check engine JEEP CHEROKEE 1994 Service Repair Manual

MAINTENANCE SCHEDULES
INTRODUCTION
Chrysler Corporation has compiled recommended
lubrication and maintenance schedules and proce-
dures to help reduce premature wear or failure over
a broad range of operating conditions.
SEVERE SERVICE MAINTENANCE
If the vehicle is involved with a severe driving con-
dition, after each 4 800-km (3,000-miles)/3-month in-
terval. A severe driving condition includes:
²frequent short trip driving less than 24 km (15
miles);
²frequent driving in a dusty environment;
²trailer towing;
²extensive engine idling;
²sustained high-speed operation;
²desert operation;
²frequent starting and stopping;
²cold-climate operation;
²off-road driving; or
²commercial service.
MAINTENANCE SCHEDULES
AT EACH STOP FOR FUEL
²Check engine oil level, add as required.
²
Check windshield washer solvent and add if required.
ONCE A MONTH
²Check tire pressure and look for unusual wear or
damage.
²Inspect battery and clean and tighten terminals as
required.
²Check electrolyte level and add water as needed.
²Check fluid levels of coolant reservoir, power steer-
ing and transmission and add as needed.
²Check all lights and all other electrical items for
correct operation.
²Check rubber seals on each side of the radiator for
proper fit.
7,500 MILES (12 000 KM) OR AT 6 MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
15,000 MILES (24 000 KM) OR AT 12 MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.²Check fluid level in battery.
²Rotate Tires.
22,500 MILES (36 000 KM) OR AT 18 MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
30,000 MILES (48 000 KM) OR AT 24 MONTHS
²Replace air cleaner filter.
²Replace spark plugs.
²Adjust drive belt.
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Check fluid level in battery.
²Drain and refill automatic transmission.
²Drain and refill transfer case.
²Rotate Tires.
37,500 MILES (60 000 KM) OR AT 30 MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Drain and refill manual transmission.
²Rotate Tires.
45,000 MILES (72 500 KM) OR AT 36 MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Check fluid level in battery.
²Rotate Tires.
52,500 MILES (84 500 KM) OR AT 42 MONTHS
²Flush and replace engine coolant.
²Check engine coolant system hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
JLUBRICATION AND MAINTENANCE 0 - 5

60,000 MILES (96 500 KM) OR AT 48 MONTHS.
²Replace air cleaner filter.
²Replace distributor cap and rotor.
²Replace ignition wires.
²Replace spark plugs.
²Adjust or replace drive belt.
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Replace fuel filter (not required for Calif. vehicles).
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Check fluid level in battery.
²Drain and refill automatic transmission.
²Drain and refill transfer case.
²Rotate Tires.
67,500 MILES (108 500 KM) OR AT 54
MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
75,000 MILES (120 500 KM) OR AT 60
MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Drain and refill manual transmission.
²Rotate Tires.
82,500 MILES (133 000 KM) OR AT 66
MONTHS
²Flush and replace engine coolant.
²Check engine coolant system, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
90,000 MILES (145 000 KM) OR AT 72
MONTHS
²Replace air cleaner filter.
²Replace spark plugs.
²Adjust drive belt.
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Check fluid level in battery.
²Drain and refill automatic transmission.
²Drain and refill transfer case.
²Rotate Tires.
97,500 MILES (157 000 KM) OR AT 78
MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
105,000 MILES (169 000 KM) OR AT 84
MONTHS
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
112,500 MILES (181 000 KM) OR AT 90
MONTHS
²Flush and replace engine coolant.
²Check engine coolant system hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Rotate Tires.
120,000 MILES (193 000 KM) OR AT 96
MONTHS
²Replace air cleaner filter.
²Replace distributor cap and rotor.
²Replace ignition wires.
²Replace spark plugs.
²Adjust or replace drive belt.
²Check engine coolant level, hoses and clamps.
²Change engine oil.
²Replace engine oil filter.
²Check exhaust system.
²Replace fuel filter (not required for Calif. vehicles).
²Lubricate steering linkage (4x4 models).
²Lubricate propeller shaft universal joints.
²Check fluid level in battery.
²Drain and refill automatic transmission.
²Drain and refill transfer case.
²Rotate Tires.
0 - 6 LUBRICATION AND MAINTENANCEJ

CAUTION: Do not overfill the engine crankcase with
oil. This will cause oil aeration and result in a de-
crease in the engine oil pressure.
