Contents: Removal ↡ Installation ↡
The vacuum booster is installed between the brake pedal and the master cylinder and serves to increase the force applied to the brake pedal. The boost is obtained by means of a vacuum supplied from the engine intake manifold through a check valve. When the brake pedal is released, the vacuum is supplied to the cavities on both sides of the inner diaphragm. When the pedal is pressed, one of the cavities communicates with the atmosphere, and thus the pressing force increases due to the pressure difference acting on the inner diaphragm. A malfunction of the vacuum booster does not affect the efficiency of the brakes, but it does require the application of more force to the brake pedal.
To check the operation of the booster, turn off the engine and press the brake pedal several times to remove the vacuum. Press the pedal and, holding it pressed, start the engine. At idle speed, the brake pedal will slightly sink to the floor of the body, which indicates normal operation of the booster.
Brake pedal, booster and master cylinder parts
1 - bracket; 2 - release spring; 3 - lock nuts; 4 - brake light switch; 5 - brake pedal; 6 - motor shield; 7 - pusher; 8 - partition; 9 - gasket; 10 - vacuum booster; 11 - sealing ring ("X"); 12 - master cylinder
Removal
1. To remove the brake booster, first remove the brake master cylinder (see Master brake cylinder).
2. Disconnect the vacuum hose by unscrewing the union nut.
3. Remove the lower part of the instrument panel inside the passenger compartment.
(Article was borrowed from the website: «MercedesMan»)
4. Disconnect the booster pushrod from the brake pedal lever by unscrewing the nut and removing the bolt (remove the retaining ring and take out the axle).
Installation
5. Installation is carried out in the reverse order of removal. In this case, a new sealing ring must be installed between the master cylinder and the amplifier.