Here I go again....PCV

[obrut]

I have a question. Is this just happing on rebuilt/modified motors or is it happing to stock motors too?

Maybe if we can figure out what mods we all did we could figure out which mod is causing the problem. What i mean is if everyone added 10 mods and 5 or 6 are the same on every engine it might help narrow down whats wrong.

I would really like to get a answer since i've been chasing this problem for about 3 years. Like i said before i stopped driving my car because of it.

 

[ijames]

I always thought that having air flow through the crankcase was a good thing, to help carry out volatile vapors, but maybe we have too much of a good thing. Okay, so what we need is to put the check valve from a vacuum brake booster into the bottom of the valve cover breather so it only opens when the crankcase is under pressure and seals to let the crankcase be under vacuum normally. I suggest a booster check valve because they are fairly large so they won't be a huge restriction when venting, they are designed to open with very pressure differential to minimize crankcase pressurization, and they look about the right size to mount on the bottom or into the breather. If you also have a breather on the passenger side, do that one too. Watch for the dipstick pushing out or valve cover gaskets starting to weep oil to make sure the check valves aren't too restrictive to handle the blowby under boost. Hmm, next time I hit the u-pull-it I'm going to have to shop for some check valves.

 

[Two Lane]

Originally posted by obrut
I would really like to get a answer since i've been chasing this problem for about 3 years.

Like i said before i stopped driving my car because of it.

WOW...that's horrible!

We gotta find the cause(s)!

It could happen tomorrow to someone new,
and no one today can point precisely to a known solution.

 

[skturbo]

obrut,

In the last post on pg.4 I list 7 reasons why this could happen. And I can think of a couple more. One of the problems is you really have to look at each car. Its hard to hear someone tell you your new motor was'nt built right, or you think a headgasket may be seeping into the valley and you have to pull it to be shure. I can go on and on.
As for your question, It can and does on stock and modified engines. But seems to be more of a problem when you start pushing it harder and harder. Keep in mind some guys look behind their throttke body and see some oil residue and panic. If your car does'nt smoke you may not have a problem. you can look in any intake with a pcv and see oil residue. But if you have puddles or smoking somethings wrong.

Steve K.

 

[skturbo]

ijames,

When your crankcase is under pressure (exe. under boost, racing, hard excelleration) that is when you need the breathers.
If you close them off you will have problems. Be carefull!

Steve K.

 

[ijames]

Steve, that's why the check valves. To close the breathers off when the crankcase is under vacuum from the pcv system to cut the airflow to a minimum, but to let the blowby vent through the breathers when the crankcase is pressurized under boost. Guess I wasn't clear enough.

 

[skturbo]

ijames,

No you were clear.
I was thinking backwards (again)
Thanks for letting me know.

You may have something there.

Thanks, Steve Kaminski

 

[JDEstill]

Carl, I've been thinking about the check valves for a while too. A chevy friend of mine thought maybe the exhaust check valves they used to use on chevys for air injection and such might work. He sent me some pics of one he has, and it looks exactly like what would fit the bill. I tried to find it on acdelco.com, and I think the part number might be 214-423, but I'm not sure. May go to the parts store in the next few days and see what one looks like in real life. As long as it isn't restrictive, this could be a Good Thing. Might not help the oil sucking up the PCV, but then it might. It would definitely improve PCV operation if nothing else. Ya know, my engine held 1.5" vac in the crankcase for over 24 hours after I blocked the breathers in? Surprised the heck out of me.

John

 

[skturbo]

Think about this

Carl and John;

I had a crankcase evacuation system on my TTA and my wifes Turbo Formula with a PCV and Felpro 1200s now that I think about it. Never had oil in the intake. Both those cars went mid 10s back in '90.

THINK ABOUT THIS;
Maybe just maybe when we are in boost the crankcase pressure is to high and the breathers cant relieve it fast enough.
When we let off the throttle the PCV starts sucking oil until it can get it under control.

Thanks for thinking,
Steve Kaminski

 

[opzWE4]

Re: Think about this

Originally posted by skturbo
Carl and John;

I had a crankcase evacuation system on my TTA and my wifes Turbo Formula with a PCV and Felpro 1200s now that I think about it. Never had oil in the intake. Both those cars went mid 10s back in '90.