(9) Start the engine and observe the oil pressure
gauge or warning lamp. If the pressure does not in-
crease or the warning lamp does not go out, stop the
engine and determine the cause of the problem.
USED ENGINE OIL DISPOSAL
Care should be exercised when disposing used en-
gine oil after it has been drained from a vehicle en-
gine. Refer to the WARNING listed above.
COOLING SYSTEM
WARNING: USE EXTREME CAUTION WHEN RE-
MOVING THE RADIATOR CAP IF THE ENGINE IS
OPERATING. DO NOT PUT YOUR HANDS NEAR
THE DRIVE BELT(S), PULLEYS OR FAN BLADE. DO
NOT STAND IN A DIRECT LINE WITH THE FAN
BLADE.
RECOMMENDED MAINTENANCE
The engine coolant level should be determined at
least once a month and more often during periods of
hot weather. Add coolant as necessary.
COOLANT LEVEL
With the engine at normal operating temperature,
observe the coolant level in thecoolant recovery bot-
tle. The coolant level must be at least above the ADD
mark and preferably at the FULL mark. Add coolant
to the coolant recovery bottleonly, if necessary.
REQUIRED MAINTENANCE
Check coolant level, and inspect condition of cool-
ing system hoses and clamps after each 12 000-km
(7,500-miles).
Initially, coolant must be drained and cooling sys-
tem flushed and filled after the first 36 months of op-
eration. Thereafter, after each 24-months interval of
vehicle operation.
RECOMMENDED MAINTENANCE
The engine cooling system should be inspected for
proper operation and for component failure at least
every 12 months.
WARNING: IF THE ENGINE HAS BEEN RECENTLY
OPERATED, USE EXTREME CARE WHEN REMOV-
ING THE RADIATOR CAP TO AVOID SCALDING
WITH HOT, PRESSURIZED COOLANT.
For additional information, refer to Section 7, Cool-
ing System.COOLANT FREEZE PROTECTION
Jeeptcooling systems contain a 50/50 mixture of
anti-freeze and distilled water coolant. This is the
recommended coolant mixture for most ambient tem-
peratures. The factory-installed anti-freeze is formu-
lated to prevent corrosion on all cooling system metal
surfaces.
The degree of coolant freeze protection should be
tested every 12 months. If the coolant is contami-
nated orrustyin appearance, cooling system should
be drained and filled with a 50/50 mixture of fresh
coolant. For additional information, refer to Group
7ÐCooling System.
ENGINE AIR CLEANER FILTER ELEMENT
RECOMMENDED MAINTENANCE
Engine performance and fuel economy can be af-
fected by a restricted air cleaner filter. The filter
should be inspected on a regular basis for excessive
air restriction.
If the filter element is saturated with oil, replace
the filter element.
REQUIRED MAINTENANCE
Engine air cleaner filter must be replaced after
each 48 000-km (30,000-miles).
If a vehicle is frequently operated in dusty
areas, the air cleaner filter should be inspected
often.
FILTER ELEMENT SERVICE/REPLACEMENT
(1) Remove the air cleaner cover from the body/
housing (Fig. 9).
(2) Remove the air cleaner filter element from the
body/housing.
Fig. 9 Air Cleaner & Filter ElementÐ2.5L and 4.0L
Engines
0 - 16 LUBRICATION AND MAINTENANCEJ

CAUTION: Do not tap the filter element or immerse
the filter in liquid to remove trapped particles.
(3) Clean filter element by gently blowing the
trapped particles from the filter with compressed air.
Direct air in the opposite direction of normal intake
air flow. Keep air nozzle at least two inches away
from the filter to avoid damage to filter.
(4) If the filter has become partially saturated with
oil, replace the filter. Test the crankcase ventilating
(CCV) system for proper operation.
(5) Wash the air cleaner cover and body/housing
(Figs. 10) with cleaning solvent and wipe dry.
(6) Install the air cleaner filter element and attach
the cover to the body/housing.
CRANKCASE VENTILATION SYSTEM
All Jeept2.5L and 4.0L engines are equipped with
a crankcase ventilation (CCV) system. Refer to
Group 25ÐEmissions, for additional information.
FUEL USAGE STATEMENTÐGAS ENGINES
Jeeptvehicles are designed to meet all emission
regulations and provide excellent fuel economy using
high quality unleaded gasoline. Only use unleaded
gasolines having a minimum posted octane of 87.
