Crankcase gas recycling system

CRANKCASE GAS RECYCLING SYSTEM

The system controls crankcase emissions of vented gases made up of air-fuel mixtures and combusted gases that leak through the piston rings, in addition to lubricant oil vapours, by causing them to recirculate to the intake.

Vent gases flow through separator (1) where they lose part of their oil content. This returns to the sump in the form of droplets. The remaining gases reach inlet sleeve through pipe (3), which contains a flame trap (2) to prevent combustion due to the flame returning from the throttle case (5).

To restrict the vacuum in the crankcase, the gsaes flow through bush (4) with port calibrated to 3.8-4 mm, which is heated by turbine cooling water to prevent the formation of ice inside the bush.

A second pipe (6) fitted with a check valve (7) is connected to the inlet manifold downstream from the throttle valve. This ensures that when the engine is idling, the vacuum in the manifold raises the valve membrane and draws in vapour from the crankcase.
When the engine is turbocharged, the pressure in the manifold closes the valve;
this prevents the crankcase being put under pressure.
The valve consists of a plastic case containing a membrane and a calibrated spring (the word crankcase is shown on the black part of the valve).