Valve, Positive Crankcase Ventilation (PCV), 3.6L: Operation: Operation

The PCV system operates by engine intake manifold vacuum. Filtered air is routed into the left side valve cover from the left CCV hose which is attached to the air cleaner housing. The metered air, along with crankcase vapors, are drawn through the PCV valve on the right side of the engine and into a passage in the intake manifold. The PCV system manages crankcase pressure and meters blow by gases to the intake system, reducing engine sludge formation.

The PCV valve contains a spring loaded plunger. This plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum.

Fig 1: PCV Valve Plunger Position -- Engine Off

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When the engine is not operating or during an engine pop-back, the spring forces the plunger back against the seat.

Fig 2: PCV Valve Plunger Position -- High Intake Manifold Vacuum

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During periods of high manifold vacuum, such as idle or cruising speeds, vacuum is sufficient to completely compress spring. It will then pull the plunger to the top of the valve. In this position there is minimal vapor flow through the valve.

Fig 3: PCV Valve Plunger Position -- Moderate Intake Manifold Vacuum

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During periods of moderate manifold vacuum, the plunger is only pulled part way back from inlet. This results in maximum vapor flow through the valve.