Replacing Brake Fluid Bleeding Brakes and Lock Control

General Information

Since brake master cylinder circuits, consisting of the push rod circuit (for front axle) and intermediate piston circuit (for rear axle) with the ABS hydraulic control unit, are completely independent of the booster circuit (brake booster and lock control), brake fluid replacing and bleeding procedures are divided into different jobs (see next page).


=== Brake master cylinder circuits (exception 3)

Booster circuit (brake booster and lock control)

1+2 To axial and lateral lock cylinders (Q and L)

-3 Feed to clutch master cylinder

4 Pump assembly

5 Pressure reservoir

6 Valve assembly (solenoids for axial and lateral locks)

7 Brake booster

8 ABS hydraulic control unit


- Only use new DOT 3 or DOT 4 (SAE J 1703) brake fluid. Total brake fluid change volume = approx. 1.6 liters.

Brake fluid must be replaced at least every two years.

Brake fluid supply tank is divided into chambers from about the middle downwards.

Procedures / Division

1. Replace brake fluid (brakes, lock control and clutch).

2. Bleed lock cylinders and pressure pipes, insofar as the hydraulic system had been disconnected after the valve assembly for lock operation.

Described in Rep.-Group 47.

3. Bleed lock or brake booster circuit, insofar as parts of the booster circuit had been replaced or the system (including intake end of the pump assembly) had been disconnected.

Described in Rep.-Group 47.

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