted to its respective jour-
nal to obtain the specified clearance between the
bearing and the journal. In production, the select fit
is obtained by using various-sized, color-coded bear-
ing inserts as listed in the Connecting Rod Bearing
Fitting Chart. The color code appears on the edge of
the bearing insert. The size is not stamped on inserts
used for production of engines.
The rod journal is identified during the engine pro-
duction by a color-coded paint mark on the adjacent
cheek or counterweight toward the flange (rear) end
of the crankshaft. The color codes used to indicate
journal sizes are listed in the Connecting Rod Bear-
ing Fitting Chart.
When required, upper and lower bearing inserts of
different sizes may be used as a pair (refer to Con-
necting Rod Bearing Fitting Chart). A standard size
insert is sometimes used in combination with a 0.025
mm (0.001 inch) undersize insert to reduce clearance
0.013 mm (0.0005 inch).
CAUTION: DO NOT intermix bearing caps. Each
connecting rod and bearing cap are stamped with
the cylinder number. The stamp is located on a ma-
chined surface adjacent to the oil squirt hole that
faces the camshaft side of the cylinder block.
(6) Install the connecting rod bearing caps and in-
serts in the same positions as removed.
Fig. 18 Ring Gap Position
Fig. 19 Rod and Piston Assembly Installation
9 - 44 2.5L ENGINEJ

VALVE COMPONENT REPLACEÐCYLINDER HEAD
NOT REMOVED
ROCKER ARMS AND PUSH RODS
This procedure can be done with the engine in or
out of the vehicle.
REMOVAL
(1) Remove the engine cylinder head cover.
(2) Remove the capscrews at each bridge and pivot
assembly (Fig. 2). Alternately loosen the capscrews
one turn at a time to avoid damaging the bridges.
(3) Check for rocker arm bridges which are causing
misalignment of the rocker arm to valve tip area.
(4) Remove the bridges, pivots and corresponding
pairs of rocker arms (Fig. 2). 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.
INSPECTION
Inspect the pivot surface area of each rocker arm.
Replace any that are scuffed, pitted, cracked or ex-
cessively 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 excessivelyworn 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 ob-
struction if this condition exists.
INSTALLATION
(1) Lubricate the ball ends of the push rods with
Mopar Engine Oil Supplement, or equivalent and in-
stall push rods in their original locations. Ensure
that the bottom end of each push rod is centered in
the tappet plunger cap seat.
(2) Using Mopar Engine Oil Supplement, or equiv-
alent, lubricate the area of the rocker arm that the
pivot contacts. Install rocker arms, pivots and bridge
above each cylinder in their originally position.
(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 Nzm (21 ft. lbs.)
torque.
(5) Install the engine cylinder head cover.
VALVE STEM SEAL AND SPRING REPLACEMENT
This procedure can be done with the engine cylin-
der head installed on the block.
REMOVAL
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.
(2) Remove capscrews, bridge and pivot assemblies
and rocker arms 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. 3).
(8) Remove valve spring and retainer (Fig. 3).
Fig. 2 Rocker Arm Assembly
J4.0L ENGINE 9 - 65