2G: Is the pvc valve required?

[spyderdrifter]

I'm looking into getting an oil catch can sometime soon to eliminate the oil buildup in the intercooler piping. I was reading descriptions on some different brands and one mentioned using the PVC valve location as an alternative hook up location. Is the PVC valve needed? Are there even benefits of not having it? I tried searching for info, but could only find posts about bad ones, nothing regarding its function or deletion. Thanks.

[DSM1G90]

You need a vacuum system to draw out the blowby gasses that are being built up in the crankcase. Prior to PCV, crankcase blowby gasses were expelled to the atmosphere by the pressure alone, but was still not an effective method to expel all of the gasses contained in the crankcase. Thus oil contamination was at its highest with hydrocarbons, acids and the like.

The EPA put a lock on that in the early '70's with recirculating the gas through the intake manifold to be reburned to reduce hydrocarbons and oil contamination.

the valve meters the amount of vacuum needed to effectively do the extraction. You take it out of the circuit completely and use the vacuum created by the intake manifold, esp at idle, you'd be drawing way too much from the crankcase, along with creating a vacuum situation in the crankcase where it could draw up actual oil up to the manifold...along with creating a super lean situation of idle mixture...and this is where the catch cans comes in handy - to remove what hydrocarbons and contamination along with other impurities that returns to the intake manifold.



Do the catch can, but leave the PCV alone.

That's the basic, but due to a search that I did, here's a better explanation from a Wiseman:

The 4G63T PCV System

Good luck-DSM

[Calan]

http://www.dsmtuners.com/forums/show...hp?p=152865548

[Spoolin92GSX]

Originally Posted by Calan

http://www.dsmtuners.com/forums/show...hp?p=152865548

Same article I followed when setting up my catch cans. Definitely keep the PCV and definitely use the check valve(s). I went with the "Improved Stock" setup and it works great.

[GSTurbo1]

You opened up pandora's box. lol

[spyderdrifter]

Very nice. Thanks guys. This is the kind of stuff I try to find on whatever I'm researching.

And for the record if anyone may have thought it, I've had no intention of removing the PVC, just curious as to side effects of it being removed and such, as well as the catch can part. You guys definitely delivered.


In addition to this, I saw in the 'improved', and 'bigger improved' diagrams, there were 2 catch cans. Is it possible to reap the benefits of the 2 can system while having only one can? Or would that essentially be too much for one can to handle?

[jayson427]

Well in most cases even with a catch can you still get just a little bit of oil that will come out of your hose going to the air intake pipe. Unless you run the tiny air filter off of that vent. Never heard off two catch cans tho.

[Spoolin92GSX]

It could be possible to run a single catch can, but it would have to have two sealed chambers with zero communication between them, as well as four fittings/lines which usually isn't very practical. Jayson the single can setups you have seen were probably the vented ones with one line from the VC, one line from the PCV, and the manifold and intake pipe capped. Those are very ineffective as Calan's article explains very well. I ran one for a short time and can testify that running two sealed cans is much better, and cleaner

[spyderdrifter]

Originally Posted by Spoolin92GSX

It could be possible to run a single catch can, but it would have to have two sealed chambers with zero communication between them, as well as four fittings/lines which usually isn't very practical.

Why would there have to be 2 chambers if they're both just catching residual oil? I don't quite understand that part.

[boost97gst]

Just leave the pcv alone(maybe put in a check valve in line if it needs it). And put in a single catch can from the side VC hose to the Intake pipe preturbo. Thats plenty of vaccuum and should do the job just fine.

[Calan]

Originally Posted by jayson427

Well in most cases even with a catch can you still get just a little bit of oil that will come out of your hose going to the air intake pipe.

Not if you use the right catch can.

Originally Posted by spyderdrifter

Why would there have to be 2 chambers if they're both just catching residual oil? I don't quite understand that part.

Because of the way the system works. In a stock configuration, the pcv line and the vent line have to be isolated while under boost, yet connected during off-boost driving. If they share a catch can, they aren't isolated any more.

[spyderdrifter]

Nice. I think I'll be seat ching one one of the cans with the two separate chambers, unless I have to get one custom made, I'll do that, if I go with the 2 can setup that is. Less clutter with one can.

[sexystover]

my problem is im pushing oil out of the oil cap and V/C gasket during boost along with pushing the dipstick out, is there a way to alleviate this?

[spyderdrifter]

Check the condition of the VC gasket, oil cap seal, and the o-rings on your dipstick; replace as nessasary. If your dipstick o-rings are bad, also check the conditions of the plastic too. It might be going bad and you'd need a new dipstick. ExtremePSI sells them, they're who I always get mine from. I had to swap oil caps due to a bad seal under the first one. Glad I got spare parts.

[WES_393]

Originally Posted by Calan

Not if you use the right catch can.



Because of the way the system works. In a stock configuration, the pcv line and the vent line have to be isolated while under boost, yet connected during off-boost driving. If they share a catch can, they aren't isolated any more.

But this can be solved by removing the stock PCV valve and running a check valve before the catch can (intake side), correct? Then you could use a single catch can and pressure could vent through both valve cover ports under boost.

my problem is im pushing oil out of the oil cap and V/C gasket during boost along with pushing the dipstick out, is there a way to alleviate this?

Are you running a high amount of boost or making considerably more than stock HP? It's possible there is a problem with the ventilation system or the engine is generating an excessive amount of pressure. Remove the PCV valve and verify that you can only blow air through it from the threaded side. The valve should close and seal completely when trying to blow air through from the barbed side. Also make sure the hose on the left side of your valve cover isn't clogged and connects to the intake pipe. If the PCV system checks out, a leak down test will tell you if an abnormal amount of pressure is being lost from the cylinders. It may be as simple as needing a higher flowing ventilation system to keep up with the increase in power and boost.

[Spoolin92GSX]

Calan nailed it. One line (ideally) vents pressure while the other draws fresh air, not at the same time though. Wes running that in my head seems like it would work, at least in theory. Could be worth a try if you don't have room for two cans and don't need a great deal of ventilation (aka very healthy engine)!

[Calan]

Originally Posted by WES_393

But this can be solved by removing the stock PCV valve and running a check valve before the catch can (intake side), correct? Then you could use a single catch can and pressure could vent through both valve cover ports under boost.

But there would be no source of air to replenish the CC while in vacuum, due to the check valve. And with that being the case (and no PCV valve), there is no need to run a line to the IM at all.

Originally Posted by sexystover

my problem is im pushing oil out of the oil cap and V/C gasket during boost along with pushing the dipstick out, is there a way to alleviate this?

Guess you missed the link a couple of times: The 4G63T PCV System

[DSM1G90]

I call it major blowby if dipstick is getting popped out...compression rings getting tired.

This could blow out main crank seals if not corrected.