engine MERCEDES-BENZ SPRINTER 2005 Service Owner's Manual

A worn, damaged wheel bearing or suspension
component are further causes of pull. A damaged
front tire (bruised, ply separation) can also cause
pull.
A common and frequently misdiagnosed pull condi-
tion is where direction of pull changes after a few
stops. The cause is a combination of brake drag fol-
lowed by fade at one of the brake units.
As the dragging brake overheats, efficiency is so
reduced that fade occurs. Since the opposite brake
unit is still functioning normally, its braking effect is
magnified. This causes pull to switch direction in
favor of the normally functioning brake unit.
An additional point when diagnosing a change in
pull condition concerns brake cool down. Remember
that pull will return to the original direction, if the
dragging brake unit is allowed to cool down (and is
not seriously damaged).
REAR BRAKE GRAB OR PULL
Rear grab or pull is usually caused by improperly
adjusted or seized parking brake cables, contami-
nated lining, bent or binding shoes and support
plates, or improperly assembled components. This is
particularly true when only one rear wheel is
involved. However, when both rear wheels are
affected, the master cylinder or proportioning valve
could be at fault.
BRAKES DO NOT HOLD AFTER DRIVING THROUGH DEEP
WATER PUDDLES
This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by
driving with the brakes very lightly applied for a
mile or two. However, if the lining is both soaked and
dirt contaminated, cleaning and/or replacement will
be necessary.
BRAKE LINING CONTAMINATION
Brake lining contamination is mostly a product of
leaking calipers or worn seals, driving through deep
water puddles, or lining that has become covered
with grease and grit during repair. Contaminated lin-
ing should be replaced to avoid further brake prob-
lems.
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 grab-like condition as the tire loses and
recovers traction. Flat-spotted tires can cause vibra-
tion and generate shudder during brake operation. A
tire with internal damage such as a severe bruise,
cut, or ply separation can cause pull and vibration.BRAKE NOISES
Some brake noise is common with rear drum
brakes and on some disc brakes during the first few
stops after a vehicle has been parked overnight or
stored. This is primarily due to the formation of trace
corrosion (light rust) on metal surfaces. This light
corrosion is typically cleared from the metal surfaces
after a few brake applications causing the noise to
subside.
BRAKE 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 brake pads in spots, metal-to-metal
contact occurs. If the condition is allowed to continue,
rotors can become so scored that replacement is nec-
essary.
BRAKE CHATTER
Brake chatter is usually caused by loose or worn
components, or glazed/burnt lining. Rotors with hard
spots can also contribute to chatter. Additional causes
of chatter are out-of-tolerance rotors, brake lining not
securely attached to the shoes, loose wheel bearings
and contaminated brake lining.
THUMP/CLUNK NOISE
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. However,
calipers that bind on the slide surfaces can generate
a thump or clunk noise.
STANDARD PROCEDURE
STANDARD PROCEDURE - MANUAL BLEEDING
Use Mopar brake fluid, or an equivalent quality
fluid meeting SAE and DOT 4 standards only. Use
fresh, clean fluid from a sealed container at all times.
(1) Remove reservoir filler caps and fill reservoir.
(2) If calipers, or wheel cylinders were overhauled,
open all caliper and wheel cylinder bleed screws.
Then close each bleed screw as fluid starts to drip
from it. Top off master cylinder reservoir once more
before proceeding.
(3) Attach one end of bleed hose to bleed screw
and insert opposite end in glass container partially
filled with brake fluid (Fig. 1). Be sure end of bleed
hose is immersed in fluid.
5 - 4 BRAKES - BASEVA
BRAKES - BASE (Continued)

INSTALLATION
INSTALLATION - FRONT
(1) Install the brake caliper adapter to the steering
knuckle. Tighten to 170 N´m (125 ft. lbs.).
(2) Install the disc brake shoes (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/BRAKE
PADS/SHOES - INSTALLATION).
NOTE: Do not install the brake hose twisted and
ensure freedom of movement.
