Crank case pressure

[Got Boooost]

Hey guys, I was on the dyno yesterday and on my last run the oil dipstick popped out about 1/2 way, luckily it didn't spew any oil, however on my ride home it did pop out a bit and spray a little oil. I was on the dyno 2 months ago and tuned the car to 20psi with no problems. Yesterday we tune to 29 psi with meth. My motor is rebuilt 4 years ago with 10-15 thousand kms on it, I'm also running 2 oil catch cans. My oil dipstick was new with the rebuild along with an oe pcv. My compression #'s are good with in 5 psi of each other and leak down test is under 10 percent. So my question is being I'm running 2 catach cans and a pcv, should I eliminate the pcv all together and put a 1/8 npt fitting in there? I'm not sure why my dipstick popped so I think I should start there, any other recomendation?

Also here's the link to how I installed my 2 catch cans step 1

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

 

[rEclipserGST]

Did you follow post #3 &/or read post #5? Also, pics of your your setup would help diagnose maybe. We can imagine a 4g63 engine bay w/ a catch-can setup. Doesn't mean we can imagine "yours".

 

[Calan]

What type of cans are they?
What shape is your dipstick in (have you replaced it recently)?

 

[banshee88]

no dont eliminate your pcv system ! check for clogged lines and replace your pcv ..and why do they tell u to run a check valve after the pcv? the pcv is a check valve ! and i wouldn't trust that plastic valve ..if that doesn't work try modifying your valve cover with bigger breather lines and add another line..or do what i have done ..don't run a line from your breather catch can to your turbos air intake .just put a air breather on your catch can

 

[Calan]

..and why do they tell u to run a check valve after the pcv?

Because stock PCV valves are notorious for leaking, even when brand new.

..don't run a line from your breather catch can to your turbos air intake .just put a air breather on your catch can

Wrong. You always want some type of negative pressure source on the crankcase if at all possible.

*****

You really should spend some time reading the article linked to in the first post.

 

[GRAVEDIGGER]

..and why do they tell u to run a check valve after the pcv? the pcv is a check valve ! and i wouldn't trust that plastic valve ..

You're supposed to run the check valve before the factory pcv valve. It should go intake manifold>usplastic check valve>oem pcv valve>valve cover.

The usplastic valve is rated to 150psi and is rock solid at checking off boost from the intake manifold, therefore preventing boost pressure from entering the crankcase. An oem pcv valve doesn't even come close.

 

[WillRaceForBeer]

Simplest explanation: More boost = more blow-by.

You're going to need more flow to your catch can(s), you may considering using both catch cans to catch blow-by similar to Setup #3, pulling vacuum from the intake on each Catch Can. You would want to modify your Valve Cover with an 3rd nipple for one of the cans, because unless all you do is race, I strongly recommend leaving your PCV functioning (with or without a Check Valve). Also theres not much need for a Catch Can in line with the PCV, at idle and cruise very little oil vapor should be sucked into your intake manifold.

 

[GRAVEDIGGER]

Also theres not much need for a Catch Can in line with the PCV, at idle and cruise very little oil vapor should be sucked into your intake manifold.

Yeah, you would think so.... Right?? Actually you wouldn't believe how much more I get out of that can than the one on the breather side of the v/c. I'm not sure if it's the race gas that I run which is producing more contaminant gasses and vapors upon warm-up or what, but all I can say is that I was surprised to see how much crap gets caught in that can. I am definitely glad to be catching it in the can instead of letting it get sucked back into the intake manifold and mixed with the oil.

 

[Got Boooost]

Thanks for all the help guys. I'm running the non vented mishimoto catch cans and after reading your posts I think I have my check valve in the wrong location ill try and get some pictures up later but this is how I have mine set up
1st catch can
Line from intake - check valve - catch can - pcv

2nd catch can
Line from breather valve cover - catch can - turbo intake tube

From your guys post I should have my check valve after the pcv? For example
Pcv - check valve - catch can - intake mani
If I have it wrong would it be causing my issue?

Thanks again for the help

Vern

 

[Calan]

What you have sounds correct.

You want it like this:

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Be sure that your check valve is oriented the correct way. You should be able to blow through it toward the IM (note the arrow in the diagram above), but not toward the catch can/VC.

 

[Got Boooost]

Ya that's how I have mine set up. I'm starting to wounder if I should add another vent line off the valve cover like step 2 in your write up?

 

[mantega4g63]

Can someone recommend the best type of catch can? One that just catches oil or one with a breather filter on top of the catch can

 

[rEclipserGST]

Can someone recommend the best type of catch can? One that just catches oil or one with a breather filter on top of the catch can

Wow. Just wow.

 

[95talongirl]

Because stock PCV valves are notorious for leaking, even when brand new.



Wrong. You always want some type of negative pressure source on the crankcase if at all possible.

