To perform an operating check, depress the brake pedal several times with the engine off to ensure there's no change in the pedal reserve distance, then start the engine and check if the pedal goes down slightly, indicating normal operation. For an airtightness check, start the engine and turn it off after one or two minutes, then depress the brake pedal slowly several times; if the pedal depresses less each time, the booster is airtight. While the engine is running, depress the brake pedal and stop the engine with the pedal depressed; if there's no change in the pedal reserve travel after holding for 30 seconds, the booster is airtight. Power brake booster units should not be disassembled due to their complexity and critical relationship to brake performance; instead, they should be replaced with a new or rebuilt unit. Begin removal by taking off the cowl cover, then remove the
Brake Master Cylinder with the remote reservoir and hoses. Pull the ABS actuator and its mounting bracket out enough for brake booster removal, disconnect the vacuum hose from the brake booster carefully, and inside the vehicle, remove the driver's knee bolster. Use a flashlight to locate the clevis connecting the booster pushrod to the brake pedal, remove the clevis-pin retaining clip, and pull out the pin. Remove the four nuts and washers holding the brake booster to the firewall, then slide the booster straight out until the studs clear the holes. For installation, follow the reverse of removal, ensuring to tighten the clevis locknut and booster mounting nuts to the specified torque. If installing a new power brake booster unit, check the pushrod clearance by measuring the distances from various points and calculating the pushrod clearance; adjust the pushrod length as necessary to achieve the correct clearance. After final installation of the master cylinder and brake hoses, adjust the brake pedal height and freeplay, and bleed the system.