Cruze

Crankcase Ventilation System Description

A crankcase ventilation system is used to consume crankcase vapours in the combustion process instead of venting vapours to the atmosphere. Fresh air from the inlet system is supplied to the crankcase, mixed with blow-by gases and then passed through a calibrated orifice into the throttle body.

The primary control is through the positive crankcase ventilation (PCV) orifice which meters the flow at a rate depending on inlet vacuum. The PCV orifice is an integral part of the camshaft cover. If abnormal operating conditions occur, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase ventilation hoses (1, 2) into the inlet system to be consumed by normal combustion.