Valve cover breather issue?

[drddan]

There is oil building up and blowing out my valve cover breather. (see pic)
After a couple days of driving, I get a small puddle of oil on the valve cover.
This is a recent thing, just started doing it. I am wondering about the PCV valve? Just put a new one in, and I wanna say this issue started about the same time. Not sure if it is related.

I just painted the cover red, and dont want oil on it.
Why is this doing that now?

[bravekozak]

When you shake the pcv valve, do you hear and feel the valve slide up and down inside? If it's stuck in the down position and cannot lift when vacuum is applied, then the crankcase fumes will follow the path of least resistance. Namely, out your crankcase filter.

[drddan]

When you shake the pcv valve, do you hear and feel the valve slide up and down inside? If it's stuck in the down position and cannot lift when vacuum is applied, then the crankcase fumes will follow the path of least resistance. Namely, out your crankcase filter.

Sounds simple doesnt it? Man, am I lazy. :p
Its cold, and I decided this year that I HATE the cold. lol I'd have to stand out in the COLD to do that!


Actually want to check the PCV and the vacuum line to the pcv to make sure its pulling like it should too.
Thanks, I knew you'd jump on a question like that

[blkfordsedan]

Is your PCV valve connected to an intake vacuum line? If you use the PCV valve w/vacuum on it, you should have a sealed system. Otherwise, you have a vacuum leak and are running lean (i.e. the engine intake is sucking unmetered air through the filter you installed). If you want to "suck" the fumes from the crankcase, you can attach the PCV line to a fitting on the bottom of the air cleaner housing. That way, all the air is flowing through the carb venturis as it should. However, if you have ring seal/blow-by issues that are causing it to build up excessive pressure in the crankcase, you'll get oil in the air cleaner/carb, just like you do on the valve cover now. The other issue is that the nipple you have the breather attached to does not have an internal baffle on the inside of the valve cover (unlike the hole where the PCV valve installs). The baffle helps keep oil from being blown directly out. Or, you could install a fitting in the exhaust pipe and attach the hose, letting the exhaust flow draw out the fumes. That's a common practice in race applications.

[iceracerdude]

When the "breathing feature" is in place like on the stock intake tube, yes it's using "already metered air" but the other feature that is often overlooked on a configuration like your's is, that hole in the stock intake tube is actually proportionately much smaller than what you've got right now! You've have in essence, eliminated that needed size difference which assists the vacuum created by the intake manifold.
Once you reduce the size of that breather hole, the manifold will finally be able to suction the oil and fumes away from the breather, and the computer will almost not notice the tiny bit of additional air. I say almost, because the oxy sensor will pick it up and compensate for you! That being said, I can't of course, speak to the condition of your valve guides or seals. Take a look at my setup, and remember, this is with 10lbs of boost!

At the end of the litte tube is a rubber cap that I made about a 3/16" inch hole in.
No catchcan "oil weaping" no worries what-so-evah. I do have a thing called a Krankvent installed over in front of the pcv valve, but that's to stop pressure from going back into the crankcase, a problem you won't realize with your na config.

[Safety Guy]

Iceracer, are you saying he needs to put a better restriction on his breather? In other words, it's "breathing too freely" right now and more restriction will slow down or stop his oil seepage?

Karl

[iceracerdude]

That's exactly right! Even with a "new" pcv valve like he's got.
Think of your thumb on the opening of the garden hose, you're really not able to stop the flow, but what a difference in the distance and perceived water pressure huh? Well my friends, the same holds true for vacuum control.
Notice the couple inches of length before I placed the restrictor, I could have more easily placed a restrictor right on the very top of that vc hose port we're all familier with right? I've left that little bit of extra 3/8" id (with the 2 90 degree bends) for any oil droplets that might collect, to simply drop back down in the vc. That's all the "oil separator" this particular engine requires, but then my pistons, rings, valves and guide seals are "fresh". You can see how easy it would be to simply add a catch can to this config, and of course in some racing venues, it would be manditory at tech inspection.

I didn't mention it before but, if you've still got the stock intake tube to look at, I think you'll be shocked to see the size of the actuall breather hole in it, it's nowhere near the size of that hose! Obviously use that hole as your guideline!
If someone's got a picture of a stock intake tube, where we can get a pic of the breather hole in it, we can maybe make up a writeup or sticky about breather design!?

[Safety Guy]

Okay, I think I know what you mean. As for the intake breather hose actual inside diameter, I also can remember the thickness of that rubber pipe and how small the opening in it was.

Along the same lines, look at the hose from the side port on this B8 (pretty sure it's a B8 ) from FM4:



I was wondering why it was standing straight up and not connected to anything. Same reason you are describing, right?

You may have to copy and paste into your pictures program and enlarge it. The hose comes out the distributor end of the VC and is leaning up against the air intake tube. It looks like this engine has a side outlet instead of the top outlet like B3s and B6s.