If a Jeeptvehicle develops occasional light spark
knock (ping) at low engine speeds, this is not harm-
ful. However,continued heavy knock at high
speeds can cause damage and should be
checked immediately.Engine damage as a result of
heavy knock operation may not be covered by the
new vehicle warranty.In addition to using unleaded gasoline with the
proper octane rating,those that contain deter-
gents, corrosion and stability additives are rec-
ommended.Using gasolines that have these
additives will help improve fuel economy, reduce
emissions and maintain vehicle performance. Gener-
ally, premium unleaded gasolines contain more addi-
tive than regular unleaded gasolines.
Poor quality gasolinecan cause problems such as
hard starting, stalling and stumble. If these problems
occur, use another brand of gasoline before consider-
ing servicing the vehicle.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with
materials that contain oxygen such as alcohol, MTBE
and ETBE. The type and amount of oxygenate used
in the blend is important. The following are gener-
ally used in gasoline blends:
ETHANOL
Ethanol (Ethyl or Grain Alcohol) properly blended,
is used as a mixture of 10 percent ethanol and 90
percent gasoline.Gasoline with ethanol may be
used in your vehicle.
METHANOL
CAUTION: Do not use gasolines containing metha-
nol. Use of methanol/gasoline blends may result in
starting and driveability problems. In addition, dam-
age may be done to critical fuel system compo-
nents.
Methanol (Methyl or Wood Alcohol) is used in a va-
riety of concentrations blended with unleaded gaso-
line. You may encounter fuels containing 3 percent
or more methanol along with other alcohols called co-
solvents.
Problems that are the result of using methanol/gas-
oline blends are not the responsibility of Chrysler
Corporation. They may not be covered by the vehicle
warranty.
MTBE/ETBE
Gasoline and MTBE (Methyl Tertiary Butyl Ether)
blends are a mixture of unleaded gasoline and up to
15 percent MTBE. Gasoline and ETBE (Ethyl Ter-
tiary Butyl Ether) are blends of gasoline and up to
17 percent ETBE. Gasoline blended with MTBE or
ETBE may be used.
CLEAN AIR GASOLINE
Many gasolines are now being blended that con-
tribute to cleaner air, especially in those areas of the
country where air pollution levels are high. These
new blends provide a cleaner burning fuel and some
are referred to asReformulated Gasoline.
Fig. 10 Air Cleaner Body/Housing & Cover
JLUBRICATION AND MAINTENANCE 0 - 17

In areas of the country where carbon monoxide lev-
els are high, gasolines are being treated with oxy-
genated materials such as MTBE, ETBE and
ethanol.
Chrysler Corporation supports these efforts toward
cleaner air and recommends the use of these gaso-
lines as they become available.
IGNITION CABLES, DISTRIBUTOR CAP AND
ROTOR
REQUIRED IGNITION SYSTEM MAINTENANCE
The ignition cables, distributor cap and rotor must
be replaced after each 96 000-km (60,000-miles). Re-
fer to Group 8DÐIgnition Systems for additional in-
formation.
IGNITION TIMING
The ignition timing for 2.5L and 4.0L engines is
not adjustable. Refer to the specifications listed on
the engine Emission Control Information Label. Re-
fer to Group 25ÐEmission Control Systems for addi-
tional information.
SPARK PLUGS
REQUIRED MAINTENANCE
The spark plugs must be replaced after each 48
000-km (30,000-miles). Refer to the Spark Plugs
chart below and to Group 8DÐIgnition Systems for
additional information.
BATTERY
RECOMMENDED MAINTENANCE
The battery electrolyte level should be checked and
the cable clamps should be inspected for corrosion.
This should be done when the oil is changed and the
oil filter is replaced.
The battery cables should be inspected for abnor-
mal clamp and battery terminal post corrosion. Ser-
vice the terminals and cable clamps as necessary.In addition, the general condition of the battery
should be determined before the start of cold and hot
weather seasons. If the battery condition is marginal
or worse, it should be replaced.
Care should be taken when disposing a bat-
tery after removal from a vehicle. Lead-acid bat-
teries are highly poisonous and, when
indiscriminately disposed, could create a prob-
lem for the environment. Contact the applicable
local city or county government agency to deter-
mine where automobile (lead-acid) batteries can
be properly disposed in the local area.