*****

You really should spend some time reading the article linked to in the first post.

Indeed. Had the dipstick blow out on my car about a month ago. Discovered the PCV valve failed. Went to the parts store.... the first one he pulled from the shelf was bad. The second one checked out and the car has been fine since.

 

[GRAVEDIGGER]

Indeed. Had the dipstick blow out on my car about a month ago. Discovered the PCV valve failed. Went to the parts store.... the first one he pulled from the shelf was bad. The second one checked out and the car has been fine since.

That one probably won't last long before it starts sticking and acting up. You should really look in to adding one of these, so you can forget about it. 3/8" Kynar® Standard Check Valves | U.S. Plastic Corp.

 

[Calan]

Ya that's how I have mine set up. I'm starting to wounder if I should add another vent line off the valve cover like step 2 in your write up?

What size lines are you running?

You really should measure your CC pressure so you know what you are dealing with.

Wow. Just wow.

Amazing isn't it?

 

[Got Boooost]

The one catch can hooked up with the pcv I'm running a 3/8 vaccum line, the second catch can I'm running a 5/16 vaccum line. I'm heading camping tomorrow and when I get back this weekend I try and find out what pressure I'm running in the cc.

Thanks again

 

[Calan]

Unhook the hose at the PCV valve, and blow into it (toward the IM). Then do the same with the one at the VC breather port, blowing toward the turbo inlet. If there is a lot of resistance in either line, there is your problem; then you just need to find out what is restricting airflow.

 

[Got Boooost]

Unhook the hose at the PCV valve, and blow into it (toward the IM). Then do the same with the one at the VC breather port, blowing toward the turbo inlet. If there is a lot of resistance in either line, there is your problem; then you just need to find out what is restricting airflow.

I took both lines off and the vent line (the small line) i can blow through pretty easily, the pcv (bigger line) line is harder to blow through, I'm going to check to make sure my check valve in in the right direction, if it is maybe i'll take it out to see if its the valve causing the problem, if its the valve do you recommend removing it all together or should i put something else in place of the check valve?

also i made a stupid mistake, i pulled the pcv to make sure it was working properly and when putting it back in i over tightened it and broke the valve cover not too happy considering my valve cover and all intercooler pipes were powder coated the same. i just bought another valve cover from a dsmtuners member but its red instead of blue, i guess its time to change the under hood colors how ever, now my car is down till it arrives.

 

[Calan]

Sucks about the VC...

BTW - What type of check valve are you running? Is it one of the Kynar ones from US Plastics?

 

[Got Boooost]

Sucks about the VC...

BTW - What type of check valve are you running? Is it one of the Kynar ones from US Plastics?

Yes, that's the one.

 

[Got Boooost]

update;
i checked to make sure my check valve was in correct and it was. i tried blowing through it and it is hard to blow through, i tried blowing through a new check valve and the same thing, its hard to do. here's a picture of my current check valve beside a new one

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here's a picture of how i have evreything set up, the red circle is where i have the check valve. the pcv is out right now b/c i broke the valve cover.

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should i remove my check valve all together? it might get rid of my extra crank case pressure but on another note, looking at my current check valve it does stop a bunch on oil and crap from going back into the intake. any recommendations?

thanks for the help

 

[Calan]

should i remove my check valve all together? it might get rid of my extra crank case pressure but on another note, looking at my current check valve it does stop a bunch on oil and crap from going back into the intake. any recommendations?

Those Kynar valves have a low crack pressure and should not be hard to blow through.

The check valve shouldn't be stopping anything; that is what catch cans are for. If a bunch of crap is building up at the check valve, it's blocking the line...which is why you are having CC pressure issues.

 

[Got Boooost]

I'll throw a new check valve in and see if that helps, Im not sure what would be causing it to get plugged up. I'll report back later next week as Im still waiting my new valve cover.

Thanks for the help

 

[WillRaceForBeer]

GotBoost, I'm not sure if it's been said, but the PCV side of the valve cover does nothing to evac crank case pressure at WOT, it should be closed and certainly will be closed if you have a check valve. As long as it is closing you might as well ignore it as it is not contributing in any way to positive crank case pressure at WOT.

I was recently at VIR road racing, and on long straights started getting positive crank case pressure. I run a very similar setup to yours.

The fact seems to be that at 20+ psi for extends pulls the engine produces more blow-by than the stock setup can handle, the pressure simply can not escape fast enough. I'm getting ready to go the greengoblin route, and increase the flow capacity during WOT with top-mounted -AN fittings. I will also be increasing the flow capacity between the catch can and intake, thus more effective vacuum pull on the crank case.

I've thought about it a lot, more flow and more vacuum is the only solution that makes sense. You mentioned a new Valve Cover, did you have it modified for more flow to the catchcan/intake?