Checking the hydraulic booster

Checking the functioning of the hydraulic booster is carried out if an exceptionally large pressure force on the brake pedal is required to achieve the desired braking effect.

• Press the brake pedal and start the engine. The pedal should drop slightly.
• Press the brake pedal at least 5 times with the engine off, then start the engine with the brake pedal depressed. The brake pedal should drop noticeably under your foot. In this case, the hydraulic booster functions normally. If not, perform a leak test.
• Otherwise, remove the vacuum hose from the hydraulic booster, start the engine. Place your finger on the end of the vacuum hose to check for low pressure.
• If there is no low pressure: check vacuum hose for leaks and damage, otherwise replace. Tighten all clamps.
• Remove the low pressure hose from the vacuum pump and use your finger to check for low pressure at the hose connection.
• If there is low pressure: measure the pressure, if necessary, replace the hydraulic booster (workshop work).

Attention: At the same time, it is imperative to replace the non-return valve in the vacuum tube, otherwise the hydraulic booster membrane may be damaged due to the penetration of fuel vapors (with a defective non-return valve).