Thread: Recent FE390 rebuild. Getting blow back smoke out of exhaust and engine. Pleas help

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keep in mind the pcv is just a smog device. i run the large moon breather to vent. if you run the pcv and a solid cap on the other side it will blow oil out every seal in the motor.

Originally Posted by shine

keep in mind the pcv is just a smog device. i run the large moon breather to vent. if you run the pcv and a solid cap on the other side it will blow oil out every seal in the motor.

When the PCV was originally designed it was a sealed system smog devise and quickly resulted in seal and other motor problems. The addition of a breather to reduce negative pressures solved the problems and the benefits were soon learned and practiced on even race motors. Improvements to the system continued including valve cover splash baffles exc.. A properly operating PCV system will also aid in keeping the internal engine parts cleaner by reducing some of the harmful gases that will cause corrosion.
IMHO, the benefits of a good operating PCV system far out ways any disadvantages and I have PCV on every motor I have.

Certainly not meaning any disrespect or trying to sound like a know it all.
IMHO, a properly installed PCV system will not cause blow by (crankcase positive pressures), as it is a vacuum based system. Not to say an improperly designed PCV system will not result in oil being introduced into the intake causing smoke. Simply, if you have the PCV removed and have excessive crankcase pressure causing extreme oil smoke to come out of the PCV port, you probably have additional conditions adding to the problem.