THINK ABOUT THIS;
Maybe just maybe when we are in boost the crankcase pressure is to high and the breathers cant relieve it fast enough.
When we let off the throttle the PCV starts sucking oil until it can get it under control.

Thanks for thinking,
Steve Kaminski

I don't know, but you may have hit a nerve there Seems the only time I have this problem, really, is AFTER I have been in the boost. I can start the car cold and let it idle for 3 hrs and it won't pull oil in through the pcv. BUT, after I've been out driving, and get into the boost, (Can't help it ) that's when it starts sucking oil. I can make a run at full boost, and then go let it sit and idle, and after 3 or 4 minutes that's when it starts smoking and the pcv is sucking oil like mad. I let the car Idle at my house the other day for 15 or 20 minutes and continually checked the pcv, and even looked down into the into the grommet for the pcv several times and saw zero oil under it. I varied the rpms several times also, and still no change. With no boost I seemed to not have any problem.

 

[opzWE4]

Just wanted to get this back up and see if anyone has had any luck with and experiments. No luck here with stopping the oil consumption by the pcv. The only thing I've been able to do to stop it is plug the pcv. I even have an oil seperator in line with the pcv and it's finally started coming past it also, it won't pull out the oil any more. The ONLY thing I've done to keep oil from getting into the intake has been plug the pcv, and I know that's probably not good. Anybody had any luck with other solutions. I tried everything I talked about, even put a check valve in there to keep boost pressure from going back through the pcv but it really didn't change a thing.

I still haven't heard anyone come up with a good explination as to why oil would come up the pcv anyway. I can't emagine that much oil vapor could cause an oil problem, but I don't know. Come on guys, I know there's some pretty smart guys out there that can figure this out.

 

[opzWE4]

TTT

 

[Drewster]

has any one pulled the turbo oil return line to see if thier pan gasket bisects the hole in the block? i was thinking of doing this and then bending the pan up out of the way if it was bisecting the hole. this would keep all the oil under the pan.

i am still in denial with the blow-by theory.

drew

 

[Russ Merritt]

The hole is under the intake gasket. I just put my motor back together this weekend and specifically checked that.

 

[Drewster]

russ...after break in, make a post to this thread and let us know if you have any oil thru the pcv line.

btw....what intake gasket did you use?

 

[Russ Merritt]

I'm sure it will, the car has always sucked oil. It started really 2 years ago when I put on a bigger turbo (stage 5, 60-1). Before that I had a ta51 (KB stage 3) and it didn't ever blow smoke on start up. I don't think there is a solution as even bone stock cars I work on have oil in the intake. Somethings you gotta live with I guess, I'm not gonna hook up an oil refinery to the line to try to stop it. I use intake gasket 96033, no cone on any surface. Install dry. I like it better than the orange steel gasket cause the ports are bigger and I have my GN1s and intake matched to it.

 

[marc86mcss]

TTT

 

[TT/Ameasap]

TTT

 

[JDEstill]

All I can add so far is that I blocked both of my breathers, no in breathing, no out breathing. This should reduce the flow through the PCV to a minimum, so if the oil sucking was a problem with high flow through the PCV, this would minimize it.

Result: after about 45min-hour drive time, and not getting into the boost at all, the clear fuel filter I put on the PCV line has a depressingly large amount of oil in it.

Haven't done anything else since then, I've got my throttle body off getting fixed up by Jay Jackson. After I fix some vac leaks, I'll keep trying. I will say that by putting the filter in the PCV line I noted less oil in the doghouse when I took it off to send to Jay. But then I don't think I had hit "oil breakthrough" yet.

John

 

[Drewster]

significant improvement

i switched the pcv over to the passenger valve cover vent using the stock breather and tywraping the pcv valve in the neck of the rubber piece (dont use metal pipe). leave another pcv valve in the intake location (not hooked up). you MUST use a breather in the driver valve cover vent/fill location for this set up.
i left my compressor filter/separator in line an have not noticed any major oil build up. the oil in the inline filter is what i would expect to see comming off of the valve cover.
my deduction with this set up is that it was not a blow-by situation but rather an oil pooling problem. so.....

oil return pressure from turbo is to high (high volume oil pump)
or intake gasket pan cannot accomidate the high volume oil from pump.

or any other problem which would not allow proper turbo oil return.

disclaimer...
this worked for me and not a absolute cure for other motors. still i recomend giving it a try.

andrew