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oil in the airbox.


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I'm removing the airfilter box and stuffing the cone filter onto the tube.

 

question.

 

what causes the oil in the airfilter? I have a brand spankin' new PCV valve to put in if I need to. What I was thinking was, instead of keeping that stupid breather hose that runs from the front of the valve cover, I would cut it short and stuff a bolt in it to seal it up? I have a hankering that my piston rings are fairly worn so I'm going to do a replacement bearing/rings/crankbearings in the summertime. Will plugging that hose stop the oil loss, or will pressure just build up and shoot the bolt into oblivion through my fender?

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Well I'm not sure about the other questions but I have a suggestion...You can by small air filters at advance that go in the top of the valve cover and then you eliminate the hose completely. jamminz.gif I can takre pics of mine if you like.

 

Cole

 

Does the air filter leak oil and make a mess?

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No not really I bought the higher dollar one so the element in it catches pretty much all of it. I also wash it out alot so it don't build up then push it all over. But for me I leak oil from every crack and creavace so I don't worry that much but it does seem to keep it from blowing all over.

 

Cole

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No not really I bought the higher dollar one so the element in it catches pretty much all of it. I also wash it out alot so it don't build up then push it all over. But for me I leak oil from every crack and creavace so I don't worry that much but it does seem to keep it from blowing all over.

 

Cole

 

Do you have any pics or a part number??

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it's a common thing with the 4.0, called blow-by. do some searching here, google, and some other Jeep boards and you will find lots of ways to help prevent it. You may just need to clean or replace the hose assembly that goes from the back of the valve cover to the manifold.

 

If it's really bad, build a catch can that the oil dumps into, with a little air-filter above the oil level.

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Don't plug the line or hole. Filtered air is supposed to enter the VC from that place to help the PCV system pull the blow by gasses in to the manifold. The little generic filters work great. You will actually see less oil with them because at high engine load ( low manifold vacuum) the tube to the air box actually starts to work in the opposite direction pulling blow by in to the air box instead or allowing air in to the VC. This isn't neccessarily bad other than the oily mess you get.

One thing to check if you have the older cast VC on your 4.0, the PCV grommet hole leads to a tube like passageway inside the cover. This extends too low and can actually reach liquid oil at higher revs, especially if on an incline. There was a bulletin to drill a 1/2 inch hole part way up the tube (VC off of course). I have seen guys just take some channel locks and break off a small piece of the bottom of the tube so that it doesn't extend quite so far down. Also make sure the little flap thing under the PCV grommet isn't stuck shut with crud.

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here's an article I found on BC4X4.com

>My 1987 4.0 FI XJ has started sucking oil into the air filter.

>It then dumps the oil on the ground. The local mechanic, says

>the oil rings are shot. He says it is cheaper to buy a reman

>than it is to overhaul the engine.

 

Before giving up on your 87 4.0 due to the oil in the filter

try a little clean up on the Crankcase Ventilation system.

Its not a traditional PVC valve system.

 

The large tube from the rocker cover is an air intake vent,

filtered air, from the air filter. The small tube at the

back of the rocker cover is supposed to always keep the

crankcase in a vacuum to keep the air & oil moving the right

direction. This usually keeps the air and oil in the large

tube traveling in the direction of the rocker cover.

 

The gromet holding the small tube at the back of the rocker

is supposed to have a 0.1 inch orfice to meter vacuum. Its

just rubber and gets plugged periodically. When it plugs,

you lose the vacuum in the crankcase, the large tube becomes

the crankcase vent (in and out) and full of oil. The large

tube entry has no baffle plate in the rocker cover and it

makes a mess that can lose 1 qt per 1000 mi.

 

Pull the small tube out of the gromit and stick a drill of

the appropriate size into the hole to clean it up, a 1/8 in

drill is close enough. don't be shy as there is a baffle

plate under the gromit to keep you from hurting anything

important. Other things to check when you find oil in the

filter is a gummed up throttle body. The idle air solenoid,

front of the TB on the passenger side with wires out of it,

can also get gummed up from the oil. Clean up the inside of

the throttle body with carb cleaner spray and remove the

idle solenoid to clean the air valve. I also check all the

wiring connections, pull them apart and reseat them.

 

When complete the idle should improve and you should be able

to feel a vacuum in the big tube pulling from the crankcase.

I do this about every 20k with my 88 4.0 and have 194k+

miles, passing the CA emissions test with original

everything, etc. BTW, a master rebuild kit is about $600.00.

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Freeroknok's pic is very similar to what I have. I can get pics if you still want but its the same. I don't know the part number but I do know that here at my Advance they sell them over near the ricer parts and over at the Big engine parts out on the floor. Youu should be able to find it pretty simple. Here is what I found on the website I had to make up a vehicle with a big simple motor to find it but this is alot like what I have.

 

http://www.partsamerica.com/ProductDetail.aspx?categorycode=5001&mfrcode=KNN&mfrpartnumber=621495

 

Let me know if you need any more help.

 

Cole

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