Brake fluid ISUZU AXIOM 2002 Service Owner's Manual

5C±9 POWER±ASSISTED BRAKE SYSTEM
Condition CorrectionPossible cause
Poor Brake ActionMaster cylinder faulty.Correct or replace.
Vacuum booster faulty.Correct or replace.
Level of brake fluid in reservoir too
low.Replenish and bleed.
Air in hydraulic circuit.Bleed
Disc brake caliper faulty.Clean or replace.
Water or oil on brake pads.Clean or replace.
Brake pads in poor contact with the
rotor.Correct
Brake pads worn.Replace
Brake disc rusted.Grind or replace.
Check valve in vacuum hose faulty.Correct or replace.

5C±10
POWER±ASSISTED BRAKE SYSTEM
Hydraulic Brakes
Filling Master Cylinder Reservoir
CAUTION: Use only specified brake fluid. Do not
use any fluid which contains a petroleum base. Do
not use a container which has been used for
petroleum based fluids or a container which is wet
with water. Petroleum based fluid will cause swelling
and distortion of rubber parts in the hydraulic brake
system. Water mixed with brake fluid lowers the fluid
boiling point. Keep all fluid containers capped to
prevent contamination.
Always fill the master cylinder reservoir when the en-
gine is cold.
Never allow the brake fluid to come in contact with
the painted surfaces.
The master cylinder reservoir must be kept properly
filled to ensure adequate reserve and to prevent air
and moisture from entering the hydraulic system.
However, because of expansion due to heat ab-
sorbed from the brakes and the engine, the reservoir
must not be overfilled. The brake fluid reservoir is on
the master cylinder, which is located under the hood
on the left side of the cowl. Thoroughly clean reser-
voir cap before removal to avoid getting dirt into res-
ervoir. Remove the diaphragm. Add fluid as required
to bring level to the ªMAXº mark on the reservoir
tank. Use ªDOT 3º Hydraulic Brake Fluid. If the fluid
cap diaphragm is stretched, return it to the original
position before installing.
Deterioration of Brake Fluid
Using any other brake fluid than specified or brake fluid
with mineral oil or water mixed in will drop the boiling point
of brake fluid. It may, in turn, result in vapor lock or
deteriorated rubber parts of the hydraulic system. Be sure
to change the brake fluid at specified intervals.
If the rubber parts are deteriorated, remove all the system
parts and clean them with alcohol. Prior to reassembly,
dry the cleaned parts with air to remove the alcohol.
Replace all the hoses and rubber parts of the system.
Leakage of Brake Fluid
With engine idling, set shift lever in the neutral position
and continue to depress brake pedal at a constant pedal
application force.
Should the pedal stroke become deeper gradually,
leakage from the hydraulic pressure system is possible.
Perform visual inspection for any signs of leakage.
Bleeding Brake Hydraulic System
A bleeding operation is necessary to remove air from the
hydraulic brake system whenever air is introduced into
the hydraulic system. It may be necessary to bleed the
hydraulic system at all four brakes if air has been
introduced through a low fluid level or by disconnecting
brake pipes at the master cylinder. If a brake pipe is
disconnected at one wheel, only that wheel
cylinder/caliper needs to be bled. If the pipes aredisconnected at any fitting located between the master
cylinder and brakes, then the brake system served by the
disconnected pipe must be bled.
1. For 4±Wheel Antilock Brake System (ABS) equipped
vehicle, be sure to remove the ABS main fuse 60A
located at the relay and fuse box before bleeding air. If
you attempt to bleed air without removing the main
fuse, air cannot be let out thoroughly, and this may
cause damage to the hydraulic unit. After bleeding air,
be sure to replace the ABS main fuse back to its
original position.
2. Set the parking brake completely, then start the
engine.
NOTE: The vacuum booster will be damaged if the
bleeding operation is performed with the engine off.
3. Remove the master cylinder reservoir cap.
4. Fill the master cylinder reservoir with brake fluid.
Keep the reservoir at least half full during the air
bleeding operation
5. Always use new brake fluid for replenishment.
6. When replenishing the brake fluid reservoir, carefully
pour in the brake fluid to prevent air bubbles from
entering the brake system.
When the master cylinder is replaced or overhauled,
first bleed the air from the master cylinder, then from
each wheel cylinder and caliper following the
procedures described below.
Bleeding the Master Cylinder
7. Disconnect the rear wheel brake pipe (1) from the
master cylinder.
Check the fluid level and replenish as necessary. If
replenished, leave the system for at least one minute.
8. Depress the brake pedal slowly once and hold it
depressed.
9. Completely seal the delivery port of the master
cylinder with your finger, where the pipe was
disconnected then release the brake pedal slowly.
10. Release your finger from the delivery port when the
brake pedal returns completely.
11. Repeat steps 8 through 10 until the brake fluid comes
out of the delivery port during step 8.
NOTE: Do not allow the fluid level in the reservoir to go
below the half±way mark.
12. Reconnect the brake pipe (1) to the master cylinder
and tighten the pipe.
13. Depress the brake pedal slowly once and hold it
depressed.
14. Loosen the rear wheel brake pipe (1) at the master
cylinder.
15. Retighten the brake pipe, then release the brake
pedal slowly.
16. Repeat steps 13 through 15 until no air comes out of
the port when the brake pipe is loosened
NOTE: Be very careful not to allow the brake fluid to come
in contact with painted surfaces.

