Assembling the vacuum booster
Brake Booster Installation Details (1 of 4)
8 - Brake fluid level sensor wiring connector; 9 - Brake fluid reservoir; 10 - Brake lines; 11 - GTZ; 12 - Vacuum line; A7/7 - Brake booster
Brake Booster Installation Details (2 of 4)
1 - Cover on the left under the instrument panel; 3 - Mounting bolt; 4 - Cotter pin; 13 - Nuts; S9/1 - Brake light switch sensor
Brake Booster Installation Details (3 of 4)
14 - Clamp bolt; 16b - Retaining ring; A7/7x1 - BAS diaphragm stroke sensor wiring connector; A7/7x2 - BAS Release Solenoid Valve/Sensor Wiring Connector; A7/7b1 - BAS diaphragm stroke sensor
Brake Booster Installation Details (4 of 4)
3 - Mounting bolt
C — Control unit
1. Disconnect the connector (8) of the brake fluid level sensor wiring on the brake fluid reservoir (9).
2. Disconnect the brake lines (10) from the brake master cylinder (11).
3. Disconnect the connector (A7/7x2) of the BAS solenoid valve/switch-sensor wiring, and the connector (A7/7x1) of the BAS diaphragm stroke sensor.
4. In order to expand the free space, unscrew the clamp bolt (14) of the ground terminal for starting the engine from an external power source.
5. After releasing the vacuum by pressing the foot brake pedal several times, disconnect the vacuum line (12) from the brake booster (A7/7) - assess the condition of the rubber bushing securing the line, and replace it if necessary.
6. To increase the free space, remove the control unit (C) and move it to the side without disconnecting any communication lines.
7. Remove the cover (1) on the left under the instrument panel.
8. Turn to the left, pull and remove the brake light switch sensor (S9/1).
9. Remove the cotter pin (4) and remove the bolt (3) securing the pusher to the foot brake pedal. Assess the condition of the bolt, and if necessary, prepare a replacement element - the cotter pin must be replaced without fail.
10. Remove the nuts (13) - all self-locking fasteners must be replaced without fail.
11. Remove the brake booster (A7/7) complete with the brake master cylinder (11).
12. Installation is carried out in the reverse order - lubricate the assembly seating surface with sealant before installation.
13. Finally, bleed the brake system (see Section Bleeding the brake system), inspect its hydraulic system for signs of developing leaks and check the correct operation of the brake lights.
BAS diaphragm stroke sensor
1. The installation details of the BAS diaphragm stroke sensor are shown in the illustration Brake booster installation details (3 of 4)
2. By pressing the foot brake pedal several times, relieve the residual vacuum in the brake booster system in order to release the sensor sealing ring.
Note: If the o-ring becomes trapped in the booster assembly, the sensor must be replaced.
(Publication taken from an online resource: «www.mercedesman.ru»)
3. In order to expand the free space, unscrew the clamp bolt (14) of the ground terminal for starting the engine from an external power source.
4. Disconnect the connector (A7/7x1).
5. Using a suitable tool, remove the retaining ring (16b) - the ring must be replaced without fail.
6. Pull the sensor (A7/7b1) out of its socket.
7. Installation is carried out in the reverse order - make sure that the sealing and retaining rings are seated correctly. Before inserting the sensor into the sealing ring, moisten it from the front with soapy water.
8. Start the engine, press the foot brake pedal several times, then turn off the ignition again and make sure there are no signs of air being sucked in through the sensor.