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Oil in air filter?

traildamage

NAXJA Forum User
Location
North carolina
When I first bought my Jeep it had oil ALL OVER the air filter! I changed the filter and oil in hopes of remedying the problem but I am stil getting oil on the filter. I noticeanother hose that runs to the engine other than the one running to the throttle body. I heard this is the oil bypass. But still I would appriciate it if someone could tell me how to remedy the problem thanx
 
Those two hoses that come out of the valve cover are for venting crankcase pressure. One is an 'Inny', the other is an 'outie'. The 'innie' pulls air from the air filter area, the outie uses vacum to pull excessive crankcase gasses out and put them into the comubstion cycle by putting the gasses into the intake manifold where they get sucked into the cylinders and burned up. When the outie' gets plugged the excessive crankcase gasses and oil fog gets pulled in thru the air cleaner and thus you get oil all over the filter. You need to remove the two hoses, pull the valve cover, clean all the sludge out and make sure the CCV valve in the back hole of the valve cover is cleaned out, then you need to make sure the hose that attaches to that ccv is also clean. Most just replace them with new ones from the dealer. Also clean the front hose too, or replace it.
 
RichP said:
Those two hoses that come out of the valve cover are for venting crankcase pressure. One is an 'Inny', the other is an 'outie'. The 'innie' pulls air from the air filter area, the outie uses vacum to pull excessive crankcase gasses out and put them into the comubstion cycle by putting the gasses into the intake manifold where they get sucked into the cylinders and burned up. When the outie' gets plugged the excessive crankcase gasses and oil fog gets pulled in thru the air cleaner and thus you get oil all over the filter. You need to remove the two hoses, pull the valve cover, clean all the sludge out and make sure the CCV valve in the back hole of the valve cover is cleaned out, then you need to make sure the hose that attaches to that ccv is also clean. Most just replace them with new ones from the dealer. Also clean the front hose too, or replace it.

Like I said....LOL but it still wont stop it all also cross drilling the towers in the inside fo the valve cover helped most for my ol 88. 2 1/2" holes in each.
 
Yes, go to the dealer and tell them you want all 3 pieces of the Crankcase vent system. Expect to spend the better part of a $100 bill at the dealer. I had the same problem on my 88 XJ Pioneer 4.0 but in 2000 I removed the valve cover, cleaned it up and reinstalled with the CCV hoses.

On cleaning the valve cover I purchased the gallon paint can of carb cleaner to soak the "snorkels" once I had removed them from the valve cover. I had carbon on mine. The can of cleaner had 3 qts of cleaner and a basket to hold the parts while soaking. I never drilled holes in the snorkels and have not had a problem since I cleaned it up.

There been lots of posts on valve cover gasket replacement, do a search on here for it. Also the use of torque wrench when installing the 15 bolts.

I do recommend when you change the CCV hoses you also pick up a new oil filler cap, they run about $3 at the dealer. You may notice oil on your valve cover, remember oil flows down hill so it coming out one of the 3 openings. If you change the CCV hoses and still leak then it the oil filler cap. I had my valve cover all clean and installed and then noticed oil. Turned out to be a worn out gasket on the oil filler cap, installed a new cap, problem solved.

The change out of the CCV items are a 52K requirement per my 88 XJ owner's manual. The CCV harness comes with vacuum hoses and once you install them you may have a better idle since you have eliminated most of your vacuum leaks you did not know you had.
 
martin said:
Yes, go to the dealer and tell them you want all 3 pieces of the Crankcase vent system. Expect to spend the better part of a $100 bill at the dealer.
When I went to the dealer for this several years ago I took this along http://www.off-road.com/jeep/cherokee/xjtech/engine/40ltr/blowby.htm - the parts guy asked to keep that so he could show it to the mechanics...they ordered plenty of additional (and unneeded) parts to try to fix blowby...
 
This is refered to as blow-by. It is common on 4.0Ls. I had the same problem with my '88 Comanche. I put on a 95 vlave cover (91-95), or the newer stamped steel ones work. The 90 degree elbows are suppose to work better than the 87-90 ones. Make sure you get a good seal on the valve cover gasket. I think this is most of the problem. I did the MADXJ update on mine. Check out thier website. I had to cut the CCV tube into 3 pieces and use fuel line between them. The 87-90 has the CCV fitting on the intake manifold farther forward than the later models. Mine use to use a quart of oil every week. Once I did all these mods, then no oil in the airfilter. I ran it for 2-3 months till the slave cylinder went.
Tom
 
Has anyone just disconected the 'out' tube and left it loose beside the engine where it won't cause problems? Or is this a bad idea and if so why?
 
heres a link on info to upgrade the CCV system. I haven't done it but I remember hearing that some people have and it has helped out a little more. http://madxj.com/ \

Has anyone just disconected the 'out' tube and left it loose beside the engine where it won't cause problems? Or is this a bad idea and if so why?

I would imagine if you plugged that hole, the oil would just push out of somewhere else but I'm not positive on that.