(3) Install the disc brake caliper. Tighten the bolt
to 14 N´m (124 in. lbs.) (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/DISC BRAKE CALIPERS
- INSTALLATION).
(4) Install the front wheels (Refer to 22 - TIRES/
WHEELS/WHEELS - INSTALLATION).
(5) Lower the vehicle.
INSTALLATION - REAR
(1) Install the brake caliper adapter to the axle
mount. Tighten to 90 N´m (66 ft. lbs.) for M12X1.5
bolt or 170 N´m (125 ft. lbs.) for M14X1.5 bolt.
(2) Install the disc brake pads (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/BRAKE
PADS/SHOES - INSTALLATION).
NOTE: Do not install the brake hose twisted and
ensure freedom of movement.
(3) Install the disc brake caliper (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/DISC
BRAKE CALIPERS - INSTALLATION).
(4) Install the rear wheels (Refer to 22 - TIRES/
WHEELS/WHEELS - INSTALLATION).
(5) Lower the vehicle.
FLUID
DIAGNOSIS AND TESTING - BRAKE FLUID
CONTAMINATION
Indications of fluid contamination are swollen or
deteriorated rubber parts.
Swollen rubber parts indicate the presence of
petroleum in the brake fluid.
To test for contamination, put a small amount of
drained brake fluid in clear glass jar. If fluid sepa-
rates into layers, there is mineral oil or other fluid
contamination of the brake fluid.
If brake fluid is contaminated, drain and thor-
oughly flush system. Replace master cylinder, ALB
Controller, caliper seals, Antilock Brakes hydraulic
unit and all hydraulic fluid hoses.
STANDARD PROCEDURE - BRAKE FLUID
LEVEL
Always clean the master cylinder reservoir and
caps before checking fluid level. If not cleaned, dirt
could enter the fluid.
The fluid fill level is indicated on the side of the
master cylinder reservoir (Fig. 13).
The correct fluid level is to the MAX indicator on
the side of the reservoir. If necessary, add fluid to the
proper level.
SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 4 specifications and SAE standards. No other
type of brake fluid is recommended or approved for
usage in the vehicle brake system. Use only Mopar
brake fluid or an equivalent from a tightly sealed
container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. An
open container of brake fluid will absorb moisture
from the air and contaminate the fluid.
CAUTION: Never use any type of a petroleum-based
fluid in the brake hydraulic system. Use of such
type fluids will result in seal damage of the vehicle
brake hydraulic system causing a failure of the
vehicle brake system. Petroleum based fluids would
be items such as engine oil, transmission fluid,
power steering fluid, etc.
Fig. 13 FLUID LEVEL TYPICAL
1 - FLUID RESERVOIR
2 - MAX LEVEL MARK
5 - 14 BRAKES - BASEVA
DISC BRAKE CALIPER ADAPTER (Continued)

(8) Raise the vehicle and adjust the ALB controller
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
ALB CONTROLLER - ADJUSTMENTS).
(9) Lower the vehicle and test drive.
ADJUSTMENTS
ADJUSTMENT
(1) Clean any debris away from the test ports caps
at the ALB controller.
(2) Connect brake adapters special tool 9297 to the
test ports at the ALB controller.
(3) Install a Pressure Gauge, Special Tool
C-4007-A, to the adapters.
(4) Tighten all tube nut fittings to 17 N´m (145 in.
lbs.) torque.
(5) Bleed any air out of the system. This includes
bleeding the air from the hose between the pressure
test fitting and pressure gauge, which is done at the
pressure gauge.
NOTE: Adjustment is determined for the automatic
load-dependent brake power control system accord-
ing to the ALB plate. This is housed in the stowage
compartment under the front passenger's door
panel. The part number of the rear spring is
stamped into the spring eye. This must correspond
to the part number of the rear spring on the ALB
plate.
(6) To accurately adjust the rear axle load you
must first determine the rear axle load by weighing
the vehicle at a local scale.
