PCV System Operation

Like the previous system, this system also uses manifold vacuum to draw crankcase vapors back into the intake manifold. Typically, blowby production is the greatest during high load operations and very light during idle and light load operations. Since the characteristics of manifold vacuum do not match the flow requirements needed for proper crankcase ventilation, a PCV valve is used to regulate blowby flow back into the intake manifold.

• During idle and deceleration, blowby production is very low, but intake manifold vacuum is very high. This causes the pintle inside the PCV valve to fully retract against spring tension. The positioning of the pintle provides a small vacuum passage and allows for low blowby flow to the combustion chamber.

Toyota Pcv Valve

• During low load cruising, the pintle inside the PCV valve is positioned somewhat in the center of its travel. This positioning allows a moderate volume of blowby flow into the combustion chamber.

Motor 457 Abscheider Blowby System

• During acceleration and high load operations, blowby production is very high. The pintle extends out further from the restriction allowing the maximum flow of blowby into the combustion chamber. During extremely high engine loads, if blowby volume exceeds the ability of the PCV valve to draw in the vapors, the excess blowby flows through the breather hose to the air cleaner housing where it can enter the combustion chamber.

• When the engine is off or it backfires, spring tension closes the valve completely preventing the release of blowby into the intake manifold. The valve closes during a backfire to prevent the flame from traveling into the crankcase where it could ignite the enclosed fuel vapors.

PCV Valve

(Engine Off, Backfire)

Pintle fully extended; valve


closed. r m fa

PCV valve closed

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  • kidane gebre
    How to service pcv system toyota tacoma?
    3 years ago

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