brake fluid ISUZU TROOPER 1995 User Guide

HYDRAULIC BRAKES 5A-3
DIAGNOSIS OF BRAKE SYSTEM
Condition
Possible Cause Correction
Brake
Pull 1. Tire inflation pressures unequal. 1. Adjust
2. Front wheel alignment incorrect. 2. Adjust
3. Unmatched tires on same axle. 3. Tires with approx. the same amount of
tread should be used on the same axle.
4. Restricted brake pipes or hoses. 4. Check for soft hoses and damaged
lines. Replace with new hoses and new
double-walled steel brake piping.
5. Water or oil on brake pads. 5. Clean or replace.
6. Brake pads hardened. 6. Replace.
7. Brake pads worn excessively. 7. Replace.
8. Brake rotor worn or scored. 8. Grind or replace.
9. Disc brake caliper malfunctioning. 9. Clean or replace.
10. Front hub bearing preload incorrect. 10. Adjust or replace.
11. Loose suspension parts. 11. Check all suspension mountings.
12. Loose
calipers. 12. Check and tighten bolts to specifi-
cations.
Brake 1. Excessive lateral runout. 1. Check per instructions.
Roughness-or If not within specifications, replace or
Chatter machine the rotor.
(Pulsates) 2. Parallelism not within specifications. 2. Check per instructions.
If not within specifications, replace or
machine the rotor.
3. Wheel bearings not adjusted. 3. Adjust wheel bearings to correct
specifications.
4. Pad reversed (steel against iron). 4. Replace brake pad and machine rotor
to within specifications.
Excessive Pedal 1. Malfunctioning vacuum booster. 1. Check vacuum booster operation and
Effort repair, if necessary.
2. Partial system failure. 2. Check front and rear brake system for
failure and repair. Also, check brake
warning
light. If a failed system
is
found, the
light should indicate a
failure.
3. Excessively worn pad. 3. Check and replace pads in sets.
4. Piston in caliper stuck or sluggish. 4. Remove caliper and rebuild.
5. Fading brakes due to incorrect pad. 5. Remove and replace with original
equipment pad or equivalent.
6. Vacuum leak to vacuum booster. 4. Check for ruptured or loose hose.
7. Check direction of check valve within 5. Correct vacuum hose direction.
vacuum hose.
8. Grease on the brake pads. 6. Replace or clean.
Excessive Brake 1. Air in hydraulic circuit. 1. Bleed hydraulic circuit.
Pedal Travel 2. Level of brake fluid in reservoir too low. 2. Replenish brake fluid reservoir to speci-
fied
level and bleed hydraulic circuit as
necessary.
3. Master cylinder push rod clearance ex-3. Adjust.
cessive.
4. Leakage in hydraulic system. 4. Correct or replace defective parts.

SA-4 HYDRAULIC BRAKES
Condition Possible Cause Correction
Brake Drag
1. Master cylinder pistons not returning 1. Adjust stop light switch and vacuum
correctly. booster operating rod. If necessary,
rebuild.
2. Restricted brake pipes or hoses. 2. Check for soft hoses or damaged pipes,
and
replace with new hoses and new
double-walled steel brake piping.
3. Parking brake maladjusted. 3. Adjust.
4. Parking brake lining clearance 4. Adjust
insufficient.
5. Brake pedal free play insufficient. 5. Adjust brake pedal height or power
cylinder operating rod.
6. Piston in master cylinder sticking. 6. Replace.
7. Piston in disc brake caliper sticking. 7. Replace piston seals.
8. Brake pads sticking in caliper. 8. Clean.
9. Return spring weakened. 9. Replace.
10. Praking brake binding. 10. Overhaul parking brakes and correct.
11. Front hub bearing preload incorrect. 11.
Adjust or replace.
12. Parking brake shoes not returning. 12.
Correct or replace brake back plate and
brake shoe
as necessary.
13. Obstructions in hydraulic circuit. 13. Clean.
14. Rotor warped excessively. 14.
Grind or replace.
15. Rear brake drum distorted. 15.
Grind or replace.
16. Check valve; vacuum hose faulty. 16. Replace.
17. Parking cable sticking. 17. Clean or replace.
Grabbing
or 1. Malfunctioning vacuum booster. 1. Check operation and correct as
Uneven Braking necessary.
Action
(All 2. Binding brake pedal mechanism. 2. Check and lubricate, if necessary.
conditions
3. Corroded caliper assembly. 3. Clean and lubricate.
listed
under
"Pulls")
Brake Noisy 1 . Brake pads worn. 1. Replace.
2. Brake pads hardened. 2. Replace.
3. Brake pads in poor contact with rotor. 3. Correct.
4. Brake disc(s) warped, worn or 4. Grind or replace.
damaged.
5. Disc brake anti-squeak shims fatigued. 5. Replace.
6. Front hub bearings loose or preload is 6. Adjust or replace.
incorrect.
7. Brake disc rusted. 7. Grind or replace.
Poor Brake 1. Master cylinder faulty. 1. Correct or replace.
Action 2. Vacuum booster faulty. 2. Correct or replace.
3. Level of brake fluid in reservoir too 3. Replenish and bleed.
low.
4. Air in hydraulic circuit. 4. Bleed.
5. Disc brake caliper faulty. 5. Clean or replace.
6. Water or oil on brake pads. 6. Clean or replace.
7. Brake pads in poor contact with rotor. 7. Correct.
8. Brake pads worn. 8. Replace.
9. Brake disc rusted. 9. Grind or replace.
10. Check valve in vacuum hose faulty. 10. Correct or replace.
•

