Oil in Air Cleaner & Need for a Air Cleaner Cover

chuckndonna67

New member
1064956

1988 YJ 4.2L - I have encountered engine oil in the air cleaner housing and the air filter was soaked with it. The only inlet that I can figure out how oil gets in is thru a hose that runs from the top of the valve cover to the air cleaner/PCV valve filter. Is there supposed to be some kind of check valve that prevents oil from the valve cover to the air cleaner housing? Or does this sound like a more serious problem? Secondly, anyone know where I can get an air cleaner cover new/used? Mine has been patched so much with duct tape---CAB :-( [addsig]
 

1064958

Hey chuckndonna67, this is a topic that has had a bunch of research here. Do a search and you can get more info than you will ever believe. No brushing you question off by any means here just a thought. You are sure to get plent of answers anyway. Seems to be common problem and if I am not confused it is from the crankcase breather or something like that. Just cant remember. Luck Tug :-D [addsig]
 
1064963

It happens t all those Jeeps. Just like Tug said it is coming from the breather. Just remove the hose and the elbow from the breather and go to Autozone and get a smalle seperate breather it will fit perfect into the rubber grommet on the rear of the valve cover. When I first got my jeep I searched for an air cleaner like that but could not find one. It sounds like you still have the stock carb. If you have the dough you should replace the carb. It would eliminate most of the hoses and the air cleaner assembly. :-D [addsig]
 

1064986

Repost:

Regarding oil in the air cleaner.
I have been reading this same topic from forum to forum. Everything from removing valve covers to rebuilding motors because of warn or broken parts. Here is a suggestion from a Jeeper that had and fixed that same problem. I now have well over 225,000 miles on my daily driven, rock crawling, 1989 YJ. (With no oil in the air cleaner) . With help from the one non-salesperson at Jeep, I fixed the problem with a $1.99 can of gumout. With the engine running you can lift the pcv valve out of the valve cover and put your finger over the end and you should have some serious suction. (While reving the engine) If not, the pcv valve does sometime clog, (When you shake it, it should rattle) To clean he suggested spraying with gumout or replacing (if necessary). But the culprit is usually inside the hose that runs from the pcv valve to the intake manifold. If you removed the air cleaner you would find a split in that (approx ½ inch outside diameter) hose. It connects two hoses together. Inside is a small orifice (approx 1/8 inch inside diameter) that gets clogged very easily. (Trying to remove the two pieces usually ruins the orifice)(It gets brittle)
Before you remove anything, with the engine running, spray gumout into the pcv valve or remove it and spray directly into the hose (keeping the rpms up, so the engine won’t stall) Depending on the severity of the clog a little or a lot of gumout will be used. (Sometimes a piece of piano wire is needed to unblock the orifice) You should notice immediately a difference in the amount of suction at the pcv valve. Reinstall the valve, shut of the motor, open and clean the excess oil from inside the air cleaner. Replace, if necessary, the air filter (this is a good time to install a K&N filter) Remove the little filter, spray it with gumout, replace it and put back all the other parts. This completely fixed my problem. Two years to find and $1.88 and five minutes to fix.

Note: With this line clogged, the pressure inside the valve cover forces oil up through the rear hose into the air cleaner. And with so much oil inside and leaking out of the air cleaner, it leaves room for shady mechanics to suggest some serious $$$ repairs.

That repair was done about 50,000 miles ago, and just to be safe; I spray out that hose along with the carb during periodical maintenance. The problem never came back.

Give this a try. It solved my problem, and at $1.88 for a can of gumout, this might be the cheapest suggestion you’ll get.

Good Luck.
[addsig]
 
1065016

MORGSTER is right, probably a clog that is causing the PCV system to run in reverse, and the intake sucking oil into the filter. Working correctly, the PCV should suck air from the intake filter. Clean the plastic orifice mentioned above and check for any collapsed/dry-rotted vacuum lines.[addsig]
 
1065021

I have the same prob with my 89 4.2L. I tried the same fix, but my hose diagram is a bit different than the book and the diagram under the hood. I checked the PCV and cleaned that and decided to check all associated hoses. One problem I had was in regards to the brittle plastic connectors. Just downstream of my PCV the hose is connected to one such connector (appears to simply be a swivel connection). While trying to disconnect it, it broke in half. Right now it's duct-taped together. A few questions:
1. Is this connector required? It has the 1/8" orifice
2. Can I buy a replacement at Napa, Autozone, Pep boys, etc.[addsig]
 

1065050

Yes, it is required, make sure the orifice stays clean. Don't know where you can get one.[addsig]
 
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