If, when braking, the effort on the pedals has noticeably increased compared to the normal state, check the brake booster with the vehicle stationary.
You will need: pliers, rubber pear.
1. With the engine off, press the brake pedal five or six times. While holding the pedal down, start the engine. The brake pedal should move forward.
2. If this does not happen, check the tightness of the vacuum booster hose connections with the check valve..
3.... and inlet pipe, if necessary, eliminate air leakage. If this does not give a positive result, then the amplifier is faulty and must be replaced.
4. In order to check the tightness of the vacuum booster, open the hood and start the engine for 1 min. Approximately 30 seconds after the engine is turned off, press the brake pedal twice, while a characteristic hiss of air entering the amplifier should be heard.
5. In addition, check the check valve of the amplifier, in the event of a malfunction of which the vacuum in the vacuum cavity of the amplifier is not maintained when the engine load changes or when it stops. To check, while holding the valve, disconnect the vacuum hose from it.
6. Remove the valve from the rubber seal of the amplifier flange and put it on the valve fitting (short, larger diameter) rubber bulb (e.g. from a hydrometer)...
7....and squeeze it.
8. If the valve is good, the bulb will remain compressed. If the bulb straightens out, replace the valve and retest the booster.
9. Reinstall the removed parts in the reverse order of removal.
Note. If a malfunction of the amplifier is found, replace it with a new one, since repair work on the amplifier is very laborious, requires appropriate skills and the use of special installation and adjustment equipment.