Vacuum Brake Booster: Service and Repair

WM 477019 Removing and installing brake booster

Tools





Preliminary work

Preliminary work for removing and installing brake booster

1. Move bonnet into service position. -> 553119 Removing and installing front pneumatic spring - section on "Removing" Service and Repair
2. Remove the brake master cylinder. -> 471519 Removing and installing brake master cylinder - section on "Removing" Service and Repair
3. Remove wiper arms. -> 922519 Removing and installing wiper arm - section on "Removing" 922519 Removing and installing wiper arm
4. Remove fastening screws -1- on the wiper linkage and remove the wiper linkage -2-.





Wiper linkage

5. Remove trim panel under dashboard on the left. -> 701919 Removing and installing trim panel under dashboard - section on "Removing" 701919 Removing and installing trim panel under dashboard

Removing brake booster

Information

- During assembly work on hydraulic connections, the electrical plug connections on the hydraulic unit must always be connected. This prevents the plug connections on the hydraulic unit and the inside of the connectors being splashed with brake fluid or water.

- Damp connectors must be wiped dry before disconnection.

- Brake fluid on electrical contacts (even thinned brake fluid) leads to corrosion and may cause faults in the system.

Information

- Brake lines are to be sealed with suitable plugs.

- To catch escaping brake fluid, place a cloth under the brake booster.





Installation position of brake light switch









Components

1. Carefully pull the vacuum line -1- out of the brake booster -2-.





Vacuum line on brake booster

2. Lever the push rod out of the brake pedal using the release tool T10189. -> 460519 Removing and installing brake pedal - section on "Removing" Service and Repair
3. Loosen the fastening nuts -1- on the brake booster under the dashboard.





Removing brake booster

Information

Make sure not to damage the push rod boot when removing the brake booster.

The seal between the brake booster and body must always be replaced.

4. Remove the brake booster.
4.1. Hold the brake lines aside carefully ahead of the brake booster.
4.2. Carefully remove the brake booster from the engine compartment and out of the vehicle.

Installing brake booster

1. Carefully fit the brake booster into the vehicle.
2. Fit the fastening nuts -1- for the brake booster under the dashboard. -> 4X00IN Tightening torques for brake mechanism 4X00IN Tightening torques for brake mechanics





Fitting brake booster

3. Fit the brake booster push rod in the brake pedal.
3.1. Press the brake pedal forward until the ball joint engages in the mounting point. -> 460519 Removing and installing brake pedal - section on "Installing" Service and Repair
4. Carefully fit the vacuum line -1- into the brake booster -2-.





Vacuum line on brake booster

Subsequent work

Subsequent work for removing and installing brake booster

1. Fit the wiper linkage -2- and screw in fastening screws -1-.





Wiper linkage

2. Fit wiper arms. -> 922519 Removing and installing wiper arm - section on "Installing" 922519 Removing and installing wiper arm
3. Fit the brake master cylinder. -> 471519 Removing and installing brake master cylinder - section on "Installing" Service and Repair
4. Fit trim panel under dashboard on the left. -> 701919 Removing and installing trim panel under dashboard - section on "Installing" 701919 Removing and installing trim panel under dashboard
5. Move bonnet out of service position. -> 553119 Removing and installing front pneumatic spring - section on "Installing" Service and Repair