Isuzu Trooper (2000 year). Manual - part 169

5C–24 POWER ASSISTED BRAKE SYSTEM

Special Tools

ILLUSTRATION

TOOL NO.

TOOL NAME

J-39242

Primary Piston Holder

(including master

cylinder attachment and

master cylinder plug

J-24460-01

Radiator Cap Tester

5C–25

POWER ASSISTED BRAKE SYSTEM

Vacuum Booster Assembly

Vacuum Booster Assembly and Associated Parts

331RW001

Legend

(1) Pin
(2) Vacuum Booster Fixing Nut
(3) Vacuum Hose

(4) Master Cylinder
(5) Vacuum Booster
(6) Snap Pin

Removal

1. Before removing the vacuum booster assembly,

disconnect and remove the brake pipes.

2. Remove master cylinder, refer to “Master Cylinder

Removal” in this section.

CAUTION: When removing the master cylinder from
the vacuum booster, be sure to get rid of the internal
negative pressure of the vacuum booster (by, for
instance, disconnecting the vacuum hose) in
advance.
If any negative pressure remains in the vacuum
booster, the piston may possibly come out when the
master cylinder is being removed, letting the brake
fluid run out.
While removing the master cylinder, further, do not
hold the piston as it can be easily pulled out. 

Outside surface of the piston is the surface on which
seals are to slide.  Care should be taken to keep the
surface free of cuts and dents.

3. Remove vacuum hose.
4. Disconnect the yoke clevis from the brake pedal.
5. Remove vacuum booster fixing nut.
6. Remove vacuum booster.

Inspection and Repair

Vacuum Hose

1. Inspect the check valve (2), which is installed inside

the vacuum hose.

2. Air should pass freely from the vacuum booster (3) to

the engine (1).

5C–26 POWER ASSISTED BRAKE SYSTEM

3. Air should not pass from the engine (1) to the vacuum

booster (3). If it does, the check valve is inoperative
and the vacuum hose built check valve must be
replaced.

360RY00002

Installation

1. Install vacuum booster and vacuum booster push rod

adjustment.

NOTE: When replacing either the master cylinder or
vacuum booster, be sure to measure push rod, and adjust
if required.

2. Remove retainer from vacuum booster front shell

using a small screwdriver. Then gently draw plate and
seal assembly out of the shell inside.

331RS003

3. Set push rod gauge J–39216 on vacuum booster, and

apply negative pressure by means of vacuum pump
J–23738–A so that the pressure in the vacuum
booster becomes 500 mm Hg.

NOTE: Be sure to apply NEGATIVE pressure after
installing a push rod gauge on the vacuum booster.

331RS004

4. Measure dimension (4).

Dimension (4) (Standard): –0.1–0.1 mm
(–0.0039–0.0039 in)

331RW002

5C–27

POWER ASSISTED BRAKE SYSTEM

5. If dimension (4) is out of the standard range, adjust

push rod using the Push Rod Support J–39241.

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6. Mount plate and seal assembly in vacuum booster

front shell. Then install the retainer.

7. Install vacuum booster fixing nut and tighten the

specified torque.

Torque: 21 N·m (16 lb ft)

8. Install yoke clevis.
9. Connect vacuum hose and make sure that the arrow

on the hose points in the direction of the engine.

10. Install master cylinder, refer to “Master Cylinder

Installation” in this section.