(7) Install the brake pedal winch Special tool 9296
between the brake pedal and the driver seat and
slowly turn the dial until the specified inlet brake
pressure is indicated at the gauge.
NOTE: The pressure gauge, connected at the ALB
controller must indicate the outlet pressure which
is assigned on the ALB plate to the rear axle load
determined.
NOTE: If the rear axle load determined is between
two figures indicated on the ALB plate, the outlet
pressure should be determined accordingly.
(8) If the pressure measured differs from the spec-
ification, adjust the ALB controller (Fig. 16).
(9) Loosen the brake pedal winch.
(10) Adjust the outlet pressure by turning the
adjusting nut (Fig. 16)To increase pressure -
tighten the adjusting nut. To reduce pressure -
loosen the adjusting nut.(11) After adjustment reinstall the brake pedal
winch and recheck the pressures and readjust if
needed.
(12) Tighten the lock adjusting nut.
MASTER CYLINDER
DIAGNOSIS AND TESTING - MASTER
CYLINDER/POWER BOOSTER
(1) Start engine and check booster vacuum hose
connections. A hissing noise indicates vacuum leak.
Correct any vacuum leak before proceeding.
(2) Stop engine and shift transmission into Neu-
tral.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure. The pedal should hold firm, if the pedal
falls away master cylinder is faulty (internal leak-
age).
(5) Start engine and note pedal action. It should
fall away slightly under light foot pressure then hold
firm. If no pedal action is discernible, power booster,
vacuum supply, or vacuum check valve is faulty. Pro-
ceed to the POWER BOOSTER VACUUM TEST.
(6) If the POWER BOOSTER VACUUM TEST
passes, rebuild booster vacuum reserve as follows:
Release brake pedal. Increase engine speed to 1500
rpm, close the throttle and immediately turn off igni-
tion to stop engine.
(7) Wait a minimum of 90 seconds and try brake
action again. Booster should provide two or more vac-
uum assisted pedal applications. If vacuum assist is
not provided, booster is faulty.
Fig. 16 ALB CONTROLLER ADJUSTER NUT
1 - ALB ADJUSTER NUT
2 - SPRING
5 - 16 BRAKES - BASEVA
ALB CONTROLLER (Continued)

POWER BOOSTER VACUUM TEST
(1) Connect vacuum gauge to booster check valve
with short length of hose and T-fitting (Fig. 17).
(2) Start and run engine at curb idle speed for one
minute.
(3) Observe the vacuum supply. If vacuum supply
is not adequate, repair vacuum supply.
(4) Clamp hose shut between vacuum source and
check valve.
(5) Stop engine and observe vacuum gauge.
(6) If vacuum drops more than one inch HG (33
millibars) within 15 seconds, booster diaphragm or
check valve is faulty.
POWER BOOSTER CHECK VALVE TEST
(1) Disconnect vacuum hose from check valve.
(2) Remove check valve and valve seal from
booster.
(3) Use a hand operated vacuum pump for test.
(4) Apply 15-20 inches vacuum at large end of
check valve (Fig. 18).
(5) Vacuum should hold steady. If gauge on pump
indicates vacuum loss, check valve is faulty and
should be replaced.
STANDARD PROCEDURE - MASTER CYLINDER
BLEEDING
A new master cylinder should be bled before instal-
lation on the vehicle. Required bleeding tools include
bleed tubes and a wood dowel to stroke the pistons.
Bleed tubes can be fabricated from brake line.
(1) Mount master cylinder in vise.
(2) Attach bleed tubes to cylinder outlet ports.
Then position each tube end into reservoir (Fig. 19).
(3) Fill reservoir with fresh brake fluid.
(4) Press cylinder pistons inward with wood dowel.
Then release pistons and allow them to return under
spring pressure. Continue bleeding operations until
air bubbles are no longer visible in fluid.
REMOVAL
(1) Using a suction gun remove as much brake
fluid from the reservoir as possible (Fig. 20).
