Brake Booster and Master Cylinder Assembly Overview
Brake Booster and Master Cylinder Assembly Overview
• Use only new brake fluid. Observe information on brake fluid reservoir!
1 Pedal Assembly
• Various versions
2 Nut, 25 Nm
• Self-locking
• Always replace after removal.
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). Refer to => [ Brake System Vacuum Pump ] Brake System Vacuum Pump.
• On vehicles with a hydraulic brake booster, a vacuum sensor is installed. Refer to => [ Brake Booster Vacuum Sensor ] Brake Booster Vacuum Sensor.
• On Diesel engines, a vacuum pump is installed for vacuum creation. Refer to => [ Vacuum Pump for Brake Booster Assembly Overview, Diesel Vehicles ] Vacuum Pump for Brake Booster Assembly Overview, Diesel Vehicles.
• Function test:
- With engine switched off, depress brake pedal firmly several times (to deplete vacuum in brake booster).
- 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).
• If malfunctioning: replace as complete unit.
• Removal and installation, refer to => [ Brake Booster ] Brake Booster.
5 Seal
6 Brake Booster Vacuum Sensor (G483)
• Only on vehicles with the hydraulic brake booster.
• Removal and installation, refer to => [ Brake Booster Vacuum Sensor ] Brake Booster Vacuum Sensor.
7 Brake Master Cylinder without Brake Light Switch
• Cannot be serviced. Replace as complete unit if malfunctioning.
• Removal and installation, refer to => [ Master Cylinder ] Master Cylinder.
8 Brake Master Cylinder with Brake Light Switch
• Cannot be serviced. Replace as complete unit if malfunctioning.
• Removal and installation, refer to => [ Master Cylinder ] Master Cylinder.
9 Brake Light Switch (F)
• Includes Brake Pedal Switch (F47).
• On vehicles through calendar week 50/05, the brake light switch is located on the brake pedal. Refer to => [ Brake Pedal Assembly Overview ] Brake Pedal Assembly Overview.
• Removal and installation, refer to => [ Brake Light Switch, from 10.05.2005 ] Brake Light Switch, from 10.05.2005.
10 Bolt, 5 Nm
11 Heat Shield
12 Nut, 25 Nm
• Self-locking
• Always replace after removal.
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.
• Removal and installation, refer to => [ Brake Booster Pressure Sensor ] Brake Booster Pressure Sensor.