5C±11 POWER±ASSISTED BRAKE SYSTEM
330RW012
17. Bleed the air from the front wheel brake pipe
connection (2) by repeating steps 7 through 16.
Bleeding the Caliper
18. Bleed the air from each wheel in the order listed
below:

Right rear caliper or wheel cylinder

Left rear caliper or wheel cylinder

Right front caliper

Left front caliper
Conduct air bleeding from the wheels in the above
order. If no brake fluid comes out, it suggests that air
is mixed in the master cylinder. In this case, bleed air
from the master cylinder in accordance with steps 7
through 17, and then bleed air from the caliper or
wheel cylinder.
19. Place the proper size box end wrench over the
bleeder screw.
20. Cover the bleeder screw with a transparent tube, and
submerge the free end of the transparent tube in a
transparent container containing brake fluid.
21. Pump the brake pedal slowly three (3) times
(once/sec), then hold it depressed.
22. Loosen the bleeder screw until fluid flows through the
tube.
23. Retighten the bleeder screw.
24. Release the brake pedal slowly.
25. Repeat steps 21 through 24 until the air is completely
removed.
It may be necessary to repeat the bleeding procedure
10 or more times for front wheels and 15 or more
times for rear wheels.
26. Go to the next wheel in the sequence after each wheel
is bled.
Be sure to monitor reservoir fluid level.
27. Depress the brake pedal to check if you feel
ªsponginessº after the air has been removed from all
wheel cylinders and calipers.
If the pedal feels ªspongyº, the entire bleeding
procedure must be repeated.28. After the bleeding operation is completed on the each
individual wheel, check the level of the brake fluid in
the reservoir and replenish up to the ªMAXº level as
necessary.
29. Attach the reservoir cap.
If the diaphragm inside the cap is deformed, reform
it and install.
30. Stop the engine.
Flushing Brake Hydraulic System
It is recommended that the entire hydraulic system be
thoroughly flushed with clean brake fluid whenever new
parts are installed in the hydraulic system. Approximately
one quart of fluid is required to flush the hydraulic system.
The system must be flushed if there is any doubt as to the
grade of fluid in the system or if fluid has been used which
contains the slightest trace of mineral oil. All rubber parts
that have been subjected to a contaminated fluid must be
replaced.
Brake Pipes and Hoses
The hydraulic brake system components are
interconnected by special steel piping and flexible hoses.
Flexible hoses are used between the frame and the front
calipers, the frame and rear axle case and the rear axle
and the rear calipers.
When the hydraulic pipes have been disconnected for
any reason, the brake system must be bled after
reconnecting the pipe. Refer to
Bleeding the Brake
Hydraulic System
in this section.
Brake Hose Inspection
The brake hose should be inspected at least twice a year.
The brake hose assembly should be checked for road
hazard, cracks and chafing of the outer cover, and for
leaks and blisters. Inspect for proper routing and
mounting of the hose. A brake hose that rubs on
suspension components will wear and eventually fail. A
light and mirror may be needed for an adequate
inspection. If any of the above conditions are observed on
the brake hose, adjust or replace the hose as necessary.
CAUTION: Never allow brake components such as
calipers to hang from the brake hoses, as damage to
the hoses may occur.

5C±15 POWER±ASSISTED BRAKE SYSTEM
P & B (Proportioning and Bypass) Valve
P & B (Proportioning and Bypass)
Valve Sectional View
350RW014
Legend
(1) Master Cylinder (Secondary)
(2) Master Cylinder (Primary)
(3) Rear Brake
(4) Front Brake
The P&B valve contains two sections, each serving a
different function.
The proportioning section of the P&B valve proportions
outlet pressure to the rear brakes after a predetermined
rear input pressure has been reached. This is done to
prevent rear wheel lock up on the vehicles with light rear
wheel loads. The valve has a by±pass feature which
assures full system pressure to the rear brakes in the
event of front brake system malfunction. Also full front
pressure is retained in the event of rear brake
malfunction.
The P&B valve is not repairable and must be replaced as
complete assembly.
Removal
1. The P&B valve is not repairable and must be replaced
as a complete assembly. Care must be taken to
prevent brake fluid from contacting any painted
surface.
2. Remove hydraulic pipes (1) and plug the pipes (1) to
prevent the loss of fluid or the entrance of dirt.
3. Remove bolt (3).
4. Remove P&B valve (2).
350RW026
Installation
1. Install P&B valve (2).
2. Install bolt (3) and tighten the bolt to the specified
torque.
Torque: 22 N´m (16 lb ft)
3. Install hydraulic pipes (1) and tighten the bolt to the
specified torque.
Torque: 15 N´m (11 lb ft)
4. After installing the brake pipes, bleed the brakes as
refer to
Bleeding Brake Hydraulic System in this
section.