HYDRAULIC BRAKES 5A-5
ON-VEHICLE SERVICE
FILLING MASTER CYLINDER
RESERVOIR
'\fl CAUTION:
'VI • 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 fluids 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 contami­
nation.
• Always fill the master cylinder reservoir when
the engine 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 absorbed
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 reservoir cap
before
removal to avoid getting dirt into reservoir.
Remove cap and diaphragm.
Add fluid as required to
bring level to the "MAX" mark on the reservoir tank.
Use
"DOT 3" 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 brake fluid at specified intervals.
If 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
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
pressure.
Should the pedal stroke become deeper gradually,
leak from the hydraulic pressure system is possible.
Make sure
by visual check that there is no leak.
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 dis­
connecting 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 pipes are
disconnected at any fitting
located between 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
40A 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. In replenishing brake fluid, take care that air
bubbles do not enter the brake fluid.
•
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 (Fig. 5A-1}
7. Disconnect the rear wheel brake pipe master
cylinder (Fig. 5A-1 ). 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 where the pipe was disconnected with
your finger, then release the brake pedal slowly.
10. Release your finger from the delivery port when
the brake
pedal returns completely.
11. Repeat steps 7 through 9 until the brake fluid
comes out of the delivery port during step 7.

5A-6 HYDRAULIC BRAKES
NOTE:
Do not allow the fluid level in the reservoir to go below
the half-way mark.
12. Reconnect the brake pipe
(j) 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 (j) at the master
cylinder (Fig. 5A-1).
15. Retighten the brake pipe, then release the brake
pedal
slowly.
16. Repeat steps 13 through 15 until no air comes out
from 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.
17. Bleed the air from the front wheel brake pipe
connection
® by repeating steps 7 through 16
(Fig.
5A-1 ).
Fig. 5A-1
Bleeding the caliper
18. Bleed the air from each wheel in the order listed
below.
• Right rear caliper
• Left rear caliper
• Right front caliper
• Left front caliper
If brake fluid does not come out or brake fluid does
not remain in the master cylinder while bleeding
each
caliper in the order listed above, the master
cylinder may contain air in its bore. First bleed the
master cylinder
as described in step 7 through 17.
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. Loose the bleeder screw until fluid flows through
the tube.
23. Retighten the bleeder screw.
24. Release the brake pedal slowly.
25. Repeat step 21 through 24 until the air is com­
pletely 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
"sponginess" after the air has been removed from
all wheel cylinders and calipers. If the pedal feels
"spongy", the entire bleeding procedure must be
repeated.
28. After the bleeding operation is completed on each
individual wheel, check the level
of brake fluid in
the reservoir and replenish up to the
"MAX" level
if 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 iffluid has been used
which contains the
slightest trace of mineral oil. All
rubber parts that have been subjected to a con­
taminated fluid
must be replaced.
BRAKE PIPES AND HOSES
The hydraulic brake system components are inter­
connected
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 hoses should be inspected at least twice a
year. The brake hose assembly should
be checked for
road hazard, cracks and chafing ofthe 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.
\fl CAUTION:
'V Never allow brake components such as calipers
to hang from the brake hoses, as damage to the
hoses may occur.

