Depress the brake pedal several times with the engine off and make sure that there is no change in the pedal reserve distance. Depress the pedal and start the engine. If the pedal goes down slightly, operation is normal. Start the engine and turn it off after one or two minutes. Depress the brake pedal several times slowly. If the pedal goes down farther the first time but gradually rises after the second or third depression, the booster is air tight. Depress the brake pedal while the engine is running, then stop the engine with the pedal depressed. If there is no change in the pedal reserve travel after holding the pedal for 30 seconds, the booster is air tight. Power brake booster units should not be disassembled. They require special tools not normally found in most service stations or shops. They are fairly complex and because of their critical relationship to brake performance it is best to replace a defective booster unit with a new or rebuilt one. To remove the booster, first unbolt the brake master cylinder from the booster and carefully pull it forward. Disconnect the hose leading from the engine to the booster. Be careful not to damage the hose when removing it from the booster fitting. Locate the pushrod connecting the booster to the brake pedal. This is accessible from the interior in front of the driver's seat. Disconnect the brake light switch wire connector, remove the pushrod bolt nuts and pull out the bolt. Discard the bolt and nuts and obtain new ones of the same part number for installation. Remove the four nuts holding the brake booster to the firewall. You may need a light to see these, as they are up under the dash area. Slide the booster straight out from the firewall until the studs clear the holes and pull the booster, brackets and gaskets from the engine compartment area. When installing the booster pushrod to brake pedal bolt, insert it from the right side on manual transmission models and from the left side on automatic transmission models. In either case, the bolt must first pass through the brake pedal, THEN the pushrod. Installation procedures are basically the reverse of those for removal. Tighten the pushrod nuts, booster mounting nuts, and the master cylinder mounting nuts to the specified torque.
