Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 987

BRAKES  5-19

5. Inspection of brake fluid pressure (Reference value)

1) Adjust the rear axle weight as specified under the

paragraph 1.

2) Install the pressure gauge on bleeder screws on the

front and rear brakes.

3) Depress the brake pedal and take reading of the

pressure gauges.

The brake fluid pressure is normal if the pressure of fluid

within the rear wheel cylinders is within the range of 34.4

±

5.5 kg/cm

2

 when pressure of fluid within the front wheel

cylinders reaches 50 kg/cm

2

.

Note:
The brake pedal should be depressed gradually until
specified pressure is reached without pumping or
adjusting foot pressure.

5-20  BRAKES

BLEND PROPORTIONING VALVE (IF SO EQUIPPED)

Structure and Operation

•

Structure

Side 

I

 shows P-valve ; side 

II

 shows bypass valve.

Bypass valve seals the routes 

4

 and 

5

 using the seal 

2

 at

the piston 

1

 end.

In addition, spring 

3

 presses against the piston 

1

, and in

order to seal out the route 

4

 and route 

5

 sufficiently, spring

3

 presses seal 

2

 against cylinder end surface.

The left figure is a characteristic curve diagram.

BRAKES  5-21

•

Operation

The operation of the P-valve by the master cylinder

pressure is unchanged up to the brake points 

A

 and 

B

.

If master cylinder fluid pressure penetrates into the second

break point 

B

, the fluid pressure pressing against the seal

2

, (which isolated route 

4

 and route 

5

), passing the route

4

 of the master cylinder side, overcomes the operating

force of the spring 

3

 + fluid pressure affecting the seal 

2

 of

the wheel cylinder, and presses the piston 

1

 to the right

side, resulting in the opening of the routes 

4

 and 

5

, and

canceling of the P-valve operation.

Then, because the master cylinder fluid pressure and the

wheel cylinder fluid pressure, up to the point 

C

, operate on

the identical surface of the seal 

2

, both have identical

ascending ratio.

However, because of the operation of spring 

3

 in the wheel

cylinder side, wheel cylinder fluid pressure operate to

preserve the balance against the master cylinder fluid

pressure on the lower level with the difference in pressure

resulting from this spring.

Valve Maintenance

In the case of fluid leak or other abnormalities, faulty valve
should be replaced.
The valve is set up at the right hand side of the 5th
crossmember near the rear axle.
Note:
The blend proportioning valve is not repairable and must
be replaced as a complete assembly.

BLEEDING OF THE BRAKE HYDRAULIC

CIRCUIT

If air enters the bake lines, it will cause poor brake action.
Therefore, bleeding should be performed if the brakes have
been used with the level of brake fluid in the reservoir
excessively low or if brake pipes have been disconnected in
the course of brake servicing.
Bleeding operation calls for co-operative action of 2 persons.

•

Set the parking brake firmly while bleeding.

•

Perform bleeding operation with ENGINE RUNNING, to

prevent damage to push rod seal.

Make sure exhaust is suitably ventilated.

•

Bleed the hydraulic system with the fluid reservoir filled to

the specified level.

•

Bleed the system starting with the rear wheel cylinder

farthest from the master cylinder.

A

 : Load sensing proportioning valve (If so equipped).

5-22  BRAKES

1. Fill the brake fluid reservoir with brake fluid.

Handle the brake with reasonable care to avoid spillage as it

is damaging to paint.

Note:
Take care to prevent foreign matter from entry, when
replenishing or replacing brake fluid.
When pouring brake fluid, if diaphragm in the oil tank cap
is stretched, be sure to place it into original position,
(fasten it), and then cap it.
2. Connect a vinyl pipe to the bleeder screw on the wheel

cylinder, caliper bode or LSPV and the other end of the pipe

in a transparent container.

3. Pump the brake pedal several times and hold it depressed.

Loosen the bleed screw to release brake fluid together with

air bubbles.

Tighten the bleeder screw before pressure is released

completely.

4. Repeat the step in paragraph 3 above until the air bubbles

disappear completely.

Securely tighten the bleeder screw when the air bubbles

disappear completely.

5. Repeat the step in paragraph 4 above on the remaining

wheel cylinders.

Bleed the system starting with rear side farthest from the

brake fluid reservoir.

6. Fill the brake fluid reservoir to the specified level.

Pour brake fluid carefully so as not to produce air bubbles.

7. If the cap diaphragm is stretched, fasten the diaphragm and

the sure to cap it after it is placed to the original position.

Note:
Never reuse the old brake fluid.