# Is air supposed to puff out of the oil cap??



## Checkpoynt Charlie (Aug 4, 2004)

This is another question that has been killing me. I just put a breather filter between the valve cover and my main oil catch can line in hopes of fixing it, but it hasn't done much if anything at all.
Could someone please go out to their car, start it up, take off their oil cap, and see how much air puffs out, then post back here what they find?
My car isn't too bad, but there's enough positive pressure in there that it feels similar to the amount of air coming out of the muffler.

From what I understand, this is blowby, in worst case meaning my piston rings are shot, but I did a compression test over spring break and got ~180PSI out of every single cylinder. So I highly doubt my rings are going gone. 
I've also read that this is just normal, but to what extent??

Also, my last question, is do I have this whole catch can system routed properly? The simplicity of it seems like it can't be wrong, but let me know if anything looks wrong.
Here is the picture of my clusterfauck of an engine bay:








Here is my oil catch can system route, highlighted for your pleasure:








And here is my oil filter housing connection:









Thanks for your time, -Travis


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## Checkpoynt Charlie (Aug 4, 2004)

Bump...anybody have a spare 2 minutes?


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## DIAF (Sep 17, 2005)

The air coming out of the oil cap is normal. Think about how the engine is built. The pistons slide up and down in the cylinders, with the bottom of the piston exposed to the oil pan. Just as air is moved by the top of the pistons, air is moved by the bottom of the pistons too. When you pull the valve cover off the motor, you can see a passage right down into the oil pan. 
By opening the oil cap, you've made the path of least resistance for the moving air to be the oil filler.


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## veedubwolfsburg (Jun 4, 2007)

*Re: (DIAF)*

Thats normal, and from what I've experienced, doesn't seem to vary much with mileage. The majority of that pressure is actually from blow-by. The oil cap will usually dance around if you unscrew it while the engine is running.
As for your PCV routing...you might want to eliminate that filter in the piping right off of your valve cover.


_Modified by veedubwolfsburg at 5:11 PM 6-5-2008_


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## infinityman (Sep 3, 2004)

*Re: (veedubwolfsburg)*

According to that picture, that catch can is basically doing nothing....


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## enginerd (Dec 15, 2001)

*Re: (infinityman)*

looks like the catch can goes back and connects to the inlet. 
connecting this after the maf sensor means that the engine can suck unmetered air in through your filter. I would eliminate this and seal/route the system just like stock with the catch can inline. 
This difference is that any oil vapors that would normally get sucked in the inlet will acumulate in your catch tank.


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## Checkpoynt Charlie (Aug 4, 2004)

Yeah, the catch can is connected to the black orb PCV valve on the inlet. From what I understand, it's a one way valve so it can only draw air into the catch can.

After searching and looking at every other catch can setup, I can't see how mine differs. How is it supposed to all be hooked up?
My catch can filled up many, many times over this past winter so it is obviously doing something, but is it supposed to be done a different way?


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## veedubwolfsburg (Jun 4, 2007)

*Re: (-Kage-)*

That filter in the line right off your valve cover is introducing unmetered air into an otherwise sealed system (all post MAF.) Therefore this could lead to potential mixture problems. But if you aren't having any drivability issues then it shouldn't really be a concern.


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## Boostin20v (Mar 22, 2000)

*FV-QR*

Ditch the filter, and get a better seal on the oil filter housing connection...there appears to be a lot of leaking oil residue around the adapter fitting.


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## FrankiEBoneZ (Jun 4, 2002)

*Re: (infinityman)*


_Quote, originally posted by *infinityman* »_According to that picture, that catch can is basically doing nothing.... 









lmao, true dat haha


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## Old Dude GTI (Dec 25, 2007)

Having that filter is like having a split stock Y-hose. If had Tiptronic the transmission wouldn't shift right and the car wouldn't run right so I can see where a manual-shift car would also run lean.


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## Checkpoynt Charlie (Aug 4, 2004)

Okay, the filter is officially off!!

Frankie and anybody else, could you please link me to some pictures of how a catch can is correctly installed?

