The closed crankcase ventilation valve is used on engines in which the crankcase gases are vented back into the intake of the engine. The purpose of the valve is to aid in regulating crankcase gas flow to the intake of the engine.
If the crankcase ventilation filter becomes too restrictive, under high intake vacuum situations, the closed crankcase ventilation will prevent the engine from siphoning crankcase gases/oil from the crankcase of the engine.
Depending on the breather systems used, the closed crankcase ventilation valve will be located:
• Under the crankcase ventilation filter cover at the top of the engine.
• At the rear of the engine on the crankcase ventilation filter support bracket, above the flywheel housing.
