Hello,

This is my first post, but searching this forum has gotten me some help in times past. Unfortunately, not in this case.

I have a 1992 Cherokee Sport (4.0 liter, 4wd) that seems to lose about 1/4 of oil every 6 weeks. The problem is, for the past few months, I've had no spots underneath my Jeep that I can see. This morning I was doing an oil change on it and my wife's car and I noticed one little oil spot underneath my front differential. I looked around it and there was, what looked like, oil all around it. About 5 months ago, I had to take a wire brush to it and scrape all the sludge off of it. But I've never really found anything leaking out of it anywhere.

All the usual culprits don't seem to be a problem here. The valve cover gasket has been replaced within the last year. There's no leaks around the oil filter. The pan gasket is still pretty sound. I'd think I was burning oil, but there's no black smoke coming out of my tailpipe. I'm just not sure how to troubleshoot this. I don't know much about differentials, so I don't know if its even possible for oil to be leaking from there. But my thought was that my having brushed the sludge off removed what was serving as a sludge-seal keeping oil in.

My comfort level working on it is moderate. I've replaced a number of things on it and my wife's car, so I'm not afraid to get my hands dirty. I'm just not sure what to check at this point. Anybody have any advice? Please don't feel hesitant to point out the obvious things.

 

Front diff RR is simple.. unbolt the cover, clean it real good spray it and inside the diff with brake cleaner. Get some black RTV put it around the diff where the holes are for the bolts and bolt the cover back on. and fill.

 

Before you fill it up let the RTV set and cure.If ya don't you could end up with a leaky seal.

 

Ok i read the post 3 times and maybe im missing somthing! How do you get from losing oil from motor to checking diff in looking for leak from motor? your diff would hav nothing to do with losing oil in motor! any ways it probably a main seal or your buning oil (oil burns blue and if your burning oil unless its sever you wont see it, running rich burns black, white smoke is water).

do your diff seal, couldnt hurt. but if there is an oil film on top of your diff then your brob lem is elswhere

 

I don't think you're missing anything, this is my lack of knowledge. I didn't think the diff would leaking motor oil, but its the only place I've seen any sort of oil dripping from. It was totally a guess and looks like it was way wrong.

So I'm not familiar enough with what the main seal is, so where would I check this? I've seen mention on this forum about the main seals being a pain the butt to replace, but doable as long as I expect a mess. Is there an online resource that goes over how to do that repair?

If I am burning oil, what does that mean for my engine? Is it on it's last legs? What kind of repair(s) would I be looking at needing? It's getting close to 250k miles on it. Thanks again for the responses.

 

Bump.

 

If you crawl under the jeep and look where the transmission meets the motor you can see if you see any oil. How to find the spot is simple. find the rear drive shaft, follow it till it meets the transfer case, then infront of that is the transmission, then follow that to the motor and you will see where the transmission and motor meet up. Look there for any oil and see if there is any oil there. This will be between the transmission and oil pan more or less. Another good way to find it is stop buy the car wash and rinse the underneath really well to clean all the oil off then drive home and let it sit a few and then look.

 

If your motor is leaking/using oil and your front diff has oil on/dripping under it I would say you are leaking oil from your engine which is in turn dripping onto your diff and then to the ground. That would explain why it may appear to be coming from the diff. Now where the oil is leaking from, i dont know, but I would look above the diff and see if there are any leaks in the general area above the diff.

 

eh.. did you check everything? Here's the common places the motor leaks- rear of valve cover - oil pan- oil filter housing- some times the front crank seal. about the front diff. idk is it leaking from the axle seals or pinion seal? theres only 4 things on the axle that would leak