checking oil JEEP CHEROKEE 1994 Service Repair Manual

PINION GEAR DEPTH INFORMATION
Ring and pinion gears are supplied as matched sets
only. The identifying numbers for the ring and pin-
ion gear are etched into the face of each gear (Fig.
40). A plus (+) number, minus (-) number or zero (0)
is etched into the face of the pinion gear. This num-
ber is the amount (in thousandths of an inch) the
depth varies from the standard depth setting of a
pinion etched with a (0). The standard setting from
the centerline of the ring gear to the back face of thepinion is 92.1 mm (3.625 inches) for Model 30 axles
(Fig. 41). The standard depth provides the best teeth
contact pattern.
THE BUTTON END ON THE PINION GEAR
HEAD IS NO LONGER A MACHINED-TO-SPECI-
FICATIONS SURFACE. DO NOT USE THIS SUR-
FACE FOR PINION DEPTH SET-UP OR
CHECKING (Fig. 41).
Compensation for depth variance is achieved by a
selected thickness oil slinger (production) or shims
(service). The slinger is placed between the inner
pinion bearing cone and gear head (Fig. 42). The
shim pack is placed under the inner (rear) bearing
cup for service. To change the pinion adjustment,
shims are available in thicknesses of 0.003, 0.005,
and 0.010 inch.The oil slinger or baffle must be
measured and the thickness included with the
total shim pack.
New gear set: note the depth variance etched
into both the original and the replacement pin-
ion gear. Add or subtract the thickness of the
Fig. 38 Mate Shaft Pin Installation
Fig. 39 Ring Gear Bolt Installation
Fig. 40 Pinion Gear ID Numbers
Fig. 41 Pinion Gear Head
JFRONT SUSPENSION AND AXLE 2 - 37

SERVICE BRAKE DIAGNOSIS
INDEX
page page
Component Inspection...................... 8
Diagnosing Parking Brake Problems.......... 10
Diagnosing Service Brake Problems........... 8
Diagnosis Procedures...................... 7
General Information........................ 7Master Cylinder/Power Booster Test.......... 11
Power Booster Check Valve Test............ 11
Power Booster Vacuum Test................ 12
Preliminary Brake Check.................... 7
Road Testing............................ 7
GENERAL INFORMATION
The diagnosis information in this section covers
service brake components which include:
²disc brake calipers
²disc brakeshoes
²drum brake wheel cylinders
²drum brakeshoes and brake drums
²drum brake support plates
²parking brake mechanism
²master cylinder/combination valve
²vacuum power brake booster
²brake pedal and brakelight switch
²brake warning light
DIAGNOSIS PROCEDURES
Service brake diagnosis involves determining if a
problem is related to a mechanical, hydraulic or vac-
uum operated component. A preliminary brake
check, followed by road testing and component in-
spection are needed to determine a problem cause.
Road testing will either verify proper brake opera-
tion or confirm the existence of a problem. Compo-
nent inspection will, in most cases, identify the
actual part responsible for a problem.
The first diagnosis step is the preliminary brake
check. This involves inspecting fluid level, parking
brake action, wheel and tire condition, checking for
obvious leaks or component damage and testing
brake pedal response. A road test will confirm or
deny the existence of a problem. The final diagnosis
procedure involves road test analysis and a visual in-
spection of brake components.
PRELIMINARY BRAKE CHECK
(1) If amber antilock light is illuminated, refer to
Antilock Brake System Diagnosis. However, if red
warning light is illuminated, or if neither warning
light is illuminated, continue with diagnosis.
(2) Check condition of tires and wheels. Damaged
wheels and worn, damaged, or underinflated tires
can cause pull, shudder, tramp and a condition simi-
lar to grab.
(3) If complaint was based on noise when braking,
check suspension components. Jounce front and rearof vehicle and listen for noise that might be caused
by loose, worn, or damaged suspension or steering
components.
(4) Inspect brake fluid level:
(a) If vehicle has one-piece master cylinder, fluid
level should be to 6 mm (1/4 in.) of reservoir rim. If
vehicle two-piece, removable reservoir, correct level
is to top of indicator rings in reservoir.
