1994 JEEP CHEROKEE tire size

not change except when a spindle or ball stud is
damaged or bent. The angle is not adjustable and the
damaged component(s) must be replaced to correct
mis-alignment.
CAUTION:Do not attempt to modify any suspension
or steering component by heating and bending.
PRE-ALIGNMENT INSPECTION
Before starting a front wheel alignment, the follow-
ing inspection and necessary corrections must be
completed.
(1) Tires with the same recommended air pressure,
size, and thread wear. Refer to Group 22, Tires And
Wheels for diagnosis information.
(2) Front wheel bearings for wear.
(3) Ball studs, steering linkage pivot points and
steering gear for looseness, roughness, binding or
wear. Refer to Group 19, Steering for additional in-
formation.
(4) Front wheels for excessive radial or lateral
runout and unbalance. Refer to Group 22, Tires And
Wheels for diagnosis information.
(5) Suspension components for wear and noise.
Check components for correct torque. Refer to Groups
2 and 3, Suspension and Axle for additional informa-
tion.
ALIGNMENT MEASUREMENTS AND ADJUSTMENTS
Before each alignment reading, the vehicle should
be jounced (rear first, then front). Grasp each bumper
at the center and jounce the vehicle up and down
several times. Always release the bumper in the
down position.Set the front end alignment to
specifications with the vehicle at its NOR-
MALLY RIDE HEIGHT.
CAMBER
The wheel camber angle (Fig. 1) is preset at ZERO
DEGREES (0É). The angle is not adjustable and can-
not be altered.
CASTER
The caster angle (Fig. 1) is set at:
²XJ manual transmission, POSITIVE 6.5 DE-
GREES (+6.5É).
²XJ automatic transmission, POSITIVE 8.0 DE-
GREES (+8.0É).
²YJ all transmissions, POSITIVE 6.0 DEGREES
(+6.0É).
Before checking the caster of the front axle for cor-
rect angle. Be sure the axle is not bent or twisted.
Road test the vehicle, and make left and right
turns. If the steering wheel returns to the center po-
sition unassisted, the caster angle is correct. How-ever, if steering wheel does not return toward the
center position unassisted, an incorrect caster angle
is probable.
Caster can be adjusted by installing the appropri-
ate size shims (Fig. 2, 3).Changing caster angle
will also change the front propeller shaft angle.
The propeller shaft angle has priority over
caster. Refer to Group 16, Propeller Shafts for
additional information.
Fig. 2 AdjustmentÐYJ Vehicles
Fig. 3 AdjustmentÐXJ Vehicles
2 - 6 FRONT SUSPENSION AND AXLEJ

ABS BRAKE DIAGNOSIS
INDEX
page page
ABS Fault Diagnosis....................... 4
ABS System Wiring and Electrical Circuits...... 4
ABS Warning Light Display.................. 3
Brake Warning Light Display................. 4
Diagnosis Procedures...................... 3
ECU Diagnosis........................... 4
HCU Diagnosis........................... 4Loss of Sensor Input....................... 3
Operating Sound Levels.................... 3
Rear Speed Sensor Air Gap................. 3
Steering Response........................ 3
Vehicle Response in Antilock Mode............ 3
Wheel/Tire Size and Input Signals............. 3
DIAGNOSIS PROCEDURES
ABS diagnosis involves three basic steps. First is
observation of the warning light display. Second is a
visual examination for low fluid level, leaks, parking
brakes applied, or obvious damage to system compo-
nents or wires. The third step involves using the
DRB II scan tool to identify a faulty component.
The visual examination requires a check of reser-
voir fluid level and all system components. Things to
look for are leaks, loose connections, or obvious com-
ponent damage.
The final diagnosis step involves using the DRB II
scan tool to determine the specific circuit or compo-
nent at fault. The tester is connected to the ABS di-
agnostic connector in the passenger compartment.
The connector is at the driver side of the center con-
sole under the instrument panel. Refer to the DRB II
scan tool Manual for tester procedures. Also refer to
the ABS Fault Diagnosis charts at the end of this
section for additional diagnosis information.
Initial faults should be cleared and the vehicle road
tested to reset any faults that remain in the system.
Faults can be cleared with the DRB II scan tool.
REAR SPEED SENSOR AIR GAP
The front wheel sensors are fixed and cannot be ad-
justed. Only the rear sensor air gap is adjustable. Air
gap must be set with a brass feeler gauge.