Fig. 17 Typical Booster Vacuum Test Connections
1 - TEE FITTING
2 - SHORT CONNECTING HOSE
3 - CHECK VALVE
4 - CHECK VALVE HOSE
5 - CLAMP TOOL
6 - INTAKE MANIFOLD
7 - VACUUM GAUGE
Fig. 18 Vacuum Check Valve And Seal
1 - BOOSTER CHECK VALVE
2 - APPLY TEST VACUUM HERE
3 - VALVE SEAL
Fig. 19 Master Cylinder Bleeding±Typical
1 - BLEEDING TUBES
2 - RESERVOIR
VABRAKES - BASE 5 - 17
MASTER CYLINDER (Continued)

INSTALLATION
(1) Install the bolts for the pedal bearing bracket
(Fig. 22). Tighten to 23 N´m (204 in. lbs.)
(2) Reconnect the plug connector for the stop lamp
switch (Fig. 22).
(3) Install the brake pedal and hook the spring
(Fig. 22).
(4) Install the retainer and pin for the brake pedal
(Fig. 22).
(5) Install the retainer and pin for the master cyl-
inder push rod (Fig. 22).
(6) Install the master cylinder (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - INSTALLATION).
POWER BRAKE BOOSTER
DESCRIPTION
All models use a tandem diaphragm, power brake
booster.
NOTE: The power brake booster is not a repairable
component. The booster must be replaced as an
assembly if diagnosis indicates a malfunction has
occurred.
OPERATION
The booster unit consists of a single housing
divided into two by a tandem diaphragm. The outer
edge of the diaphragm is secured to the housing. The
booster push rod, which connects the booster to the
brake pedal and master cylinder, is attached to the
center of the diaphragm. A check valve is used in the
booster outlet connected to the engine intake mani-
fold. Power assist is generated by utilizing a combi-
nation of vacuum and atmospheric pressure to boost
brake assist.
REMOVAL
(1) Using a suction gun remove as much brake
fluid from the reservoir as possible.
(2) Disconnect the brake level switch electrical
connector.
(3) Remove the brake lines from the master cylin-
derSeal off the ends and bore holes with plugs.
(4) Remove the master cylinder from the booster.
(5) Remove the booster vacuum hose and check
valve (Fig. 23).
(6) Remove the pedal push rod clip (Fig. 23).
(7) Remove the booster mounting nuts (Fig. 23).
(8) Remove the booster from the vehicle.
INSTALLATION
(1) Install the brake booster to the vehicle.(2) Install the booster mounting nuts (Fig. 23).
Tighten to 25 N´m (221 in.lbs.).
(3) Install the push rod pin & clip (Fig. 23).
(4) Install the brake booster vacuum line and
check valve (Fig. 23).
(5) Install the master cylinder to the brake
booster. Tighten to 28 N´m (248 in.lbs.).
(6) Install the brake lines to the master cylinder.
Tighten to 14 N´m (124 in.lbs.).
(7) Install the brake level switch electrical connec-
tor.
(8) Bleed the base brake system (Refer to 5 -
BRAKES - STANDARD PROCEDURE).
ROTORS
REMOVAL
REMOVAL - FRONT (SRW)
(1) Raise and support the vehicle.
(2) Remove the front wheels.
(3) Remove the front brake pads (Fig. 24).
(4) Remove the caliper adapter (Fig. 24).
(5) Install two lug studs to secure the disc brake
rotor when the locking bolt is removed.
(6) Remove the locking bolt for the disc brake rotor
(Fig. 24).
(7) Remove the two lug nuts.
(8) Remove the disc brake rotor (Fig. 24).
