Although some maintenance schedules include an interval for replacing the positive crankcase ventilation, or PCV, valve, others may not. In the latter case, a general recommendation is to replace ...

Also inspect the rubber grommets that seal the PCV valve and the breather pipe to the valve covers. When these harden or crack, fumes can escape and dirt can get into the engine.

The PCV valve controls the amount of crankcase flow volume depending on the engine's load. With large throttle openings (high engine loads), more blow-by gases are produced and the PCV system ...