(b) On models with ABS brakes, preferred level
is to MAX mark on reservoir. Acceptable level is
between MAX and MIN marks.
(c) Remember that fluid level in the front and
rear reservoir compartments will decrease in pro-
portion to normal lining wear. However, if fluid
level is abnormally low, look for leaks at calipers,
wheel cylinders, brakelines and master cylinder.
(5) Inspect brake fluid condition:
(a) Fluid should be reasonably clear and free of
foreign material.Note that brake fluid tends to
darken over time. This is normal and should
not be mistaken for contamination. If fluid is
clear of foreign material, it is OK.
(b) If fluid is highly discolored, or appears to con-
tain foreign material, drain out a sample with a
clean suction gun. Pour sample in a glass container
and note condition.
(c) If fluid separates into layers, obviously con-
tains oil, or a substance other than brake fluid,
system seals and cups will have to be replaced and
hydraulic system flushed.
(6) Check parking brake operation. Verify free
movement and full release of cables and foot pedal or
hand lever. Also note if vehicle was being operated
with parking brake partially applied.
(7) Check brake pedal operation. Verify that pedal
does not bind and has adequate free play. If pedal
lacks free play, check pedal and power booster for be-
ing loose or for bind condition. Do not road test until
condition is corrected.
(8) If components inspected look OK, road test the
vehicle.
ROAD TESTING
(1) If amber warning light is illuminated, problem
is with antilock system component. Refer to Antilock
Brake System Diagnosis.
JBRAKES 5 - 7

BRAKE BLEEDINGÐBRAKE FLUID AND LEVELÐBRAKELINES AND HOSES
INDEX
page page
Brake BleedingÐXJ/YJ with ABS Brakes....... 14
Brake BleedingÐXJ/YJ with Standard Brakes . . . 13
Brake Fluid Contamination.................. 13
Brake Fluid Level........................ 13Brakeline Charts......................... 15
Brakelines and Hoses..................... 15
Combination Valve....................... 15
Recommended Brake Fluid................. 13
RECOMMENDED BRAKE FLUID
The only brake fluid recommended for Jeep vehi-
cles with standard or antilock brakes, is Mopar brake
fluid, or an equivalent fluid meeting SAE J1703 and
DOT 3 standards.
Use new brake fluid only to top off the master
cylinder or refill the system. Never use re-
claimed fluid, fluid not meeting the SAE/DOT
standards or fluid from an unsealed container.
Do not use fluid from any container that has
been left open for any length of time. Fluid in
open containers can absorb moisture.
BRAKE FLUID LEVEL
Always clean the master cylinder and cover before
checking fluid level. If not cleaned, dirt from the
cover could enter the fluid. Also check the cover seal
and replace it if torn or distorted.
Correct fluid level is to within 6 mm (1/4 in.) of the
reservoir rim, or to the fill mark on models with a
plastic reservoir. Refer to the Antilock Brake section
for fluid levels on models equipped with ABS brakes.
BRAKE FLUID CONTAMINATION
Oil in the fluid will cause brake system rubber
seals to soften and swell. The seals may also become
porous and begin to deteriorate.
If fluid contamination is suspected, drain off a sam-
ple from the master cylinder. A suction gun or simi-
lar device can be used for this purpose.
Empty the drained fluid into a glass container.
Contaminants in the fluid will cause the fluid to sep-
arate into distinct layers. If contamination has oc-
curred, the system rubber seals, hoses and cups must
be replaced and the system thoroughly flushed with
clean brake fluid.
BRAKE BLEEDINGÐXJ/YJ WITH STANDARD
BRAKES
Use Mopar DOT 3 brake fluid, or an equivalent
meeting SAE/DOT standards J1703-F and DOT 3, to
fill and bleed the system.
On standard brake models, bleeding can be per-
formed either manually or with pressure equipment.
However, if pressure equipment is used, it will be
necessary to hold the front brake metering valveopen in order to bleed the front brakes. The valve
can be held open with a tension clip tool or by hand.
It will also be necessary that a suitable size pressure
tank hose adapter be available for use on the master
cylinder.