Correct air gap is important to proper signal gen-
eration. An air gap that is too large may cause com-
plete loss of sensor input. Or, a gap that is too small
could produce a false input signal, or damaging con-
tact between the sensor and tone ring.
WHEEL/TIRE SIZE AND INPUT SIGNALS
Antilock system operation is dependant on accurate
signals from the wheel speed sensors. Ideally, the ve-
hicle wheels and tires should all be the same size
and type. However, the Jeep ABS system is designed
to function with a compact spare tire installed.
OPERATING SOUND LEVELS
The ABS pump and solenoid valves may produce
some sound as they cycle on and off. This is a normal
condition and should not be mistaken for faulty oper-
ation.
VEHICLE RESPONSE IN ANTILOCK MODE
During antilock braking, the HCU solenoid valves
cycle rapidly in response to ECU inputs.
The driver will experience a pulsing sensation
within the vehicle as the solenoids decrease, hold, or
increase pressure as needed. A pulsing brake pedal
will also be noted.
The pulsing sensation occurs as the solenoids cycle
during antilock mode braking. A slight pulse in the
brake pedal may also be noted during the dynamic
self check part of system initialization.
STEERING RESPONSE
A modest amount of steering input is required dur-
ing extremely high deceleration braking, or when
braking on differing traction surfaces. An example of
differing traction surfaces would be when the left
side wheels are on ice and the right side wheels are
on dry pavement.
LOSS OF SENSOR INPUT
Sensor malfunctions will most likely be due to
loose connections, damaged sensor wires, incorrect
rear sensor air gap, or a malfunctioning sensor. Ad-
ditional causes of sensor faults would be sensor and
tone ring misalignment or damage.
ABS WARNING LIGHT DISPLAY
ABS Light Illuminates At Startup
The amber ABS light illuminates at startup as
part of the system self check feature. The light illu-
minates for 2-3 seconds then goes off as part of the
normal self check routine.
ABS Light Remains On After Startup
An ABS system fault is indicated when the light
remains on after startup. Diagnosis with the DRB II
JBRAKES 5 - 3

when the cover is off. The second involves adding to,
or filling the cylinder reservoirs with a non-recom-
mended fluid.
Brake fluid contaminated with only dirt, or debris
usually retains a normal appearance. In some cases,
the foreign material will remain suspended in the
fluid and be visible. The fluid and foreign material
can be removed from the reservoir with a suction
gun but only if the brakes have not been applied. If
the brakes are applied after contamination, system
flushing will be required. The master cylinder may
also have to be disassembled, cleaned and the piston
seals replaced. Foreign material lodged in the reser-
voir compensator/return ports can cause brake drag
by restricting fluid return after brake application.
Brake fluid contaminated by a non-recommended
fluid will usually be discolored, milky, oily looking,
or foamy. In some cases, it may even appear as if the
fluid contains sludge.However, remember that
brake fluid will darken in time and occasionally
be cloudy in appearance. These are normal con-
ditions and should not be mistaken for contami-
nation.
If some type of oil has been added to the system,
the fluid will separate into distinct layers. To verify
this, drain off a sample with a clean suction gun.
Then pour the sample into a glass container and ob-
serve fluid action. If the fluid separates into distinct
layers, it is definitely contaminated.
The only real correction for contamination by non-
recommended fluid is to flush the entire hydraulic
system and replace all the seals.
BRAKE NOISE
Squeak/Squeal
Brake squeak or squeal may be due to linings that
are wet or contaminated with brake fluid, grease, or
oil. Glazed linings and rotors with hard spots can
also contribute to squeak. Dirt and foreign material
embedded in the brake lining will also cause squeak/
squeal.
A very loud squeak or squeal is frequently a sign
of severely worn brake lining. If the lining has worn
through to the brakeshoes in spots, metal-to-metal
contact occurs. If the condition is allowed to continue,
rotors can become so scored that replacement is nec-
essary.
Thump/Clunk
Thumping or clunk noises during braking are fre-
quentlynotcaused by brake components. In many
cases, such noises are caused by loose or damaged
steering, suspension, or engine components. How-
ever, calipers that bind on the slide surfaces can gen-
erate a thump or clunk noise. In addition, worn out,
improperly adjusted, or improperly assembled rear
brakeshoes can also produce a thump noise.Chatter/Shudder
Brake chatter, or shudder is usually caused by
loose or worn components, or glazed/burnt lining. Ro-
tors with hard spots can also contribute to chatter.
Additional causes of chatter are out of tolerance ro-
tors, brake lining not securely attached to the shoes,
loose wheel bearings and contaminated brake lining.
