Quote:
Originally Posted by KyFarm
thanks for the info, but it raises questions that I don't understand, maybe you could help.
I get that there is POSITIVE crankcase pressure that is being vented and regulated with the PCV, but why doesn't having basically an open, filtered port, the breather, destroy the point of the PCV valve. Isn't there the same pressure under each valve cover?
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The way the OEM PCV system is designed, the PCV valve sucks air out of one valve cover which in turn pulls air from the crankcase which gets its air from the other valve cover via the hose connecting to the PCV air filter in the main air filter housing. Having the PCV air filter on the valve cover just means that extra blowby air is vented to the atmosphere instead of being burned by getting sucked down the carb. IIRC - the main time that there is too much blowby for the PCV valve is under high throttle or when the rings are near end of life. The main reason for the air breather on the opposite valve cover is to allow extra clean air into the motor guts for the times when the PCV valve is sucking more air then the motor is making via blowby.