Positive Crankcase Ventilation: Description and Operation

CRANKCASE VENTILATION

Crankcase gases are removed from the cylinder block (and cylinder head to an extent) to an oil trap (1) where oil is separated from the crankcase gases and returned to the oil sump. The hose to the cylinder head equalizes differences in pressure between the upper and lower parts of the engine.

When the Turbocharger cuts in, crankcase gases flow through the crankcase hose (5) through heating nipple (6) to the fresh air intake.

When there is little load on the engine or when it is idling there is no under-pressure in the fresh air hose upstream of the Turbocharger and only a small quantity of crankcase gases are formed. Because of this a vacuum hose (7), to lead crankcase gases directly to the intake manifold at low loads, goes from the heating nipple to a calibrated intake downstream of the throttle.

The heating nipple is calibrated to provide a controlled flow of crankcase gases. Power to the PTC type nipple is supplied by the engine management system main relay and prevents water vapor in the crankcase gases from freezing in the fresh air intake hose at low temperatures.

The PTC nipple temperature stabilizes at approximately 80°C (176°F) as soon as the engine is started.