engine CHRYSLER VOYAGER 2002 User Guide

Light spark knock at low engine speeds is not
harmful to your engine. However, continued heavy
spark knock at high speeds can cause damage and
immediate service is required. Engine damage result-
ing from operation with a heavy spark knock may
not be covered by the new vehicle warranty.
Poor quality gasoline can cause problems such as
hard starting, stalling and hesitations. If you experi-
ence these symptoms, try another brand of gasoline
before considering service for the vehicle.
Over 40 auto manufacturers world-wide have
issued and endorsed consistent gasoline specifications
(the Worldwide Fuel Charter, WWFC) to define fuel
properties necessary to deliver enhanced emissions,
performance and durability for your vehicle. We rec-
ommend the use of gasolines that meet the WWFC
specifications if they are available.
REFORMULATED GASOLINE
Many areas of the country require the use of
cleaner burning gasoline referred to as ªreformulat-
edº gasoline. Reformulated gasoline contain oxygen-
ates, and are specifically blended to reduce vehicle
emissions and improve air quality.
We strongly support the use of reformulated gaso-
line. Properly blended reformulated gasoline will pro-
vide excellent performance and durability for the
engine and fuel system components.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with
oxygenates such as 10% ethanol, MTBE, and ETBE.
Oxygenates are required in some areas of the country
during the winter months to reduce carbon monoxide
emissions. Fuels blended with these oxygenates may
be used in your vehicle.
CAUTION: DO NOT use gasoline containing METH-
ANOL. Gasoline containing methanol may damage
critical fuel system components.
MMT IN GASOLINE
MMT is a manganese-containing metallic additive
that is blended into some gasoline to increase octane.
Gasoline blended with MMT provide no performance
advantage beyond gasoline of the same octane num-
ber without MMT. Gasoline blended with MMT
reduce spark plug life and reduce emission system
performance in some vehicles. We recommend that
gasoline free of MMT be used in your vehicle. The
MMT content of gasoline may not be indicated on the
gasoline pump; therefore, you should ask your gaso-
line retailer whether or not his/her gasoline contains
MMT.
It is even more important to look for gasoline with-
out MMT in Canada because MMT can be used atlevels higher than allowed in the United States.
MMT is prohibited in Federal and California refor-
mulated gasoline.
SULFUR IN GASOLINE
If you live in the northeast United States, your
vehicle may have been designed to meet California
low emission standards with Cleaner-Burning Cali-
fornia reformulated gasoline with low sulfur. If such
fuels are not available in states adopting California
emission standards, your vehicles will operate satis-
factorily on fuels meeting federal specifications, but
emission control system performance may be
adversely affected. Gasoline sold outside of California
is permitted to have higher sulfur levels which may
affect the performance of the vehicle's catalytic con-
verter. This may cause the Malfunction Indicator
Lamp (MIL), Check Engine or Service Engine Soon
light to illuminate. We recommend that you try a dif-
ferent brand of unleaded gasoline having lower sulfur
to determine if the problem is fuel related prior to
returning your vehicle to an authorized dealer for
service.
CAUTION: If the Malfunction Indicator Lamp (MIL),
Check Engine or Service Engine Soon light is flash-
ing, immediate service is required; see on-board
diagnostics system section.
MATERIALS ADDED TO FUEL
All gasoline sold in the United States and Canada
are required to contain effective detergent additives.
Use of additional detergents or other additives is not
needed under normal conditions.
FUEL SYSTEM CAUTIONS
CAUTION: Follow these guidelines to maintain your
vehicle's performance:
²The use of leaded gas is prohibited by Federal
law. Using leaded gasoline can impair engine perfor-
mance, damage the emission control system, and
could result in loss of warranty coverage.
²An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your dealer for service assistance.
²When pulling a heavy load or driving a fully
loaded vehicle when the humidity is low and the tem-
perature is high, use a premium unleaded fuel to
help prevent spark knock. If spark knock persists,
lighten the load, or engine piston damage may result.
