Rotary Car Club - Crankcase ventilation?

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- - Crankcase ventilation? (https://rotarycarclub.com/showthread.php?t=1556)

Quote:

Originally Posted by MazdaMike (Post 118400)

Its not air, its Positive Pressure in the crankcase. If not properly vented can easily pop out seals like your front main or rear main, or just make every seal leak.
Though most of you may already know the point of the PCV system is to vent that pressure and recirculate it for combustion, not only do oil vapours contribute to airborne HC emissions, I believe they also form a particulate in the air which is also harmful to humans. For the life of me I can't remember why theres positive pressure, all I can remember is the vapors and mist are from the oil sloshing around the crankcase.

the positive pressure is from combustion blowby that gets past the seals.

Quote:

Originally Posted by RETed (Post 117351)

If you're going to TRACK the car, cap the lower fitting!
Oil can climb up the passage and actually dump out of the lower fitting.
This is a good reason to always use the top fitting as a rule of thumb.

-Ted

In the past I've followed this rule of thumb but after last years experience on the street, I changed my setup a little this time around. Even on the street now, I would say cap the lower fitting. I was filling my ~pt container every few hundred miles with blowby nastiness. I thought it was creeping up the oil filter which is why I built a little funnel type device inside the filler to prevent this from happening. It didn't make a shit of difference which tells me it's coming from the nipple on the int iron. New setup has this capped.