Monday, October 17, 2011

What is PCV Valve?

There is no PCV valve on all engines.
Some models like Ford Escort, GM FWD cars with the Quad Four engine, etc. there is no spring-loaded PCV valve. These models ventilate the crankcase with a small breather hose and calibrated orifice.
The PCV valve is a spring-loaded valve with a specific orifice size designed to restrict the amount of air that's siphoned from the crankcase into the intake manifold.The air flow through the valve must be controlled within certain limits
This is necessary because air drawn through the valve from the crankcase has a leaning effect on the fuel mixture much the same as a vacuum leak.
At idle, air flow is reduced because little blowby is produced. When the engine is cruising and vacuum is high, airflow through the PCV valve is at a maximum to purge the blowby vapors from the crankcase.Pinch the PCV hose at idle and if the engine raises in RPM, then your PCV valve is good. If not, then replace it.

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