Brake Booster and Master Brake Cylinder Overview

Brake Booster and Master Brake Cylinder Overview

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






1 Pedal Assembly

2 Self-Locking Hex Nut

• Always replace after removing it.

• 25 Nm

3 Gasket

• For brake booster

4 Brake Booster

• On gasoline engines, vacuum is supplied from intake manifold.

• Some vehicles with gasoline engine and automatic transmission are equipped with a brake system vacuum pump (V192).

• On vehicles with a hydraulic brake booster, a vacuum sensor is installed.

• Functional check:

- With engine switched off, depress brake pedal firmly several times (to deplete vacuum in tool).

- 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).

• Removing and installing, refer to => [ Brake Booster ] Brake Booster

5 Seal

6 Brake Booster Vacuum Sensor (G483)

• Only on vehicles with the hydraulic brake booster

• Removing and installing, refer to => [ Brake Booster Vacuum Sensor (G483) ] Brake Booster Vacuum Sensor (G483)

7 Brake Master Cylinder without Brake Lamp Switch

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

• Removing and installing, refer to => [ Brake Master Cylinder ] Brake Master Cylinder

8 Brake Master Cylinder with Brake Lamp Switch

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

• Removing and installing, refer to => [ Brake Master Cylinder ] Brake Master Cylinder

9 Brake Lamp Switch (F)

• Includes brake pedal switch (F47)

• On vehicles through calendar week 45/05, the brake lamp switch (F) is located on the brake pedal, refer to => [ Brake Pedal Overview ] Brake Pedal Overview

• Removing and installing, refer to => [ Brake Lamp Switch, from 10.05.2005 ] Service and Repair

10 Inner Torx(R) Bolt

• 5 Nm

11 Heat Shield

12 Self-Locking Hex Nut

• Always replace after removing it.

• 25 Nm

13 Brake Line

• 14 Nm

• Master brake cylinder/secondary piston circuit to hydraulic unit

14 Brake Line

• 14 Nm

• Master brake cylinder/primary piston circuit to hydraulic control unit

15 Sealing Plugs

• Coat with brake fluid and press into brake fluid reservoir

16 Brake Fluid Reservoir

17 Cap

18 Sealing Plugs

• Connection for vacuum hose

19 Vacuum Hose

• Insert into brake booster

20 Brake Booster Pressure Sensor (G294)

• On vehicles with FSI engine without hydraulic brake vacuum booster

• Removing and installing, refer to => [ Brake Booster Pressure Sensor ] Brake Booster Pressure Sensor