Fig. 23 POWER BRAKE BOOSTER
1 - VACUUM LINE & CHECK VALVE
2 - BRAKE BOOSTER
3 - GASKET
4 - MOUNTING NUTS (4)
5 - PUSH ROD PIN
6 - SECURING CLIP
VABRAKES - BASE 5 - 19
PEDAL (Continued)

COOLING
TABLE OF CONTENTS
page page
COOLING
OPERATIONÐCOOLING SYSTEM...........1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS.............................1DIAGNOSIS AND TESTING - COOLING
SYSTEM.............................2
ACCESSORY DRIVE.......................5
ENGINE................................9
COOLING
OPERATIONÐCOOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
The cooling system also provides a means of heat-
ing the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
²PROLONGED IDLE
²VERY HIGH AMBIENT TEMPERATURE
²SLIGHT TAIL WIND AT IDLE
²SLOW TRAFFIC
²TRAFFIC JAMS
²HIGH SPEED OR STEEP GRADES
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.
²Increasing engine speed for more air flow is rec-
ommended.TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
AIR CONDITIONING; ADD-ON OR AFTER MARKET:
A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer's specifications.
RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt(s)
²Brakes (possibly dragging)
²Changed parts. Incorrect water pump or pump
rotating in wrong direction due to belt not correctly
routed
²Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, (Refer to 7 - COOLING - DIAGNOSIS AND
TESTING)
VACOOLING 7 - 1

DIAGNOSIS AND TESTING - COOLING SYSTEM
COOLING SYSTEM DIAGNOSISÐDIESEL ENGINE
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATUREGAUGE READS
LOW1. Vehicle is equipped with a heavy
duty cooling system.1. None. System operating normaly.
2. Temperature gauge not
connected2. Connect gauge.
3. Temperature gauge connected
but not operating.3. Check gauge. Refer (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
4. Coolant level low. 4. Fill cooling system. (Refer to 7 -
COOLING - STANDARD
PROCEDURE)
TEMPERATURE GAUGE READS
HIGH. COOLANT MAY OR MAY
NOT BE LEAKING FROM SYSTEM1. Vehicle overloaded, high ambient
(outside) temperatures with A/C
turned on, stop and go driving or
prolonged operation at idle speeds.1. Temporary condition, repair not
required. Notify customer of vehicle
operation instructions located in
Owners Manual.
2. Temperature gauge not
functioning correctly.2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
3. Air traped in cooling 3. Drain cooling system (Refer to 7 -
COOLING - STANDARD
PROCEDURE) and refill (Refer to 7
- COOLING - STANDARD
PROCEDURE)
4. Radiator cap faulty. 4. Replace radiator cap.
5. Plugged A/C or radiator cooling
fins.5. Clean all debre away from A/C
and radiator cooling fins.
6. Coolant mixture incorrect. 6. Drain cooling system (Refer to 7 -
COOLING - STANDARD
PROCEDURE) refill with correct
mixture (Refer to 7 - COOLING -
STANDARD PROCEDURE).
7. Thermostat stuck shut. 7. Replace thermostat.
8. Bug screen or winter front being
used.8. Remove bug screen or winter
front.
9. Viscous fan drive not operating
properly.9. Check viscous fan (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
10. Cylinder head gasket leaking. 10. Check for leaking head gaskets
(Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
11. Heater core leaking. 11. Replace heater core.
12. cooling system hoses leaking. 12. Tighten clamps or Replace
hoses.
7 - 2 COOLINGVA
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
13. Brakes dragging. 13. Check brakes. (Refer to 5 -
BRAKES/HYDRAULIC/
MECHANICAL - DIAGNOSIS AND
TESTING)
TEMPERATURE GAUGE READING
INCONSISTENT ( ERRATIC,
CYCLES OR FLUCTUATES)1. Heavy duty cooling system,
extream cold ambient (outside)
temperature or heater blower motor
in high position.1. None. System operating normaly.
2. Temperature gauge or gauge
sensor defective.2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
3. Temporary heavy usage or load. 3. None. Normal condition.
4. Air traped in cooling system. 4. Fill cooling system (Refer to 7 -
COOLING - STANDARD
PROCEDURE).
5. Water pump 5. Replace water pump.
6. Air leak on suction side of water
pump.6. Check for leak. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING)
RADIATOR CAP LEAKING STEAM
AND /OR COOLANT INTO
RESERVOIR BOTTLE.
