Servo cylinder — checking operation (Mercedes-Benz S-Class W126)

If you have to press the pedal very hard to brake, you should check the operation of the servo cylinder.

With the engine off, press the brake pedal all the way down at least 5 times, then, keeping the pedal pressed, start the engine. With the engine running, the pedal should go down under the pressure of your foot.

If this does not happen, disconnect the vacuum hose from the servo cylinder and start the engine. Place your finger near the end of the hose to check if a vacuum is created.

If there is no vacuum, check the hose for leaks or damage and replace it if necessary. Tighten all clamps.

If vacuum is present, it should be measured and the servo cylinder replaced if necessary (the work is performed by a specialist).

[Article borrowed from the web portal: www.mercedesman.ru]