7.2.9 Vacuum booster checks
It is important to know that while sitting in the driver's seat, you shall always check the technical condition of the vacuum booster. How to do it? It can be done easily…
The following procedures must be performed in order to check the operation of the vacuum booster of brake system:
1. Start the engine for 1-2 minutes and then stop it. The first time you press the brake pedal, it is fully depressed. But the next time you press the pedal stroke becomes larger with each press, then the booster works properly. In case if the pedal stroke height remains the same, the booster is not working properly.
Figure 7.8 Illustration to c. 1.
2. With the engine idle, depress the brake pedal several times. Then press the brake pedal and start the engine. In case if the pedal moves down slightly, this is normal operation of the booster. In case if the pedal movement is not changed, then the booster is working good.
Figure 7.9 Illustration to c.2.
3. With the engine running, press the brake pedal and then stop the engine. Hold the pedal pressed for about 30 seconds. In case if the height of the pedal does not change, the booster works fine, if the pedal rises - the booster is defective.
Figure 7.10 Illustration to c. 3.
Perform the three tests described above. In case if at least during one of the three tests vacuum booster does not work properly, check the check valve, vacuum hose, and booster for damage.
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