2005 MERCEDES-BENZ SPRINTER engine

DRIVELINE VIBRATION
Drive Condition Possible Cause Correction
Propeller Shaft Noise 1) Undercoating or other foreign
material on shaft.1) Clean exterior of shaft and wash
with solvent.
2) Loose U-joint clamp screws. 2) Install new clamps and screws
and tighten to proper torque.
3) Loose or bent U-joint yoke or
excessive runout.3) Install new yoke.
4) Incorrect driveline angularity. 4) Measure and correct driveline
angles.
5) Rear spring center bolt not in
seat.5) Loosen spring u-bolts and seat
center bolt.
6) Worn U-joint bearings. 6) Install new U-joint.
7) Propeller shaft damaged or out
of balance.7) Installl new propeller shaft.
8) Broken rear spring. 8) Install new rear spring.
9) Excessive runout or unbalanced
condition.9) Re-index propeller shaft, test,
and evaluate.
10) Excessive drive pinion gear
shaft runout.10) Re-index propeller shaft and
evaluate.
11) Excessive axle yoke deflection. 11) Inspect and replace yoke if
necessary.
12) Excessive transfer case runout. 12) Inspect and repair as necessary.
Universal Joint Noise 1) Loose U-joint clamp screws. 1) Install new clamps and screws
and tighten to proper torque.
2) Lack of lubrication. 2) Replace as U-joints as
necessary.
PROPELLER SHAFT BALANCE
NOTE: Removing and indexing the propeller shaft
180É relative to the yoke may eliminate some vibra-
tions.
If propeller shaft is suspected of being out of bal-
ance, verify with the following procedure:
(1) Place vehicle in netrual.
(2) Raise and support the vehicle by the axles as
level as possible.
(3) Clean all foreign material from propeller shaft
and universal joints.
(4) Inspect propeller shaft for missing balance
weights, broken welds, and bent areas.
NOTE: If propeller shaft is bent, it must be replaced.
(5) Inspect universal joints for wear, properly
installed and correct alignment with the shaft.
(6) Check universal joint clamp screws torque.
(7) Remove wheels and tires. Install wheel lug
nuts to retain the brake drums/rotors.(8) Mark and number propeller shaft six inches
from the pinion yoke end at four positions 90É apart.
(9) Run and accelerate the vehicle until vibration
occurs. Note intensity and speed the vibration
occurred. Stop the engine.
(10) Install a screw clamp at position 1 (Fig. 1).
(11) Start engine and re-check for vibration. If lit-
tle or no change in vibration is evident, move clamp
to the next positions and repeat vibration test.
NOTE: If there is no difference in vibration at the
other positions, the vibration may not be propeller
shaft.
(12) If vibration decreased, install a second clamp
(Fig. 2) and repeat vibration test.
(13) If additional clamp causes additional vibra-
tion, separate clamps 1/2 inch above and below the
mark. Repeat the vibration test (Fig. 3).
(14) Increase distance between clamps and repeat
test until vibration is at the lowest level. Bend the
slack end of the clamps so the screws will not loosen.
3 - 2 PROPELLER SHAFTVA
PROPELLER SHAFT (Continued)

REAR AXLE
TABLE OF CONTENTS
page page
REAR AXLE
DESCRIPTION.........................10
OPERATION...........................10
DIAGNOSIS AND TESTING................10
STANDARD PROCEDURE - DRAIN AND FILL . . 11
REMOVAL.............................11
INSTALLATION.........................12
SPECIFICATIONS.......................13
SPECIAL TOOLS.......................14
AXLE SHAFTS
REMOVAL.............................15
INSTALLATION.........................15AXLE BEARINGS/SEALS
REMOVAL.............................17
INSTALLATION.........................17
AXLE SHAFTS - DUAL REAR WHEELS
REMOVAL.............................19
INSTALLATION.........................19
AXLE HUB BEARINGS/SEALS
REMOVAL.............................20
INSTALLATION.........................20
PINION SEAL
REMOVAL.............................22
INSTALLATION.........................22
REAR AXLE
DESCRIPTION
The axle housings consist of a cast iron center sec-
tion with axle tubes extending from either side. The
tubes are pressed into and welded to the differential
housing to form a one-piece axle housing. The SRW
axle has semi-floating axle shafts, DRW has full-
floating axle shafts.
NOTE: Axle seals, axle bearings, pinion seal and
differential cover are the only serviceble compo-
nents. If differential is damaged/noisy the axle must
be replaced.
OPERATION
The axle receives power from the transmission
through the rear propeller shaft. The rear propeller
shaft is connected to the pinion gear which rotates
the differential through the gear mesh with the ring
gear bolted to the differential case. The engine power
is transmitted to the axle shafts through the pinion
mate and side gears. The side gears are splined to
the axle shafts.
DIAGNOSIS AND TESTING
NOTE: Axle seals, axle bearings, pinion seals and
differential cover are the only serviceble compo-
nents. If differential is damaged/noisy the axle must
be replaced.
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, incorrect pinion depth, tooth
contact, worn/damaged gears, or the carrier housing
not having the proper offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate 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:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
cle turns. A worn pinion shaft can also cause a snap-
ping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearingshave a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
3 - 10 REAR AXLEVA