RSLUBRICATION & MAINTENANCE0-5
FLUID TYPES (Continued)
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²The use of fuel additives which are now being
sold as octane enhancers is not recommended. Most
of these products contain high concentrations of
methanol. Fuel system damage or vehicle perfor-
mance problems resulting from the use of such fuels
or additives is not the responsibility of
DaimlerChrysler Corporation and may not be covered
under the new vehicle warranty.
NOTE: Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
DESCRIPTION - FUEL REQUIREMENTS -
DIESEL ENGINE
WARNING: DO NOT USE ALCOHOL OR GASOLINE
AS A FUEL BLENDING AGENT. THEY CAN BE
UNSTABLE UNDER CERTAIN CONDITIONS AND
HAZARDOUS OR EXPLOSIVE WHEN MIXED WITH
DIESEL FUEL.
Use good quality diesel fuel from a reputable sup-
plier. For most year-round service, number 2 diesel
fuel meeting ASTM specification D-975 will provide
good performance. If the vehicle is exposed to
extreme cold (below -18ÉC/0ÉF) or is required to oper-
ate at colder than normal conditions for prolonged
periods, use climatize No. 2 diesel fuel or dilute the
No. 2 diesel fuel with 50% No. 1 diesel fuel. This will
provide better protection from fuel gelling or wax
plugging of the fuel filters.
Diesel fuel is seldom completely free of water. To
prevent fuel system trouble, including fuel line freez-
ing in winter, drain the accumulated water from the
fuel/water separator using the fuel/water separator
drain provided. If you buy good quality fuel and fol-
low the cold weather advice above, fuel conditioners
should not be required in your vehicle. If available in
your area, a high cetane ªpremiumº diesel fuel may
offer improved cold starting and warm up perfor-
mance.
DESCRIPTION - ENGINE OIL - DIESEL
ENGINES
Use only Diesel Engine Oil meeting standardMIL-
2104Cor API ClassificationCD or higherorCCML
D4, D5.
SAE VISCOSITY GRADE
CAUTION: Low viscosity oils must have the proper
API quality or the CCMC G5 designation.
To assure of properly formulated engine oils, it is
recommended that SAE Grade 10W-40 engine oilsthat meet Chrysler material standard MS-6395, be
used. European Grade 10W-40 oils are also accept-
able.
Oils of the SAE 5W-40 or 8W-80 grade number are
preferred when minimum temperatures consistently
fall below -12ÉC.
FLUID FILL/CHECK
LOCATIONS
DESCRIPTION
The fluid check/fill point locations are located in
each applicable service manual section.
LUBRICATION POINTS
DESCRIPTION
Lubrication point locations are located in each
applicable Sections.
MAINTENANCE SCHEDULES
DESCRIPTION
9Maintenance Schedule Information not included in
this section, is located in the appropriate Owner's
Manual.9
HOISTING
STANDARD PROCEDURE - HOISTING
Refer to Owner's Manual provided with vehicle for
proper emergency jacking procedures.
WARNING: THE HOISTING AND JACK LIFTING
POINTS PROVIDED ARE FOR A COMPLETE VEHI-
CLE. WHEN THE ENGINE OR REAR SUSPENSION
IS REMOVED FROM A VEHICLE, THE CENTER OF
GRAVITY IS ALTERED MAKING SOME HOISTING
CONDITIONS UNSTABLE. PROPERLY SUPPORT OR
SECURE VEHICLE TO HOISTING DEVICE WHEN
THESE CONDITIONS EXIST.
CAUTION: Do not position hoisting device on any
suspension component, including the front suspen-
sion crossmember, the rear leaf springs, and the
rear axle. Do not hoist on the front and rear
bumpers, the lower liftgate crossmember, the lower
radiator crossmember, the down standing flanges
on the sill or the front engine mount.
FOR PROPER HOIST PLACEMENT REFER
TO (Fig. 5).