BRAKELINING CONTAMINATION
Brakelining contamination is usually a product of
leaking calipers or wheel cylinders, driving through
deep water puddles, or lining that has become cov-
ered with grease and grit during repair.
WHEEL AND TIRE PROBLEMS
Some conditions attributed to brake components
may actually be caused by a wheel or tire problem.
A damaged wheel can cause shudder, vibration and
pull. A worn or damaged tire can also cause pull.
Severely worn tires with very little tread left can
produce a condition similar to grab as the tire loses
and recovers traction.
Flat-spotted tires can cause vibration and wheel
tramp and generate shudder during brake operation.
A tire with internal damage such as a severe
bruise or ply separation can cause pull and vibration.
DIAGNOSING PARKING BRAKE PROBLEMS
Adjustment Mechanism
Parking brake adjustment is controlled by a
cable tensioner mechanism. This applies to 1991
through 1994 YJ models and 1992 and later XJ
models. The cable tensioner, once adjusted at
the factory, will not need further adjustment un-
der normal circumstances. There are only two
instances when adjustment is required. The first
is when a new tensioner, or cables have been in-
stalled. And the second, is when the tensioner
and cables are disconnected for access to other
brake components.
Parking Brake problem Causes
In most cases, the actual cause of an improperly
functioning parking brake (too loose/too tight/wont
hold), can be traced to a drum brake component.
The leading cause of improper parking brake
operation, is excessive clearance between the
brakeshoes and the drum surface. Excessive
clearance is a result of: lining and/or drum wear;
oversize drums; or inoperative shoe adjuster
components.
Excessive parking brake lever travel (sometimes
described as a loose lever or too loose condition), is
the result of worn brakeshoes/drums, improper
brakeshoe adjustment, or mis-assembled brake parts.
A ``too loose'' condition can also be caused by inop-
erative brakeshoe adjusters. If the adjusters are mis-
5 - 10 BRAKESJ

CONNECTING ROD BEARING CLEARANCE
Engine connecting rod bearing clearances can be
determined by use of Plastigage, or equivalent. The
following is the recommended procedures for the use
of Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire
width of the bearing cap shell (Fig. 2). Position the
Plastigage approximately 6.35 mm (1/4 inch) off cen-
ter and away from the oil holes. In addition, suspect
areas can be checked by placing the Plastigage in the
suspect area.
(3) The crankshaft must be turned until the con-
necting rod to be checked starts moving toward the
top of the engine. Only then should the rod cap with
Plastigage in place be assembled. Tighten the rod
cap nut to 45 Nzm (33 ft. lbs.) torque.DO NOT ro-
tate the crankshaft or the Plastigage may be
smeared, giving inaccurate results.
(4) Remove the bearing cap and compare the width
of the flattened Plastigage with the scale provided on
the package (Fig. 3). Plastigage generally comes in 2
scales (one scale is in inches and the other is a met-
ric scale). Locate the band closest to the same width.
This band shows the amount of clearance. Differ-
ences in readings between the ends indicate the
amount of taper present. Record all readings taken
(refer to Engine Specifications).
(5) Plastigage is available in a variety of clearance
ranges. The 0.025-0.076 mm (0.001-0.003 inch) range
is usually the most appropriate for checking engine
bearing clearances.
REPAIR DAMAGED OR WORN THREADS
Damaged or worn threads can be repaired. Essen-
tially, this repair consists of:
²Drilling out worn or damaged threads.
²Tapping the hole with a special Heli-Coil Tap, or
equivalent.
²Installing an insert into the tapped hole.
This brings the hole back to its original thread size.
CAUTION: Be sure that the tapped holes maintain
the original center line.Heli-Coil tools and inserts are readily available
from automotive parts jobbers.
SERVICE ENGINE ASSEMBLY (SHORT BLOCK)
A service replacement engine assembly (short
block) may be installed whenever the original cylin-
der block is defective or damaged beyond repair. It
consists of the cylinder block, crankshaft, piston and
rod assemblies. If needed, the camshaft must be pro-
cured separately and installed before the engine is
installed in the vehicle.
A short block is identified with the letter ``S'' stamped
on the same machined surface where the build date
code is stamped for complete engine assemblies.
Installation includes the transfer of components
from the defective or damaged original engine. Fol-
low the appropriate procedures for cleaning, inspec-
tion and torque tightening.
HYDROSTATIC LOCK
When an engine is suspected of hydrostatic lock
(regardless of what caused the problem), follow the
steps below.
