PCV stands for positive crankcase ventilation. It uses engine vacuum to draw unburned fuel and combustion gases out of the crankcase, preventing pressure buildup and oil contamination. The system relies on a calibrated one-way valve that modulates flow based on manifold vacuum, ensuring idle stability while burning off harmful emissions during normal operation.
Check the PCV valve to see if it rattles, because a stuck one will push oil right past the main seals.
A plugged PCV valve is a primary cause of mysterious oil leaks, as crankcase pressure will force oil out of the weakest gasket or seal.
Also heard as
- positive crankcase ventilation
Related terms
Blow-by
Combustion gases that escape past the piston rings and enter the engine crankcase.
EVAP
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The engine component that distributes incoming air or air-fuel mixture evenly to each cylinder.
Oil burner
A slang term for a vehicle powered by a diesel engine.