0 - 6 LUBRICATION & MAINTENANCERS
FLUID TYPES (Continued)
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The hoisting points are identified by S.A.E.
inverted triangle hoisting symbols (Fig. 5). The front
hoisting points are at the bottom of the font rail
below the hoisting symbol approximately 250 mm
behind the front suspension crossmember. When
using outboard lift hoists, verify that the hoist lift
pads have been properly adjusted to eliminate con-
tact between the hoist arm and the down standing
flange on the sill. The rear hoisting points are the
leaf spring front mounting brackets. The hoist pad
must be positioned to pick up the flanges on the
bracket, not the leaf spring.
When servicing the leaf springs or the leaf spring
mounting brackets, special provisions are required to
support the rear of the vehicle. Position the rear
hoist pads under the horizontal surface on the bot-
tom of the sill, inboard adjacent to the flange and
centered fore/aft between the jacking indicator tabs
on the lower flange.DO NOT HOIST ON THE
FLANGE.Place a soft pad between the hoist and the
painted surface on the sill to avoid scratching the fin-
ish.JUMP STARTING
STANDARD PROCEDURE - JUMP STARTING
WARNING: REVIEW ALL SAFETY PRECAUTIONS
AND WARNINGS. (Refer to 8 - ELECTRICAL/BAT-
TERY SYSTEM/BATTERY - STANDARD PROCE-
DURE).
WARNING: DO NOT JUMP START A FROZEN BAT-
TERY, PERSONAL INJURY CAN RESULT.
WARNING: DO NOT JUMP START WHEN MAINTE-
NANCE FREE BATTERY INDICATOR DOT IS BRIGHT
COLOR.
WARNING: DO NOT ALLOW JUMPER CABLE
CLAMPS TO TOUCH EACH OTHER WHEN CON-
NECTED TO A BOOSTER SOURCE.
WARNING: DO NOT USE OPEN FLAME NEAR BAT-
TERY
WARNING: REMOVE METALLIC JEWELRY WORN
ON HANDS OR WRISTS TO AVOID INJURY BY
ACCIDENTAL ARCING OF BATTERY CURRENT.
WARNING: WHEN USING A HIGH OUTPUT BOOST-
ING DEVICE, DO NOT ALLOW BATTERY VOLTAGE
TO EXCEED 16 VOLTS.
WARNING: REFER TO INSTRUCTIONS PROVIDED
WITH DEVICE BEING USED.
CAUTION: DO NOT ATTEMPT TO PUSH OR TOW
THE VEHICLE TO START IT. THE VEHICLE CANNOT
BE STARTED THIS WAY. PUSHING WITH ANOTHER
VEHICLE MAY DAMAGE THE TRANSAXLE OR THE
REAR OF THE VEHICLE.
(1) Raise hood on disabled vehicle and visually
inspect engine compartment for:
²Battery cable clamp condition, clean if necessary.
²Frozen battery.
²Clear or bright color test indicator, if equipped.
²Generator drive belt condition and tension.
²Fuel fumes or leakage, correct if necessary.
CAUTION: If the cause of starting problem on dis-
abled vehicle is severe, damage to booster vehicle
charging system can result.
Fig. 5 HOISTING AND JACKING POINTS
1- DRIVE ON LIFT
2 - FRAME CONTACT LIFT (SINGLE POST)
2 - CHASSIS LIFT (NON-AXLE DUAL POST)
2 - OUTBOARD LIFT (DUAL POST)
2 - FLOOR JACK
3 - S.A.E. HOISTING SYMBOLS
RSLUBRICATION & MAINTENANCE0-7
HOISTING (Continued)
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(2) When using another vehicle as a booster
source, park the booster vehicle within cable reach.
Turn off all accessories, set the parking brake, place
the automatic transmission in PARK or the manual
transmission in NEUTRAL and turn the ignition
OFF.
(3) On disabled vehicle, place gear selector in park
or neutral and set park brake. Turn off all accesso-
ries.
(4) Connect jumper cables to booster battery. RED
clamp to positive terminal (+). BLACK clamp to neg-
ative terminal (-). DO NOT allow clamps at opposite
end of cables to touch, electrical arc will result.
