PCV woes

[boznuttz]

Ok, heres the deal:

I'll be boosting my car in a few days on a low boost setup, but now I have an issue. My PCV valve is shot and I'm seeing some blow by in the valve cover. If I don't do anything and boost the KA24DE as it is, then chances are I'll have to deal with higher afr's, more blowby, oil in the spark plugs, leaking valve cover gasket, damaged piston rings.......or even predetonation. That and the higher HC levels will break down the oil and just really mess with the motor.

....don't want that, so I'd like a quick temporary fix.

Rather than changing the PCV valve (which is a PITA on a DOHC), I was considering alternate options to start out with since I will be strapped on time.

One of my favored ideas was actually pretty simple. I was thinking of routing an oil catch can off of the PCV and re routing the other hose into the intake before the turbo so that it is not pressurized. Although during WOT with the TB open, the crankcase will not be able to build up pressure to be released since it seems like the PCV is busted anyway and will just flow vented air from the crankcase into the valve cover anyway. At least this way can have a temporary setup to relieve some pressure in the valve cover without worrying about a lot of oil getting back into my intake.

Crankcase > busted PCV > oil catch > unpressurized intake (before the turbo and behind the MAF)

Eventually I'd like to replaced the PCV and run the catch can directly from that while I plug up the 4 connections in the intake manifold itself and set it up the proper way......since stock should NOT be an option on boosted cars.

Anyone wanna chime in on this idea?

I think it really relies more on blow by to vent the crank case, which is my major concern.

Any yeah......I wish it was a SOHC.


Modified by boznuttz at 3:58 PM 12/13/2007

[ppctx]

Your description of the suspected problem and solution was a little difficult for me to follow... but what I think you are saying is that your pcv may be stuck open (maybe closed?) and and you want a quick and dirty fix? Here's are some nice lengthy discusions over at ka-t.org http://www.ka-t.org/forums/viewtopic.php?t=27437 http://www.ka-t.org/forums/vie...ight= You shoud have done it right before you boosted (but were to lazy), you didn't, now your having problems and want to take the lazy way out again? Do it right and be done with it.
Modified by ppctx at 2:05 PM 12/13/2007

[krazydriver]

Check this out.http://www.ka-t.org/forums/vie...t=pcvand the article from the threadhttp://forums.nasioc.com/forum...91523Yeah it's a wrx, but the pcv setup is the same for everything.

You want to retain the factory pcv setup to siphon out blowby at idle, yet you need a y in the pcv hose so that blowby can still be taken care of during boost situations.

I'm pulling my intake manifold next week to clean up some stuff, and while it's off i'm going to route all the hoses to do this setup.

[boznuttz]

Oh, this had nothing to do with boost, lol. This thing is stuck open due to it's age. And I had a little blowby as it was N/A.

Of course I check out KA-t quite often, but this was always one topic that everyone always had a little difficulty with since no one can agree.

The PVC system isn't really beneficial on a boosted car, so returning it to stock isn't really on my agenda.

[boznuttz]

Yeah, it seems like many of the routes I was looking at would not provide sufficient vacuum at idle. Ugh, I'll explain a few more of my ideas as this day goes on.

I stayed up all night studying for 3 finals back to back to back.....only to have the snow cancel two of them.

The best I have seen is a setup like this where the air from the oil catch can is recirculated right before the turbo in which it is placed further behind the MAF as to account for metered air. But even still, if the VC remains open like that, I'm sure there could be a significant loss in air.

Just for kicks though, I'm curious as to what a few members here are running. I know that no quick fix it solutions really work, but I'm just curious as to any setups that do work that simulate a PCV valve not working, or just an open flow of air from the crank case.

The stock PCV isn't practical on a turbocharged motor, and it seems that no one really agrees online, lol.

Me so braindead today!
Modified by boznuttz at 4:03 PM 12/13/2007

[ppctx]

That stinks on the cancelled test, once your in that frame of mind, you're ready to get it done. The pic below is the same concept except it allows for normal pcv operation when at idle and with the check valves, the pcv isn’t having to deal with keeping out boost pressure (which I've read somewhere that the pcv could only handle about 5psi before it started letting pressure back into the crank?). My thought on the open VC breather is that factory only taped back into the intake for emissions, to make sure there was no way the gases could escape to atmosphere, when the pcv was overwhelmed by excessive blow by gas. Open breather allows fresh air flow thru the crank and doesn’t fight the pcv opening.

[krazydriver]

well here's what i was going to do.

sorry about the MSpaint, but it's all i got. I figured this way i get vacuum to the crankcase under all conditions, with a catch can inline.

[boznuttz]

As a temporary thing, I think I'll run a catch can from the VC back into the intake right before the turbo since I sort of am worried about unmetered air going into the VC (such as if the VC just had a filter on it), and in a few weeks, I'll replace the stock PCV valve. I'll be on low boost for a while, so I actually may not have to worry as much.

I have been looking into LSx, or even a few cheap 1UZFEs....... he he he. This KA doesn't really have to last that long, but since we are on topic, we might as well make this thread useful and get some good info in here for members that want a reliable setup that will LAST, lol.
Modified by boznuttz at 6:19 PM 12/13/2007

[distantcrowd]

Personally I dont use it I DELETE the system basicly...

On any of my cars I plug the lower PCV valve(weld it shut or get a vacume plug) and run a hose from the valve cover to the ground letting all of the blowby to exit on to the ground, off of and away from my clean motor...

I have yet to go turbo but when I do I will run the same way I dont think there will be any driveability issues because I dont have any problems now...

[nelson8708]

just so you know if you decide to replace the pcv valve use a sr20 valve. They can take more boost pressure with out leaking. I think the ka valve starts to leak around 10-12psi.

[boznuttz]

They are pretty much the same things.

[EstoMax]

They are pretty much the same things.

they are not.. the sr20 valve holds more boost out of the crank case someone did actually test this by hooking an air compressor up to them.

Marko

[boznuttz]

Oh word? I guess I learned something tonight, lol. I'd like to find a diagram of how the SR PCV ventilation system is set up.

[emo_tactical9]

Ha! My thread was quoted!

[Florida240sx]

Distant you got any good running ka24de's?

[MxExUx]

I'm with the delete the system guy. Remember that PCV is an emissions system that simply recirculates the blow-by gases back into the intake to prevent them from being released into the atmosphere. Since you guys are adding a turbo to your engines then I don't think you're that concerned with complying with emission standards.

[krazydriver]

^ except for the fact that the PCV is essential to prevent the blowing out of the seals on the crankcase especially in a boost situation.

Your car will make more power with a proper PCV setup then with it blocked off, because windage in the crankcase adds drag to the crank which lessens power to the wheels. the PCV system flows fresh air through removing the windage/oil spray/blowby that breaks down the oil/ etc.