Oil In Air Filter (jeep Newbie Here)

indyfireman419 · 10-26-2007, 08:23 PM

Ok, I know this has prob been addressed here before but not real sure yet on how to navigate and search effectivly. I have a 92 Cherokee 4.0 and stock airbox. I opened it up to find quite a bit of oil in it and on the filter. The parts guy at the local store who is a self proclaimed "Jeep guy" said this is common and that there is no fix to it due to poor design. I would have to think that someone if not DC came up with a fix of there own. He said that there is no PCV valve and that the lines are just vents and will always leak oil like that....

cnskate · 10-26-2007, 09:41 PM

I had the same problem with my 94 and I fixed it by replacing the clogged vent hoses and spraying some cleaner in the valve cover vents(I changed my oil right after). The hose kit is cheap and common from a dealer. Find a new "Jeep" guy.

pgdyk · 10-26-2007, 09:52 PM

The valve cover on these jeeps are a crappy design, at high rpm all the oil flying around in there gets past that little roof in the valve cover that is supposed to keep oil out and let air escape. The lines get clogged like said before. It could also be a more serious but unlikely problem - heavy blowby, but if you don't burn oil you don't have that problem. And in my book, any tube that runs from the valve cover to the air box is pcv. I think there is a write up on this forum somewhere about oil in the air cleaner.

indyfireman419 · 10-26-2007, 10:26 PM

I saw a write up about using a different pcv and tube setup involving a air cuck fitting. I believe it was probably for the one closest to the firewall that goes into the manifold????

**balloo93** · 10-26-2007, 10:42 PM

I went ahead and spent the $25 or so and replaced mine with 00-01 CCV lines. Nice new clean fixtures and a wider tube in the rear.

I think I have that link in the Tech/FAQ sticky.

BB1980 · 10-26-2007, 10:55 PM

The way it was designed was to allow fresh filtered air to enter the valve cover on the front connection and then the intake manifold would suck the pressure off through the way smaller tube running to the back of the VC. When the smaller tube gets clogged or whatnot, the suction starts pulling the blowby through the larger airbox hose and the oil starts dripping on the filter. I am testing a PCV valve inline on the larger front hose to see what difference it makes. I will get some pictures up after a little while.

AZ Jeff · 10-27-2007, 08:01 PM

Quote:

Originally Posted by BB1980

The way it was designed was to allow fresh filtered air to enter the valve cover on the front connection and then the intake manifold would suck the pressure off through the way smaller tube running to the back of the VC. When the smaller tube gets clogged or whatnot, the suction starts pulling the blowby through the larger airbox hose and the oil starts dripping on the filter. I am testing a PCV valve inline on the larger front hose to see what difference it makes. I will get some pictures up after a little while.

If you are using the front opening the valve cover to vent crankcase vapors, WHERE is your inlet for fresh air into the crankcase?

The crankcase ventilation system needs an inlet and an outlet. Sounds like you turned your inlet into an outlet, so where is the new inlet?

BB1980 · 10-27-2007, 11:25 PM

Quote:

Originally Posted by AZ Jeff

If you are using the front opening the valve cover to vent crankcase vapors, WHERE is your inlet for fresh air into the crankcase?

The crankcase ventilation system needs an inlet and an outlet. Sounds like you turned your inlet into an outlet, so where is the new inlet?

Quote:

Originally Posted by BB1980

The way it was designed was to allow fresh filtered air to enter the valve cover on the front connection

That is the inlet. The front is the inlet that should let fresh air IN to the crankcase, and the rear vents it into the intake. The problem comes when the rear gets clogged and it trys to vent through the front into the airbox and gets oil into the filter and can get up to the throttle body as well due to engine suction. I was trying to put a PCV in line to not allow the front to vent backwards into the airbox, but found out tonight that when the rear gets clogged, the crankcase gets pressurized and the jeep started sputtering in high gear under load. There was oil trying to push past the oil fill cap to vent out.

A better fix would probably be to allow the front to go both ways but to put a catch bottle inline that would collect the oil and be able to be drained.

This link is for an XJ Jaguar I found while searching, but looks interesting.
http://bernardembden.com/xjs/pcvfilter/index.htm

BB1980 · 10-28-2007, 11:01 AM

This also looks helpful:

http://jeep.off-road.com/jeep/articl....jsp?id=257985

http://jeep.off-road.com/jeep/articl....jsp?id=257836

AZ Jeff · 10-28-2007, 11:10 AM

Quote:

Originally Posted by BB1980

This also looks helpful:

http://jeep.off-road.com/jeep/articl....jsp?id=257985

http://jeep.off-road.com/jeep/articl....jsp?id=257836

Thosse links reference the later style CCV plumbing that Jeep introduced to improve the flow rate (and reduce clogging) of the crankcase vent system.

I know of no later style CCV system that have developed the "puking of oil into the air filter" issue that plagued older 4.0 engines.

I think that it's safe to say that installing that cheap (and proven) upgrade would fix your crankcase venting issues once and for all.

indyfireman419 · 10-30-2007, 12:27 PM

I went to the madxj website and found the parts list for the conversion. My local dealer wants 55.00 just for the 2000 intake manifold nipple. Hell for that I might as well buy a new intake off ebay for 100.00. Anyone have luck finding an online parts distrubtor to find all the necessary parts???? They want 35.00 for everything else needed including a new front tube assembly for the front.....