1. Performance check.
A) Depress the brake pedal several times with the engine off and check that the pedal travel does not change.
b) Press the brake pedal and start the engine. If the brake pedal smoothly goes down, the vacuum booster is operational.
2. Air tightness test.
A) Start the engine and stop after one or two minutes of operation. Slowly press the brake pedal several times. If the pedal goes lower on the first press than on the second and third, then the vacuum booster is tight.
b) Depress the brake pedal with the engine running and stop it with the pedal depressed. If the distance between the floor and the depressed pedal does not change within thirty seconds, then the vacuum booster is sealed.