Bad Oil Leak

I've been noticing a lot of oil drip puddles under my '90 XJ 4.0, even when parked in a spot for only a few hours, and when I checked the dipstick the other day I was down to the bottom tip of the stick! I changed the oil probably a month ago, and it has gone about 1200-1500 miles. I went to the store and added 2 quarts of oil, and the level wasn't even up to the "Add" line. So I figure it lost about 3 out of 6 quarts in those 1500 miles.

I've started checking all around the engine, it seems to be coming from the back right side of the engine. It is too far back to be the oil sending unit or the oil filter, it is coming from way back near the tranny and the firewall. I crawled underneath and everything is covered in oil, the tranny, the transfer case, even the frame rails nearly back to the rear axle.

I've read a lot of other posts on here about leaks from the oil pan gasket and the main seal. Could this be my problem? I don't think it is the oil pan, but I am not sure where the main seal even is. There is a ton of oil down on the block and on the front and bottom on the tranny, so it seems too high to be the oil pan.

Any good suggestions or ideas about what is the cause of the leak? Should I just try cleaning everything of oil and looking for where it is coming from? I couldn't see it at all, it seemed to be coming down the right side of the block way back near the tranny, no way to get a close look. Should I try using a flourescent dye? If anyone has any good ideas, it would be greatly appreciated.

1st. CLEAN everything.
2nd. If you haven't just replace the valve cover gasket. Alot of leaks come from the back.
3rd. Never start your rig without checking the oil till the problem is fixed.
4th. If you haven't done the oil filter adapter, its a $15.00 fix. I would just do it for the hell of it, cause you have too sooner or later.

5th. If it turns out to be the oil pan, do the main at the same time.


Enjoy. It only took me most of a weekend with a bitchy wife, and 2 kids wondering when I'd get done.

Take your time, do it right. And you shouldn't have to do it again for a long time.

First the valve cover gasket does a better job of imitating a rear main seal leak then the rear seal itself does. Best method to check is to COMPLETELY degrease the engine, get all the old oil off and then drive it checking it for new leaks. The O rings on the oil filter mount can be the cause, the fan can push the oil back along side the motor, you can also have a leak from the distributor O ring. There is also another one, a plug, on the back of the block between the engine and the tranny into one of the oil galleries, only way to check that is to get a look see up into flywheel territory, You can drop the starter for a limited look, not having an auto I don't know if they have an access plate under there or not, if so you can remove the access plate and see from there.
Also check your air filter, if you have excessive crank case pressure it could be pushing oil UP the dipstick filler tube. Thats about all I can think of now other than the obvious stuff like leaky head gasket or crack somwhere...

on mine, which has an oil filter adapter leak, the adapter area is always caked with oil, and there is always a drop of oil on the filter from dripping off of it. for the valve cover gasket leaks, degrease, and do a thorough spot-check-i've had those bolts get hand-tight before and just tightening them up got rid of the seeping that it was doing. for a leak that heavy, i would suspect pan or rear main. if it's one or the other, do both, because if it's the pan, you might as well do the rear main while you're in there, and if it's the rear main, you pretty much have to do the pan anyway. hope that helps.

Thanks for all the tips. I do not think it is the filter, as the leaking oil is definitely coming down the backside of the engine. But I will first look at the valve cover, and replace the gasket if it appears to be the problem. Then I might try the pan and main seal.

I'll have to wait until the weekend after next to do the pan and seal, as I am going on vacation this weekend.

Thanks again for all the help.

Update: I replaced the valve cover gasket using RTV gasket maker, and boy did that not work. The leak got noticably worse, I could see the drips after driving it hard. So I think I better get an actual gasket in there. Does anyone have any experiences similar to this? Any recommendations on what to do?

Get the cork gasket- it is like $7.00. You can rtv it onto the valve cover ( and let dry over night) in a couple spots to make sure that its does not move when you replace the cover as it can be a tight fit between the radiator hoses.

Mine leaked bad too- until I replaced the CCV and the valve cover gasket.

SoCalGuy said:

Update: I replaced the valve cover gasket using RTV gasket maker, and boy did that not work. The leak got noticably worse, I could see the drips after driving it hard. So I think I better get an actual gasket in there. Does anyone have any experiences similar to this? Any recommendations on what to do?

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I *really* DON'T like RTV at all, Felpro makes 3 different gaskets for the cover, one is all cork [tan], the second is cork/rubber [tan cork w/black dots] and the third on is all rubber/neophrene [all black] I prefer the all neophrene one, it's pretty much resuable.

SoCalGuy said:

So I figure it lost about 3 out of 6 quarts in those 1500 miles.

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That's nothing...my old '90 lost a quart every 50 miles or so. :shocked:

Yeah I know how you feel with the bad oil leak, mine did the same thing....combo of valve cover and oil pan, lots of smoke and burnt oil smell. I don't like the neophrene seal because I've had one rip apart while tightening down the cover, replaced it with the cork/neophrene mix and some rtv worked like a charm. For the oil pan get the 1 pice gasket, I also rtved it but you don't have to.

You get a lot of different opinions on the gaskets. I have had great luck with using RTV. I think the trick is to put a bead down, let it sit for about 30-45 minutes and then put the valve cover / pan on and only snug them down by hand. The next morning, torque it down to specs. FOr me, it has worked great. Both on my valve cover and oil pan. As others mentioned, do the rear main at the same time as you have done most of the hard work already.
BSD

I had the same problem. I had already changed the o-rings in the oil filter adapter housing. I thought it was a rear main seal but every time I cleaned it the leak did not appear to be from there. I found that my oil pressure switch mounted directly above the oil filter had started to leak. The switch only has one wire going into it but the switch is manufactured with what looks like a two wire switch with a sealing plug in the empty pin hole. Basically the sealing plug let loose and that is where my oil leak is coming from. New oil pressure switch on the way. Basically I am losing about a quart of oil a week from this leak. Don't know if this will help but it is another area to look at. Just unplug your oil pressure switch and see if there is oil in the mating side of your switch if there is, the seal has let loose.

I just finally replaced the oil filter o-rings last week and was feeling optimistic because there wasn't any o-rings in there to begin with! Adding seals where there weren't any before has to fix the leak, I hoped. But, I am still seeing smaller drip puddles in my parking space, less than before though.

Next I am going to try to tackle the oil pan and main seal. Thanks for all the suggestions from everyone. Here's another question before I continue, how much hell am I going to have to go through to get the oil pan off an unlifted XJ? I've heard things like disconnecting the exhaust, removing the starter and even unbolting and lifting the engine. Please say it ain't necessary?

does the term "oil bath" mean anything to you?..it soon will.
here ya go- have fun!
http://www.jeepin.com/features/rearmain/index.asp

Ive been pondering doing this on mine soon....but Im only leaking a little...might just wait till the flood.