Brake system TEVES MK IV
The brake booster should be checked if an unusually high force must be applied to the brake pedal to achieve sufficient braking effect.
Start the engine and press the brake pedal. With the pedal pressed, turn off the engine. Keep the pedal pressed for about 30 seconds. If the pedal travel does not change during this time, the brake booster is OK.
Press the brake pedal firmly at least 5 times with the engine off, then start the engine with the pedal pressed. Now the brake pedal should be felt well under your foot. This means that the brake booster is functioning properly. Otherwise, you should check the booster for leaks.
To check, unscrew the vacuum hose at the brake booster and start the engine. Place your finger on the end of the vacuum hose to check if a vacuum is created.
If there is no vacuum, check the vacuum hose for leaks and damage, replace the hose if necessary. Tighten all clamps securely.
If there is a vacuum: measure the vacuum, replace the brake booster if necessary (service station work).
Caution: Always replace the check valve in the vacuum line, as if the check valve is faulty, fuel vapors penetrating the brake booster diaphragm may damage the brake booster diaphragm.