Review all warnings in this procedure.
(5) On disabled vehicle, connect RED jumper cable
clamp to positive (+) terminal. Connect BLACK
jumper cable clamp to engine ground as close to the
ground cable attaching point as possible (Fig. 6).
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - STANDARD PROCEDURE).
(6) Start the engine in the vehicle which has the
booster battery, let the engine idle a few minutes,
then start the engine in the vehicle with the dis-
charged battery.
CAUTION: Do not crank starter motor on disabled
vehicle for more than 15 seconds, starter may over-
heat and could fail.
(7) If engine does not start within 15 seconds, stop
cranking engine and allow starter to cool (15 min-
utes), before cranking again.DISCONNECT CABLE CLAMPS AS FOLLOWS:
²Disconnect BLACK cable clamp from engine
ground on disabled vehicle.
²When using a Booster vehicle, disconnect
BLACK cable clamp from battery negative terminal.
Disconnect RED cable clamp from battery positive
terminal.
²Disconnect RED cable clamp from battery posi-
tive terminal on disabled vehicle.
TOWING
STANDARD PROCEDURE - TOWING
WARNINGS AND CAUTIONS
WARNING: DO NOT ALLOW TOWING ATTACHMENT
DEVICES TO CONTACT THE FUEL TANK OR LINES,
FUEL LEAK CAN RESULT.
DO NOT LIFT OR TOW VEHICLE BY FRONT OR
REAR BUMPER.
DO NOT GO UNDER A LIFTED VEHICLE IF NOT
SUPPORTED PROPERLY ON SAFETY STANDS.
DO NOT ALLOW PASSENGERS TO RIDE IN A
TOWED VEHICLE.
USE A SAFETY CHAIN THAT IS INDEPENDENT
FROM THE TOWING ATTACHMENT DEVICE.
CAUTION: Do not damage brake lines, exhaust sys-
tem, shock absorbers, sway bars, or any other
under vehicle components when attaching towing
device to vehicle.
Do not secure vehicle to towing device by the use
of front or rear suspension or steering components.
Remove or secure loose or protruding objects from
a damaged vehicle before towing.
Refer to state and local rules and regulations before
towing a vehicle.
Do not allow weight of towed vehicle to bear on
lower fascia, air dams, or spoilers.
RECOMMENDED TOWING EQUIPMENT
To avoid damage to bumper fascia and air dams
use:
²FWD vehicles, use of a flat bed towing device or
a wheel lift is recommended (Fig. 7).
²AWD vehicles, a flat bed towing device or a
wheel lift and towing dolly is recommended (Fig. 7).
When using a wheel lift towing device, be sure the
disabled vehicle has at least 100 mm (4 in.) ground
clearance. If minimum ground clearance cannot be
reached, use a towing dolly. If a flat bed device is
used, the approach angle should not exceed 15
degrees.
Fig. 6 JUMPER CABLE CLAMP CONNECTIONS
1 - BATTERY NEGATIVE TERMINAL
2 - POSITIVE JUMPER CABLE
3 - TEST INDICATOR (IF EQUIPPED)
4 - BATTERY POSITIVE TERMINAL
5 - BATTERY
6 - NEGATIVE JUMPER CABLE
0 - 8 LUBRICATION & MAINTENANCERS
JUMP STARTING (Continued)
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GROUND CLEARANCE
CAUTION: If vehicle is towed with wheels removed,
install lug nuts to retain brake drums or rotors.
A towed vehicle should be raised until the lifted
wheels are a minimum 100 mm (4 in.) from the
ground. Be sure there is at least 100 mm (4 in.)
clearance between the tail pipe and the ground. If
necessary, remove the wheels from the front end of
the vehicle and lower the front end closer to the
ground, to increase the ground clearance at the rear
of the vehicle. Install lug nuts on wheel attaching
studs to retain brake drums or rotors.
LOCKED VEHICLE TOWING
When a locked vehicle must be towed with the
front wheels on the ground, use a towing dolly or flat
bed hauler.
