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

• Mounting bracket, removing and installing, refer to => [ Mounting Bracket ] Mounting Bracket.

• Brake pedal, removing and installing, refer to => [ Brake Pedal ] Brake Pedal.

2 Nut

• 25 Nm

• Always replace if removed.

• Follow the tightening sequence.

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.

• Functional check:

- 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).

• Removing and installing (vehicles with a 5-cylinder gasoline engine), refer to => [ Brake Booster ] Brake Booster.

• Removing and installing (vehicles with a 6-cylinder gasoline engine), refer to => [ Brake Booster ] Brake Booster.

• Removing and installing (vehicles with a 4-cylinder diesel engine), refer to => [ Brake Booster ] Brake Booster.

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

• Check the brake booster vacuum system for faults. Refer to => [ Vacuum System, Checking ] Testing and Inspection

5 Seal

6 Brake Master Cylinder

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

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

• Removing and installing (vehicles with a 5-cylinder gasoline engine), refer to => [ Master Brake Cylinder ] Master Brake Cylinder.

• Removing and installing (vehicles with a 6-cylinder gasoline engine), refer to => [ Master Brake Cylinder ] Master Brake Cylinder.

• Removing and installing (vehicles with a 4-cylinder diesel engine), refer to => [ Master Brake Cylinder ] Master Brake Cylinder.

7 Nut

• 25 Nm

• Always replace if removed.

8 Bolt

• 5 Nm

9 Brake Light Switch (F)

• Includes Brake Pedal Switch (F47)

• Removing and installing, refer to => [ Brake Light Switch ] Service and Repair.

10 Brake Line

• 14 Nm

• Master brake cylinder/secondary piston circuit for the ABS hydraulic unit (N55).

• Identification: 6.5 mm and tube fitting with M12 x 1 thread.

11 Brake Line

• 14 Nm

• Master brake cylinder/primary piston circuit for the ABS hydraulic unit (N55).

• Identification: 6.5 mm and tube fitting with M12 x 1 thread.

12 Sealing Plugs

• Connection for vacuum hose.

13 Sealing Plugs

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

14 Brake Fluid Reservoir

• Only use new brake fluid conforming to US-Norm FMVSS 116 DOT 4.

15 Cap

• With the brake fluid level warning switch (F34).

16 Vacuum Line

• Insert into brake booster.

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

• Check if brake booster is malfunctioning. Refer to => [ Vacuum System, Checking ] Testing and Inspection.

17 Vacuum Diaphragm (G608)