INSPECTION/SERVICE
WARNING: WEAR SAFETY GLASSES, RUBBER
GLOVES AND PROTECTIVE CLOTHING WHEN HAN-
DLING/SERVICING A BATTERY. THE BATTERY
ELECTROLYTE CONTAINS SULFURIC ACID AND
WILL CAUSE HARM IF IT CONTACTS SKIN, EYES
OR CLOTHING. IT WILL ALSO DAMAGE PAINTED
(AS WELL AS UN-PAINTED) SURFACES OF A VEHI-
CLE. IF SULFURIC ACID CONTACTS ANY OF
THESE, FLUSH IMMEDIATELY WITH LARGE
AMOUNTS OF WATER. IF SULFURIC ACID CON-
TACTS SKIN OR EYES, GET IMMEDIATE MEDICAL
ATTENTION. DO NOT SMOKE IN THE VICINITY OF
A BATTERY. KEEP OPEN FLAMES AND SPARKS
AWAY FROM BATTERY FILLER CAPS BECAUSE
EXPLOSIVE GAS IS ALWAYS PRESENT.
(1) Disconnect the battery negative cable and then
the positive cable.
(2) Clean the battery cable clamps and terminal
posts with a wire brush and a battery terminal
cleaner.
(3) Pry the battery cell filler caps upward to re-
move them and inspect each filler well (low-mainte-
nance batteries only, not applicable to maintenance-
free batteries). It could possibly be necessary to
loosen the battery holddown clamp to remove the
caps. Maintain the electrolyte level above the battery
plates and at the bottom of the filler well ring. Add
distilled water or low-mineral content drinking wa-
ter, if necessary. In freezing weather (below 0ÉC/
32ÉF), add the water just before driving to ensure
that it mixes thoroughly with the electrolyte. This
will prevent it from freezing.
(4) Remove the battery holddown strap and clean
the battery case/battery tray.Clean with bicarbonate
of soda (baking soda) and water. Rinse and dry the
battery case/tray thoroughly after cleaning.
(5) Position the battery in the tray and install the
holddown strap.Do not over-tighten the nuts.
(6) Connect the battery positive cable and then the
negative cable to the battery.
SPARK PLUGS
0 - 18 LUBRICATION AND MAINTENANCEJ

DRIVETRAIN
INDEX
page page
Automatic Transmission.................... 23
Drive Shafts............................ 27
Front and Rear Axles..................... 26
Hydraulic Clutch......................... 22Manual Transmission...................... 22
Rubber and Plastic Hoses/Tubing............ 28
Transfer Case........................... 25
HYDRAULIC CLUTCH
RECOMMENDED MAINTENANCE
Check fluid level in the hydraulic clutch master
cylinder reservoir (Fig. 1) at the same time engine
oil is changed and oil filter is replaced. Add fluid as
necessary.
FLUID SPECIFICATION
The only fluid recommended for use in a hydraulic
clutch system is MOPAR Brake And Hydraulic
Clutch Fluid., or an equivalent fluid.
CAUTION: Never use reclaimed brake fluid or fluid
from an unsealed container. In addition, do not use
fluid from a container that has been opened and al-
lowed to stand for an extended length of time.
Moisture in the air can be absorbed by the fluid,
which causes dilution with loss of effectiveness.
FLUID LEVEL
Remove the master cylinder fluid reservoir cap
(Fig. 2). The fluid level is determined by its height inrelation to the level indicator ring (Fig. 3) located in-
side the reservoir. If necessary, add fluid until the
height is level with the indicator ring.
MANUAL TRANSMISSION
RECOMMENDED MAINTENANCE
The lube oil level in manual transmissions should
be determined at the same time as the engine oil is
changed and the oil filter is replaced. Add lube oil as
necessary.
Fig. 1 Hydraulic Clutch (YJ)ÐTypical
Fig. 2 Hydraulic Clutch Master Cylinder Fluid
Reservoir
Fig. 3 Hydraulic Clutch Fluid Level
0 - 22 LUBRICATION AND MAINTENANCEJ

Under normal driving conditions, manual trans-
mission lube oil should be changed after each 60
000-km (37,500 miles). With severe driving condi-
tions, after each 29 000-km (18,000 miles).
LUBRICANT SPECIFICATION
When it becomes necessary to add to or change the
lube oil in a Jeeptmanual transmission, use SAE
75W-90, API Quality Grade GL-5 gear lubricant.
LUBRICANT LEVEL
The fill-hole plug for all manual transmissions is
located on the right side of the case (Fig. 4). Deter-
mine the lubricant level according to the following
procedure.
