Fig. 4.31. The scheme of recirculation of the fulfilled gases: And — on the cold engine; B — on the engine which is warmed up up to the temperature of 40 °C, on partial loadings; 1 — a hose from the thermal vacuum switch to the recirculation valve; 2 — a hose from the thermal vacuum switch to the carburetor; 3 — the carburetor; 4 — the thermal vacuum switch; 5 — a head of cylinders; 6 — a final collector; 7 — an inlet pipe; 8 — the recirculation valve

Part of cars is supplied with system of recirculation of the fulfilled gases (fig. 4.31) which consists of the valve of recirculation 8 installed on the gas pipeline, the thermal vacuum switch 4 screwed in a water shirt of a head of cylinders, and two connecting hoses.

Recirculation of the fulfilled gases to the inlet highway is carried out on the engine which is warmed up up to the temperature of cooling liquid not below 35 — 40 °C on partial loadings. The system of recirculation of the fulfilled gases does not idle also at full opening of butterfly valves.

For check of operability of system of recirculation of the fulfilled gases it is necessary to increase on the heated-up engine the frequency of rotation of a bent shaft idling from the small frequency of rotation up to 3000 ^min.-1, no more, and to watch visually movement of a rod of the valve 8.

If the rod does not move, to check presence of the managing director of depression on the diaphragm mechanism of the valve of recirculation. If depression is available, then the valve which needs to be replaced is faulty.

In the absence of the operating depression it is necessary to replace the thermal vacuum switch.