Chrysler RG Voyager. Manual — part 658

NOTE: The power brake booster assembly is not a
repairable component and must be replaced as a
complete assembly if found to be faulty in any way.
The check valve located on the power brake
booster face is not repairable, but it can be
replaced separately from the power brake booster.

The different engine combinations used in this

vehicle require different vacuum hose routings to the
power brake booster. All vacuum hoses must be
routed from the engine to the power brake booster
without kinks or excessively tight bends.

OPERATION

The power brake booster reduces the amount of

force required by the driver to obtain the necessary
hydraulic pressure to stop a vehicle.

The power brake booster is vacuum operated. The

vacuum is supplied from the intake manifold on the
engine through a vacuum hose and the power brake
booster check valve (Fig. 64).

As the brake pedal is depressed, the power brake

booster’s input rod moves forward (Fig. 64). This
opens and closes valves in the power booster allowing
atmospheric pressure to enter on one side of a dia-
phragm. Engine vacuum is always present on the
other side. This difference in pressure forces the out-
put rod of the power brake booster out against the
primary piston of the master cylinder. As the pistons
in the master cylinder move forward this creates the
hydraulic pressure in the brake system.

DIAGNOSIS AND TESTING - POWER BRAKE
BOOSTER

BASIC TEST

(1) With engine off, depress and release the brake

pedal several times to purge all vacuum from the
power brake booster.

(2) Depress and hold the pedal with light effort (15

to 25 lbs. pressure), then start the engine.

The pedal should fall slightly, then hold. Less effort

should be needed to apply the pedal at this time. If
the pedal fell as indicated, perform the VACUUM
LEAK TEST listed after the BASIC TEST. If the
pedal did not fall, continue on with this BASIC
TEST.

(3) Disconnect the vacuum hose on the vacuum

check valve, then place a vacuum gauge in line
between the vacuum hose and the valve.

(4) Start the engine.
(5) When the engine is at warm operating temper-

ature, allow it to idle and check the vacuum at the
gauge.

If the vacuum supply is 12 inches Hg (40.5 kPa) or

more, the power brake booster is defective and must
be replaced. If the vacuum supply is below 12 inches
Hg, continue on with this BASIC TEST.

(6) Shut off the engine.
(7) Connect the vacuum gauge to the vacuum ref-

erence port on the engine intake manifold.

(8) Start the engine and observe the vacuum

gauge.

If the vacuum is still low, check the engine tune

and repair as necessary. If the vacuum is above 12
inches Hg, the hose or check valve to the booster has
a restriction or leak.

Once an adequate vacuum supply is obtained,

repeat the BASIC TEST.

VACUUM LEAK TEST

(1) Disconnect the vacuum hose on the vacuum

check valve, then place a vacuum gauge in line
between the vacuum hose and the valve.

(2) Start the engine.
(3) Allow the engine to warm up to normal operat-

ing temperature and engine idle.

(4) Using vacuum line pliers, close off the vacuum

supply hose near the booster, but before the vacuum
gauge, then observe the vacuum gauge.

If the vacuum drop exceeds 1.0 inch Hg (3.3 kPa)

in one minute, repeat the above steps to confirm the
reading. The vacuum loss should be less than 1.0
inch Hg in one minute time span. If the loss is more
than 1.0 inch Hg, replace the power brake booster. If
it is not, continue on with this test.

(5) Remove the pliers from the hose temporarily.

Fig. 65 MASTER CYLINDER AND BOOSTER

1 - POWER BRAKE BOOSTER
2 - BOOSTER IDENTIFICATION LABEL
3 - FLUID LEVEL SWITCH CONNECTOR
4 - PRIMARY BRAKE TUBE NUT
5 - SECONDARY BRAKE TUBE NUT
6 - MASTER CYLINDER

RS

BRAKES - BASE

5 - 45

POWER BRAKE BOOSTER (Continued)

(6) Apply light effort (approximately 15 lbs. of

force) to the brake pedal and hold the pedal steady.
Do not move the pedal once the pressure is applied
or the test results may vary.