FLAT TOWING WITH TOW BAR
²Three speed automatic transaxle vehicles can be
flat towed at speeds not to exceed 40 km/h (25 mph)
for not more than 25 km (15 miles). The steering col-
umn must be unlocked and gear selector in neutral.
²Four speed electronic automatic transaxle vehi-
cles can be flat towed at speeds not to exceed 72
km/h (44 mph) for not more than 160 km (100 miles).
The steering column must be unlocked and gear
selector in neutral.
²AWD models should not be flat towed. For addi-
tional information, refer toRECOMMENDED TOW-
ING EQUIPMENTin this section.
FLAT BED TOWING TIE DOWNS
CAUTION: Do not tie vehicle down by attaching
chains or cables to suspension components or
engine mounts, damage to vehicle can result.
The vehicle can be tied to a flat bed device using
the two pair of front slots on the bottom surface of
the rails, behind the front wheels. The two pair of
rear slots on the bottom of the rail between the
bumper extension bolts and on the bottom of the rail
just rearward of the jounce bumper. Vehicles
equipped with a rear sway bar have brackets at this
location.
TOWING ± FRONT WHEEL LIFT
If the vehicle is being towed from the front, when-
ever possible ensure at least 10 inches road clearance
to the tires.
TOWING ± REAR WHEEL LIFT
If a vehicle cannot be towed with the front wheels
lifted, the rear wheels can be lifted provided the fol-
lowing guide lines are observed.
CAUTION: Do not use steering column lock to
secure steering wheel during towing operation.
²On AWD vehicles, all four wheels must be free to
rotate. Use towing dollies at unlifted end of vehicle.
²Unlock steering column and secure steering
wheel in straight ahead position with a clamp device
designed for towing.
²Three speed automatic transaxle vehicles can be
flat towed at speeds not to exceed 40 km/h (25 mph)
for not more than 25 km (15 miles). The steering col-
umn must be unlocked and gear selector in neutral.
²Four speed electronic automatic transaxle vehi-
cles can be flat towed at speeds not to exceed 72
km/h (44 mph) for not more than 160 km (100 miles).
The steering column must be unlocked and gear
selector in neutral.
Fig. 7 RECOMMENDED TOWING
1 - WHEEL LIFT
2 - FLAT BED
RSLUBRICATION & MAINTENANCE0-9
TOWING (Continued)
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THRUST ANGLE
Thrust angle is the averaged direction the rear
wheels are pointing in relation to the vehicle's center
line (Fig. 6). The presence of negative or positive
thrust angle causes the rear tires to track improperly
to the left or right of the front tires (dog tracking).
²Negative thrust angle means the rear tires are
tracking to the left of the front tires.
²Positive thrust angle means the rear tires are
tracking to the right of the front tires.
Improper tracking can cause undue tire wear, a
lead or pull and a crooked steering wheel. Excessive
thrust angle can usually be corrected by adjusting
the rear wheel toe so that each wheel has one-half of
the total toe measurement.
