Removing and Installing Brake Master Cylinder

WM 471519 Removing and installing brake master cylinder

Information
The brake components (brake booster, brake master cylinder, hydraulic unit) are installed under the luggage compartment cover -2-.

Luggage compartment cover

The brake master cylinder -B- is secured to the brake booster -C- with two hexagon nuts -1-.

1 - Brake master cylinder mount
2 - Brake booster mount

Brake master cylinder mount

Preliminary work
1. Remove cover over the brake master cylinder (front luggage compartment cover).

There are two types of luggage compartment covers -1- (illustrations below).

Removing luggage compartment cover

Removing luggage compartment cover

Removing brake master cylinder
1. Suck brake fluid out of the reservoir or pump out the brake fluid using the brake pedal via a front and rear brake caliper. Use a collecting bottle.
2. Pull electric line -Arrow- off the reservoir -A-. Undo the brake lines -Arrows- on the brake master cylinder -B-. Close the brake lines and connections with suitable plugs.

Brake lines on brake master cylinder

3. Undo the fastening nuts -1- on the brake master cylinder. Pull out brake master cylinder -B-.

1 - Brake master cylinder mount
2 - Brake booster mount

Brake master cylinder mount

Installing brake master cylinder
1. Install in reverse order. Tighten fastening nuts -1- on the brake master cylinder to the prescribed tightening torque. When fitting the reservoir, make sure it engages correctly.

1 - Brake master cylinder mount
2 - Brake booster mount

Brake master cylinder mount

2. Bleed the brake system and adjust the brake-fluid level.
3. Carry out the following tests:
^ Check the system for leaks.
^ Then start the engine. Brake-related lights in the instrument cluster must go out when the engine is running.
^ Carry out a function test on the brakes.

Subsequent work
Install cover over brake master cylinder (luggage compartment cover) -1-.

Installing luggage compartment cover