Volkswagen Golf/Jetta 2 manual

Vacuum servo unit - testing
Braking system / Vacuum servo unit - testing

1 The vacuum servo unit is located between the brake pedal and the master cylinder.

2 Normally, the unit is very reliable but if it becomes faulty, it should be renewed. In the event of a failure, the hydraulic system is in no way affected, except that higher pedal pressures will be necessary.

3 To test the servo unit, depress the brake pedal several times with the engine switched off to dissipate the vacuum. Apply moderate pressure to the brake pedal then start the engine. The pedal should move down slightly if the servo unit is operating correctly.

4 To test the check valve in the vacuum hose, disconnect it from the hose then blow through the valve in the direction of the arrow marking.

Air should pass through the valve. If air is blown in the reverse direction, it should not pass through the valve. Renew the valve if defective.

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