Q: How to perform an operating check on the Brake Booster?
A: To check the power brake unit, depress the brake pedal several times with the engine off. The pedal reserve shouldn't change. Depress the pedal, start the engine; the pedal should drop slightly. For airtightness, start and stop the engine. Depress the pedal multiple times; it should rise after the second or third push. With the engine running, depress the pedal, turn off the engine and hold for 30 seconds. No change indicates an airtight booster. For removal, detach the master cylinder from the power brake unit and disconnect the vacuum hose. Unlink the brake pushrod from the pedal and remove the booster's nuts. Lift the unit out. For installation, attach the unit with four nuts, connect the pushrod, tighten retaining nuts, reconnect the vacuum hose, and reattach the master cylinder. Bleed the brakes if lines were disconnected.