B3000 SE Regular Cab 4WD V6-3.0L OHV (1998)
Brake Master Cylinder: Testing and Inspection
NORMAL CONDITIONS
The following conditions are considered normal and are not indications that the brake master cylinder is in need of service.
Condition 1: During normal operation of the brake master cylinder, the fluid level in the brake master cylinder reservoir will rise during brake
application and fall during release. The net fluid level (after brake application and release) will remain unchanged.
Condition 2: A trace of brake fluid will exist on the booster shell below the master cylinder mounting flange. This results from the normal lubricating
action of the master cylinder bore and seal.
Condition 3: Fluid level will decrease with pad wear.
ABNORMAL CONDITIONS
Changes in brake pedal feel or travel are indicators that something could be wrong in the brake system. Refer to Brakes / Testing and Inspection /
Procedures for Conventional Brake System Diagnosis.
BYPASS CONDITION TEST
1. Disconnect the brake lines at the brake master cylinder.
2. Plug the outlet ports of the brake master cylinder.
3. Apply the brakes. If brake pedal height cannot be maintained, the brake master cylinder has an internal leak and must be replaced.
COMPENSATOR PORT CHECK
The purpose of the compensator ports in the brake master cylinder is to supply any additional brake fluid required by the system due to brake pad wear
and to allow brake fluid returning from the brake lines to the brake master cylinder to enter the brake master cylinder reservoir.
The returning brake fluid will cause a slight turbulence in the brake master cylinder reservoir. Turbulence seen in the brake master cylinder reservoir
upon release of the brake pedal is normal and shows that the compensating ports are not plugged.
