Topic: 2.5 liter spewing oil into my air box.

[tallrugbyguy]

ok, so i have a 95 yj 2.5 and after a three hour ride on the highway i relized that i had about a liter of oil leak out of my air box on the to street.
so i got into ashop the next day and had a pressure test done and all four cylinders are at about 125 each.
although that isent great it dosent sond like its shot... There was one vacume leack he found and it was a vacume hose near the back of the engine. sorry not sure which one. he is sudjesting a rebuild but he is kinda baffled as well since the engine runs decent and just has the usual noise that a 2.5 always has..

no oil in the antifreeze and no antifreeze in the oil. although there is a little in the line that runs from the top of the engine but i think that is just condensation from the airbox.
if you have anyother questions let me know.
basically im just wondering if ther could be something else. mabey not a rebuild at this point..
thanks
Shane

[oldjeep]

Very common in the 2.5L.  Install a catch can in the middle of the CCV hose and remember to drain it once in a while.

[neale_rs]

Try cleaning out the vaccuum orifice in the valve cover.  It has a tube from the cover to the intake manifold.

[Bounty Hunter]

It's possible that disconnected vacuum line was part of the CCV system. (closed crankcase ventilation).  The CCV system allows crankcase vapors to be burnt in the engine by routing them from the valve cover to the intake manifold.  If that CCV line is clogged or disconnected, the CCV system will run in reverse and push oil from the valve cover to the airbox.

The crankcase gets fresh air from the airbox, so with the jeep running pull the airbox end of the hose coming from the valve cover.  It should be sucking air into the valve cover, if it's not then the CCV is not working properly.

Find the hose from the valve cover to the intake manifold.  Remove the fitting where it attaches to the valve cover and make sure the small orifice inside is open and free of carbon build-up.

I wouldn't jump into a rebuild or a band-aid fix of a catch can.

[oldjeep]

It's possible that disconnected vacuum line was part of the CCV system. (closed crankcase ventilation).  The CCV system allows crankcase vapors to be burnt in the engine by routing them from the valve cover to the intake manifold.  If that CCV line is clogged or disconnected, the CCV system will run in reverse and push oil from the valve cover to the airbox.

The crankcase gets fresh air from the airbox, so with the jeep running pull the airbox end of the hose coming from the valve cover.  It should be sucking air into the valve cover, if it's not then the CCV is not working properly.

Find the hose from the valve cover to the intake manifold.  Remove the fitting where it attaches to the valve cover and make sure the small orifice inside is open and free of carbon build-up.

I wouldn't jump into a rebuild or a band-aid fix of a catch can.

You're saying that the CCV sucks from the airbox?  That would be backwards of any CCV or PVC system I've ever seen.

[st.chevrolet]

Bounty Hunter is correct! On the 91-95 2.5 the tube from the air box to the top rear of the valve cover is the fresh air inlet to the engine, therefore it should suck at the air box end. The tube on the drivers side front of the valve cover contains the metered orifice and connects to manifold vacuum.

[tallrugbyguy]

ok so i puller the hose at the air box and it was just barley sucking. could only tell if i pluged it for a few secons then let go and i could hear a inrush of air. should it be sucking more?
now should the smaller hose to the intake manifold be sucking or blowing into the intake? i wouild assume blowing.

although the mechanic said that he fixed the whistle i can still hear the same noise as i could have befor. obvious a vacume somewhere just having a hell of a time finding it.
thanks for the help.
now that i think of it i will rev the engine and see what way the vacume is going, since the only time thaere is alot of oil is when im on the highway for a extended time.

[Bounty Hunter]

now should the smaller hose to the intake manifold be sucking or blowing into the intake? i wouild assume blowing.

The smaller hose from the intake manifold to the valve cover should be sucking into the intake, this is where the crankcase vapors are burned.  Sounds like the larger tube from the valve cover to the airbox should have more vacuum sucking into the valve cover.

[Bounty Hunter]

You're saying that the CCV sucks from the airbox?  That would be backwards of any CCV or PVC system I've ever seen.

Yes, that's what I'm saying.  Crankcase fumes are sucked into the intake manifold and burned.  The crankcase needs a fresh air source and that is the large line from the airbox.  If it flowed as you suggested, it would blow a large amount of oil into the airbox, as many do when something is wrong and the CCV is working in reverse.

[tallrugbyguy]

hmmm right. so i probably have a plug or leak somewhere, or mabey nothing. ill do some more digging.
thanks alot.
anyone know where i can get a diagram of all the vacume hoses and such so i can see on paper how the system flows?
Shane

[Jeffy]

hmmm right. so i probably have a plug or leak somewhere, or mabey nothing. ill do some more digging.
thanks alot.
anyone know where i can get a diagram of all the vacume hoses and such so i can see on paper how the system flows?
Shane

Look at the underside of the hood. There should be a sticker with the emission system and it's routing.

[spedyr6]

I had a similar problem, just from the sound of it not as much oil on the air filter. Took off the brass fitting on the valve cover and it was mostly plugged up. Cleaned it out along with the hose it connects to and no oil on the air filter since.

[tallrugbyguy]

it has gotten a bit better since one vacume line was pluged in , hopfully it is only the vacume lines.

[czjeeper]

What is the cause of low vacuum at the rear valve cover bolt?

[tallrugbyguy]

dont know, lines look fine. i have a whistle that i can not diagnose, could be it..