Brake Master Cylinder: Service and Repair

Brake Master Cylinder

Special tools, testers and auxiliary items required

• Brake Charger/Bleeder Unit (VAS 5234)

Removing

- Remove the plenum chamber cover.

- Remove the engine compartment seal and cover strip in the area of the brake booster.

- Remove the facing wall of the plenum chamber.

- Place sufficient lint free cloths in the plenum chamber in the area of the master cylinder.

- Extract as much brake fluid as possible from the brake fluid reservoir using the (VAS 5234) or (V.A.G 1869/4).

- Disconnect the connector from the brake fluid level warning switch (F34).

- Disconnect the connector from the brake pressure sensor.

- Remove the brake fluid reservoir, press the engagement straps toward the outside of the reservoir and simultaneously pull the brake fluid reservoir out of sealing plugs.

- Remove the left front brake line from the retainer on the master cylinder.

- Disconnect the brake lines from the master cylinder and seal the brake lines using sealing plugs from kit (1H0 698 311 A).

- Remove the master cylinder nuts.

- Carefully take the master cylinder out of the brake booster.

Installing

- Installation is performed in the reverse order of removal.

Observe the following points when installing:

- When installing the master cylinder and brake booster together, make sure that the push rod is correctly located in the master cylinder.

The O-ring between the master cylinder and brake booster is present.

- Bleed the brake system. Refer to => [ Brake System Bleeding ] Service and Repair.

After bleeding the brake system, the basic setting for brake pressure sensor 1 (G201) must be performed.

(VAS 5051), connecting and selecting functions. Refer to => [ VAS 5051, Connecting and Selecting Functions ] Testing and Inspection.