The hydraulic and mechanical problems that apply to conventional brake systems also apply to power brakes, and should be checked for if the tests below do not reveal the problem.
Test for a system vacuum leak as described below:
- Operate the engine at idle without touching the brake pedal for at least one minute.
- Turn off the engine, and wait one minute.
- Test for the presence of assist vacuum by depressing the brake pedal and releasing it several times. Light application will produce less and less pedal travel, if vacuum was present. If there is no vacuum, air is leaking into the system somewhere.
Test for system operation as follows:
- Pump the brake pedal (with engine off) until the supply vacuum is entirely gone.
- Put a light, steady pressure on the pedal.
- Start the engine, and operate it at idle. If the system is operating, the brake pedal should fall toward the floor if constant pressure is maintained on the pedal.
Power brake systems may be tested for hydraulic leaks just as ordinary systems are tested.
REMOVAL & INSTALLATION
- Working inside the car below the instrument panel, disconnect the booster valve operating rod from the brake pedal assembly.
- Open the hood and disconnect the wires from the stop light switch at the brake master cylinder.
- Disconnect the brake line at the master cylinder outlet fitting.
- Disconnect the manifold vacuum hose from the booster unit.
- Remove the four bracket-to-dash panel attaching bolts.
- Remove the booster and bracket assembly from the dash panel, sliding the valve operating rod out from the engine side of the dash panel.
- Mount the booster and bracket assembly to the dash panel by sliding the valve operating rod in through the hole in the dash panel, and installing the attaching bolts.
- Connect the manifold vacuum hose to the booster.
- Connect the brake line to the master cylinder outlet fitting.
- Connect the stop light switch wires.
- Working inside the car below the instrument panel, install the rubber boot on the valve operating rod at the passenger side of the dash panel.
- Connect the valve operating rod to the brake pedal with the bushings, eccentric shoulder bolt, and nut.