Sweezy

Hey all, im about to install a catch can setup for my 2003 Subaru Impreza GX (yes, non turbo i know), and have a question, from what i've gathered, its simply connect the can intake to the bottom of the PCV system, and the "out" portion of the can, back into the throttle body area, however, there is also a small, other hose, coming from the base, that connects to the factory air box (which im getting rid of), do i need that extra bit? (i'd imagine i probably shouldnt block it), can i just put one of those little breather filters on that and be done with it? the baffled can i got didnt have the usual breather filter sitting on top. Has anyone sorted this mod about before? appreciate all feedback, thanks in advance!

John 37

It sounds like the bottom pipe is to drain the oil from the catch tank. If so, 2 options. Run it back to sump somehow or plug it and routinely empty the catch tank.

Sweezy

Sorry I didnt realize I could upload photos to the posts (picture from my dirty parts car), the part I'm referring to is what I'm pointing at, it typically has a small hose that goes directly to the airbox, I'm leaning towards putting a breather filter on it and then the other 2 ports will be for the feed and return lines for the baffled catch can I have, thoughts? Any reason not to put a breather filter on there? Or could I just plug it? Thanks again

John 37

I'm not fully sure what the PCV valve does and my car's a turbo so this is based on head scratching and non Subaru engines.
The PCV valve extracts gasses from the crankcase. It has 2 outlets. One goes to the inlet manifold. This does 2 things. It limits the vacuum the manifold can draw on the crankcase and, in the case of a turbo, acts as a non return valve preventing the manifold pressuring the crankcase when on boost. The other connection is to the inlet duct. It vents the crankcase when the inlet manifold is on boost or there's not enough suction to handle the load or operate the N/R valve.
I'm sure others will chip in if I'm wrong.

Don Clark

Non Turbo





Turbo (UK car will not have the "leakge detection" sensor function)

John 37

Thanks Don.