(1) Remove the fill-hole plug (Fig. 4) from the
transmission. The lube oil should be level with the
bottom edge of the fill hole. The level can be slightly
below the bottom edge of the fill hole if the lube oil
is cold.
If the transmission is warm, lube oil could drip
out of the fill hole. This is acceptable but the
lube oil should not gush out of the fill hole.
(2) If not acceptable, raise the lube oil level to the
bottom edge of the transmission fill hole. Use SAE
75W-90, API Quality Grade GL-5 gear lubricant.
Add lube oil in small amounts to raise the
level.
(3) Install the fill-hole plug in the transmission.
Tighten the plug with 37 NIm (27 ft. lbs.) torque.
LUBE OIL CHANGE
When it becomes necessary to change manual
transmission lube oil, use the following procedure.
(1) Raise and support the vehicle.
(2) Remove the fill-hole plug from the transmis-
sion.
(3) Place a container to collect the lube oil under
the transmission drain-hole plug.(4) Remove the drain-hole plug and drain the lube
oil from the transmission into the container.
Care should be exercised when disposing used
lube oil after it has been drained from a trans-
mission.
(5) Install the drain-hole plug in the transmission.
Tighten the plug with 37 NIm (27 ft. lbs.) torque.
(6) Fill the transmission until the lube oil begins
to drip out of the fill hole with SAE 75W-90, API
Quality Grade GL-5 gear lubricant.
(7) Install the fill-hole plug in the transmission.
Tighten the plug with 37 NIm (27 ft. lbs.) torque.
(8) Remove the support and lower the vehicle.
AUTOMATIC TRANSMISSION
RECOMMENDED MAINTENANCE
Check fluid level in automatic transmissions (Fig.
5) the same time the engine oil is changed and the
oil filter is replaced. Add ATF as necessary.
Under normal driving conditions, the ATF should
be changed and the filter replaced after each 48
000-km (30,000-miles). With severe driving condi-
tions, after each 29 000-km (12,000-miles).
ATF SPECIFICATIONS
When it becomes necessary to add fluid (ATF) to a
Jeeptautomatic transmission (or when the ATF is
replaced), use:
²MerconŸ ATFonlyfor AW-4 automatic transmis-
sions (XJ vehicles), and
²MOPAR ATF PLUS type 7176 (or an equivalent
MerconŸ/Dexron IIŸ ATF) for 998 automatic trans-
missions (YJ vehicles).
SPECIAL ADDITIVES
The addition of any special-type fluid to a Jeept
automatic transmission is not recommended. The
only exception is the addition of black-light detection
Fig. 5 AW-4 Automatic Transmission (XJ)
Fig. 4 Manual Transmission Fill- & Drain-Hole
PlugsÐTypical
JLUBRICATION AND MAINTENANCE 0 - 23

(2) Depending on fluid temperature, if the level is
below the FULL HOT mark or the FULL COLD
mark on the dipstick, add power steering fluid.
(3) Install the cap on the reservoir.
MANUAL STEERING GEARÐYJ VEHICLES
RECOMMENDED MAINTENANCE
The manual steering gear should be inspected for
damage at the same time as the engine oil is
changed and the oil filter is replaced. Repair as nec-essary (refer to Group 19ÐSteering for additional in-
formation and service procedures).
POWER BRAKE SYSTEM
RECOMMENDED MAINTENANCE
The condition of the brake system should be in-
spected and the fluid level in the master cylinder
should be checked each time the brake system is ser-
viced. Add brake fluid and repair as necessary.
In addition, the brake system should be operation-
ally tested periodically to ensure that it is function-
ing normally.
FLUID SPECIFICATION
Jeeptpower brake systems require MOPAR
Heavy-Duty Brake Fluid, or an equivalent product
identified as conforming to FMVSS No. 116, DOT-3
and SAE J-1703 specifications.
Usenew brake fluid onlywhen adding fluid to
the reservoir, to fill the brake system. Never use re-
claimed fluid.
BRAKE FLUID LEVEL
STANDARD POWER BRAKE SYSTEM
(1) Clean the cover and the sides of the brake fluid
reservoir.
(2) Detach the bail retainer from the reservoir
cover and remove the cover from the reservoir.
(3) The brake fluid level should be 6 mm (1/4 in)
below the rim of each reservoir well for XJ and YJ
Vehicles (Fig. 7). If not, add brake fluid as necessary.
(4) Inspect the reservoir cover bail retainer for ten-
sion and the cover for proper fit. The cover should fit
tight and have a good seal.