(1) Perform the Fuel Pressure Release Procedure
(refer to Group 14, Fuel System).
(2) Disconnect the negative cable from the battery.
(3) Inspect air cleaner, induction system and in-
take manifold to ensure system is dry and clear of
foreign material.
(4) Place a shop towel around the spark plugs to
catch any fluid that may possibly be under pressure in
the cylinder head. Remove the plugs from the engine.
CAUTION: DO NOT use the starter motor to rotate
the crankshaft. Severe damage could occur.
(5) With all spark plugs removed, rotate the crank-
shaft using a breaker bar and socket.
(6) Identify the fluid in the cylinders (i.e. coolant,
fuel, oil, etc.).
(7) Make sure all fluid has been removed from the
cylinders.
(8) Repair engine or components as necessary to
prevent this problem from occurring again.
(9) Squirt engine oil into the cylinders to lubricate
the walls. This will prevent damage on restart.
(10) Install new spark plugs. Tighten the spark
plugs to 37 Nzm (27 ft. lbs.) torque.
(11) Drain engine oil. Remove and discard the oil
filter.
(12) Install the drain plug. Tighten the plug to 34
Nzm (25 ft. lbs.) torque.
(13) Install a new oil filter.
(14) Fill engine crankcase with the specified
amount and grade of oil (refer to Group 0, Lubrica-
tion and Maintenance).
(15) Connect the negative cable to the battery.
(16) Start the engine and check for any leaks.
Fig. 3 Clearance Measurement
9 - 4 ENGINESJ

Plastigage across full width of the lower insert at the
center of bearing cap. Plastigage must not crumble
in use. If brittle, obtain fresh stock.
(6) Install bearing cap and connecting rod on the
journal and tighten nuts to 45 Nzm (33 ft. lbs.)
torque. DO NOT rotate crankshaft. Plastigage will
smear, resulting in inaccurate indication.
(7) Remove the bearing cap and determine amount
of bearing-to-journal clearance by measuring the
width of compressed Plastigage (Fig. 7). Refer to En-
gine Specifications for the proper clearance.Plasti-
gage should indicate the same clearance across
the entire width of the insert. If the clearance
varies, it may be caused by either a tapered
journal, bent connecting rod or foreign material
trapped between the insert and cap or rod.
(8) If the correct clearance is indicated, replace-
ment of the bearing inserts is not necessary. Remove
the Plastigage from crankshaft journal and bearing
insert. Proceed with installation.
(9) If bearing-to-journal clearance exceeds the spec-
ification, install a pair of 0.0254 mm (0.001 inch) un-
dersize bearing inserts. All the odd size inserts must
be on the bottom. The sizes of the service replace-
ment bearing inserts are stamped on the backs of the
inserts. Measure the clearance as described in the
previous steps.
(10) The clearance is measured with a pair of
0.0254 mm (0.001 inch) undersize bearing inserts in-
stalled. This will determine if two 0.0254 mm (0.001
inch) undersize inserts or another combination is
needed to provide the correct clearance (refer to Con-
necting Rod Bearing Fitting Chart).FOR EXAMPLE:If the initial clearance was
0.0762 mm (0.003 inch), 0.025 mm (0.001 inch) un-
dersize inserts would reduce the clearance by 0.025
mm (0.001 inch). The clearance would be 0.002 inch
and within specification. A 0.051 mm (0.002 inch)
undersize insert would reduce the initial clearance
an additional 0.013 mm (0.0005 inch). The clearance
would then be 0.038 mm (0.0015 inch).
(11) Repeat the Plastigage measurement to verify
your bearing selection prior to final assembly.
(12) Once you have selected the proper insert, in-
stall the insert and cap. Tighten the connecting rod
bolts to 45 Nzm (33 ft. lbs.) torque.
Fig. 7 Measuring Bearing Clearance with Plastigage
CONNECTING ROD BEARING FITTING CHART
9 - 36 2.5L ENGINEJ

SIDE CLEARANCE MEASUREMENT
Slide snug-fitting feeler gauge between the con-
necting rod and crankshaft journal flange. Refer to
Engine Specifications for the proper clearance. Re-
place the connecting rod if the side clearance is not
within specification.
PISTON FITTING
MICROMETER METHOD
(1) Measure the inside diameter of the cylinder
bore at a point 58.725 mm (2-5/16 inches) below top
of bore.
(2) Measure outside diameter of the piston. Be-
cause pistons are cam ground, measure at right an-
gle to piston pin at center line of pin (Fig. 8).
