another ccv, valve cover, blow-by question.

Hello everyone, new member here. Had a question about the ccv, blow-by topic. I did the search and read a bunch of posts. I have a question about "normal" vapors under the valve cover. Should I be able to see any of the vapors with the oil filler cap off? If I see any smoke do I have blow-by or should you "normally" see some smoke?

background: just replaced the valve cover gasket with a clean of the ccv system in the process. had oil soaked air filter but I think that was caused by the leaking valve cover gasket providing the highest pressure air source available. I see a bit of smoke when oil filter cap or rear intake vacum source line removed.

thanks for any help and/or ideas.

edit: also another question. what would normal pressure under the valve cover be? Does the metered hole in the rear of the valve cover and the fresh air from the air box keep the pressure more neutral? or is the air under that valve cover lower then outside air? thanks again

If you take off the rear vacuum line then you will see some vapor at the oil fill area. Since there is no vacuum the gases are just going to rise out of that hole. If you put the vacuum back on then you should see little to no gases escaping.

There is no substantial pressure in the VC area, you just have a slow steady stream of fresh air coming in and vapors leaving. That is the whole point of the system, to prevent pressure from building up.

K

I'm not sure what you mean by pressure under valve covers, but it is typical for higher milage engines to have a little 'blow-by' emission. If these vapors are visable when you remove the oil filler cap, then you probably have a clogged PVC/vacuum line. This is the small plastic vacuum tube that connects the valve cover to the intake manifold, where the vapors are sucked out from under the valve cover and recycled via the intake manifold. Replacing or cleaning out this line usually takes care of this.

depending on the year jeep you can check this site out http://www.madxj.com/MADXJ/technical/technicalfiles/JAvalveCover/ValveCover.htm it's a upgrade on Madxj's site to the ccv system i did it and posted to this thread http://www.naxja.org/forum/showthread.php?t=57488 ... Oil in the air filter means that the rear hose or fittings are blocked

thanks for the help. I cleaned the whole system while I did the valve cover gasket.

How much vapor/smoke is normal under the valve cover? Should I be able to see it or should it be such a small amount that I cannot see anything?

thanks again

JMH I think that I have another cause of oil in the filter other than the rear line being clogged. I had a leaking valve gasket and I think that can cause the oil there too. Since ambient air was allowed to enter the through the bad seal, both the rear hose(to the intake) and the front hose(to the airbox) were lower pressure sources. This drew oil/air vapors into the airbox.

that is kinda why I am wondering about the amount to smoke/vapors that I have. I would like to compare with other owners. Now that I have replaced the gasket I am trying to see if I would still have oil on my filter in the future. Just don't get to drive enough to just drive it and find out!

thanks for your post!

From all the post that i have read, 99% of the time it's the ccv blocked which in turn forces that pressure back into the air box hose. I doubt that the valve gasket would cause (anything is possible though ) that as the rear lines are on a vacuum.. What happen to mine was the fitting in the valve cover was not blocked but the hose was totally block as well as the fitting that goes into the manifold. In turn this back presuure pushed oil out the front hose into the air intake box and covered the filter as well as caused a valve cover leaked in the rear looked as if the rear main seal had gone bad. anyway good luck hope you get it fixed, trying to trace a wire myself which like a jungle.

cool I guess I will test the rear line by taking off the top of the air box to see if I can feel the vacum where it draws air from the airbox.

but back to the question of what do you see when you are looking at the vapors? is there smoke mixed in? how much? should I see any at all?

thanks again

I solved my oil in the filter problems by taking that rear line off and putting a whole can of degreaser through it. A lot of nasty came out. Haven't had oil in the filter for 5K miles.

87manche so now what do you see as far as the vapors go? is there any smoke mixed in? if so how much?

I was thinking about the pressure under the VC also because I was thinking about the 3mm hole in the rear fitting. The articles that I have read about upgrading the system are making that hole bigger. Just wonding why they selected that size. Was there a reason? Probably not too imporant but just wondering if there were trying to keep some pressure under the VC.

I see vapors coming out if I plug up the rear line. I would say that is normal on any car. My saturn is the same way.

The orifice size is a complimise of sorts. It is in essence a vacuum leak, too big and you will have vaccum operation problems, heater valve, temp control valves, high idle, crappy gas mileage. If it is too small it will not be able to keep the pressure inside the engine down and will clog very quickly. Sure you could probably open it up alittle with no ill effect, or you could just keep it clean in the first place.

K

yeah roger that katarn, I see that the articles and discussions in other threads seem to suggest that enlarging it is what to do, but I was kinda thinking that just maintaining what I have is what I will do.

thanks for your help

Where did you get these part numbers from? I tried NAPA, Autozone, and Jeep dealership and I couldn't find any numbers to match up?

i need to clean the rear line, but man i havent owned a jeep w/ a stock jeep engine that didnt have some blow by on the filter....they can be awful about it..esp the 2.5's