COMBINATION VALVE/P & B
(PROPORTIONING AND BYPASS) VALVE
The combination valve/P & B valve contains two
sections, each serving a different function.
The proportioning section
of the combination valve/
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 a
front brake system malfunction, also full front pressure
is retained in the event
of rear brake malfunction.
HYDRAULIC BRAKES 5A 9
The combination valve has a pressure differential
warning switch which is designed to constantly
compare front and rear brake pressure
from the
master
cylinder and turn on the brake system warning
light on the instrument panel in the event of a front or
rear system malfunction. The valve and switch are so
designed that the switch
will latch in the "warning"
position once a malfunction has occurred. The only
way the light can be turned off is to repair the
malfunction and
apply a pedal force required to
develop line pressure. The combination valve/P & B
valve is not repairable and must be replaced as a
complete assembly.
P&B valve
(Antilock brake system model only)
Master cylinder (Primary)
Combination valve (Rear wheel antilock model only)
Pressure differential warning switch
Master
cylinder (Secondary)
..(> ..(> Master cylinder (Secondary) Master
cylinder
(Primary)
..(> ..(>
Front brake
Rear brake
Combination Valve
Electrical Circuit Test (RWAL
model
Fig. 5A-4
only)
1.
2.
3.
Disconnect the wmng connector at the
combination
valve (Fig. 5A-5).
• Connect a jumper wire from the harness to
ground.
Turn the ignition key to
"ON".
•
The warning light should come on.
• If the light will not come on, check the bulb. If
the bulb is good, refer to Chassis Electrical
(Sec.
8) for further diagnosis.
Turn the ignition off.
• Disconnect jumper wire and connect the
harness to the switch
terminal.
Combination Valve (RWAL model only)
Warning
Switch Test
1. Raise the vehicle.
• Support
with suitable safety stands.
2. Attach a hose to a rear brake bleeder screw.
• Immerse the opposite end of the hose into a
container
partially filled with clean brake fluid.
3.
4.
5.
6.
7.
¢ Front RH brake
Front LH brake
Rear brake
• Make sure the master cylinder reservoir is full.
Turn the ignition key to "ON".
• Open
the bleeder screw while a helper applies
moderate pressure to the brake pedal.
•
The warning light should come on.
• Close the bleeder screw before the helper
releases
the brake pedal.
Reapply the brake pedal with moderate to heavy
pressure.
• The light should go out.
Attach a hose
to a front brake bleeder screw.
• Immerse the opposite end of the hose into a
container
partially filled with clean brake fluid.
• Make sure the master cylinder reservoir is full.
Turn the ignition key to "ON".
• Open
the bleeder screw while a helper applies
moderate pressure to the brake pedal.
•
The warning light should come on.
• Close the bleeder screw before the helper
releases
the brake pedal.
Reapply
the brake pedal with moderate to heavy
pressure.
• The light should go out.

