Positive Crankcase Ventilation: Description and Operation

PCV Flow:

PURPOSE:
The Positive Crankcase Ventilation (PCV) system is used to provide scavenging of crankcase vapors to prevent discharging into the atmosphere.

OPERATION:
Fresh air from the air cleaner is supplied to the crankcase, mixed with blow-by gases and then passed through the PCV valve into the intake manifold. To maintain idle quality, the PCV valve restricts the flow when intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the air inlet duct to be consumed by normal combustion.