MANUAL BLEEDING PROCEDURE
(1) If master cylinder has been overhauled or a
new cylinder will be installed, bleed cylinder on
bench before installation. This shortens time needed
to bleed system and ensures proper cylinder opera-
tion.
(2) Wipe master cylinder reservoir and cap clean
with shop towels.
(3) Remove cover and fill master cylinder reservoir
with Mopar, or equivalent DOT 3 brake fluid.
(4) Open all caliper and wheel cylinder bleed
screws.
(5) Close bleed screws after fluid begins flowing
from each bleed screw.
(6) Top off master cylinder reservoir again.
(7) Use following bleed sequence:
²master cylinder
²right rear
²left rear
²right front
²left front
(8) Observe following brake bleeding precautions:
²Do not pump brake pedal at any time while bleed-
ing. Air in system will be compressed into small bub-
bles that are distributed throughout hydraulic
system. This will make a second and third bleeding
operation necessary.
²Bleed only one wheel brake unit at a time and use
a bleed hose to bleed each wheel brake unit (Fig. 7).
²Attach one end of bleed hose to bleed screw and in-
sert opposite end in glass container partially filled
with brake fluid (Fig. 7). Glass container makes it
easier to see air bubbles as they exit the bleed hose.
²Be sure end of bleed hose is immersed in fluid. Im-
mersing hose end in fluid prevents air from being
drawn back into cylinder and brakeline.
(9) Bleed master cylinder first. Have helper oper-
ate brake pedal while bleeding each master cylinder
fluid outlet line.
JBRAKES 5 - 13

Leakage Test. Do this if it is certain that coolant is
being lost and no leaks can be detected.
²Drops Slowly: Shows a small leak or seepage is oc-
curring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect the radiator,
hoses, gasket edges and heater. Seal any small leak
holes with a Sealer Lubricant or equivalent. Repair
leak holes and reinspect the system with pressure
applied.
²Drops Quickly: Shows that a serious leakage is oc-
curring. Examine the system for serious external
leakage. If no leaks are visible, inspect for internal
leakage. Large radiator leak holes should be repaired
by a reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION
Remove the oil pan drain plug and drain a small
amount of engine oil. Coolant, being heavier will
drain first, or operate engine to churn oil, then ex-
amine dipstick for water globules. Inspect the trans-
mission dipstick for water globules. Inspect the
transmission fluid cooler for leakage. Operate the en-
gine without the pressure cap on the radiator until
thermostat opens.
Attach a Pressure Tester to the filler neck. If pres-
sure builds up quickly, a leak exists as result of a
faulty cylinder head gasket or crack in the engine.
Repair as necessary.
WARNING: DO NOT ALLOW PRESSURE TO EX-
CEED 124 KPA (18 PSI). TURN THE ENGINE OFF.
TO RELEASE THE PRESSURE, ROCK THE TESTER
FROM SIDE TO SIDE. WHEN REMOVING THE
TESTER, DO NOT TURN THE TESTER MORE THAN
1/2 TURN IF THE SYSTEM IS UNDER PRESSURE.
If there is no immediate pressure increase, pump
the Pressure Tester until the indicated pressure is
within the system range. Vibration of the gauge
pointer indicates compression or combustion leakage
into the cooling system.WARNING: DO NOT DISCONNECT THE SPARK
PLUG WIRES WHILE THE ENGINE IS OPERATING.
CAUTION: Do not operate the engine with a spark
plug shorted for more than a minute. The catalytic
converter may be damaged.
Isolate the compression leak by shorting each
spark plug to the cylinder block. The gauge pointer
should stop or decrease vibration when spark plug
for leaking cylinder is shorted. This happens because
of the absence of combustion pressure.
COMBUSTION LEAKAGE TEST (WITHOUT
PRESSURE TESTER)
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
Drain sufficient coolant to allow for thermostat re-
moval. Refer to Thermostat Replacement. Disconnect
the water pump drive belt.
Disconnect the upper radiator hose from the ther-
mostat housing. Remove the housing and thermostat.
Install the thermostat housing.
Add coolant to the radiator to bring the level to
within 6.3 mm (1/4 in) of the top of the thermostat
housing.
CAUTION: Avoid overheating. Do not operate the
engine for an excessive period of time. Open the
draincock immediately after the test to eliminate
boil over of coolant.