5A-1 0 HYDRAULIC BRAKES
8. Turn the ignition key off.
• If the warning light does not come on during
steps 3 and
6, but does light when a jumper is
connected to ground, the warning switch
portion
of the valve is faulty. Do not
disassemble any portion of the valve. It must
be replaced.
9. Remove the safety stands.
• Lower the vehicle.
• Check and fill the master cylinder to the proper
level.
VALVE REPLACEMENT
Removal steps 1. Hydraulic pipes
2. Warning switch
connector (Combination valve only)
3. Bolt
4. Combination valve/P&B valve
Installation
steps
To install, follow the removal steps in the reverse order.
Fig. 5A-5
1••1 REMOVAL
• The combination valve/P & 8 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.
1. Hydraulic pipes
• Plug the pipes to prevent the loss of fluid or the
entrance
of dirt.
2. Warning switch connector (Combination valve
only)
3. Bolt
4. Combination valve/P & B valve
1••1 INSTALLATION
4.
3. Combination valve/P & B valve
Bolt
I~I_T_o_r_qu_e_N_·_m_(lb_·_in_) ___,_ ___ 1_3_(_1_13_) __ _
2. Warning switch connector (Combination valve
only)
1. Hydraulic pipes
~~~ Torque N·m (lb·ft) 16 (12)
After installing the brake pipes, bleed brakes as
described in this section.
•

SA 16 HYDRAULIC BRAKES
MASTER CYLINDER ASSEMBLY
GENERAL DESCRIPTION
The master cylinder contains two pistons that supply
the hydraulic pressure
for a dual-circuit braking
system. The primary piston provides the fluid pressure
to the
front brakes, while the secondary piston
provides the fluid pressure
to the rear brakes. l.f ~he
pressure is lost from either system, the rema1n1ng
system will function to stop the vehicle.
\fl CAUTION:
VI • The master cylinder is not repairable. If found
defective,
it must be replaced as complete
assembly.
• If any hydraulic component is removed or
disconnected, it may be necessary to bleed all
or part of the brake system. (Refer to "On­
Vehicle Service" previously in this section.)
• The torque values specified are for dry,
unlubricated fasteners.
• Perform service operations on a clean bench
free
from all mineral oil materials.
Fig.
5A-15
•

HYDRAULIC BRAKES 5A-17
ON-VEHICLE SERVICE
FLUID RESERVOIR TANK
2
T 4
3 1
Removal steps
1. Electrical connector 2. Retainer
3. Fluid reservoir
4. 0-ring
Installation steps
To install, follow the removal steps in the reverse order.
Fig. 5A-16
1••1 REMOVAL
NOTE:
Before removing fluid reservoir, remove brake fluid
from fluid reservoir.
1. Electrical connector
2. Retainer (Fig. 5A-17)
Fig. 5A-17
3. Fluid reservoir
• The fluid level sensor is built into the fluid
reservoir (Except rear wheel anti lock model). It
cannot be removed for servicing.
4. 0-ring
1••1 INSTALLATION
To install, follow the removal steps in the reverse
order, noting the
following points;
4. 0-ring (Fig. 5A-18)
• 0-ring must be set onto the fluid reservoir,
before
installing fluid reservoir.
Fluid reservoir
0-ring
Fig. 5A-18

SA-18 HYDRAULIC BRAKES
MASTER CYLINDER ASSEMBL V
6
2
Removal steps
1.
Electrical connector
2. Brake pipes
3. 2 attaching nuts
4. Combination valve/P&B
valve and bracket
5. Master cylinder
6.
Spacer and 2gaskets
Installation steps
To
install, follow the removal steps in the reverse order.
5
4
Fig. 5A-19
1••1 REMOVAL
\i7 CAUTION:
'V When removing master cylinder from vacuum
booster, be sure
to get rid of the internal negative
pressure
of the vacuum booster (by, for instance,
disconnecting 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 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.
Electrical connector
2. Brake pipes
• After disconnecting the brake pipe, cap or tape
the openings
of the brake pipe to prevent the
entry of foreign matter.
3. 2
attaching nuts
4. Combination valve/P & B valve and bracket
5. Master cylinder
6. Spacer and 2 gaskets
1••1 INSTALLATION
6. Spacer and 2 gaskets
5. Master cylinder
• When replacing the master cylinder or vacuum
booster
or both, always measure the vacuum
booster push rod protrusion and adjust
it as
necessary. (Refer to "Vacuum Booster
Assembly" in Section 5A 1.)
4. Combination valve/P & B valve and bracket
3. 2 attaching nuts
• Tighten the attaching nuts to the specified
torque.
~~~ Torque N·m (lb·in) 13 (113)
2. Brake pipes
• Tighten the brake pipe to the specified torque.
1~1 Torque Master cylinder side 12 (1041b·in)
N·m (lb·ft) Others
16 (12)
1. Electrical connector
•

HYDRAULIC BRAKES SA-19
UNIT REPAIR
MASTER CYLINDER
• The master cylinder is not repairable and must
be replaced as 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.
IL•I 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
• 0-ring
rfil FUNCTIONAL INSPECTION OF MASTER
l..!aJ CYLINDER PISTON (Fig. SA-20)
Push the primary piston with your fingers to check that
it travels smoothly. If the motion is questionable,
replace
the master cylinder as a complete assembly.
Primary piston
Fig. 5A-20
["j"1i"l FUNCTIONAL INSPECTION OF MASTER
I..!:::..J CYLINDER (Fig. 5A-21 and 5A-22)
Inspect the master cylinder for function as follows. If
any abnormal function is found, replace with a new
one.
1®.1 Primary piston holder: J-39242
(including master cylinder attachment and
master
cylinder plug)
• Install
the primary piston holder onto the
master
cylinder with the spacer (2 bolts) with its
adjusting
bolt screwed in up to the "0" line (Fig.
5A-21)
Master cylinder Primary piston holder
Fig. 5A-21
1®.1 Radiator cap tester: J-24460-01
•
Connect master cylinder attachment with the
end
of radiator cap tester, and apply air
pressure
with the cap tester. Make sure there is
no rise in pressure and
that with the adjusting
bolt further screwed in 5 mm (align the
adjusting
bolt to the "5" line). There should be a
pressure increase
of 0.5kg/cm2 or more (Fig.
5A-22).
\f7 NOTE:
VI When checking the front (or primary) side, be sure
to mount master cylinder plug in the rear (or
secondary) port.
~ "0" line "5" line
Apply air
No pressure Pressure
pressure
to rise. increase of
the front and 0.5 kg/cm2 or
rear ports more
Remarks Checks port Checks air
into the atmos-
tightness
of the
pheric pressure pressure
chamber chamber