Jeep Rear Main Seal Leak

[jeepman3071]

I've replaced several Jeep 4.0L rear main seals over the years. It isn't a great design to begin with. I replaced the one in my Wrangler about 2 years ago. It was leaking enough where it was dripping on the ground, and coating the transmission and skid plate while driving. I could see a slight groove in the crank from the seal. When I replaced it, the leak was 90% fixed, but still weeped a tiny bit where it was wet around that area. I figured it was due to the groove I saw in the crank, and was happy that the leak was mostly fixed.

Oddly enough, I ran Maxlife synthetic 5w30 and after 3000 miles or so I went under the Jeep for something else and noticed the RMS was completely dry, no weeping at all, so I've just continued to run that oil and everything seems dry so far.

 

[fedvet]

On my ‘96 Cherokee 4.0L, I replaced the RMS myself about 10 years ago. It’s started to leak again this past year, getting much worse this past month.

I decided to take it to a local mechanic shop which I really like and have them replace it, which they did last week. They used a Mahle oil pan gasket and RMS. You don’t have to pull the transmission to replace it, the pan comes off (with struggle) and you take the rear bearing cap off and you can get to the RMS.

Well unfortunately it was still leaking, a bit better but still leaking. I took it on a long trip this weekend and then dropped it off at the shop this morning. They just called back and they’ve already got the whole transmission out to get a better look at it and sent me these pics. They’re going to replace the seal again, but this time with OEM seals. I told them to replace the oil pan too while they’re at it.

The mechanic is thinking if the crankshaft might have some wear, maybe it’s not sealing so good? What do you guys think? I really like this shop. They seem really honest and they go the extra mile so far, with other stuff too.

Second pic is the leak after it was replaced the first time. 3rd pic was before they worked on it.

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I’m thinking I’d let the shop keep digging. They sound honest and competent.

 

[andyd]

I used to be on a Jeep forum. We had a saying : If your jeep doesn't leak oil , it is probably empty

 

[Nick1994]

I used to be on a Jeep forum. We had a saying : If your jeep doesn't leak oil , it is probably empty

Fingers crossed, we are still dry!