DIAGNOSIS AND TESTING - SUSPENSION AND STEERING
CONDITION POSSIBLE CAUSES CORRECTION
Front End Whine On Turns 1. Defective wheel bearing 1. Replace wheel bearing
2. Incorrect wheel alignment 2. Check and reset wheel alignment
3. Worn tires 3. Replace tires
Front End Growl Or
Grinding On Turns1. Defective wheel bearing 1. Replace wheel bearing
2. Engine mount grounding 2. Check for motor mount hitting frame rail
and reposition engine as required
3. Worn or broken C/V joint 3. Replace C/V joint
4. Loose wheel lug nuts 4. Verify wheel lug nut torque
5. Incorrect wheel alignment 5. Check and reset wheel alignment
6. Worn tires 6. Replace tires
7. Front strut pin in upper strut mount 7. Replace the front strut upper mount and
bearing
Front End Clunk Or Snap
On Turns1. Loose lug nuts 1. Verify wheel lug nut torque
2. Worn or broken C/V joint 2. Replace C/V joint
3. Worn or loose tie rod 3. Tighten or replace tie rod end
4. Worn or loose ball joint 4. Tighten or replace ball joint
5. Worn/loose control arm bushing 5. Replace control arm bushing
6. Loose stabilizer bar. 6. Tighten stabilizer bar to specified torque
Fig. 6 Thrust Angle
RSWHEEL ALIGNMENT2-49
WHEEL ALIGNMENT (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
7. Loose strut mount to body
attachment7. Tighten strut attachment to specified
torque
8. Loose crossmember bolts 8. Tighten crossmember bolts to specified
torque
Front End Whine With
Vehicle Going Straight At A
Constant Speed1. Defective wheel bearing 1. Replace wheel bearing
2. Incorrect wheel alignment 2. Check and reset wheel alignment
3. Worn tires 3. Replace tires
4. Worn or defective transaxle gears
or bearings4. Replace transaxle gears or bearings
Front End Growl Or
Grinding With Vehicle
Going Straight At A
Constant Speed1. Engine mount grounding 1. Reposition engine as required
2. Worn or broken C/V joint 2. Replace C/V joint
Front End Whine When
Accelerating Or
Decelerating1. Worn or defective transaxle gears
or bearings1. Replace transaxle gears or bearings
Front End Clunk When
Accelerating Or
Decelerating1. Worn or broken engine mount 1. Replace engine mount
2. Worn or defective transaxle gears
or bearings2. Replace transaxle gears or bearings
3. Loose lug nuts 3. Verify wheel lug nut torque
4. Worn or broken C/V joint 4. Replace C/V joint
5. Worn or loose ball joint 5. Tighten or replace ball joint
6. Worn or loose control arm bushing 6. Replace control arm bushing
7. Loose crossmember bolts 7. Tighten crossmember bolts to specified
torque
8. Worn tie rod end 8. Replace tie rod end
Road Wander 1. Incorrect tire pressure 1. Inflate tires to recommended pressure
2. Incorrect front or rear wheel toe 2. Check and reset wheel toe
3. Worn wheel bearings 3. Replace wheel bearing
4. Worn control arm bushings 4. Replace control arm bushing
5. Excessive friction in steering gear 5. Replace steering gear
6. Excessive friction in steering shaft
coupling6. Replace steering coupler
7. Excessive friction in strut upper
bearing7. Replace strut bearing
Lateral Pull 1. Unequal tire pressure 1. Inflate all tires to recommended
pressure
2. Radial tire lead 2. Perform lead correction procedure
2 - 50 WHEEL ALIGNMENTRS
WHEEL ALIGNMENT (Continued)
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²Wheel bearings
²Engine
²Transmission
²Exhaust
²Propeller shaft (vibration)
²Vehicle body (drumming)
Driveline module noises are normally divided into
two categories: gear noise or bearing noise. A thor-
ough and careful inspection should be completed to
determine the actual source of the noise before
replacing the driveline module.
The rubber mounting bushings help to dampen-out
driveline module noise when properly installed.
Inspect to confirm that no metal contact exists
between the driveline module case and the body. The
complete isolation of noise to one area requires
expertise and experience. Identifying certain types of
vehicle noise baffles even the most capable techni-
cians. Often such practices as:
²Increase tire inflation pressure to eliminate tire
noise.
²Listen for noise at varying speeds with different
driveline load conditions
²Swerving the vehicle from left to right to detect
wheel bearing noise.
All driveline module assemblies produce noise to a
certain extent. Slight carrier noise that is noticeable
only at certain speeds or isolated situations should be
considered normal. Carrier noise tends to peak at a
variety of vehicle speeds. Noise isNOT ALWAYSan
indication of a problem within the carrier.
TIRE NOISE
Tire noise is often mistaken for driveline module
noise. Tires that are unbalanced, worn unevenly or
are worn in a saw-tooth manner are usually noisy.
They often produce a noise that appears to originate
in the driveline module.