Dean
 
Many many moons ago they had what were called 'road pipes' in engines. On the ford 6's and 289's they were in the front of the engine and went right into the block. Excess pressure as well as oil fog went out these 1" pipes and dumped directly down to the street. If you look at old B&W movies from the 40's and 50's that show traffic driving on concrete roads you will see that there are big black lines in the road. That is from oil being blown out of the engines. When they put PCV valves in them it cut down on this but it was not untill 68 or so that they did away with the road pipes and turned it into a closed system. Just a bit of history trivia.. :lecture:
 
OK so i went to cherokee america's and MADXJ sites and read everything on blow by and cleaning the throttle body. So here is what I think I am going to do buy the whole crankcase/valve cover vent system, pull the valve cover off and clean it, get a new oil filler cap (might as well stop that leak too!) then I think I will clean the throttle body. Now I am hoping this will solve two problems the blow by and the low idle. I should be able to do this on a Saturday if I get all the parts ahead of time, don't you think? :repair:
:geek:
 
RichP said:
Many many moons ago they had what were called 'road pipes' in engines. On the ford 6's and 289's they were in the front of the engine and went right into the block. Excess pressure as well as oil fog went out these 1" pipes and dumped directly down to the street. If you look at old B&W movies from the 40's and 50's that show traffic driving on concrete roads you will see that there are big black lines in the road. That is from oil being blown out of the engines. When they put PCV valves in them it cut down on this but it was not untill 68 or so that they did away with the road pipes and turned it into a closed system. Just a bit of history trivia.. :lecture:
The "invention" of the "closed crankcase ventilation" (CCV) system assumes that any pressure generated in the crankcase is more than offset by the vacuum drawn into the intake manifold thru the crankcase vent tube. In most vehicles, is this vacuum is regulated by the PCV valve. In the XJ, it's regulated by a controlled orifice in the valve cover, matched with a small diameter tube between in the intake manifold and the valve cover port.

This works fine when the system is new. When it gets old, and carboned up, it sucks less crankcase vapors. Add to this the fact that old and poorly maintained engines have more blowby, and you wind up with a pressurized crankcase, with vapors looking for any way out. They find an easy route back through the air filter.

Cleaning the CCV vent in the valve cover, and the orifice tube, will help this. Upgrading to the later style CCV vent tube is also helpful on early vehicles.
 
AZ Jeff said:
The "invention" of the "closed crankcase ventilation" (CCV) system assumes that any pressure generated in the crankcase is more than offset by the vacuum drawn into the intake manifold thru the crankcase vent tube. In most vehicles, is this vacuum is regulated by the PCV valve. In the XJ, it's regulated by a controlled orifice in the valve cover, matched with a small diameter tube between in the intake manifold and the valve cover port.

This works fine when the system is new. When it gets old, and carboned up, it sucks less crankcase vapors. Add to this the fact that old and poorly maintained engines have more blowby, and you wind up with a pressurized crankcase, with vapors looking for any way out. They find an easy route back through the air filter.

Cleaning the CCV vent in the valve cover, and the orifice tube, will help this. Upgrading to the later style CCV vent tube is also helpful on early vehicles.

What he said, Ive never seen an older 4.0 with over 100,000 NOT put oil into the filter no matter what you do, but you can limit the amount
 
I just went to Auto Zone and bought one of those cheap Mini air filter thingies (I think they are called breathers). Just in case no one understands what I’m talking about…instead of having the tube that goes from the top of the engine to the air filter box, the innie tube as RichP calls it, I basically bought a mini air filter (its like 2 inches long and 1”1/2 inch across) and put it where the tub would originally go. I think it cost around 5 to 10 dollars.

That solved the whole problem with oil getting on my filter. I don’t think that it hurts anything. Would it?
 
Snarky said:
That solved the whole problem with oil getting on my filter. I don’t think that it hurts anything. Would it?

Only if the EPA cops looks under your hood. LOL...

Engine shouldn't care but I have a high mile XJ and it was getting messy. I have Smog tests. After replacing all the CCV plumbing (local Kragen had a Chinese replacement sitting on the shelf for about $45) and cleaning valve cover baffles, air filter barely gets wet with oil and EPA is happy.
 
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If you want to eliminate oil in your air filter, get a 1997 or later valve cover and rubber gasket. I put a 2001 wrangler valve cover on my 1988 with 215k and I no longer am getting any oil in my air filter. This is the first time since I've owned it. It's wonderful, best mod so far.
 
what did they do to the new valve covers that makes them work better? a friend of mine just changed his jeep over to a pcv valve setup. this setup created a lot of extra vaccuum also.
 
PapaPump said:
what did they do to the new valve covers that makes them work better? a friend of mine just changed his jeep over to a pcv valve setup. this setup created a lot of extra vaccuum also.
As I alluded to in my previous post, they increased the size of the suction orifice in the valve cover, and increased the size of the suction tube that connects to the intake manifold.
 
Snarky said:
I just went to Auto Zone and bought one of those cheap Mini air filter thingies (I think they are called breathers). Just in case no one understands what I’m talking about…instead of having the tube that goes from the top of the engine to the air filter box, the innie tube as RichP calls it, I basically bought a mini air filter (its like 2 inches long and 1”1/2 inch across) and put it where the tub would originally go. I think it cost around 5 to 10 dollars.

That solved the whole problem with oil getting on my filter. I don’t think that it hurts anything. Would it?


I done this same mod about 4 months ago, and it works great. Drips a little oil out of the filter but, not much. It's worth doing to keep the oil out of the intake system. I let the little filter hang down on the driver side, so it don't drip on the engine.
 
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