Checking the vacuum brake booster

The vacuum brake booster reduces the force on the brake pedal, thereby making driving easier. The operation of the vacuum brake booster is based on the use of vacuum in the intake manifold. When the vacuum booster fails, the brake system does not work, but it is necessary to apply much more effort to press the brake pedal.

Press the brake pedal several times with the engine off to create the same pressure in the cavities of the vacuum booster, close to atmospheric. At the same time, by the force applied to the pedal, determine if the valve body is sticking. Stop the brake pedal in the middle of its travel and start the engine. With a working vacuum booster, the brake pedal should move forward after starting the engine. If the pedal does not move forward, check the attachment of the hose tip, the connection of the tip flange mounting in the amplifier, the condition of the hose and fitting. On vehicles with diesel engines, check the operation of the vacuum pump.