1. The vacuum booster is designed to increase the force on the master cylinder pistons due to the vacuum created in the engine intake manifold.
2. During operation, no maintenance is required for the unit. The amplifier changes only after a very high mileage of the car. The need for replacement is felt by increasing the effort on the pedal required for braking.
3. To check the operation of the amplifier, press the brake pedal several times. The pedal stroke should not change with each press.
4. Keeping the pedal depressed, start the engine - the pedal should noticeably move forward.
5. Keeping the pedal depressed, stop the engine - within 30 seconds after stopping, the position of the pedal should not change.
6. Start the engine again, stop after 1-2 minutes. Press the pedal with force several times - the pedal travel should gradually decrease.
7. If the pedal stroke differs from that described above, then do the following.
1). Check up a condition of hoses before and after the control valve, replace the damaged hoses.
2). Check the condition of the check valve. To do this, remove the air from the hose with your mouth. If you feel air leaks, replace the valve. In the presence of a pump, create a pressure of about 200 Torr on the valve on the amplifier side. The pressure drop should not exceed 6 Torr in 15 seconds.
3). In the opposite direction, the valve must pass air. Otherwise, replace the valve.
4). Check amplifier. To do this, turn on the vacuum gauge between the valve and the amplifier and start the engine, gradually increasing the speed, bring the vacuum to 500 torr and stop the engine. The pressure drop should not exceed 25 Torr in 15 seconds. Otherwise, replace the amplifier.
5). Perform these checks with the brake pedal fully depressed. If the leakage exceeds the specified limits, replace the amplifier.