Tire noise changes with different road surfaces, but
driveline module noise does not. Inflate all four tires
with approximately 20 psi (138 kPa) more than the
recommended inflation pressure (for test purposes
only). This will alter noise caused by tires, but will
not affect noise caused by the differential. Rear axle
noise usually ceases when coasting at speeds less
than 30 mph (48 km/h); however, tire noise contin-
ues, but at a lower frequency, as the speed is
reduced.
After test has been completed lower tire pressure
back to recommended pressure.
GEAR NOISE (DRIVE PINION AND RING GEAR)
Abnormal gear noise is rare and is usually caused
by scoring on the ring gear and drive pinion. Scoring
is the result of insufficient or incorrect lubricant in
the carrier housing.Abnormal gear noise can be easily recognized. It
produces a cycling tone that will be very pronounced
within a given speed range. The noise can occur dur-
ing one or more of the following drive conditions:
²Drive
²Road load
²Float
²Coast
Abnormal gear noise usually tends to peak within
a narrow vehicle speed range or ranges. It is usually
more pronounced between 30 to 40 mph (48 to 64
km/h) and 50 to 60 mph (80 to 96 km/h). When objec-
tionable gear noise occurs, note the driving condi-
tions and the speed range.
BEARING NOISE (DRIVE PINION AND
DIFFERENTIAL)
Defective bearings produce a rough growl that is
constant in pitch and varies with the speed of vehi-
cle. Being aware of this will enable a technician to
separate bearing noise from gear noise.
Drive pinion bearing noise that results from defec-
tive or damaged bearings can usually be identified by
its constant, rough sound. Drive pinion front bearing
is usually more pronounced during a coast condition.
Drive pinion rear bearing noise is more pronounced
during a drive condition. The drive pinion bearings
are rotating at a higher rate of speed than either the
differential side bearings or the axle shaft bearing.
Differential side bearing noise will usually produce
a constant, rough sound. The sound is much lower in
frequency than the noise caused by drive pinion bear-
ings.
Bearing noise can best be detected by road testing
the vehicle on a smooth road (black top). However, it
is easy to mistake tire noise for bearing noise. If a
doubt exists, the tire treads should be examined for
irregularities that often causes a noise that resem-
bles bearing noise.
ENGINE AND TRANSMISSION NOISE
Sometimes noise that appears to be in the driv-
eline module assembly is actually caused by the
engine or the transmission. To identify the true
source of the noise, note the approximate vehicle
speed and/or RPM when the noise is most noticeable.
Stop the vehicle next to a flat brick or cement wall
(this will help reflect the sound). Place the transaxle
inNEUTRAL. Accelerate the engine slowly up
through the engine speed that matches the vehicle
speed noted when the noise occurred. If the same
noise is produced, it usually indicates that the noise
is being caused by the engine or transaxle.
3 - 26 REAR DRIVELINE MODULERS
REAR DRIVELINE MODULE (Continued)
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BI-DIRECTIONAL
OVERRUNNING CLUTCH
DESCRIPTION
The bi-directional overrunning clutch (BOC) (Fig.
