In a Volvo S80, the brake booster increases power to the brakes via a hydraulic system, helping you stop prior to colliding with the car in front of you. The Volvo S80 is a full-size sedan, and requires a substantial amount of force to be applied to the brakes to stop the car. As such, it is important to replace the brake booster if it is damaged or out of service -- a misfunctioning brake booster seriously decreases the safety of the car.
Remove the positive battery cable and air filter box, then unbolt the automatic brake system, or ABS, pump from the car. Remove the master cylinder from the brake booster.
Inside the vehicle, disconnect the brake pedal from the brake booster.
Remove the brake line and vacuum line from the brake booster. Unbolt the brake booster from the bulkhead and remove it.
Position the new brake booster. Bolt it in place. Install the vacuum line and brake fluid line.
Reinstall the master cylinder, ABS pump, air filter box, and battery cable.
Connect the brake pedal.
Bleed the brakes by having an assistant pump and hold the brake pedal. With the pedal held down, locate the bleeder port on one of the front brake calipers and loosen it. Repeat the process until the brake pedal feels stiff again. Refill the brake fluid during this process as necessary.