The difference between cylinder bore diameter and
piston diameter is piston-to-bore clearance.
FEELER GAUGE METHOD
(1) Remove the rings from the piston.
(2) Insert a long 0.025 mm (0.001 inch) feeler
gauge into the cylinder bore.
(3) Insert the piston, top first, into cylinder bore
alongside the feeler gauge. With entire piston in-
serted into cylinder bore, the piston should not bind
against feeler gauge.
(4) Repeat steps with a long 0.051 mm (0.002 inch)
feeler gauge. The piston should bind.
(5) If the piston binds on 0.025 mm (0.001 inch)
feeler gauge, the piston is too large or cylinder bore
is too small. If the piston does not bind on 0.051 mm
(0.002 inch) feeler gauge, the piston is too small for
cylinder bore. Pistons up to 0.102 mm (0.004 inch)undersize may be enlarged by knurling or shot-peen-
ing. Replace pistons that are 0.102 mm (0.004 inch)
or more undersize.
PISTON PIN
REMOVAL
Piston pins are press-fitted into the connecting rods
and require no locking device.
(1) Position the piston and connecting rod assem-
bly on an arbor press.
(2) Apply force to a piloted driver and press the
pin completely out of the connecting rod and piston
assembly (Fig. 9). Note position of the pin through
the gauge window of removal support tool.
INSPECTION
(1) Inspect the piston pin and pin bore in the con-
necting rod for nicks and burrs. Remove as neces-
sary. Never reuse a piston pin after it has been
installed in and removed from a connecting rod.
(2) With the pin removed from the piston and con-
necting rod, clean and dry piston pin bores and the
replacement piston pin.
(3) Position the piston so that the pin bore is in
vertical position. Insert the pin in bore. At room tem-
perature, the replacement pin should slide com-
pletely through the pin bore in piston by force of
gravity.
(4) Replace piston if pin jams in the pin bore.
INSTALLATION
(1) Insert the piston pin pilot through the piston
and connecting rod pin bores. Ensure that the arrow
on the piston crown is pointing up (Fig. 10).
Fig. 8 Piston Dimensions
Fig. 9 Piston Pin Removal/Installation
J2.5L ENGINE 9 - 37

BEARING-TO-JOURNAL CLEARANCE (CRANKSHAFT
INSTALLED)
When using Plastigage, check only one bearing
clearance at a time.
Install the grooved main bearings into the cylinder
block and the non-grooved bearings into the bearing
caps.
Install the crankshaft into the upper bearings dry.
Place a strip of Plastigage across full width of the
crankshaft journal to be checked.
Install the bearing cap and tighten the bolts to 108
Nzm (80 ft. lbs.) torque.
DO NOT rotate the crankshaft. This will cause
the Plastigage to shift, resulting in an inaccurate
reading. Plastigage must not be permitted to
crumble. If brittle, obtain fresh stock.
Remove the bearing cap. Determine the amount of
clearance by measuring the width of the compressed
Plastigage with the scale on the Plastigage envelope
(Fig. 5). Refer to Engine Specifications for the proper
clearance.
Plastigage should indicate the same clearance
across the entire width of the insert. If clearance var-
ies, it may indicate a tapered journal or foreign ma-
terial trapped behind the insert.
If the specified clearance is indicated and there are
no abnormal wear patterns, replacement of the bear-
ing inserts is not necessary. Remove the Plastigage
from the crankshaft journal and bearing insert. Pro-
ceed to Crankshaft Main BearingÐInstallation.
If the clearance exceeds specification, install a pair
of 0.025 mm (0.001 inch) undersize bearing inserts
and measure the clearance as described in the previ-
ous steps.
The clearance indicated with the 0.025 mm (0.001
inch) undersize insert pair installed will determine if
this insert size or some other combination will pro-
vide the specified clearance.FOR EXAMPLE:If the clearance was 0.0762 mm
(0.003 inch) originally, a pair of 0.0254 mm (0.001
inch) undersize inserts would reduce the clearance by
0.0254 mm (0.001 inch). The clearance would then be
0.0508 mm (0.002 inch) and within the specification.
A 0.051 mm (0.002 inch) undersize bearing insert
and a 0.0254 mm (0.001 inch) undersize insert would
reduce the original clearance an additional 0.0127
mm (0.0005 inch). The clearance would then be
0.0381 mm (0.0015 inch).
CAUTION: Never use a pair of inserts that differ
more than one bearing size as a pair.
