Redoing PCV with the turbo 3.4

Aaron · Post by **Aaron** » Sat Dec 27, 2008 2:10 pm

I can't find any one of my 20 build threads for this car, so I'll start another one.

I was having a problem with my PCV/breather lines. When I'd boost hard, high RPM, and let off the throttle, it'd smoke a bit, which I'm thinking is the cylinders pulling oil past the rings. The 96 DOHC has a single breather line, off the front valve cover only, and a PCV nipple on the distribution block in the valley under the LIM. I T'ed these 2 lines into one, and ran it to a catch can. On the other nipple of the catch can, I had a check valve, then sent it to the intake manifold for a vacuum source.

The new setup, keeps the breather and PCV separate. The PCV is left like the factory had it, from the valley port to the intake manifold, with a PCV valve in it. The breather line goes from the valve cover to the catch can. The other port on the catch can will eventually have a small filte on it, but for now will be left open (Tight on money). I think this will work much better.

In the future, I plan on redoing the breather system even more. This will include custom nipples on the valve covers (Both), that are 1/2" or even 5/8", so much bigger than the factory setup. They will then go to a catch can, which is vented by 2 of those filters.

Boscolingus · Post by **Boscolingus** » Sat Dec 27, 2008 2:22 pm

don't forget an oil return from the catch can. I should be going out to WCF on Monday and Tuesday, I'll snap some pics of Chris' DOHC setup sitting on the cradle. I'll show you how he did his, worst case scenario send me the valve covers and I can weld on the AN bungs and polish them like I did his...

Aaron · Post by **Aaron** » Sat Dec 27, 2008 2:59 pm

Boscolingus wrote:don't forget an oil return from the catch can. I should be going out to WCF on Monday and Tuesday, I'll snap some pics of Chris' DOHC setup sitting on the cradle. I'll show you how he did his, worst case scenario send me the valve covers and I can weld on the AN bungs and polish them like I did his...

It won't collect much oil, but some yes. I could return that to the pan, or just count it out and keep it topped on oil, which I do anyways. I also have an extra 1.5qts of low oil protection because of my pan, so it won't be a problem.

That's what I'm going to do eventually, but I can't afford to right now.

Shaun41178(2) · Post by **Shaun41178(2)** » Sat Dec 27, 2008 3:20 pm

I didn't run mine back to the pan either. But then again mine doesn't create a lot of blowby to where its pushing a ton of oil out the valve cover and into my breather. Not only that but the factory valve covers on the pushrod motors have a baffle system in it to keep that from happening.

Also I just vented mine to atmosphere. I didn't route it to a vacuum source like aaron did. I won't be creating a vacuum in the crankcase like aaron will be with his routing so myrings won't seal as well, but I did it this way to keep oil vapors from being sucked back into my motor and contaminating the intake charge thus increasing chances for preignition, and oiling up the intake manifold like a factory setup would.

Aaron · Post by **Aaron** » Sat Dec 27, 2008 3:33 pm

Well, I'm redoing it to be like your's now, but how I originally had it, it was like you said.

Boscolingus · Post by **Boscolingus** » Sat Dec 27, 2008 4:49 pm

The catch can I made for the SRT-4 is similar, it is a dual chaber with baffles, but no return ( my asshole puckered when I thought about drilling a hole into an oil pan that I'm making payments on ). I have the PVC/TB side going to one side of the catch can, and the TB/valve cover going to the other side. Each is thier own chamber but built as one box to save room.

No drain back, just drain valves that I monitor every oil change. The initial problem though is that the OEM vent from the vavle cover just isn't big enough, maybe 5/16'' I.D., just not enough diameter to breathe

Aaron · Post by **Aaron** » Sat Dec 27, 2008 4:57 pm

Boscolingus wrote:The catch can I made for the SRT-4 is similar, it is a dual chaber with baffles, but no return ( my asshole puckered when I thought about drilling a hole into an oil pan that I'm making payments on ). I have the PVC/TB side going to one side of the catch can, and the TB/valve cover going to the other side. Each is thier own chamber but built as one box to save room.

No drain back, just drain valves that I monitor every oil change. The initial problem though is that the OEM vent from the vavle cover just isn't big enough, maybe 5/16'' I.D., just not enough diameter to breathe

Maybe I should run the PCV to the other nipple on the catch can then? But then it would not get vacuum, which I thought it needed? I also forgot to mention, in addition to the PCV valve, I also put a check valve in the PCV line. So the engine will be able to pull a vacuum from the crankcase, but under boost, will not pressurize it.

That's my problem too. My line is only ~5/16" as well, and there is only one, not one from each valve cover. I really need to upgrade that.

The Dark Side of Will · Sat Dec 27, 2008 5:34 pm

PCV stands for positive crank case ventilation. Its purpose is to flow air through the crank case, NOT to lower crank case pressure. It prevents the accumulation of acidic blow-by products, water vapor and such in the oil.

Remember that the pressure inside your crank case is what's pushing the oil up the pickup tube to your oil pump. If you drop your crank case pressure too far, you won't get any oil to your pump.

Aaron · Post by **Aaron** » Sat Dec 27, 2008 5:43 pm

Ok. Well my PCV system is stock now (Minus the check valve), only the breather has been modified, and it feeds to a catch can instead of the intake tube.

Now I can run a line from the intake, pre-turbo, to the other port on the catch can so that I have vacuum when the throttle is closed, yet it won't put oil into my intake tract. Would this be better than just leaving the other pot on the catch can open?

Boscolingus · Post by **Boscolingus** » Sat Dec 27, 2008 8:02 pm

Here is the way I did my setup, for reference. Difference is that instead of 2 seperate catch cans there are 2 cans within one location on my car....

I myself didn't understand the need for the check valve when the PVC valve is the check valve...

darkhorizon · Post by **darkhorizon** » Sun Dec 28, 2008 3:56 pm

my catchcan is the ground behind my trunk

Boscolingus · Post by **Boscolingus** » Sun Dec 28, 2008 4:14 pm

hahaha, if it's not leaking something, then something is wrong

Aaron · Post by **Aaron** » Sun Dec 28, 2008 4:27 pm

darkhorizon wrote:my catchcan is the ground behind my trunk

So it's on par with the rest of your halfass build.

Boscolingus · Post by **Boscolingus** » Sun Dec 28, 2008 6:10 pm

think of it like the SR-71, it leaks like no tomorrow on the tarmac, but once in the air and at speed everything swells up and is A.O.K. - - or something like that

but, I won't let you park on my driveway

darkhorizon · Post by **darkhorizon** » Sun Dec 28, 2008 10:36 pm

I get almost no blowby, I also have it wrapped up in a little loop, so it doesnt drip when there is no pressure on it.

Boscolingus · Post by **Boscolingus** » Sun Dec 28, 2008 11:06 pm

I find your lack of faith in the blowby disturbing, do not under estimate the power of the blowby...

darkhorizon · Post by **darkhorizon** » Mon Dec 29, 2008 1:34 pm

I think I have a home depot style water seperator in the garage somewhere, i will rig something up soon.

This might be neat, $10 bucks.

http://cgi.ebay.com/ebaymotors/Air-DRIE ... veQ5fTools

Boscolingus · Post by **Boscolingus** » Mon Dec 29, 2008 5:15 pm

thats exactly what the guys on the SRT forum were using, as shown in the pics above. I just didn't want to do anything cheese-dick like that