Mercedes-Benz Sprinter / Dodge Sprinter. Manual — part 192

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 CYLIN-
DER / 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.

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.

Fig. 16 ALB CONTROLLER ADJUSTER NUT

1 - ALB ADJUSTER NUT
2 - SPRING

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

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(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).

(2) Remove the fluid reservoir (Fig. 20) or (Fig. 21)

(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
FLUID RESERVOIR - REMOVAL).

(3) Remove the brake lines Seal off the ends and

bore holes with plugs. (Fig. 20) or (Fig. 21)

(4) Remove the master cylinder mounting nuts

(Fig. 20) or (Fig. 21). Check brake booster for
damage due to leaking master cylinder. It is not
possible to repair the master cylinder.

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

Fig. 20 MASTER CYLINDER

1 - SUCTION GUN
2 - BRAKE FLUID CAP
3 - BRAKE FLUID LEVEL INDICATOR
4 - O-RING
5 - NUT
6 - BRAKE LINE
7 - MASTER CYLINDER
8 - FLUID RESERVOIR

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BRAKES - BASE

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INSTALLATION

(1) Install the master cylinder to the brake booster

(Fig. 20). Tighten to 28 N·m (248 in. lbs.).

(2) Install the brake lines (Fig. 20). Tighten to 14

N·m (124 in. lbs.).

(3) Install the fluid reservoir (Fig. 20) (Refer to 5 -

BRAKES/HYDRAULIC/MECHANICAL/FLUID RES-
ERVOIR - INSTALLATION).

(4) Bleed the brake system.
(5) Check the brake system for any leaks.

PEDAL

REMOVAL

(1) Remove the master cylinder (Refer to 5 -

BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - REMOVAL).

(2) Remove the retainer and pin for the master

cylinder push rod (Fig. 22).

(3) Remove the retainer and pin for the brake

pedal pivot bolt (Fig. 22).

(4) Unhook the spring and remove the brake pedal

(Fig. 22).

(5) Disconnect the plug connector on the stop lamp

switch (Fig. 22).

(6) Remove the bolts and remove the pedal bearing

bracket (Fig. 22).

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

Fig. 21 MASTER CYLINDER (DRW)

1 - POWER BRAKE BOOSTER
2 - RESERVOIR
3 - BRAKE LINES
4 - PRESSURE PORTS
5 - MASTER CYLINDER

Fig. 22 BRAKE PEDAL

1 - MOUNTING BOLT
2 - PEDAL BEARING BRACKET
3 - STOP LAMP SWITCH
4 - CLIP
5 - PIVOT BOLT
6 - RETURN SPRING
7 - PEDAL
8 - PUSH ROD BOLT
9 - PUSH ROD
10 - CLIP
11 - BOLT
12 - WASHER

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BRAKES - BASE

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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-

der Seal 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).

REMOVAL - REAR (SRW)

(1) Raise and support the vehicle.
(2) Remove the rear wheels.
(3) Remove the rear disc brake pads (Fig. 25).
(4) Remove the disc brake caliper adapter (Fig.

25).

(5) Apply the parking brake.
(6) Install two lug studs to secure the disc brake

rotor when the locking bolt is removed.

(7) Remove the locking bolt for the disc brake rotor

(Fig. 25).

(8) Remove the two lug nuts.
(9) Release the parking brake.

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

Fig. 24 FRONT DISC BRAKE ROTOR

1 - CALIPER ADAPTER BOLT
2 - CALIPER ADAPTER
3 - GUIDE BOLT
4 - WEAR INDICATOR
5 - DISC BRAKE CALIPER
6 - DISC BRAKE PADS
7 - LOCKING BOLT
8 - DISC BRAKE ROTOR

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BRAKES - BASE

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