Start the engine and accelerate rapidly three times
(to approximately 3000 rpm) while observing the
coolant. If internal engine combustion gases are leak-
ing into the cooling system, bubbles will appear in
the coolant. If bubbles do not appear, there is no in-
ternal combustion gas leakage.
COOLANT RESERVE/OVERFLOW SYSTEM
The system works along with the radiator pressure
cap. This is done by using thermal expansion and
contraction of the coolant to keep the coolant free of
trapped air. It provides:
²A volume for coolant expansion and contraction.
²A convenient and safe method for checking/adjust-
ing coolant level at atmospheric pressure. This is
done without removing the radiator pressure cap.
²Some reserve coolant to cover minor leaks and
evaporation or boiling losses.
Fig. 20 Pressurizing SystemÐTypical
JCOOLING SYSTEM 7 - 19

ENGINE COOLANT TEMPERATURE SENSOR TEST
To perform a complete test of this sensor and its
circuitry, refer to the DRB scan tool. Also refer to the
appropriate Powertrain Diagnostics Procedures man-
ual. To test the sensor only, refer to the following:
The sensor is installed in the thermostat housing
(Fig. 12).
(1) Disconnect wire harness connector from sensor
(Fig. 12).
(2) Test the resistance of the sensor with a high in-
put impedance (digital) volt-ohmmeter. The resis-
tance should be less than 1340 ohms at normal
engine operating idle temperature. For resistance
values, refer to the Sensor Resistance chart. Replace
the sensor if it is not within the range of resistance
specified in the chart.
(3) Test continuity of the wire harness. This is
done between Powertrain Control Module (PCM)
wire harness connector terminal-2 and the sensor
connector terminal. Also check continuity between
wire harness terminal-4 to the sensor connector ter-
minal. Repair the wire harness if an open circuit is
indicated.
IGNITION SECONDARY CIRCUIT DIAGNOSIS
CHECKING FOR SPARK
CAUTION: When disconnecting a high voltage cable
from a spark plug or from the distributor cap, twist
the rubber boot slightly (1/2 turn) to break it loose.
Grasp the boot (not the cable) and pull it off with a
steady, even force.
(1) Disconnect the ignition coil secondary cable
from center tower of the distributor cap. Hold the ca-
ble terminal approximately 12 mm (1/2 in.) from a
good engine ground (Fig. 13).WARNING: BE VERY CAREFUL WHEN THE ENGINE
IS CRANKING. DO NOT PUT YOUR HANDS NEAR
THE PULLEYS, BELTS OR THE FAN. DO NOT
WEAR LOOSE FITTING CLOTHING.
(2) Rotate (crank) the engine with the starter mo-
tor and observe the cable terminal for a steady arc. If
steady arcing does not occur, inspect the secondary
coil cable. Refer to Spark Plug Cables in this group.
Also inspect the distributor cap and rotor for cracks
or burn marks. Repair as necessary. If steady arcing
occurs, connect ignition coil cable to the distributor
cap.
(3) Remove a cable from one spark plug.
Fig. 12 Coolant Temperature SensorÐTypical
SENSOR RESISTANCE (OHMS)
Fig. 13 Checking for SparkÐTypical
8D - 12 IGNITION SYSTEMSJ

(4) Using insulated pliers, hold the cable terminal
approximately 12 mm (1/2 in.) from the engine cylin-
der head or block while rotating the engine with the
starter motor. Observe the spark plug cable terminal
for an arc. If steady arcing occurs, it can be expected
that the ignition secondary system is operating cor-
rectly. If steady arcing occurs at the spark plug ca-
bles, but the engine will not start, connect the DRB
scan tool. Refer to the Powertrain Diagnostic Proce-
dures service manual for DRB operation.
FAILURE TO START TEST
To prevent unnecessary diagnostic time and wrong
test results, the previous Checking For Spark test
should be performed prior to this test.
WARNING: SET PARKING BRAKE OR BLOCK THE
DRIVE WHEELS BEFORE PROCEEDING WITH THIS
TEST.
(1) Unplug the ignition coil harness connector at
the coil (Fig. 14).
