Posted by OnAllCylinders Staff
on September 21, 2020 at 12:26 pm
What is the purpose of a PCV valve?
The PCV valve is an important part of your crankshaft
ventilation system. It serves a few primary function related to regulating positive
Your vehicle’s PCV valve works by stopping excessive
amounts of oil from being drawn out of the crankcase and regulating the amount
of vacuum applied to the crankcase. At low rpm, when vacuum is high, the valve
closes slightly to reduce airflow. At higher rpm, when vacuum is reduced, the
valve opens more to increase airflow.
The valve also acts as a one-way check valve to prevent
forced induction or a backfire. In other words, it won’t allow the crankcase to
Here’s a useful diagram of a PCV valve working at low rpm, high rpm, and during a backfire event:
Now you know what a PCV valve does, but you might be
wondering how it affects vehicle performance. The valve controls the PCV
system, which—when properly maintained—can help the engine generate a little
The slight vacuum in the crankcase improves the seal of
the piston rings and valve stems, which keeps the compression in the chamber at
the desired level. A PCV system also reduces windage and oil aeration, which
can cause drag on the rotating assembly and rob your ride of some of its power.
Follow your maintenance schedule and make sure the PCV
valve and hoses stay clean and clear to extend the life of your oil and engine.