6.1.2. Check of operation of the vacuum amplifier of brakes without tester

Fig. 6.3. Check of operation of the vacuum amplifier


Start the engine for one-two minutes and then muffle it. Several times press not a pedal of a brake with usual effort when braking. If by the first pressing a brake pedal it is squeezed out against the stop, and by the subsequent pressing its course gradually decreases, the vacuum amplifier works normally. If by consecutive pressing a pedal its course remains invariable, the vacuum amplifier of brakes means it is faulty (fig. 6.3).
At the idle engine press several times a pedal of a brake and be convinced that the course of a pedal of a brake changes. Then, without releasing a brake pedal, start the engine. If the brake pedal slightly fell, it means that the vacuum amplifier is serviceable. If after start of the engine the pedal remained on the place, the vacuum amplifier means it is faulty.

Fig. 6.4. Check of serviceability of the vacuum amplifier


At the working engine press a pedal of a brake and then kill the engine. Hold a pedal of a brake pressed during 30 pages. If the provision of a pedal does not change, the vacuum amplifier of brakes means it is serviceable. If the pedal of a brake rises, the vacuum amplifier means it is faulty (fig. 6.4).
If results of one of the carried-out inspections were unsatisfactory, it is necessary to look for malfunction in a vacuum hose, the backpressure valve or the vacuum amplifier of brakes.