Oil catch can - using T to connect PCV and breather???

[tsi1991awd]

So I'm installing a catch can that I made from a Husky filter element used for air compressors. It has one in and one out on it. Can a T fitting be used to connect the PCV and breather hoses and then have one hose into the IN portion of the catch can?

I'm not sure if the T will interfere with oil flow into the can (if any oil comes out at all) that is my main concern.

 

[Calan]

....Some cream colored grease looking stuff....

That's normal for a catch can or filter setup.

The "cream colored grease looking stuff" is a mix of water and oil. As your catch can (or filter) cools when you shut off the motor, condensation forms and mixes with the oil in it.

 

[tsi1991awd]

Well I've been driving with this setup for about 2000 miles and haven't had any problems whatsoever. Don't get too much oil in the cans, I check after I shut the car off every time. So that said, I believe you CAN run the AN fitting with absolutely no problems whatsoever.

 

[Cmele89]

can one of you guys post a picture or two so i can see some setups?

 

[AWD_Hybrid]

This is a single catch can setup. To ground is hidden.

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Cheers !

 

[andy4g63]

Here it is, how it is done...
I don't like to run it into INTAKE pipe. It is OK, but it gets oily inside and sometimes, you can't tell, if your turbo went bad, or just from vapors. I like mine IC pipes dry.

 

[kenamond]

Although these setups mentioned above will "work" in that you'll keep oil out of your intake pipe and intake manifold, they don't "work" in the sense that you defeat the purpose of the PCV system. Here are some of the things a stock system does that you're not getting in the photo or the cartoon.

When the IM is at vaccuum, it pulls *much* harder than the intake pipe, and this pulls blowby out of the crankcase.

The PCV valve has a brass snokel that reaches into the open air under the baffles in the VC. If you remove it and put a regular fitting on the VC, oil running down the wall of the VC will get sucked into your breather line. If that's going to a catchcan, you fill the can faster and go through oil faster.

Under boost, the PCV valve is supposed to close and block boost pressure from entering the crankcase. If it isn't sealing, you pressurize your crankcase, which isn't supposed to happen. When the PCV is closed, the VC breather ventilates the increased blowby (at that point, you're under load and you have more blowby).

The PCV valve is also a metering orifice, and your idle may be affected by removing it, but the ISC may hide that for you.

What blacknspooln mentions is a way to "do it all". The check valves you can get last longer than the OEM valves. The PCV catch can traps oil. The VC breather catch can traps oil. The PCV valve's snorkel keeps oil in the motor. And the PCV valve properly meters air during idle.

In the picture, there is no way to ventilate the crankcase with fresh air. Sure, there are two places for the blowby to exit, but that leaves fuel and exhaust in the crankcase...there's no source of fresh air. That's normally coming at idle or deceleration by pulling clean air through the VC breather and taking nasty fumes out the PCV valve to the IM to have a 2nd go at the motor. So your oil gets dirty faster, and absorbs the fuel, both of which degrade the oil's performance.

 

[habitatguy187]

Just last week I drilled another hole close to the breather tube and JB-welded a brass fitting in it, allowing more crankcase pressure to escape, while still maintaining the pcv system. As kenamond said you want to keep pulling the gasses out of the crankcase that cause the oil to break down.

 

[GalantGreg]

Ok, now I am confused. It is no good to make a system like Andy4G63 using a catchcan with two lines going into it???

 

[kergilman]

In a normally aspirated motor, the intake manifold pressure is *always* lower than the crank case pressure, so the PCV only goes one way in those cars.

Hey Kenamond, could you please elaborate on this statement a little? I was under the impression that I would have the same PCV valve as the 4g63 engines: that they would all check pressure from the direction of the TB but allow vacume to pull from the crankcase to the TB.

Reading through this, I see my current catch can design is wrong:

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...but in my situation I cannot see how I would have an issue, I just need to move my catch can to the other side between the VC and the PCV.

 

[kenamond]

To do it right, you need two catch cans. Also, if you use the stock PCV valve and put a catch can between the PCV valve and IM, you'll boost the catch can. If it can take it, fine. Otherwise, you get a check valve and put it between the IM and catch can.

If you have a draw-through MAS, you need the VC breather to come from the intake pipe, or you suck unmetered air through the filter (in your picture).

Both catch cans should be sealed (one inlet, one outlet).

 

[tsi1991awd]

I have had no problems with my setup after 7 or 8k miles. I am using the straight fitting.

 

[kenamond]

I have had no problems with my setup after 7 or 8k miles. I am using the straight fitting.

And statements like this are why folks keep doing it the wrong way...no offense. If you do some of the wrong setups, you'll notice right away. With others, it's more of a long term issue. If you don't have the VC breather connected to the intake pipe, you draw unmetered air into the engine and run lean. The ECU will compensate, but it messes up your fuel trims. If you boost your crank case, you pop your dipstick tube and spew oil all over the place or potentially damage seals...and crimping the dipstick tube is usually a hack for a messed-up PCV system or excessive blowby. If you bypass the PCV valve, your oil absorbs the fuel fumes and exhaust soot faster because the crankcase isn't being ventilated with fresh air (in through the VC breather, out through the PCV valve to the IM when idling or shifting or otherwise letting off the throttle and producing vaccuum in the IM). If you replace the PCV valve with a fitting, you lose the snorkel and oil running down the inside walls of the VC gets sucked or blown out the fitting, and it either ends up in your IM or catch can, but the oil disappears more rapidly from the motor. It's a complicated little system, and it's easy to misunderstand it. But it's not much harder to "fix it" correctly without compromising any of its functions.