My 95 Grand Cherokee (Inline 6, 4.0L, 112K miles) has an oil leak that looks like it's coming from inside where the flywheel is (near the oil pump). Is this the rear main seal?

I think so. That seems to be where I noticed leaking back around 90 to 100K and eventually got the rear seal replaced. It was not a fast leak so topping off on a regular basis is what I did for awhile. Got it replaced and that was that for awhile. It's leaking again now at 180K, but unless it gets worse than topping off with say quarter of a quart each week, I'm not going to worry over it. I can buy a lot of oil for the cost.

Another leak that I've seen on these postings and I've had is the valve cover. Standing in front and looking along the right side of the cover oil will leak out into fairly small puddle(s) top side of intake manifold, kinda like beneath the fuel line. That's not overly expensive to have the cover taken off and resealed. That one I should have probably done myself.

Also, check around the oil adapter to which your oil filter threads onto. I've been plagued with that one. Seems the adapter has a seal (o-ring I think) that will leak. I've had that redone a couple of times. Again not overly expensive, and probably could have done myself if I had a little more shop savvy, or found this forum earlier to ask how.

porkmclain,

Thanks for the response. I would imagine that this is the only route for oil to get into the crankcase. My valve cover gasket is leaking also, but that is *another* problem I have to fix. Ironically, I have also replaced the oil adaptor ring in the past when it was leaking.

Again, thanks for your input.

i have the same problem and replaced the main seal. my problem is i use synthetic oil (mobil) which will always get past any seal. seals work because of friction. if you reduce the friction (oil type, loss of resilience, damaged seal) it will leak, always.

Thanks for the thought. I use Valvoline MaxLife every 3000 miles.

i have the same problem and replaced the main seal. my problem is i use synthetic oil (mobil) which will always get past any seal. seals work because of friction. if you reduce the friction (oil type, loss of resilience, damaged seal) it will leak, always.

I'm told you should try the synthetic blend. It doesn't leak like pure synthetic.

How much for the rear seal fix?

Thanks
Bob

The estimate I got from the dealer was $425 for an oil pump replacement. It's about the same amount of work as doing the rear main. So I would think the cost would be similar. If you want to try it your self check this out.
http://www.jeepsunlimited.com/forums/showthread.php?s=&threadid=509447
Good luck.
ByronP

I'm told you should try the synthetic blend. It doesn't leak like pure synthetic..............
my reply
How much for the rear seal fix?
the rear seal was covered under the warranty. I just had my transmission repaired (torque converter took a dump) and the rear main seal was not leaking. i paid 1100 for the trans repair which included a new and better trans cooler. the labor for the rearmain seal wouldbe about 500 i think. it is a two piece seal if you didn't know.BTW, stock trans coolers are crap. If your trans cooler lines have a check valve in line, you should remove it. I only have 80k miles on my jeep (5.2L 4x4) but I tow an 8000lb boat/trailer. I have about 4000 miles of towing on the transmission, so the failure was expected. I have a lift on my jeep and c rated tires. don't try towing this much without suspension and tire upgrades... and $1100 ready for the trans repair. I think 2000 miles through the mountains is what killed my tranny. gas mileage average for trip to canada and back was 8.9 mpg. incidentally, my boss' name is wolfram.
Thanks
Bob
blahblahwhydoesitsaymymessageistooshort?

If your Mech inclined you can do this. Time consuming,Jeep is one of the easier ones. The Motors with a 1 piece seal most have to remove the Motor.
When trying to locate a oil leak wipe down the Motor, start it up and look for oil . Sometimes you have to crawl underneath make sure you use Jack stands. Ive seen oil leals from Intake Manifolds and Valve Covers looks like they are comming from the rear main. Asfor Synthetic Ive run 50,000 On my XJ 4.0 with over 150,000 MI. and 40,000 on my ZJ 5.2 with a 115,000 MI. with no problem yet!

If your looking to replace the rear main on a 4.0, you'll spend moretime removing and cleaning the oil pan, than doing the actual replacement of the seal. Look at the XJ portion of this forum, there is a thread about replacing the rear seal. Not hard at all, just a little time consuming.

if u need instructions on replacing the RMS email me Joe dksob81@hotmail.com also include he engine size.

The estimate I got from the dealer was $425 for an oil pump replacement. It's about the same amount of work as doing the rear main. So I would think the cost would be similar. If you want to try it your self check this out.
http://www.jeepsunlimited.com/forums/showthread.php?s=&threadid=509447
Good luck.
ByronP

Thanks ByronP
I'll review it and see if I'm up to it!

Thanks for the info. Hope your boss is making us Wolfram's proud!?

Thanks everyone for the advice. I think I better do a good analysis first.
I'll wash it down and see if I can pinpoint my problem. I'll get back in a while.

Thanks again.
Bob