(7) Have an assistant reattach the vacuum line

pliers to the vacuum supply hose.

(8) Allow 5 seconds for stabilization, then observe

the vacuum gauge.

If the vacuum drop exceeds 3.0 inches Hg (10 kPa)

in 15 seconds, repeat the above steps to confirm the
reading. The vacuum loss should be less than 3.0
inches Hg in 15 seconds time span. If the loss is
more than 3.0 inches Hg, replace the power brake
booster. If it is not, the booster is not defective.

(9) Remove the pliers and vacuum gauge.

REMOVAL

REMOVAL - LHD

CAUTION: Reserve vacuum in power brake booster
must be pumped down (removed) before removing
master cylinder from booster. This is necessary to
prevent booster from sucking in any contamination
as master cylinder is removed. This can be done
simply by pumping the brake pedal, with the vehi-
cle’s engine not running, until a firm feeling brake
pedal is achieved.

(1) With engine not running, pump the brake

pedal until a firm pedal is achieved (4-5 strokes).

(2) Remove negative battery cable terminal from

battery.

(3) Remove positive battery cable terminal from

battery.

(4) Remove battery thermal guard shield.
(5) Remove battery clamp, nut and battery from

the battery tray.

(6) Remove screw securing engine coolant filler

tube to battery tray.

(7) If the vehicle is equipped with speed control,

disconnect the vacuum hose at the vacuum tank built
into the battery tray.

(8) Remove the two nuts and one bolt securing bat-

tery tray in place. Remove battery tray.

(9) If vehicle is equipped with speed control:

(a) Disconnect wiring harness connector from

the speed control servo.

(b) Remove the two servo mounting nuts.
(c) Lay speed control servo off to the side, out of

the way.
(10) Remove the wiper module (unit). (Refer to 8 -

ELECTRICAL/WIPERS/WASHERS/WIPER

MOD-

ULE - REMOVAL)

(11) Disconnect wiring harness connector from

brake fluid level switch in master cylinder fluid res-
ervoir (Fig. 66).

CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.

(12) Clean area where master cylinder assembly

attaches to power brake booster. Use only a solvent
such as Mopar

t Brake Parts Cleaner or equivalent.

(13) Disconnect

primary

and

secondary

brake

tubes from ABS integrated control unit or non-ABS
junction block (Fig. 67). Install sealing plugs in the
now open brake tube ports and install caps on ends
of tubes.

NOTE: It is not necessary to remove the brake
tubes from the master cylinder when removing the
master cylinder from the vacuum booster.

(14) Remove two nuts attaching master cylinder to

power brake booster (Fig. 67).

(15) Slide master cylinder straight out of power

brake booster. Remove master cylinder with primary
and secondary tubes from vehicle.

CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.

Fig. 66 Master Cylinder And Booster

1 - POWER BRAKE BOOSTER
2 - BOOSTER IDENTIFICATION LABEL
3 - FLUID LEVEL SWITCH CONNECTOR
4 - PRIMARY BRAKE TUBE NUT
5 - SECONDARY BRAKE TUBE NUT
6 - MASTER CYLINDER

5 - 46

BRAKES - BASE

RS

POWER BRAKE BOOSTER (Continued)

(16) Disconnect vacuum hose from check valve

located on vacuum booster. DO NOT REMOVE
CHECK

VALVE

FROM

POWER

BRAKE

BOOSTER.

(17) Inside vehicle, remove silencer panel under

instrument panel below steering column.

(18) Locate the booster input rod to brake pedal

connection under the instrument panel. Position a
small screwdriver between the center tang on the
power brake booster input rod to brake pedal pin
retaining clip (Fig. 68).

(19) Rotate screwdriver enough to allow retaining

clip center tang to pass over end of brake pedal pin.

Then pull retaining clip off brake pedal pin. Discard
retaining clip. It is not to be reused. Replace
only with a new retaining clip when assem-
bling.