Fig. 4 Power Steering SystemÐXJ Vehicles
Fig. 5 Power Steering SystemÐYJ Vehicles
Fig. 6 Power Steering Fluid Reservoir
DipstickÐTypical
0 - 32 LUBRICATION AND MAINTENANCEJ

AXLE NOISE/VIBRATION DIAGNOSIS
INDEX
page page
Driveline Snap........................... 17
Gear and Bearing Noise................... 16
General Information....................... 16Low Speed Knock........................ 17
Vibration............................... 17
GENERAL INFORMATION
Axle bearing problem conditions are usually caused
by:
²Insufficient or incorrect lubricant
²Foreign matter/water contamination
²Incorrect bearing preload torque adjustment
²Incorrect backlash (to tight)
When serviced, the bearings must be cleaned thor-
oughly. They should be dried with lint-free shop tow-
els.Never dry bearings with compressed air.
This will overheat them and brinell the bearing
surfaces. This will result in noisy operation after
repair.
Axle gear problem conditions are usually the result
of:
²Insufficient lubrication
²Incorrect or contaminated lubricant
²Overloading (excessive engine torque) or exceeding
vehicle weight capacity
²Incorrect clearance or backlash adjustment
Insufficient lubrication is usually the result of a
housing cover leak. It can also be from worn axle
shaft or pinion gear seals. Check for cracks or porous
areas in the housing or tubes.
Using the wrong lubricant will cause overheating
and gear failure. Gear tooth cracking and bearing
spalling are indicators of this.
Axle component breakage is most often the result
of:
²Severe overloading
²Insufficient lubricant
²Incorrect lubricant
²Improperly tightened components
Overloading occurs when towing heavier than rec-
ommended loads. Component breakage can occur
when the wheels are spun excessively. Incorrect lu-
bricant quantity contributes to breakage. Loose dif-
ferential components can also cause breakage.
Incorrect bearing preload or gear backlash will not
result in component breakage. Mis-adjustment will
produce enough noise to cause service repair before a
failure occurs. If a mis-adjustment condition is not
corrected, component failure can result.
Excessive bearing preload may not be noisy. This
condition will cause high temperature which can re-
sult in bearing failure.
GEAR AND BEARING NOISE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant. Incorrect backlash, tooth contact, or worn/dam-
aged gears can cause noise.
Gear noise usually happens at a specific speed
range. The range is 30 to 40 mph, or above 50 mph.
The noise can also occur during a specific type of
driving condition. These conditions are acceleration,
deceleration, coast, or constant load.
When road testing, accelerate the vehicle to the
speed range where the noise is the greatest. Shift
out-of-gear and coast through the peak-noise range.
If the noise stops or changes greatly, check for insuf-
ficient lubricant. Incorrect ring gear backlash, or
gear damage can cause noise changes.
Differential side and pinion gears can be checked
by turning the vehicle. They usually do not cause
noise in straight-ahead driving. These gears are
loaded during vehicle turns. If noise does occur dur-
ing vehicle turns, the side or pinion gears could be
worn or damaged. A worn pinion gear mate shaft can
also cause a snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion gear bear-
ings can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
sound.
Pinion gear bearings have a constant-pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs the pinion rear bearing is
the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential
bearing noise is also constant and varies only with
vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
2 - 16 FRONT SUSPENSION AND AXLEJ

level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion gear shaft bore will also cause low speed
knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft
²Missing drive shaft balance weight
²Worn, out-of-balance wheels
²Loose wheel lug nuts
²Worn U-joint
²Loose spring U-bolts
²Loose/broken springs
²Damaged axle shaft bearings
²Loose pinion gear nut
²Excessive pinion yoke run out
²Bent axle shaft
Check for loose or damaged front-end components
or engine/transmission mounts. These componentscan contribute to what appears to be a rear-end vi-
bration. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined be-
fore starting any repair.
Refer to Group 22ÐTires And Wheels for addi-
tional information involving vibration diagnosis.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed
²Loose engine/transmission/transfer case mounts
²Worn U-joints
²Loose spring mounts
²Loose pinion gear nut and yoke
²Excessive ring gear backlash
²Excessive differential side gear-to-case clearance
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the ve-
hicle on a hoist with the wheels free to rotate.
Instruct the helper to shift the transmission into
gear. Listen for the noise, a mechanics stethoscope is
helpful in isolating the source of a noise.
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