5C±21 POWER±ASSISTED BRAKE SYSTEM
Fluid Reservoir Tank
Fluid Reservoir Tank and Associated Parts
330RW003
Legend
(1) Fluid Reservoir
(2) Electrical Connector(3) O±ring
(4) Retainer
Removal
NOTE: Before removing the fluid reservoir, remove the
brake fluid from the fluid reservoir.
1. Disconnect electrical connector.
2. Remove retainer (1).
330RW004
3. Remove fluid reservoir and the fluid level sensor built
into the fluid reservoir. The fluid level sensor cannot
be removed for servicing.
4. Remove O±ring.
Installation
To install, follow the removal steps in the reverse order,
noting the following points:
1. O±ring (1) must be set onto the fluid reservoir (2),
before installing fluid reservoir.
330RW005

5C±22
POWER±ASSISTED BRAKE SYSTEM
Master Cylinder Assembly
Master Cylinder Assembly and Associated Parts
330RW010
Legend
(1) Electrical Connector
(2) Master Cylinder
(3) 2 attaching Nuts(4) P&B Valve and Bracket
(5) Brake Pipes
(6) Spacer and 2 gaskets
Removal
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.
1. Disconnect electrical connector.
2. Remove brake pipes and after disconnecting the
brake pipe, cap or tape the openings of the brake pipe
to prevent the entry of foreign matter.
3. Remove 2 attaching nuts.
4. Remove P&B valve and bracket.5. Remove master cylinder.
6. Remove spacer and the 2 gaskets.
Inspection and Repair
Master Cylinder
The master cylinder is not repairable and must be
replaced as a complete assembly if found defective.
Inspection
Excessive brake pedal travel, malfunction or dragging
brake suggests that the master cylinder is defective. In
such cases perform the following visual check:
Visual Check
Make parts replacement as required if wear, distortion,
nicks, cuts, corrosion, or other abnormal conditions are
found through the following parts inspection:

Master cylinder body

Fluid reservoir

O±ring

5C±25 POWER±ASSISTED BRAKE SYSTEM
Vacuum Booster Assembly
Vacuum Booster Assembly and Associated Parts
331RW005
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.
Do not hold the piston while removing the master cy-
liner, the piston 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.

5C±33 POWER±ASSISTED BRAKE SYSTEM
Removal
NOTE: If a squealing noise occurs from the front brake
while driving, check the pad wear indicator plate. If the
indicator plate contacts the rotor, the disc pad assembly
should be replaced.

Draw out two±thirds of the brake fluid from the
reservoir.

Raise the vehicle and support it with suitable safety
stands.
1. Remove wheel and tire assembly, refer to
Wheels
and Tires System
in Section 3E.
2. Remove lock bolt (1).
302RW004
3. Rotate caliper assembly and support the caliper
assembly so that the brake hose is not stretched or
damaged.
4. Remove pad assembly with shim.
5. Remove Clip.
Installation
1. Install clip.
302RS005
2. Apply special grease (approximately 0.2 g) to both
contacting surfaces of the inner shims (2). Wipe off
extruded grease after installing. Install pad assembly
with shim.
302RW005
Legend
(2) Inner Shim
(3) Wear Indicator
(4) Inner Side

5C±34
POWER±ASSISTED BRAKE SYSTEM
302RW006
3. Carefyully use adjustable pliers to bottom the piston
into the caliper bore. Do not pull or twist the flexible
hose or damage will occur.
Install caliper assembly.
Set caliper assembly in place.
302RS008
4. Install lock bolt (5) and tighten the bolt to the specified
torque.
Torque: 74 N´m (54 lb ft)
302RW018
5. Install wheel and tire assembly, refer to Wheels and
Tires System
in Section 3E.
6. Pump the brake pedal several times to make sure that
the pedal is firm. Check the brake fluid level in the
reservoir after pumping the brakes.

5C±37 POWER±ASSISTED BRAKE SYSTEM
Removal
1. Raise the vehicle and support with suitable safety
stands.
2. Concernig wheel and tire assembly, refer to
Wheels
and Tires System
in Section 3E.
3. Remove the bolt and gaskets, then disconnect the
flexible hose from the caliper and after disconnecting
the flexible hose (1), cap or tape the openings to
prevent entry of foreign material.
302RW009
4. Since the brake fluid flows out from the connecting
coupler, place a drain pan under the vehicle.
5. Remove guide bolt (2).
6. Remove lock bolt (3).
302RW010
7. Remove caliper assembly.
8. Remove support bracket with pad assembly and take
care not to damage the flexible brake hose when
removing the support bracket.9. Remove pad assembly with shim and mark the lining
locations if they are to be reinstalled.
10. Remove clip.
Installation
1. Install clip.
302RS005
2. Apply special grease (approximately 0.2 g) to both
contacting surfaces of the inner shims (4). Wipe off
extruded grease after installing. Install pad assembly
with shim.
302RW011
Legend
(4) Inner Shim
(5) Wear Indicator
(6) Inner Side