I'm not sure whose car that is but I'm thinking about a close copy of the way he ran his intake pipe and VAF so I can keep Aqua's battery in the stock location. I was looking at some plastic pipe in Home Depot this morning but couldn't find anything that looked like a good 180 degree bend.

Karl

[blkfordsedan]

When the "breathing feature" is in place like on the stock intake tube, yes it's using "already metered air" but the other feature that is often overlooked on a configuration like your's is, that hole in the stock intake tube is actually proportionately much smaller than what you've got right now! You've have in essence, eliminated that needed size difference which assists the vacuum created by the intake manifold.
Once you reduce the size of that breather hole, the manifold will finally be able to suction the oil and fumes away from the breather, and the computer will almost not notice the tiny bit of additional air. I say almost, because the oxy sensor will pick it up and compensate for you! That being said, I can't of course, speak to the condition of your valve guides or seals. Take a look at my setup, and remember, this is with 10lbs of boost!

At the end of the litte tube is a rubber cap that I made about a 3/16" inch hole in.
No catchcan "oil weaping" no worries what-so-evah. I do have a thing called a Krankvent installed over in front of the pcv valve, but that's to stop pressure from going back into the crankcase, a problem you won't realize with your na config.

That's all true and a very good point.

Just a few questions:

Why would you want to suck unfiltered air into the crankcase? I know in your case the inlet tube is pressurized so you can't connect to it. But the B8 in the picture Karl posted just doesn't make sense to me. Why didn't they just put a fitting in the inlet tube with a small orifice and do it right? In drddan's case, he could install a small fitting in the bottom of the air cleaner housing and run a tube from it to the nipple on the valve cover.
Which leads to the next question; what exactly is the purpose of the little hose that attaches from the VC to the intake tube? I assume it's to provide an air inlet to keep the PCV system from creating a vacuum lock in the crankcase? (unfortunately, in the case of my B3 it now acts as an oil injector that fills the inlet tube w/oil and keeps the K&N filter and throttle body lubed)

:laughing8:

[blkfordsedan]

Here's a couple good links I found - may have answered my own questions! Looks like this is a universal issue- be it Corvettes, Mustangs or Festivas!

http://www.autoshop101.com/forms/h63.pdf

http://www.digitalcorvettes.com/forums/showthread.php?t=118723

http://www.fordmuscleforums.com/all-ford-techboard/438432-very-annoying-pcv-system.html

[bravekozak]

good ol' days

In the good ol' days, they just had a tube hanging down and the negative pressure caused by the breeze passing over it just pulled the vapors out of the crancase so that it wouldn't varnish up the inside of the valve cover and valvetrain. Nowadays you can't get away with that. It must be a closed system. I have a nipple on my air cleaner with a filter just for suppying clean air to that little nipple on the valve cover. That is an old picture. I cut out that tubing in the middle of the air cleaner.

[1988festivazoom]

I had a similar problem on my b6-me after I had the head shaved 20 thou. It would get massive amounts of oil in the intake. I figured it was a bad head gasket or something causing iregular crankcase pressure. I faught this problem for a couple months then I just got tired of it and bought an aftermarket turbo catch can and bam problem solved. No mure oil in the intake and no more exhaust smoke! I'm not sure what exactly was causing me to have so much cc pressure but after I switched to amsoil I have never had any oil in the catch can..... not sure why...

[iceracerdude]

The purpose of the "air in" from the intake tube source is simply fresh air for the engine. The factory design is obviously for metered fresh air, but In my case, it's unmetered fresh air. And you're right, my goal was to keep my "pressure" source from actually pressureizing the back sides of my pistons! They make a Krankvent solution for that, but that's another explaination for another day.
A lot of people think that the pcv valve is a check valve. It is, but it isn't. We really think of a true "check valve" as a "one way valve" right? The pcv valve on factory turbo cars does act more like a check valve, but on na cars, it's pretty "leaky" by design. It's really designed/made to stop a violent "backfire" from going back into the engine's vc or worse yet, all the way to the crankcase. That's why when you blow "backwards" into a pcv valve, it will generally let air pass, it's only supposed to slow the air down at closed throttle, that is unless there's a violent back fire, at which point it should slam shut.
That last picture of the engine with the vent hose pointing straight up, will surely catch some oil and allow it to drain back, but the hose is now devoid of the necessary restriction. A very easy thing to correct at this point.

[drddan]

Wow, thanks all! Man, that was a good discussion.
It has been suggested to me to hook up a hose to the air claener on the carb, as iceracerdude suggested. Also like the idea of a restrictor. I will do this and see what happens. Thanks to all!

I assume it's to provide an air inlet to keep the PCV system from creating a vacuum lock in the crankcase?

Yes, air comes in the the tube from air filter, thru the valve cover,and goes back out the pcv valve.

Positive
Crankcase
Ventilation

[bravekozak]

Are you certain that there is no deposits or crud under the oil baffle inside your valve cover? Have you ever taken out all of those little screws to see the grunge underneath? Clean it out and retest. Be careful with the gasket. Try not to tear it. It's an intricate diecut.