Positive Crankcase Ventilation: Description and Operation

The blow-by gases and vapors in the crankcase are recycled by being drawn into the combustion chambers and burned there rather than being vented to the atmosphere. As the vapors leave the crankcase, they pass through a trap. This device separates liquid oil from the vapors and returns the oil to the sump. The vapors then enter a hose connecting the trap to the air cleaner. A flame trap in the hose prevents the vapors in the crankcase from being ignited in case of A backfire. A baffle at the air cleaner disperses the vapors as they enter. The vapors become part of the intake charge, entering through the intake manifold into the combustion chambers.