Functional check
1. Without starting the engine, depress the foot brake pedal several times. Check that there is no change in pedal back travel (distance between pedal and floor).
2. Keeping the pedal depressed, start the engine. If immediately after starting the pedal slightly «fails», therefore, the vacuum brake booster is working properly.
Leak test
1. Run the engine for a couple of minutes, then shut it off. Slowly depress the foot brake pedal several times. If at first the pedal stroke is gradually reduced with each squeeze, however, after three or four strokes it stabilizes, the tightness of the vacuum booster assembly is not broken.
2. Depress the foot brake pedal while the engine is running. Keeping the pedal depressed, stop the engine. If after 30 seconds of keeping the pedal depressed, its reserve stroke does not change, therefore, the tightness of the vacuum booster assembly is not broken, if necessary, check the operation of the check valve of the booster servo (valve purge should be possible only in one direction). On diesel models, check the vacuum pump for proper operation (see Section Replacing and checking the vacuum pump of the brake booster servo (diesel models)). No violations are observed, replace the brake booster servo unit - the unit cannot be repaired and in case of failure it must be replaced as an assembly.
Visitor comments