(2) Connect a set of small jumper wires (18 gauge
or smaller) between the ignition coil and coil electri-
cal connector (Fig. 15).
(3) Determine that sufficient battery voltage (12.4
volts) is present for the starting and ignition sys-
tems.
(4) Crank the engine for 5 seconds while monitor-
ing the voltage at the coil positive terminal:
²If the voltage remains near zero during the entire
period of cranking, refer to On-Board Diagnostics in
Group 14, Fuel Systems. Check the powertrain con-
trol module (PCM) and auto shut down relay.
²If voltage is at near battery voltage and drops to
zero after 1-2 seconds of cranking, check the cam-
shaft position sensor-to-PCM circuit. Refer to On-
Board Diagnostics in Group 14, Fuel Systems.
²If voltage remains at near battery voltage during
the entire 5 seconds, turn the key off. Remove the60-way connector (Fig. 16) from the PCM. Check 60-
way connector for any spread terminals.
(5) Remove test lead from the coil positive termi-
nal. Connect an 18 gauge jumper wire between the
battery positive terminal and the coil positive termi-
nal.
(6) Make the special jumper shown in Figure 17.
Using the jumper,momentarilyground terminal-19
of the 60-way connector. A spark should be generated
at the coil cable when the ground is removed.
(7) If spark is generated, replace the powertrain
control module (PCM).
(8) If spark is not seen, use the special jumper to
ground the coil negative terminal directly.
(9) If spark is produced, repair wiring harness for
an open condition.
Fig. 14 Coil Harness ConnectorÐTypical
Fig. 15 Coil TerminalsÐTypical
Fig. 16 PCM 60-Way Connector
Fig. 17 Special Jumper Ground-to-Coil Negative
Terminal
JIGNITION SYSTEMS 8D - 13

(3) Honing should be done by moving the hone up
and down fast enough to get a crosshatch pattern.
The hone marks should INTERSECT at 50É to 60É for
proper seating of rings (Fig. 1).
(4) A controlled hone motor speed between 200 and
300 RPM is necessary to obtain the proper crosshatch
angle. The number of up and down strokes per
minute can be regulated to get the desired 50É to 60É
angle. Faster up and down strokes increase the cross-
hatch angle.
(5) After honing, it is necessary that the block be
cleaned to remove all traces of abrasive. Use a brush
to wash parts with a solution of hot water and deter-
gent. Dry parts thoroughly. Use a clean, white, lint-
free cloth to check that the bore is clean. Oil the
bores after cleaning to prevent rusting.
MEASURING WITH PLASTIGAGE
CRANKSHAFT MAIN BEARING CLEARANCE
Engine crankshaft bearing clearances can be deter-
mined by use of Plastigage, or equivalent. The fol-
lowing is the recommended procedures for the use of
Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) The total clearance of the main bearings can
only be determined by removing the weight of the
crankshaft. This can be accomplished by either of
two methods:
METHOD - 1 (PREFERRED)ÐShim the bear-
ings adjacent to the bearing to be checked. This will
remove the clearance between upper bearing shell
and the crankshaft. Place a minimum of 0.254 mm
(0.010 inch) shim between the bearing shell and the
adjacent bearing cap. Tighten the bolts to 18 Nzm (13
ft. lbs.) torque.
²ALL ENGINESÐWhen checking No.1 main bear-
ing; shim No.2 main bearing.²ALL ENGINESÐWhen checking No.2 main bear-
ing; shim No.1 and No.3 main bearing.
²ALL ENGINESÐWhen checking No.3 main bear-
ing; shim No.2 and No.4 main bearing.
²ALL ENGINESÐWhen checking No.4 main bear-
ing; shim No.3 and No.5 main bearing.
²2.5L ENGINEÐWhen checking No.5 main bear-
ing; shim No.4 main bearing.
²4.0L ENGINEÐWhen checking No.5 main bear-
ing; shim No.4 and No.6 main bearing.
²4.0L ENGINEÐWhen checking No.6 main bear-
ing; shim No.5 and No.7 main bearing.
²4.0L ENGINEÐWhen checking No.7 main bear-
ing; shim No.6 main bearing.
Remove all shims before assembling engine.
