cheetah chrome

Do you install the check valve to atmosphere that is just after the output of the AOS (944.107.324.00) in your custom hoses to the catch can? I'll be installing the the venturi delete and a Saikou Michi catch can which I think is a pretty common setup so hopefully someone has run into this before. Search yielded nothing.

theedge

No, you dont need a check valve. You want to plumb it back to the intake before the turbo like stock. Installing a catch can and venting it to the atmosphere is a waste of time. When its plumbed back to the intake (pre turbo) it always has a vacuum, thus itll never need a check valve as air wont ever flow backwards into the catch can.

cheetah chrome

I was under the impression that the valve flowed in the other direction (I can see how when I called it a "check valve to atmosphere" above it was misleading...I'm an idiot, bare w/ me). My understanding of the valve is that under high boost (high vacuum in the mentioned section of plumbing) crankcase oil vapors would get sucked into the intake and cause slight smoking. This valve would allow some outside air into the plumbing while holding the correct crank case vacuum.

So I guess the next question is do I have a correct understanding of the valve?

I'll be plumbing the output of the catch can back into the intake as stock.

Thanks!

Spidey944

If you were sucking pure oil back into the intake then you would smoke, but crankcase vapors coming through the catch can wont smoke.

CurtP

I was just reading up on this in the Official Venturi Delete Thread and there's some debate on what the check valve does. One train of thought is that it helps prevent exhaust smoke. The other is that it keeps pressure from building up in the AOS causing a leak/rupture.

I have no idea what it actually does. It sounded like conjecture to me.

cheetah chrome

Does anyone have one of these valves sitting around that they can see which direction it flows? And, is it an unrestricted flow (ie is it a check valve or a pressure relief valve)?

eniac

Air can go out, but not in.

There's a very light spring that holds a round plastic piece down inside the valve. It's best to remove this since if your getting excess pressure in that line then you have some other serious problems. Remove it because that round plastic piece inside can easily get turned sideways which would create a vacuum leak.