Crankcase Ventilation (PCV)
Crankcase ventilation removes blow-by gases from the engine and burns them in the intake instead of releasing them.
What is Crankcase Ventilation (PCV)?
Positive crankcase ventilation (PCV) uses a valve or an oil separator to control gas flow. The system also prevents pressure build-up that would push oil out of seals. Many engines integrate the oil separator and PCV valve into the valve cover. When it fails, the whole cover may need to be replaced.
How it works
Gases from the crankcase pass through an oil separator, where oil droplets are removed, and are drawn into the intake manifold by vacuum.
Why it matters for your car
A blocked or failed PCV system can cause oil leaks, high oil consumption, rough idle or whistling noises. A split PCV hose is a common vacuum leak. Excess crankcase pressure can show up as a whistle, a hard-to-remove oil filler cap or oil pushed past seals.
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