And yes, the adapter fitting is a bit loose. I'm going to email 034 motorsports about that one. Instead of sitting in there firm, it wobbles around. I tried using gasket sealant, which is mostly what you see on the adapter, but there is that residue on the filter housing. It leaks, but not too much, but it definitely isn't good.
Thanks for the help so far, I appreciate it


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## FrankiEBoneZ (Jun 4, 2002)

*Re: (-Kage-)*

I dont have any pictures, unless you wanna see my setup but its WAY different then yours.
You basically just want a line from the crank case breather (bottom one near the oil filter) and the valve cover breather going to the catch can. Then either a filter on the catch can to vent out, or another line back into the intake like there is on stock cars. I personally would just let it breath out to the atmosphere, its easier and cleaner looking.


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## Checkpoynt Charlie (Aug 4, 2004)

Okay, so it should just go from Valve cover --> Catch Can in port --> Catch Can Out port --> Oil Filter Hosing?
But if you do that, and put a filter in between, that would be the same thing as when I put the filter next to the valve cover. It's just a little farther away, right?
I respect how you guys say mine is hooked up wrong, though it does fill up with oil and water vapors so it does work. I really don't understand the big difference between a 'correctly functioning' setup and mine, so please enlighten me


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## speeding-g60 (Aug 1, 2004)

*Re: (-Kage-)*

here ya go. both VC and block breather to can. nothing else. this is mine, how i did it. when i had one like yours, i made the outlet of the can have the little filter on it, and the VC and block "T" into the inlet.
this is how mine is now.


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## infinityman (Sep 3, 2004)

*Re: (speeding-g60)*

If you don't care about oil getting anywhere, can't you just stick a filter right before the catchcan and let it vent?


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## speeding-g60 (Aug 1, 2004)

*Re: (infinityman)*

the pressure has to go THROUGH the catch can, and vent from there. so it is inline with the way out to atmosphere....
this way, it traps the schit inside, and releases the pressure. make sense?


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## veedubwolfsburg (Jun 4, 2007)

*Re: (infinityman)*


_Quote, originally posted by *infinityman* »_If you don't care about oil getting anywhere, can't you just stick a filter right before the catchcan and let it vent?

It all depends on whether you are routing the lines back into your intake. If you aren't, and just using an atmospheric can, it really doesn't matter how creative you get with the plumbing.


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## infinityman (Sep 3, 2004)

*Re: (speeding-g60)*


_Quote, originally posted by *speeding-g60* »_the pressure has to go THROUGH the catch can, and vent from there. so it is inline with the way out to atmosphere....
this way, it traps the schit inside, and releases the pressure. make sense?


what I'm saying, is can you just NOT run a catch can, and in place of it just stick a filter? That means no re-routing back into intake either.
basically right where the crankcase and valve cover meet, stick a filter right there and be done.


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## FrankiEBoneZ (Jun 4, 2002)

*Re: (infinityman)*


_Quote, originally posted by *infinityman* »_If you don't care about oil getting anywhere, can't you just stick a filter right before the catchcan and let it vent?

yep, hell you could just leave nothing there... I believe it was Steve back in the day just had a hose hanging off the side of the valve cover so it dumped oil on the ground lmao.
EDIT: For the record, are we seriously going this hard on the installation of a catch can? lol Just run some damn lines to the can, and let the can vent out, DONE! lol


_Modified by FrankiEBoneZ at 3:06 PM 6-7-2008_


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## speeding-g60 (Aug 1, 2004)

*Re: (infinityman)*


_Quote, originally posted by *infinityman* »_
what I'm saying, is can you just NOT run a catch can, and in place of it just stick a filter? That means no re-routing back into intake either.
basically right where the crankcase and valve cover meet, stick a filter right there and be done.

yes. when i got my swap, the block breather was a hose pointing down to the ground. end of story. but it would get real messy under the hood, especially if the OP is getting that much crap in the can in the first place.....


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## Checkpoynt Charlie (Aug 4, 2004)

Thanks speeding-g60, though the only difference I see is that you have a filter on the oil catch compared to my line running to the PCV check valve on my intake hose. 
From what I understand, is you guys want me to take that hose I have from the oil catch can --> intake hose and replace it with a filter on the catch can and eliminate the PCV check valve. Right??


