For check stop the engine after that press a brake pedal some times and detain her in the bottom position. Start up the engine, the pedal should pass on some millimetres further. If it has not occurred, the reasons can be the following:

- The damaged hose on a way from a collector to the vacuum amplifier of brakes or негерметичность in connections;

- Check up a hose together with the return valve, for this purpose remove a hose from the amplifier of brakes, start up the engine and allow to it to work idling. If you do not hear rhythmical noise at всасывании, close the free end of a hose a finger. If after that in a hose the vacuum is not formed, it means is damaged also it it is necessary to replace;

- The rubber lining between the main brake cylinder and the amplifier of brakes is damaged;

- The air filter on an amplifier rod is faulty. Remove the filter by means of a wire with a hook on the end. The new filter screw to an average part and press into a seat round a rod. Pay attention to that the filter round a rod has been closed, otherwise not filtered air can get in the amplifier of brakes;

Fig. 282. The main brake cylinder with the vacuum amplifier: 1 — a feeding tank; 2 — the vacuum amplifier; 3 — a rod; 4 — the main brake cylinder

- The amplifier diaphragm is damaged. In this case it is necessary to replace the amplifier in gathering on new (fig. 282).