New to forum, 2015 JKU with 3.5 AEV, Prodigy Stage 2

[Bkeef]

So to clarify I have a snorkel PCV valve attached to valve cover then line comes off and check valve is inserted in line off intake. Mounts under cover. Looks different than yours

[UselessPickles]

Looks different than yours

That's because I customized my install (as described in the link to more details) to retain an OEM-like appearance


None of my pictures show the PCV valve itself. The rubber elbow in my pictures is what slides onto the PCV valve and connects the PCV valve to the stock plastic hose.

Prodigy provides this hose with the brass check valve, and I just didn't like how it looked:





Maybe this will help clear things up... This is what the stock engine looks like without the engine cover:




Here's the PCV system highlighted:




Compare to the pictures of my setup I posted previously, and you'll see that I'm simply reusing the original plastic hoses, with some modifications to include the brass check valve in the PCV hose.

Red is the PCV hose, running from the PCV valve on the passenger side of the engine to the intake manifold.
Yellow is the breather (aka, "make up air") hose running from the air box to the breather port on the driver side of the engine.

The arrows indicate the normal flow direction of air. When the manifold has vacuum (no boost), it sucks air from the crankcase through the PCV valve and hose, which in turn sucks air from the air box through the breather hose back into the crankcase. This continuously sucks oil vapors and blow-by gasses (fuel vapors and exhaust fumes that snuck past the piston rings) out of the crankcase and replaces it with fresh air.

Regardless of whether you use the hoses provided by Prodigy, or customize it with the original plastic hoses like I did, you need that brass check valve in between the PCV valve and the intake manifold, installed to allow air to flow toward the intake manifold.

When on boost, the check valve prevents boost from reaching the crankcase through the PCV hose/valve. However, boost means more blow-by gases entering the crankcase past the piston rings, so you end up with oil vapors and blow-by gasses flowing backwards through the breather hose.

With the stock setup, no big deal. Those gasses flow into the air box, and immediately get sucked back into the intake manifold and burned up in the engine. With the Prodigy setup, it vents to atmosphere. If you have any dips in your breather hose, it could possibly act as a trap to collect condensed oil vapors. Once it collects enough oil in the dip to act as a partial blockage in the hose, the next time you use some boost, the blow-by gasses flowing backward through the breather hose could blow that trapped oil out the end of the breather hose.

I think it's important to make sure the breather hose runs up-hill from the engine breather port to allow condensed oil vapors to drip back into the engine (instead of out of the end of the breather), AND make sure there's no dips in the hose that could let oil pool up. The original hard plastic breather hose conveniently meets these requirements, and requires no modifications to use. Just remove the S-shaped rubber hose that used to connect it to the air box, and pop the small breather filter on.

If the brass check valve is backward, that could also explain the mess you're getting. That would allow boost to directly enter the crankcase and forcefully blow oil vapors out through the breather hose.