6.2.4. Check of the backpressure valve of a vacuum hose (amplifier of brakes)
Remove collars and a vacuum hose.
Fig. 6.10. Scheme of check of the backpressure valve
Give serially vacuum and pressure to a vacuum hose from the engine and be convinced that air can go only to one party (fig. 6.10).
If air passes in both directions, replace a vacuum hose.