Vacuum Brake Booster: Description and Operation
Brake master cylinder with brake booster, removing and installing
Special tools, testers and auxiliary items required
^ Release tool T40024
Sealing plug repair kit, Part no. 1H0 698 311 A
Removing
- Remove glove compartment on drivers side.
- Rotate brake light switch -1- 45 degrees to left and remove.
- Use release tool T40024 to separate brake pedal from brake booster.
Extracting brake fluid using brake filler/bleeder unit VAS 5234
- Remove plenum chamber cover.
- Lay out sufficient lint-free cloths in area of plenum chamber.
- Open brake fluid reservoir.
- Extract brake fluid.
- Disconnect connector from float warning indicator sensor -1-.
- Disconnect vacuum hose -2-.
- Remove securing bolt -1- for brake fluid reservoir.
Note:
^ Protect the plenum chamber against any escaping brake fluid.
^ The underside of the brake fluid reservoir clips into the brake master cylinder.
- To remove reservoir, press locking tab down and at the same time, remove brake fluid reservoir from sealing plugs.
- Remove brake fluid reservoir and lay it to one side.
- Disconnect brake lines -1- and -2- and seal with sealing plugs from repair kit, Part No. 1H0 698 311 A.
- Lay out sufficient lint-free cloths in the area of the hydraulic control unit.
- Disconnect brake lines -1- and -2- and remove together with rubber grommet.
- Remove brake booster securing bolts -1- (Torx T45).
- Remove brake booster with brake master cylinder.
On vehicles installed with cross brace the cross brace must be removed.
- Removing and installing cross brace.
- Remove securing nuts for brake master cylinder -1-.
- Carefully remove brake master cylinder from brake booster.
Installing
When installing, note the following points:
Note:
^ Clean any residual brake fluid off plenum chamber before installing brake master cylinder.
^ When assembling brake master cylinder with brake booster unit, make sure push rod is properly positioned in brake master cylinder.
- Adjust brake light switch.
- Bleed brake system.