FOR EXAMPLE:DO NOT use a standard size up-
per insert and a 0.051 mm (0.002 inch) undersize
lower insert.
If the clearance exceeds specification using a pair
of 0.051 mm (0.002 inch) undersize bearing inserts,
measure crankshaft journal diameter with a mi-
crometer. If the journal diameter is correct, the
crankshaft bore in the cylinder block may be mis-
aligned, which requires cylinder block replacement
or machining to true bore.
If journals 1 through 5 diameters are less than
63.4517 mm (2.4981 inches), replace crankshaft or
grind crankshaft down to accept the appropriate un-
dersize bearing inserts.
Once the proper clearances have been obtained,
proceed to Crankshaft Main BearingÐInstallation.
MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT
REMOVED)
Remove the crankshaft from the cylinder block (re-
fer to Cylinder Block - Disassemble).
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal
with a micrometer. Measure at two locations 90É
apart at each end of the journal.
The maximum allowable taper and out of round is
0.013 mm (0.0005 inch). Compare the measured di-
ameter with the journal diameter specification (Main
Bearing Fitting Chart). Select inserts required to ob-
tain the specified bearing-to-journal clearance.
Once the proper clearances have been obtained,
proceed to Crankshaft Main BearingÐInstallation.
INSTALLATION
(1) Lubricate the bearing surface of each insert
with engine oil.
(2) Loosen all the main bearing caps. Install the
main bearing upper inserts.
(3) Install the lower bearing inserts into the main
bearing caps.
(4) Install the main bearing cap(s) and lower in-
sert(s).
(5) Clean the rear main bearing cap (No.5) mating
surfaces.
Fig. 5 Measuring Bearing Clearance with Plastigage
9 - 42 2.5L ENGINEJ

The difference between cylinder bore diameter and
piston diameter is piston-to-bore clearance.
FEELER GAUGE METHOD
(1) Remove the rings from the piston.
(2) Insert a long 0.025 mm (0.001 inch) feeler
gauge into the cylinder bore.
(3) Insert the piston, top first, into cylinder bore
alongside the feeler gauge. With entire piston in-
serted into cylinder bore, the piston should not bind
against feeler gauge.
(4) Repeat steps with a long 0.051 mm (0.002 inch)
feeler gauge. The piston should bind.
(5) If the piston binds on 0.025 mm (0.001 inch)
feeler gauge, the piston is too large or cylinder bore
is too small. If the piston does not bind on 0.051 mm
(0.002 inch) feeler gauge, the piston is too small for
cylinder bore. Pistons up to 0.102 mm (0.004 inch)
undersize may be enlarged by knurling or shot-peen-
ing. Replace pistons that are 0.102 mm (0.004 inch)
or more undersize.
PISTON PIN
REMOVAL
Piston pins are press-fitted into the connecting rods
and require no locking device.
(1) Position the piston and connecting rod assem-
bly on an arbor press.
(2) Apply force to a piloted driver and press the
pin completely out of the connecting rod and piston
assembly (Fig. 9). Note position of the pin through
the gauge window of removal support tool.INSPECTION
(1) Inspect the piston pin and pin bore in the con-
necting rod for nicks and burrs. Remove as neces-
sary. Never reuse a piston pin after it has been
installed in and removed from a connecting rod.
(2) With the pin removed from the piston and con-
necting rod, clean and dry piston pin bores and the
replacement piston pin.
(3) Position the piston so that the pin bore is in
vertical position. Insert the pin in bore. At room tem-
perature, the replacement pin should slide com-
pletely through the pin bore in piston by force of
gravity.
(4) Replace piston if pin jams in the pin bore.
INSTALLATION
(1) Insert the piston pin pilot through the piston
and connecting rod pin bores. Ensure that the arrow
on the piston crown is pointing up (Fig. 10).
(2) Position the pin pilot, piston and connecting
rod on a support with the squirt hole of the connect-
ing rod to the left-hand side (Fig. 10).
(3) Insert piston pin through the upper piston pin
bore and into the connecting rod pin bore.
(4) Position the piloted driver inside the piston pin
(Fig. 9).
(5) Using an arbor press, press the piston pin
through the connecting rod and piston bores until pin
pilot indexes with mark on the support. The piston
pin requires a 8 900 N (2,000 pounds) press-fit. If lit-
tle effort is required to install piston pin in a con-
necting rod, or if the rod moves laterally on the pin,
the connecting rod must be replaced.
Fig. 8 Piston Dimensions
Fig. 9 Piston Pin Removal/Installation
J4.0L ENGINE 9 - 77