Brake Master Cylinder: Service and Repair
WM 471519 Removing and installing brake master cylinder
Preliminary work
Preliminary work for removing and installing brake master cylinder
1. Move bonnet into service position. -> 553119 Removing and installing front pneumatic spring - section on "Removing" Service and Repair
2. Remove the left cross panel. -> 508119 Removing and installing cross panel - section on "Removing" Service and Repair
Removing brake master cylinder
Information
- Before disconnecting the brake lines, place a clean absorbent cloth underneath.
- Close off brake lines with a suitable plug immediately after disconnecting.
Information
- In the event of assembly work at the hydraulic connections, all the electric plug connections in the area of the connection point must always be connected. This prevents the inside of the plug connections from being splashed with brake fluid or water.
- Clean any plug connections that have become dirty or damp during removal or fitting with a lint-free cloth.
- Brake fluid on electrical contacts (even thinned brake fluid) leads to corrosion and may cause faults in the system.
- Remove any escaping brake fluid immediately; rinse with water and dry thoroughly if necessary.
Information
- The pictures shown in this document may differ from the original.
- However, this does not affect the validity and relevance of the pictures.
Installation position of brake master cylinder
Brake master cylinder components
1. Release the sieve filter -1- using a suitable tool -2- and remove it from the brake fluid reservoir -3-.
Sieve filter in brake fluid reservoir
2. Drain the brake fluid from the brake fluid reservoir using a suitable tool, e.g. a double-action hand pump.
3. Disconnect the brake lines -2- from the brake master cylinder -3-.
Brake fluid reservoir
3.1. Unscrew cap screws.
3.2. Pull brake lines out of the bores.
3.3. Immediately close off brake lines and bores in the brake master cylinder with suitable stoppers.
4. Release electric plug connection -1- for the brake fluid level indicator -a- and pull it off -A-.
5. Release and unplug electric plug connection for the brake light switch. -> 943619 Removing and installing brake light switch - section on "Removing" Service and Repair
Information
If the brake master cylinder is to be replaced, first remove the brake fluid reservoir and then unscrew the fastening nuts for the brake master cylinder.
6. Loosen the fastening nuts -1- on the brake master cylinder -2- at the brake booster -3-.
Removing brake master cylinder
7. Carefully remove the brake master cylinder -1- and brake fluid reservoir -2- from the brake booster -3- and set them down on a suitable surface.
Removing brake master cylinder
Replacing brake master cylinder
Information
If the brake master cylinder is to be replaced, first remove the brake fluid reservoir and then unscrew the fastening nuts for the brake master cylinder.
Information
When replacing the brake master cylinder or the brake fluid reservoir, the latter is not repositioned until the brake master cylinder has been installed.
1. Remove the brake light switch. -> 943619 Removing and installing brake light switch - section on "Removing" Service and Repair
2. Loosen the fastening screw -1- used to secure the brake fluid reservoir -2- to the brake master cylinder -3-.
Fastening screw on brake master cylinder
3. Lever out the brake fluid reservoir -1- using a suitable tool -2- and remove it from the brake master cylinder -3-.
Removing brake fluid reservoir
4. Remove rubber seals -1- from the brake master cylinder -2- and replace them if necessary.
Rubber seals on brake master cylinder
Installing brake master cylinder
1. Carefully insert the brake master cylinder -1- together with the brake fluid reservoir -2- into the brake booster -3-.
Fitting brake master cylinder (shown with reservoir)
2. Fit the fastening nuts -1- on the brake master cylinder -2- at the brake booster -3-. -> 4X00IN Tightening torques for brake hydraulics [1][2]Hydraulic System, Brakes
Fastening nuts on brake master cylinder
3. If the brake master cylinder was replaced, press the brake fluid reservoir -2- into the brake master cylinder -2- ( -arrow- ).
Fitting brake fluid reservoir
3.1. Fit the fastening screw -1- used to secure the brake fluid reservoir -2- to the brake master cylinder -3-. -> 4X00IN Tightening torques for brake hydraulics [1][2]Hydraulic System, Brakes
Fastening screw on brake master cylinder
4. Fit the brake lines -2- on the brake master cylinder -3-.
Fitting brake master cylinder
5. Plug in electric plug connection -1- for the brake fluid level indicator -A- and lock it -a-.
6. Fit the brake light switch if necessary. -> 943619 Removing and installing brake light switch - section on "Installing" Service and Repair
7. Insert the sieve filter -1- into the brake fluid reservoir -3-.
Sieve filter in brake fluid reservoir
Subsequent work
Subsequent work for removing and installing brake master cylinder
1. Install left cross panel. -> 508119 Removing and installing cross panel - section on "Installing" Service and Repair
2. Change the brake fluid. -> 470855 Changing brake fluid Service and Repair
3. Move bonnet out of service position. -> 553119 Removing and installing front pneumatic spring - section on "Installing" Service and Repair