Brake Booster and Brake Master Cylinder Assembly Overview

Brake Booster and Brake Master Cylinder Assembly Overview

• Use only new brake fluid. Observe information on brake fluid reservoir!





1 Pedal Assembly

2 Nut, 25 Nm

• Self-locking

• Always replace after removal.

3 Gasket

• For brake booster.

4 Brake Booster

• On gasoline engines, the required vacuum is supplied either by the intake manifold or by a mechanical vacuum pump.

• Some gasoline vehicles with a DSG transmission, but not having an hydraulic brake booster, have a Brake Vacuum Pump (V192). Refer to => [ Brake System Vacuum Pump ] Service and Repair.

• On diesel engines, a vacuum pump is installed for vacuum creation. Refer to => [ Brake Booster Vacuum Pump, Diesel ] Brake Booster Vacuum Pump, Diesel.

• Function test:

- With engine switched off, depress brake pedal firmly several times (to exhaust the vacuum in the unit).

- Depress and hold brake pedal with average foot pressure and start engine. If brake booster is working properly, pedal will be felt to give noticeably under foot (booster assistance becomes effective).

• Replace as a unit in the event of malfunction (previously, check all vacuum lines).

• Removal and installation, refer to => [ Brake Booster ] Brake Booster.

5 Seal

6 Brake Master Cylinder

• Allocation, refer to the => Electronic Parts Catalog (ETKA).

• Cannot be serviced. Replace as complete unit if malfunctioning.

• Removal and installation, refer to => [ Brake Master Cylinder ] Brake Master Cylinder.

7 Brake Light Switch (F)

• Includes Brake Pedal Switch (F47)

• Removal and installation, refer to => [ Brake Light Switch ] Service and Repair.

8 Bolt, 5 Nm

9 Clip

10 Heat Shield

11 Nut, 25 Nm

• Self-locking

• Always replace after removal.

12 Brake Line, 14 Nm

• Brake master cylinder/secondary piston circuit to hydraulic unit.

13 Brake Line, 14 Nm

• Brake master cylinder/primary piston circuit to hydraulic control unit.

14 Sealing Plugs

• Moisten with brake fluid and press into brake fluid reservoir.

15 Brake Fluid Reservoir

16 Cap

17 Vacuum Hose

• Insert into brake booster.

18 Vacuum Diaphragm (G608)

• On vehicles with a hydraulic brake booster.

• Removal and installation, refer to => [ Vacuum Sensor ] Vacuum Sensor.

• Some vehicles, without a hydraulic brake booster, have a Brake Booster Pressure Sensor (G294).

• Brake booster pressure sensor, removal and installation, refer to => [ Brake Booster Pressure Sensor ] Brake Booster Pressure Sensor.

19 Sealing Plugs

• Connection for vacuum hose.