Nissan 47210-42F00 MASTERVACUUM Assembly-Brake

Check all vacuum lines and connectors for deterioration; a small vacuum leak can substantially affect the power brake system. Start by removing the negative terminal cable, then the master cylinder bolts and with the brake hose still connected, pull out the master cylinder and the power booster assembly. Then, turn the vacuum graphic to off, and disconnect vacuum hoses on the booster as well as the pushrod in the pedal clevis. Remove the booster to the engine compartment by taking out the bolt that secures it at the bottom of the dash. When installing, simply locate the brake booster assembly into the car and fix the master cylinder assembly to it. Attach the booster pushrod to the clevis of the pedal and the vacuum hoses to the brake booster. Last of all, join the battery, switch on the engine, and test for the proper functioning of the brake.

When the brake pedal is depressed, the vacuum source is closed off, allowing atmospheric pressure to enter one side of the diaphragm, which causes the master cylinder pistons to move and apply the brakes.