Hey Guys,
I took my 1996 xj with a 4.0 and AW4 to a trusted mechanic about a month and half ago to have the rear main seal and oil filter adapter seals replaced. It was awesome having a jeep that didn't leak until it started again 2 weeks later.It was weird how it would leak too. I would come out to one or two drops and other times to a big puddle about the size of a softball.

Took it back to the shop and he fixed it again. Great no leak again! Fast forward 3 weeks to the present and its started leaking. This time it's more consistent and leaves a baseball size puddle over night with an active drip while the engine is on.

I have verified that the rear main is leaking by using some oil dye and a blacklight. I do not see oil coming from anywhere else on the motor.I called up the mechanic and he doesnt know why it would be leaking again but will replace it for the 3rd time now.

Do you guys have any insight on what might be the issue here? He said the motor looks fine and that nothing is out of tolerance. Is there a "best" rear main seal out there? He said he used a generic seal the parts store had because he couldn't find any felpros. I feel bad asking him to do this a 3rd time, but also dont want oil all over the place so I'm going to order the seal and bring it in.
If you guys have part numbers for RMS that has worked best in your experience that would be greatly appreciated.

I see BS 40612 for the FlePro.

Thank you in advanced. This thing is becoming a headache.

 

I wonder if your mechanic is doing the job correctly. Is he replacing the rear main seal every time or just the oil pan gasket? I’m pretty sure it’s either an incorrectly placed rear main seal, incorrectly sealed oil pan gasket (no RTV around rear main) or more likely a warped oil pan. Good luck at least your mechanic is honoring his work by re-doing it.

 

I used a Felpro rear main seal on my 96. Make sure the back of the valve cover isn't leaking as well as the back of the oil pan gasket. I used FelPro for all of them. The oil pan also gets a small amount of rtv front and rear.

 

I want to believe he is doing it correctly. He replaced the rear main seal both times as far as I know. He said he put RTV as well. Maybe it was nicked each time. I think the felpro is the only gasket that comes with the paper guide so that could be it I guess.

I checked the valve cover and oil pan gasket. Passenger side of the motor is completely dry around distributor, oil filter, and oil pressure sensor.

Here is a picture of the leak with the dye and black light. This was maybe 20 seconds after turning it on.

 

Scoring or grooves on the crankshaft?

 

When the mechanic had it all apart he said nothing was scored or grooved.

 

Make sure he uses the genuine Felpro seal the next time.
There's a lot of junk and fakes coming from China on almost every auto part.

 

I realized that the average age of the mechanics at the shop I use are anywhere from 5 to 10 years older than my Jeep.
I downloaded the FSM on to a USB stick and keep it on the console when I take my Jeep in to the shop.
I let them know about it and they have used it and thanked me for it. After all, I have never seen another Jeep at the shop in the 4 years I have been doing business with them.
It may be a case where your mechanic is using general knowledge and not specific referenced information.
I had the rear main seal and oil pan gasket replaced. I provided the Fel-Pro products. Two years and dry as a bone in the sun.
Can't hurt, maybe will help....
Hope it does.

 

Well, 2 things come to mind.

1. You're supposed to use Loctite 518 (or equivalent) on the bearing cap to seal the cap. Here's the pic from the FSM. Perhaps they didn't?



2. Perhaps it's the oil pan gasket that's leaking.

 

Yup, If the rear main journal of the crankshaft is not damaged and allowing oil to pass through the seal, there has to be an installation error. You might want to ask this "mechanic" if they are applying RTV to the rear main cap and also the front and rear corners of the oil pan gasket sealing surface. Or you could just do the job yourself, it's pretty straight forward.






https://www.rockauto.com/en/moreinfo...80314&jsn=1082

 

Thanks guys,
I will buy a tube of the 518 locktite to bring as well and show him the reference material above. It's possible he is not familiar with the specifics that the jeep requires. Normally I work on my car, but my wife and I just had a baby so I needed it fixed. Plus I'm not being charged for the redos.

 

Make sure to bring him a big box of donuts and coffee for the redos!

 

Good Idea hahaha

 

The leak is fixed as of February. I gave him the diagrams above with new felpro gaskets and the correct sealant. The jeep has been dry as a bone. Thanks for the help.

 

It was the donuts that fixed it.