28) works as a mechanical disconnect between the
front and rear axles, preventing torque from being
transferred from the rear axle to the front. The BOC
is a simply an overrunning clutch which works in
both clockwise and counter-clockwise rotations. This
means that when the output (the rear axle) is rotat-
ing faster in one direction than the input (front axle),
there is no torque transmission. But when the input
speed is equal to the output speed, the unit becomes
locked. The BOC provides significant benefits regard-
ing braking stability, handling, and driveline durabil-
ity. Disconnecting the front and the rear driveline
during braking helps to maintain the braking stabil-
ity of an AWD vehicle. In an ABS/braking event, the
locking of the rear wheels must be avoided for stabil-
ity reasons. Therefore brake systems are designed to
lock the front wheels first. Any torque transfer from
the rear axle to the front axle disturbs the ABS/brak-
ing system and causes potential instabilities on aslippery surface. The BOC de-couples the rear driv-
eline as soon the rear wheels begin to spin faster
than the front wheels (front wheels locked) in order
to provide increased braking stability. Furthermore
the BOC also reduces the likelihood of throttle off
over-steer during cornering. In a throttle off maneu-
ver, the BOC once again de-couples the rear driveline
forcing all the engine brake torque to the front
wheels. This eliminates the chance of lateral slip on
the rear axle and increases it on the front. The vehi-
cle will therefore tend to understeer, a situation
which is considered easier to manage in most circum-
stances. During this maneuver, and during the ABS
braking event, the BOC does not transmit torque
through to the rear wheels. The rear driveline mod-
ule, with the BOC, will perform the same as a front
wheel drive vehicle during these events. The gear
ratio offset between the front and rear differentials
force the BOC into the overrunning mode most of the
time. This allows BOC to significantly reduce the
rolling resistance of the vehicle, which improves fuel
consumption, allows the downsizing of the driveline
components, and prevents the PTU and propshaft
joints from overheating.
3 - 36 REAR DRIVELINE MODULERS
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CONDITION POSSIBLE CAUSES CORRECTION
EXCESSIVE PEDAL
TRAVEL (ONE FRONT
WHEEL LOCKS UP
DURING HARD BRAKING)1. One of the two hydraulic circuits
to the front brakes is malfunctioning.1. Inspect system for leaks. Check
master cylinder for internal malfunction.
PEDAL PULSATES/
SURGES DURING
BRAKING1. Rear brake drum out of round or
disc brake rotor has excessive
thickness variation.1. Isolate condition as rear or front.
Reface or replace brake drums or
rotors as necessary.
PEDAL IS SPONGY 1. Air in brake lines. 1. Bleed brakes.
2. Power brake booster runout
(vacuum assist).2. Check booster vacuum hose and
engine tune for adequate vacuum
supply. Refer to power brake booster
diagnosis and testing.
PREMATURE REAR
WHEEL LOCKUP1. Contaminated brake shoe linings. 1. Inspect and clean, or replace shoes.
Repair source of contamination.
2. Inoperative proportioning valve
(non-ABS vehicles).2. Refer to proportioning valve
diagnosis and testing. Replace valve as
necessary.
3. Improper power brake booster
assist.3. Refer to power brake booster in the
diagnosis and testing section.
STOP/BRAKE LAMPS
S TAY O N1. Brake lamp switch out of
adjustment.1. Replace brake lamp switch.
2. Brake pedal binding. 2. Inspect and replace as necessary.
3. Obstruction in pedal linkage. 3. Remove obstruction.
4. Power Brake Booster not allowing
pedal to return completely.4. Replace power brake booster.
VEHICLE PULLS TO
RIGHT OR LEFT ON
BRAKING1. Frozen brake caliper piston. 1. Replace frozen piston or caliper.
Bleed brakes.
2. Contaminated brake shoe lining. 2. Inspect and clean, or replace shoes.
Repair source of contamination.
3. Pinched brake lines. 3. Replace pinched line.
4. Leaking piston seal. 4. Replace piston seal or brake caliper.
5. Suspension problem. 5. Refer to the Suspension group.
PARKING BRAKE -
EXCESSIVE HANDLE
TRAVEL1. Rear drum brakes or rear disc
brake parking brake shoes out of
adjustment.1. Adjust rear drum brake shoes, or
rear parking brake shoes on vehicles
with rear disc brakes.
STANDARD PROCEDURE - BASE BRAKE
BLEEDING
NOTE: This bleeding procedure is only for the vehi-
cle's base brakes hydraulic system. For bleeding
the antilock brakes hydraulic system, (Refer to 5 -
BRAKES - ABS - STANDARD PROCEDURE)CAUTION: Before removing the master cylinder
cover, thoroughly clean the cover and master cylin-
der fluid reservoir to prevent dirt and other foreign
matter from dropping into the master cylinder fluid
reservoir.
RSBRAKES - BASE5-7
BRAKES - BASE (Continued)
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