Purpose of your Stock PCV System:
The PCV (Positive Crankcase Ventilation) system is designed to regulate and remove fumes from the engine crankcase, and to alleviate crankcase pressure which could cause oil leaks or seal damage. It’s a way for gases to escape in a controlled manner from the crankcase of an internal combustion engine.
During normal operation of an internal combustion engine, there’s a compressed air and fuel mixture inside the combustion chamber that is ignited and as a result, forces the piston down. A small amount of that ignited mixture leaks past the piston rings and ends up in the crankcase. This leakage is often referred to as “blow-by” (leakage past the piston rings), as well as oil mist.