Oil Leak Question

1994 XJ Sport, 4.0L I6, AW4, 4x2, 4 door.

I have a question, and, yes, I have searched. I have an oil leak (at the bottom, near the front of the transmission, and just behind the oil pan...rear main area), and I'm trying to narrow it down. Recently, I found that my valve cover gasket was leaking a lot at the rear. Tightening didn't do much good, so I put on a new one. It leaked for awhile until I tightened it up some more. Now, before I tightened it, you could reach your hand back behind the engine and feel oil. I've run it awhile, and now if I reach back there, I just feel a slight oily residue. I always thought that it would just be whatever is left of what I cleaned up. However, there is still oil dripping from the transmission. I figured that maybe there was just oil left from wherever down there, and it was just dripping out. I started to worry when it didn't really stop. It's leaking down onto the exhaust, and is smoking...not a lot, but I'm worried that it could turn into a fire hazard if it gets any worse. I'm unsure about the valve cover. Should it have this residue? Or perhaps the engine is just burning off whatever oil is leaking and leaving the residue like the exhaust is?

Also, I have considered the possibility of the rear main and the oil filter leaking. There isn't really any oil around the area of the filter, so I've focused on the rear main. However, I'm not really sure what to look for. I went and cleaned the front of the transmission so that I could get a better look. Basically, there was a bunch of crud caked around where the transmission connects to the engine. After I cleaned all of the mud and everything, I saw that there was a gap between the oil pan (at the back where there's a little half-moon carved into it for the shaft to connect to the torque converter) and the transmission. I cranked the XJ up, and I could see the shaft spinning. No oil came out. My question is: am I supposed to be able to see that? I was only concerned because there was a lot of crud in the area, and I didn't know if there was supposed to be any room for crud to get up there. But, if the rear main was leaking, would it immediately visible? I ran the car for about 10 minutes, and nothing came out.

My appologies if I'm asking stupid questions. I'm still trying to familiarize myself with this car and engines period. I'm trying to do all the maintenance myself because I have a very, very low budget. It's a great car, though, but I've got about 140,000, and am having to deal with all of the little things that go wrong (leaks, squeaks, etc...). Engine runs very strong, though. I appreciate any help that is offered.

One picture is worth a thousand words.
There should be a cover between the oil pan and the trany but that wouln't stop a rear main seal leak.

First things first - give the area a good cleaning, take a short drive, and check again. You'd be surprised how many leaks can "false" in that area and mislead you.

Possible leaks -
If it's all over the transmission and not on the engine, then I'd suspect either the rear main or the transmission input seal. Depends on what's leaking...

If it's on the engine and transmission, I'd suspect either valve cover or oil filter mount. If it's above the oil filter mount, I'd suspect either (the oil filter mount carries oil under pressure, which can spray - check the spray patter) and if its' below, it's definitely the oil filter mount. If the oil doesn't look "sprayed," I'd suspect the valve cover, since it's just oil under gravity.

But first, clean the engine and take a short drive, so you can see the leak afresh and get a better idea what's going on...

5-90

langer1 said:

One picture is worth a thousand words.
There should be a cover between the oil pan and the trany but that wouln't stop a rear main seal leak.

Click to expand...

There is a cover, however...it doesn't completely meet with the tranny.

I will be able to get a picture tomorrow.

Right now I think I'm going to go drive it around some and then check.

EDIT: Ok, I drove it about 2 miles or so...enough for it to get to normal engine temp and stay there. Well, some of the crud that was in that gap came out (I'm guessing because I took off the outer layer...it has room to). No wetness in that area. No oil on the tranny. On the engine, around the top of the oil pan on the right side (when facing the car), there is some wetness. I suspect that it's coming from that area. Could that be the oil pan gasket itself? Or could it be something else leaking?

That cover on the lower bellhousing is an "inspection cover" - and it's meant to keep crap out of the bellhousing. There's no seal or gasket - nor any need for one. It's a "dry" cover, and doesn't seal anything.

If you've got fluid coming from behind there, even odds it's the rear main or the transmission input seal.

5-90

Nope, no oil coming from around there. I think the leak is either the oil pan gasket or the valve cover gasket. I'll look at it more today.

Check the oil filter adapter area. Just replaced the o-rings on mine a while back.

I just took mine in today to get it inspected and do some of my own work on it while it was up on the lift. Few months ago I found that the timing cover bolts had backed out and were being held in place by the harmonic balancer so I tightened them back up, it was one of those things I could not see till I had the water pump off and the front opened up, front skid and splash bib were in the way from underneath. Today up on thelift I noticed that the oil pan was wet, water and oil. Checked the oil pan bolts and several were loose, snugged them back up but it's going up on the lift again tomorrow, I was in a hurry so did not do a proper job, will remedy that in the morning.
Right now I'm putting winter blades on all the jeeps and the wifes car, replacing the headlight switch on one of the TJ's and need to pull my resistor pack on my XJ and replace the thermal fuse I just picked up even though I have a new fuse pack coming in on monday from the dodge dealer who does jeeps..

I recently replaced conrod bearings and rear main seal. I also included a new valve cover gasket. That was on my 92 which was using about 1 qt/week. It is totally dry now and I have been tightening the valve cover bolts about once a week now.

My 90 leaked too so I thought I would check the valve cover bolts. Surprise! They were really loose. After tightening them up and keeping them tight my leaks have nearly stoped. The only significant leak are from the transmission coolant lines in front of the engine around the radiator.