Positive Crankcase Ventilation: Description and Operation

Valve Cover Labyrinth:

PURPOSE

The Positive Crankcase Ventilation (PCV) system directs crankcase "blowby" to the intake system in order to prevent vapors from escaping to the atmosphere.

Components of the crankcase ventilation system include:
Valve cover
Vent hose

OPERATION

An oil trap is also integrated into the cylinder head cover. A labyrinth formed by cast webs is sealed at the bottom by a sheet-metal cover with molded rubber seal.

Return openings in the webs allow the trapped oil to flow back into the cylinder head. The almost oil-free fumes that remain are conducted to the intake manifold for combustion, in order to comply with pollutant emissions legislation.

An oil shield on the intake camshaft reduces the oil splash accumulation in the crankcase breather.