Vacuum Booster Block Non-Return Valve — Checking Serviceability (Skoda Favorit)

1. When checking the valve for proper operation, remember that its function is to allow air to flow in only one direction, namely from the vacuum booster unit. If the valve allows air to flow in both directions or neither, it is faulty and must be replaced.

2. To check the valve, disconnect the hose from the vacuum booster unit and blow into it - air should pass freely through the valve. Now try to sharply suck in air through the hose - the valve should not allow the slightest leak.

3. If the valve is faulty, replace it (see Chapter 7).