heard during a coast, the front pinion bearing is the
source.
Differential bearings usually produce a low pitch
noise. Differential bearing noise is similar to pinion
bearing noise. The pitch of differential bearing noise
is also constant and varies only with vehicle speed.
Axle shaft bearingsproduce 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
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 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(s).
²Worn or out-of-balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rearend vibra-
tion. Do not overlook engine accessories, brackets
and drive belts.
NOTE: All driveline components should be exam-
ined before starting any repair.
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.
²Transmission shift operation.
²Loose engine/transmission/transfer case mounts.
²Worn U-joints.
²Loose spring mounts.
²Loose pinion gear nut and yoke.
²Excessive ring gear backlash.
²Excessive 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 vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listenfor the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
STANDARD PROCEDURE - DRAIN AND FILL
NOTE: Drain oil when warm.
(1) Clean area around oil fill plug and drain plug.
(2) Remove oil drain plug and drain oil (Fig. 1).
(3) Install oil drain plug and tighten to N´m 100
(74 ft. lbs.).
(4) Remove oil fill plug and fill housing up to bot-
tom edge of oil fill hole (Fig. 1).
(5) Install oil fill plug and tighten to N´m 100 (74
ft. lbs.).
REMOVAL
(1) Raise and support the vehicle.
(2) Position a suitable lifting device under the axle
and secure axle to device.
(3) Remove wheels and tires.
(4) Unplug wear indicator cable (Fig. 2) and (Fig.
3).
(5) Detach cable connector for brake pad wear
indicator.
(6) Remove ABS sensor and clamp bushing from
mounting bore.
NOTE: The right-hand ABS sensor cable is labeled
at the factory with a white tag.
(7) Remove cable ties from the park brake cables.
Release connection cable of brake pad wear indicator
and ABS sensor cable up to the relay unit of the
parking brake.
(8) Remove brake cables from adjuster.
(9) Remove brake calipers with adapters and lines.
Fig. 1 FILL PLUG
1 - FILL PLUG
2 - DRAIN PLUG
VAREAR AXLE 3 - 11
REAR AXLE (Continued)

ROAD TESTING
(1) If complaint involved low brake pedal, pump
pedal and note if it comes back up to normal height.
(2) Check brake pedal response with transmission
in Neutral and engine running. Pedal should remain
firm under constant foot pressure.
(3) During road test, make normal and firm brake
stops in 25-40 mph range. Note faulty brake opera-
tion such as low pedal, hard pedal, fade, pedal pulsa-
tion, pull, grab, drag, noise, etc.
(4) Attempt to stop the vehicle with the parking
brake only and note grab, drag, noise, etc.
PEDAL FALLS AWAY
A brake pedal that falls away under steady foot
pressure is generally the result of a system leak. The
leak point could be at a brake line, fitting, hose, or
caliper/wheel cylinder. If leakage is severe, fluid will
be evident at or around the leaking component.
Internal leakage (seal by-pass) in the master cylin-
der caused by worn or damaged piston cups, may
also be the problem cause.
An internal leak in the ABS or RWAL system may
also be the problem with no physical evidence.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up worn linings,
rotors, drums, or rear brakes out of adjustment are
the most likely causes. The proper course of action is
to inspect and replace all worn component and make
the proper adjustments.
SPONGY PEDAL
A spongy pedal is most often caused by air in the
system. However, thin brake drums or substandard
brake lines and hoses can also cause a spongy pedal.
The proper course of action is to bleed the system,
and replace thin drums and substandard quality
brake hoses if suspected.
HARD PEDAL OR HIGH PEDAL EFFORT
A hard pedal or high pedal effort may be due to
lining that is water soaked, contaminated, glazed, or
badly worn. The power booster or check valve could
also be faulty.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
The primary cause of pulsation are disc brake
rotors with excessive lateral runout or thickness vari-
ation, or out of round brake drums. Other causes are
loose wheel bearings or calipers and worn, damaged
tires.NOTE: Some pedal pulsation may be felt during
ABS activation.
BRAKE DRAG
Brake drag occurs when the lining is in constant
contact with the rotor or drum. Drag can occur at one
wheel, all wheels, fronts only, or rears only.
Drag is a product of incomplete brake shoe release.
Drag can be minor or severe enough to overheat the
linings, rotors and drums.
Minor drag will usually cause slight surface char-
ring of the lining. It can also generate hard spots in
rotors and drums from the overheat-cool down pro-
cess. In most cases, the rotors, drums, wheels and
tires are quite warm to the touch after the vehicle is
stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and
drums to the point of replacement. The wheels, tires
and brake components will be extremely hot. In
severe cases, the lining may generate smoke as it
chars from overheating.
Common causes of brake drag are:
²Seized or improperly adjusted parking brake
cables.
²Loose/worn wheel bearing.
²Seized caliper or wheel cylinder piston.
²Caliper binding on corroded bushings or rusted
slide surfaces.
²Loose caliper mounting.
²Drum brake shoes binding on worn/damaged
support plates.
²Mis-assembled components.
²Long booster output rod.
If brake drag occurs at all wheels, the problem
may be related to a blocked master cylinder return
port, or faulty power booster (binds-does not release).
BRAKE FADE
Brake fade is usually a product of overheating
caused by brake drag. However, brake overheating
and resulting fade can also be caused by riding the
brake pedal, making repeated high deceleration stops
in a short time span, or constant braking on steep
mountain roads. Refer to the Brake Drag information
in this section for causes.
BRAKE PULL
Front brake pull condition could result from:
²Contaminated lining in one caliper
²Seized caliper piston
²Binding caliper
²Loose caliper
²Rusty caliper slide surfaces
²Improper brake pads
²Damaged rotor
VABRAKES - BASE 5 - 3
BRAKES - BASE (Continued)

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)