(TEMPERATURE GAUGE MAY
READ HIGH)1. Radiator cap defective. 1. Replace radiator cap.
2. Radiator neck surface damaged. 2. Replace radiator.
HOSE OR HOSES COLLAPSE
WHEN ENGINE IS COOLING.1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
reservior/overflow system.1. Replace radiator cap, check vent
hose between radiator and reservoir
bottle for blockage also check
reservoir bottle vent for blockage.
NOISY FAN 1. Fan blade(s) loose, damaged. 1. Replace fan blade assembly.
2. Thermal viscous fan drive. 2. None. Normal condition.
3. Fan blades striking surrounding
objects.3. Locate contact point and repair
as necessary.
4. Thermal viscous fan drive
bearing.4. Replace viscous fan drive
assembly.
5. Obstructed air flow through
radiator.5. Remove obstruction.
INADEQUATE AIR CONDITIONER
PERFORMANCE (COOLING
SYSTEM SUSPECTED)1. Radiator and/or A/C condenser
air flow obstructed.1. Remove obstruction and/or clean.
VACOOLING 7 - 3
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
2. Thermal viscous fan drive not
working.2. Check fan drive. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
3. Air seals around radiator
damaged or missing.3. Inspect air seals, repair or
replace as necessary.
INADEQUATE HEATER
PERFORMANCE. GUAGE MAY OR
MAY NOT READ LOW.1. Heavy duty cooling system, and
cooler ambient temperatures.1. None. Normal condition.
2. Obstruction in heater hoses. 2. Remove hoses, remove
obstruction.
3. Water pump damaged. 3. Replace water pump.
HEAT ODOR 1. Damaged or missing drive line
heat shields.1. Repair or replace damaged or
missing heat shields.
2. Thermal viscous fan drive
damaged.2. Check thermal viscous fan drive.
(Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DIAGNOSIS AND TESTING)
7 - 4 COOLINGVA
COOLING (Continued)

ACCESSORY DRIVE
TABLE OF CONTENTS
page page
BELT TENSIONERS
DESCRIPTION..........................5
OPERATION............................5
DRIVE BELTS
DIAGNOSIS AND TESTING - ACCESSORY
DRIVE BELT..........................5REMOVAL.............................8
INSTALLATION..........................8
BELT TENSIONERS
DESCRIPTION
CAUTION: Do not attempt to check belt tension with
a belt tension gauge on vehicles equipped with an
automatic belt tensioner.
Drive belts on all engines are equipped with a
spring loaded automatic belt tensioner. This ten-
sioner maintains constant belt tension at all times
and requires no maintenance or adjustment.
OPERATION
WARNING: THE AUTOMATIC BELT TENSIONER
ASSEMBLY IS SPRING LOADED. DO NOT ATTEMPT
TO DISASSEMBLE THE TENSIONER ASSEMBLY.
The automatic belt tensioner maintains correct belt
tension using a coiled spring within the tensioner
housing. The spring applies pressure to the tensioner
arm pressing the arm into the belt, tensioning the
belt.
If a new belt is being installed, the arrow must be
within approximately 3 mm (1/8 in.) of indexing
mark. Belt is considered new if it has been used 15
minutes or less. If this specification cannot be met,
check for:
²The wrong belt being installed (incorrect length/
width)
²Worn bearings on an engine accessory (A/C com-
pressor, power steering pump, water pump, idler pul-
ley or generator)
²A pulley on an engine accessory being loose
²Misalignment of an engine accessory
²Belt incorrectly routed.
DRIVE BELTS
DIAGNOSIS AND TESTING - ACCESSORY
DRIVE BELT
VISUAL DIAGNOSIS
When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 1), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) arenotnor-
mal. Any belt with cracks running along a rib must
be replaced (Fig. 1). Also replace the belt if it has
excessive wear, frayed cords or severe glazing.
Fig. 1 Belt Wear Patterns
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
VAACCESSORY DRIVE 7 - 5