Road test the brakes by making a brake application at about 20 mph to determine if the vehicle stops evenly and quickly. If the pedal has a spongy feel, when applying the brakes, air is present in the hydraulic system. Bleed the system at each wheel cylinder.

With the engine stopped and the transmission in neutral, apply the brake several times to exhaust all vacuum in the system. While depressing the brake pedal, start the engine. If the vacuum system is operating, the pedal will tend to move away under foot pressure, and less pressure will be required to hold the pedal in the applied position. If no action is felt, the vacuum system is not f unctioning.

Stop the engine and again exhaust all vacuum in the system. Without starting the engine, depress the brake pedal and hold foot pressure on the pedal. If the pedal gradually falls away under foot pressure, the hydraulic system is leaking.

To check the vacuum check valve, start the engine and accelerate to 20 mph and turn off the ignition. Immediately close the throttle to-build up the vacuum supply. Wait at least 90 seconds and apply the brakes. if not vacuum assisted, the vacuum check valve or vacuum cylinder is leaking.