METHOD - 2 (ALTERNATIVE)ÐThe weight of
the crankshaft is supported by a jack under the coun-
terweight adjacent to the bearing being checked.
(3) 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
that area. Tighten the bearing cap bolts of the bear-
ing being checked to 108 Nzm (80 ft. lbs.) torque.DO
NOT rotate 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.
Fig. 1 Cylinder Bore Crosshatch Pattern
Fig. 2 Placement of Plastigage in Bearing Shell
JENGINES 9 - 3

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

A correct lubricant level check can only be made
when the vehicle is level; use a drive-on hoist to en-
sure this. Also allow the lubricant to settle for a
minute or so before checking. These recommenda-
tions will ensure an accurate check and avoid an un-
der-or-overfill condition.
HARD SHIFTING
Hard shifting is usually caused by a low lubricant
level, improper or contaminated lubricants, compo-
nent damage, incorrect clutch adjustment, or by a
damaged clutch pressure plate or disc.
Substantial lubricant leaks can result in gear, shift
rail, synchro and bearing damage. If a leak goes un-
detected for an extended period, the first indications
of a problem are usually hard shifting and noise.
Incorrect or contaminated lubricants can also con-
tribute to hard shifting. The consequence of using
non-recommended lubricants is noise, excessive wear,
internal bind and hard shifting.
Improper clutch release is a frequent cause of hard
shifting. Incorrect adjustment or a worn, damaged
pressure plate or disc can cause incorrect release. If
the clutch problem is advanced, gear clash during
shifts can result.
Worn or damaged synchro rings can cause gear
clash when shifting into any forward gear. In some
new or rebuilt transmissions, new synchro rings maytend to stick slightly causing hard or noisy shifts. In
most cases, this condition will decline as the rings
wear-in.
TRANSMISSION NOISE
Most manual transmissions make some noise dur-
ing normal operation. Rotating gears can generate a
mild whine that may only be audible at extreme
speeds.
Severe, obviously audible transmission noise is
generally the result of a lubricant problem. Insuffi-
cient, improper, or contaminated lubricant can pro-
mote rapid wear of gears, synchros, shift rails, forks
and bearings. The overheating caused by a lubricant
problem, can also lead to gear breakage.
TRANSMISSION REMOVAL
(1) Shift transmission into first or third gear. Then
raise vehicle on hoist.
(2) Support engine with adjustable jack stand. Be
sure to position wood block between jack and oil pan.
(3) Disconnect necessary exhaust system compo-
nents.
(4) Disconnect rear cushion and bracket from
transmission (Fig. 5). Then remove skid plate, or
rear crossmember.
(5) Disconnect transfer case shift linkage, vehicle
speed sensor wires, and vent hose.
Fig. 5 Rear Mount Components (YJ Shown)
JAX 4/5 MANUAL TRANSMISSION 21 - 3

Measure diameter of the output shaft journal sur-
faces with a micrometer (Fig. 44). Second gear sur-
face minimum diameter is 37.96 mm (1.495 in.).
Third gear surface minimum diameter is 34.98 mm
(1.377 in.). Replace the shaft if either of these sur-
faces are worn beyond specified limits.
Measure output shaft runout with a dial indicator
(Fig. 45). Runout should not exceed 0.05 mm (0.002 in.).
Install the needle bearing and inner race in the
first gear. Then check oil clearance between the gear
and inner race (Fig. 46). Clearance should be 0.009 -
0.032 mm (0.0004 - 0.0013 in.).
Install the needle bearings and the second, third
and counter fifth gears on the output shaft. Check oil
clearance between the gears and shaft with a dial in-
dicator (Fig. 47).
Oil clearance for all three gears is 0.009 - 0.0013
mm (0.0004 - 0.0013 in.).
Check synchronizer ring wear (Fig. 48). Insert each
ring in matching gear. Measure clearance between
Fig. 44 Checking Shaft And Race Diameters
Fig. 45 Checking Output Shaft Runout
Fig. 46 Checking Gear-To-Race Clearance
Fig. 47 Checking Gear-To-Shaft Clearance
21 - 14 AX 4/5 MANUAL TRANSMISSIONJ