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Removing PCV system?

Posted: Wed Jun 27, 2012 5:19 pm
by 2.2TLegacy
Just as the title says, is it possible? I would like to clean up the engine bay a bit and removing that system would help a bunch. Also its not my daily and I am slowly turning it into a track car.

I know its possible on some cars because I did it on my 2008 VW GTI but the system in my TLeg seems to be more complicated.

Anyone do this? Or should I just forget it.

Re: Removing PCV system?

Posted: Thu Jun 28, 2012 6:29 pm
by Legacy777
I would not recommend doing it since the PCV system helps equalize and reduce pressure in the crankcase. Having a vacuum pulled on the crankcase via either the PCV valve or pre turbo will help pull those vapors out of the crankcase and reduce pressure.

You could technically vent that to atmosphere, but I've heard of some folks that have done that and have issues with it spitting oil out of the vents. Like I said, I would keep the functionality of the system in tact, even if you reroute or add a catch can, etc.

Re: Removing PCV system?

Posted: Thu Jun 28, 2012 11:15 pm
by 2.2TLegacy
Has anyone messed around with re-routing? Im working with a ej20g intake mani and a ej22t block so it might be different from the stock ej22t intake.

Like I said, sole purpose is to clean up the bay a bit, with the build everything is a bit cramped and it would be nice to delete some of those vacuum/pcv lines.

Re: Removing PCV system?

Posted: Fri Jun 29, 2012 6:02 pm
by Legacy777
You can re-route things, but the overall connection points should end up going to the same place. I wouldn't touch the plastic crossover pipe under the manifold. The other vent lines on the heads need to tie into the intake piping post MAF and pre turbo. The main crankcase vent on the back of the motor needs to be routed to BOTH the PCV valve and the intake piping post MAF & pre turbo. How you accomplish that is completely up to your imagination.

Re: Removing PCV system?

Posted: Sun Sep 20, 2015 8:05 pm
by Grayguy
Resurrection from the dead!

When I built my wife's 06' wrx, I just T'd the valve cover vents and crank case vent together, and vented them to the ground (hose runs back to the rear of the tranny) and This hasn't caused any negatives, and now the intake /fmic doesn't get filled with oil. Seems like a win win in my book.

Re: Removing PCV system?

Posted: Mon Sep 21, 2015 3:17 pm
by cj91legss
Grayguy wrote:Resurrection from the dead!

When I built my wife's 06' wrx, I just T'd the valve cover vents and crank case vent together, and vented them to the ground (hose runs back to the rear of the tranny) and This hasn't caused any negatives, and now the intake /fmic doesn't get filled with oil. Seems like a win win in my book.
Wouldn't this be a huge vacuum leak?

Re: Removing PCV system?

Posted: Mon Sep 21, 2015 8:31 pm
by robertpaige
As long as the post-MAF pre-turbo inlet for those hoses are plugged, it should be fine.

I may try what Grayguy is saying... Kimo if you do it before me let me know how it works

Re: Removing PCV system?

Posted: Mon Sep 21, 2015 9:02 pm
by macipusy
In my opinion, it is important to retain a good vacuum on the system when manifold is in vacuum conditions. I once plugged off the PCV only, retaining vacuum in boost, and found a lot of water moisture mixed with oil in the form of 'cheese' all through the breather lines. If this amount moisture gets back into the crankcase and mixes with oil, it will cause pitting of the bearings.

Re: Removing PCV system?

Posted: Mon Sep 21, 2015 11:48 pm
by Grayguy
I have been running this setup for about 5k miles now, and the oil changes have all looked great (new Motor so it was done at 500, 1000, and 2000 miles, and is dues again at 5000). I asked my tuner what they did on all their shop cars and this is it, so that sealed the deal for me running it like I do.

Re: Removing PCV system?

Posted: Mon Sep 21, 2015 11:50 pm
by jamal
robertpaige wrote:As long as the post-MAF pre-turbo inlet for those hoses are plugged, it should be fine.

I may try what Grayguy is saying... Kimo if you do it before me let me know how it works
No, don't do that. You're going to end up dumping oil all over the ground.

Leave the system alone, or if you are worried about it pulling too much oil (like on a high powered track car), then add a good air-oil seperator system. That generally results in more lines going around places and extra cans in the engine bay though.

Re: Removing PCV system?

Posted: Tue Sep 22, 2015 1:28 am
by robertpaige
Grayguy wrote:I have been running this setup for about 5k miles now, and the oil changes have all looked great (new Motor so it was done at 500, 1000, and 2000 miles, and is dues again at 5000). I asked my tuner what they did on all their shop cars and this is it, so that sealed the deal for me running it like I do.


If its working for you without issue, maybe i'll give it a try. You ran both valve covers and the block breather together and vented to air? And then plugged the turbo inlet? What about the PCV valve? Then again, if we cant cap the lines off then it kind of defeats the cleaner bay look.

Re: Removing PCV system?

Posted: Tue Sep 22, 2015 1:44 am
by cj91legss
I was able to tuck mine under everything on my 225t hybrid. I drilled the valve covers and tapped them for barbed fittings.

Re: Removing PCV system?

Posted: Tue Sep 22, 2015 2:18 am
by Alphius
Running a road draft crank vent is the ultimate F-U to the environment. I'm not a hippie or anything, but even I take pause at the thought of spewing oil vapor willy-nilly into the environment. A properly designed and set up PCV system with a catch can is worlds better than a draft tube, and environmentally conscious too.

Re: Removing PCV system?

Posted: Sun Sep 27, 2015 3:42 pm
by Legacy777
To echo what Alphius and Jamal are saying....leave the PCV system functionality in tact. With the system hooked up properly you should have a slight vacuum applied to the crankcase, this is a better situation than having atmospheric pressure applied to the crankcase. Piston rings seal better with negative pressure (vacuum) on the crankcase and like mentioned it doesn't spew oil vapor into the environment and your engine bay.