Thread: Finding a way to Reduce Oily Blow By Gases

What if we stick on a bigger PCV Valve? I doubt constantly keeping it open is not a good idea because outside air can get sucked in right?

I'm wondering if this is the reason why there are some monstrous SR's from factory? Maybe they don't have as much pressure in the crankcase?

It's a one way valve man. Air will only get sucked in on the T side, where it would normally be able to get sucked in anyways, provided the crankcase pressure is low enough

No no I mean removing the PCV valve altogether

I wouldn't know what to say, here. I don't know whether the t fitting has a constant vacuum, or not. I would assume, that since there was originally a pipe going from the intake to this fitting, that it is supposed to see vacuum, like Danja said in the other thread. Fresh air to help dilute the blow by gunk before it re-entered the intake manifold, via PCV?

I guess I'll just put a catch can on it like I had originally planned, and slap a filter on the other end of the catch can.

Thats interesting because I don't believe I've ever felt a vacuum on the T, I always have felt air blowing out. Oily air for that reason.

I submitted a how to rewire the Oil Separator to avoid sending oil to the intake, I will post up the thread when it gets approved

Well I can't really send a line to the intake, as I'm running an open turbo setup right now. I wonder why I always feel vacuum, then? I may have to dig thru the FSM to determine whether you should be seeing air come out, or in.

I replaced the PCV yesterday, found out that the old one would not prevent blowing of air from the nipple, even though it should. It rattled, and I cleaned it with brake clean, and it still wouldn't seal.

Well if you unhook the PCV Valve, then you shouldn't haven't to run the breather back to the intake hehe.



Let us know if you find anything in the FSM

The T fitting flows air both in and out, all depending on the crankcase and manifold pressure (this is what it says in the FSM). That's why you guys are confused about it haha.

From page 1:

Seems like I have one of those high blow by engines. Since mine seems to be high blow by all the time.

the whole point of the pcv system is to reduce crankcase pressure. So you don't really need the pcv valve if you are NA, but it reduces emissions. When you are turbo you need some sort of more advanced system to control crankcase pressure. You basically want as little as possible! The pcv valve is just there to regulate the pressure in the crankcase.

Remove it if you want. You may have to make little adjustments to idle and such but it will run fine. Remember, blowby gasses were metered at some point! So venting straight to atmosphere does make a slight difference in afr at low throttle and high vacuum conditions. Why is this? because even though they are wasted blow-by gasses they are reused by the engine via the pcv system. They are not metered again before reentry into the intake manifold though.

Having a higher blowby will make the engine run a little richer (if pcv air is vented to atmosphere) but not by a large amount.

The pcv valve normally puts the crankcase and vc under a slight vacuum, but on the nissans it can't keep up. Remember, the less pressure you have in the crankcase the better! You see all these big power V8 guys putting electric pumps on their engines to pull out as much blowby as possible! On a high horsepower 4 cyl some guys run several lines out of the vc to vent crankcase pressure.