So I noticed an oil leak on my 95 Jeep Cherokee 4.0L. Its a small leak ( I assume) as I have never had a problem with my oil pressure fluctuating or having to add oil due to low volume. I had my Jeep at the mechanics to check it out and he said it could be the rear main seal and to fix it, he would have to remove the tranny, etc and it would be $400-500 dollars. He also said that if it wasnt a bad leak he could add some sort of "quick seal" ( not sure of the product he mentioned) that might fix the problem. He said the product could "regenerate" the seal and stop the leak. I have heard problems about these kind of products. If it can clog a leak what else could it clog up, you know? So, I'm at a crossroads as to what to do. I've had the Jeep for about 5 years and never have had an issue with the oil leak. I just got tired of doing maint. and seeing the underbody covered in oil. Thanks!

 

Find a new mechanic.

There are quite a few write ups to perform the repair. It's simple and cheap. Price the seal and a oil pan gasket at your local auto parts store. That is how much it will cost you do do the repair. Time it with your next oil change.

 

i've never thought much of these "wonder products". If you could apply it right at the problem area they would be great but they go everywhere. Anyway, From what I have read here I believe the rear main seal is constructed in two pieces. This allows you to replace it without removing the tranny. Your mechanic may be trying to screw you but lets give him the benefit of the doubt and say he just doesn't realize this about the 4.0.

Was reading this thread earlier today https://www.cherokeeforum.com/f2/how...n-seal-123479/

 

The transmission does not need to be removed to replace the RMS. First step in determining an oil leak is to take a bottle or two of degreaser (simple green works well for this) and go to the local car wash and clean the engine well. Once it's all nice and pretty you can drive for a day or two and then look to determine exactly where the oil is coming from. Start at the top and work your way down as oil coming from the back of the valve cover or the oil filter adapter can sometimes look like it's coming from the RMS.

 

Well I talked to the mechanic again and stated that the tranny shouldnt have to be removed in order to replace the RMS. He said it was whether or not the tranny was in 1 or 2 pieces. He said it varied by engine type and I had the one piece so the tranny would have to be removed. He went on to say that I might have several leaks. He knew for sure that the gasket and o-ring behind the oil filter was leaking and he was going to replace both. He then suggested that I drive it for a couple of days and bring it back to recheck the leak. He couldnt tell for sure if that was the only leak and it was a cheap place to start. He said it might be the only leak but wouldnt know until it was driven after replacing the gasket and o-ring on the oil filter thingy. Thoughts? I tried to explain things the best I could, sorry!

 

If you have a basic set of tools and don't have a fear of dirt/grease then please perform the work yourself. Such basic things can be completed with little effort and the help of this great community.

http://jeep-xj.info/HowtoRearMain.htm

The dealer can provide the oil filter adapter o-rings. Oil pan gasket and and rear main seal is all that is needed for that repair.

Even if you had to buy a basic set of tools you could do this for under $100.00. As stated before, time the repairs with your next oil change so you don't drain good oil.

 

Common causes of oil leaks on the 4.0

1) Valve cover
2) Oil filter adapter
3) Distributor (not super common)
4) CCV system
5) Rear main seal

Clean the engine, determine exactly where the leaks are coming from then read on here or shoot me a PM if your search skills aren't great and I will like you to writeups on how to fix all the possible leaks. No need for a mechanic unless you don't have the tools/basic know how to do automotive repairs.

Jeep Deep linked you to the RMS repair writeup so that's one place to take a good look

 

can you link me the CCV and valve cover? Thanks so much

 

I replaced the RMS in my 92 XJ with the 4.0, the oil pan not the easiest thing to get out cuz the axle is in the way but once u find the right angle it comes out, i found it easier to loosen the main bearing caps and let the crank drop a little bit then soap up the top half of the RMS and slide it in, but just make sure u torque the mains back up to the right specs

 

Here's some good CCV info
https://www.cherokeeforum.com/f2/2-p...-cover-103745/

Once you get the CCV components apart it's just a matter of cleaning them up and reinstalling.

Valve cover gasket writeup:
https://www.cherokeeforum.com/f51/va...writeup-46054/

 

Your mechanic is dead wrong. There are a bunch of write ups on how to do a RMS, and even a video. Its also simple to replace your oil adapter O rings and write ups on that too.

Sounds like your mechanic has gone fishing.

 

This mechanic is full of crap. ALL 4.0s have 2 piece main seals. Don't go there anymore. You've got eyes. The drip could very well be the oil filter adapter seals. Look at the back of the valve cover. All the leaks will drip from the rear main seal area for one good reason: The engine sits nose-up and the RMS area is the lowest point.

 

Hear is the best write-up for CCV elbows and grommets. I'd do the valve cover gasket and those at the same time.
http://www.jeepforum.com/forum/f310/...ite-up-733669/

As far as a "quick seal" product, DONT!! Get that rear main seal changed (which is a 2 piece seal - the tranny does not need to be dropped, just the oil pan to get to it). I had a rear main seal leak when I first got my xj and put the lucas additive that supposedly stops the rear main seal leak. Well, when I changed my oil after that, it came out bubbly and foamy and nasty. And you don't want that going on in your crankcase. Avoid those "temporary solutions" and get it changed by a different mechanic if you can't do it yourself (although I suggest learning how to and giving it a go yourself )

 

I want to thank everyone for their input and advice. I will see if I can do the RMS myself with the help of a friend, thanks again everyone! will keep you posted

 

How about VERIFYING it's the RMS first?