(20) Slide booster input rod off pedal pin.
(21) Remove the four nuts attaching power brake

booster to dash panel (Fig. 69).

(22) Slide power brake booster forward and remove

through engine compartment (Fig. 70).

CAUTION: Do not attempt to disassemble the power
brake vacuum booster. It is serviced ONLY as a
complete assembly.

Fig. 67 Master Cylinder Mounting

1 - MASTER CYLINDER MOUNTING NUTS
2 - MASTER CYLINDER
3 - SECONDARY TUBE NUT AT ICU
4 - PRIMARY TUBE NUT AT ICU

Fig. 68 Vacuum Booster Input Rod Retaining Pin

1 - BRAKE PEDAL
2 - INPUT ROD
3 - SCREWDRIVER
4 - RETAINING CLIP
5 - BRAKE PEDAL PIN

Fig. 69 Booster Mounting

1 - DASH BRACKET
2 - POWER BRAKE BOOSTER
3 - BRAKE PEDAL ASSEMBLY

Fig. 70 Booster Removal/Installation

RS

BRAKES - BASE

5 - 47

POWER BRAKE BOOSTER (Continued)

REMOVAL - RHD

CAUTION: Reserve vacuum in power brake booster
must be pumped down (removed) before removing
master cylinder from booster. This is necessary to
prevent booster from sucking in any contamination
as master cylinder is removed. This can be done
simply by pumping the brake pedal, with the vehi-
cle’s engine not running, until a firm feeling brake
pedal is achieved.

(1) With engine not running, pump the brake

pedal until a firm pedal is achieved (4 or 5 strokes).

(2) Remove negative battery cable terminal from

battery.

(3) Remove positive battery cable terminal from

battery.

(4) Remove battery thermal guard shield.
(5) Remove battery clamp, nut and battery from

the battery tray.

(6) If the vehicle is equipped with speed control,

disconnect the vacuum hose at the vacuum tank built
into the battery tray.

(7) Remove the two nuts and one bolt securing bat-

tery tray in place. Remove battery tray.

(8) If vehicle is equipped with speed control:

(a) Disconnect wiring harness connector from

the speed control servo.

(b) Remove the two servo mounting nuts.
(c) Lay speed control servo off to the side, out of

the way.
(9) If the vehicle is equipped with the 2.5L diesel

engine, remove the coolant recovery pressure con-
tainer and bracket. (Refer to 7 - COOLING/ENGINE/
COOLANT

RECOVERY

PRESS

CONTAINER

-

REMOVAL)

(10) Disconnect wiring harness connector from

brake fluid level switch in master cylinder fluid res-
ervoir (Fig. 71).

CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.

(11) Clean area where master cylinder assembly

attaches to power brake booster. Use only a solvent
such as Mopar

t Brake Parts Cleaner or equivalent.

NOTE: It is not necessary to remove the brake
tubes from the master cylinder when removing the
master cylinder from the booster.

(12) Remove two nuts attaching master cylinder to

power brake booster (Fig. 72).

(13) Slide master cylinder straight out of power

brake booster. Lay master cylinder with primary and
secondary tubes to the side, out of the way.

CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.

(14) Disconnect vacuum hose from check valve

located on booster. DO NOT REMOVE CHECK
VALVE FROM POWER BRAKE BOOSTER.

Fig. 71 RHD Master Cylinder And Power Brake

Booster

1 - POWER BRAKE BOOSTER
2 - BRAKE FLUID LEVEL SWITCH
3 - FLUID RESERVOIR
4 - MASTER CYLINDER

Fig. 72 RHD Master Cylinder Mounting

1 - PRIMARY BRAKE TUBE NUT
2 - SECONDARY BRAKE TUBE NUT
3 - MASTER CYLINDER MOUNTING NUTS

5 - 48

BRAKES - BASE

RS

POWER BRAKE BOOSTER (Continued)