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## 5inchMAF (Sep 12, 2007)

*Re: (Old Dude GTI)*


_Quote, originally posted by *Old Dude GTI* »_Having that filter is like having a split stock Y-hose. 

not trying to jack your thread, but what happens when the Y-hose rips (or having a air filter inline to to pcv valve)? what are some of the things that go wrong?

mine ripped and the car is running rough. i was just wondering what is happening as a result of the ripped hose that is making it run rough....


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## veedubwolfsburg (Jun 4, 2007)

*Re: (BIGGEE TALLS)*


_Quote, originally posted by *BIGGEE TALLS* »_
not trying to jack your thread, but what happens when the Y-hose rips (or having a air filter inline to to pcv valve)? what are some of the things that go wrong?

mine ripped and the car is running rough. i was just wondering what is happening as a result of the ripped hose that is making it run rough....

This opening introduces unmetered air into your intake system (does not pass through your MAF sensor.) The symptoms of this would probably be similar to those of a bad MAF sensor (idle issues, loss of power, etc.)


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## Checkpoynt Charlie (Aug 4, 2004)

I hate to say this, but my catch can is hooked up correctly. 
After looking at this thread: http://forums.vwvortex.com/zerothread?id=3856529 that's the way I have it setup.
My hoses may be five times longer, but it's hooked up the same so I don't know what the big deal is. But if you do, just tell me exactly what's wrong.
Though I will take the flying saucer off my TIP and put a little filter on the catch can just to eliminate any possibility of oil going into the intake.


_Modified by -Kage- at 9:32 PM 6-7-2008_


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## infinityman (Sep 3, 2004)

*Re: (-Kage-)*


_Quote, originally posted by *-Kage-* »_I hate to say this, but my catch can is hooked up correctly. 


I hate to say this, but it's not. 
This is how the picture in that thread is. 
Instead of the filter on top, you can route it back into the intake if you'd like. All that other crap going into your airbox, blah blah is all junk and isn't needed.


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## SlowGolf1 (Jan 8, 2007)

*Re: (infinityman)*

Run the block beather to a T, the other side hooks up to the valve cover and the last port on the T goes to the can. From there you can put a filter on the can or run hose from the other port to the intake http://****************.com/smile/emthup.gif


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## bootymac (Apr 19, 2005)

*FV-QR*


_Quote »_









Although it's run a bit differently, the overall setup looks correct to me. All air going back into the intake system from the crankcase passes through the oil catch http://****************.com/smile/emthup.gif


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## veedubwolfsburg (Jun 4, 2007)

*Re: FV-QR (bootymac)*

How is this hard to understand? The only thing keeping his original setup from being successful is the filter right off of the valve cover. You either run a filter to evacuate the pressure OR you route it back into the intake. You DO NOT run both.


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## Hestman1.8T (Mar 26, 2008)

*Re: (infinityman)*


_Quote, originally posted by *infinityman* »_
I hate to say this, but it's not. 
This is how the picture in that thread is. 
Instead of the filter on top, you can route it back into the intake if you'd like. All that other crap going into your airbox, blah blah is all junk and isn't needed.
















I have an AEB head and AN AEB valve cover. The AEB valve cover has no vent tube on it like the small port head does. should i run my old valve cover or do i need to just run a tube from the block breather to the catch can? head isnt on yet i just want to know


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## bootymac (Apr 19, 2005)

*Re: FV-QR (veedubwolfsburg)*


_Quote, originally posted by *veedubwolfsburg* »_How is this hard to understand? The only thing keeping his original setup from being successful is the filter right off of the valve cover. You either run a filter to evacuate the pressure OR you route it back into the intake. You DO NOT run both.

But he already removed the filter...

_Quote, originally posted by *-Kage-* »_Okay, the filter is officially off!!


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## veedubwolfsburg (Jun 4, 2007)

*Re: FV-QR (bootymac)*

Thought you were referencing to the specific setup in the picture. With the filter removed, things are fine.


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## l88m22vette (Mar 2, 2006)

*Re: FV-QR (veedubwolfsburg)*









Elbow is from block breather, other hose is from valve cover breather, large 90° hose coming off the top goes into the stock TIP. Your filter off the vc defeats the purpose of a catch can.


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