Removing
1. Remove the main brake cylinder.
2. Remove the ASR support pump.
3. Check up the main brake cylinder on absence of damages and leaks.
4. Unscrew or unhook the vacuum tube 8 from the vacuum booster 16. Press the brake pedal several times to reduce the pressure in the vacuum booster.
5. Disconnect connector A7/7x1, A7/7x2 from the BAS control unit, or on models with ESP, disconnect the connector from the solenoid valve switch and BAS diaphragm displacement sensor on the vacuum booster. On models with BAS and ESP, the BAS control unit is integrated with the ESP control unit.
6. Remove the bottom cover of the panel of devices.
7. Disconnect the brake pedal return spring.
8. Remove the retainer and pin 26.
9. Remove nut 23 from bracket 22.
10. Remove the vacuum booster 16.
11. Check gasket 16.
Installation
Installation is carried out in the reverse order of removal.
Examination
1. Press the brake pedal to reduce the pressure in the vacuum booster.
2. Disconnect the tester from the vacuum booster.
3. Attach pressure gauge 051 to the brake caliper with adapter.
4. Attach pedal force sensor 060 to the brake pedal.
5. Start the engine and build up a pressure of 0.75-0.80 bar by depressing and releasing the accelerator pedal. If a vacuum is reached that is significantly lower than required, or the vacuum immediately decreases, then the sealing ring between the vacuum booster and the brake master cylinder is damaged, or the valve in the vacuum tube must be checked.
6. Apply the required force on the accelerator pedal and read the pressure in the line.
The pressure in the hydraulic actuator, depending on the pressure on the brake pedal, is given in the Specifications.