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Unread 10-16-2003, 12:40 AM   #1
RockinXJ
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Rear Main Seal Replacement

Ok, so last Friday I decide I'm going to replace my rear main seal to get my XJ to stop leaking oil. I bought the rear main seal, a new oil pan seal, and some new oil to go in after all is complete. I took out 28 bolts to remove the oil pan, removed the rib plate that ties all of the main bearing caps together, removed the rear main bearing cap, removed and replaced the lower portion of the seal in the bearing cap, and I noticed something while removing the upper portion of the seal from the block. The area that the rear main seal contacts on the crankshaft was not smooth like it should be. I assume it should be as smooth as glass like the rest of the crankshaft, but the contact area has minute ripples in it just where the seal touches. Is this the way it should be? After properly re-installing everything and getting the bolts torqued to specs, I took it for a test drive and all was good except for a minor drip compared to what it was doing. I am thinking it is still leaking due to the ripple in the contact surface. What would cause such a thing?

Also, while I was under the Jeep turning wrenches, I noticed I had a transmission fluid leak where the metal strap holds the two lines to the bottom of the transmission near the starter. I further investigated the leak by removing the strap, and low and behold, the strap had worn a hole in the side of the tranny line after 192,400 miles. My fix was to cut about an inch out of each of the two lines and replace the setion removed with a compression fitting. After about 400 miles on it, it is not leaking, and still sending transmission fluid to the cooler up front as it should.

If you have any input on either subject, please feel free to post.

Thanks

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Unread 10-16-2003, 10:46 AM   #2
Tumbleweed
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I'm getting ready to do the same job, as my 91 with 110,000 is seaping and it hits the exhaust. so I read your post with interest.

No, the crank journal should be smooth everywhere, the bearing needs a smooth surface and the rubber seal won't follow a rough surface. Replacing the seal will help but not fix this leak. Unfortunately this can only be cured by taking the crank out and having it cleaned up or replaced. You may find it easier and cheaper to keep replacing the seal when the seaping becomes a full on leak, until you are ready to do a rebuild.

Sorry for the bad news, but that's my understanding of the rubber/ steel sealing concept. If I'm wrong I don't mind being corrected.

The lesson to the rest of us here is that allowing a failed seal to remain in place may end up doing more damage. I just got this XJ and both the front and rear crank seals are seaping, now I'm a little more motivated to get if fixed. I hope I don't find any suprises.

How long would you estimate you spent on the job. 4 hrs? 6?
Also what did you need to do to get the axle low enough for the oil pan to come out. I'll be doing this in my driveway, and could use any input to reduce the time it takes to get in there. I've read my chilton manual and I hope it's not too much of a PITA.

Regards,
Ethan
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Unread 10-16-2003, 12:48 PM   #3
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You'll have to keep changing them only if you use the wrong parts. Getting a plain seal will get you a seal intended for a fresh rebuilt engine with a smooth crank.

The groove happens because the oil makes the seal turn hard as a rock. This in turn causes the seal to groove the crank seal surface. There is supposed to be a problem solver type rear main seal that has a double lip that fixes leaks due to grooves. The second lip makes contact with the fresh ungrooved surface of the crank, if I'm not mistaken it also has a tad more depth for a better fit against a now smaller crank diameter.

Also those with 3" or more of lift should have no problem removing the oilpan due to axle clearance. That's the distance all the manuals usually tell you to drop the front axle.

Mark

Last edited by XJMark; 10-16-2003 at 12:57 PM..
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Unread 10-16-2003, 02:19 PM   #4
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When I did the job on my unlifted '89, disconnecting the swaybar links let the axle drop far enough to get the pan off. (What a splendid time that would be to install quick disconnects.) I pushed the axle down just a bit more with a bottle jack. The PITA part of the job on mine was getting the top half of the seal out of the block. Never could budge it, and finally decided it was best to leave it alone rather than risk breaking/clobbering it. Replacing just the lower half bought me a year of practically drip-free driving.

LarryJ
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Unread 10-16-2003, 11:30 PM   #5
RockinXJ
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Quote:
Originally Posted by Tumbleweed

How long would you estimate you spent on the job. 4 hrs? 6?
Also what did you need to do to get the axle low enough for the oil pan to come out. I'll be doing this in my driveway, and could use any input to reduce the time it takes to get in there. I've read my chilton manual and I hope it's not too much of a PITA.

Regards,
Ethan
I'd say probably about 8 hours, but I was working slowly, and I had to repair the tranny lines while I was underneath it, so take that as you will. Basically, you drain the oil, drop the oil pan, remove the rib plate bolted to the main bearing caps, remove the rear main bearing, drive the upper part out with a punch, and pull the lower part out with a small flat bladed screwdriver and some needle nose pliers.

The most time consuming part was removing the oil pan. I have a 3" lift with adj. LCA's that let the axle droop enough to pull the pan out. I had jack stands under the "frame" too.
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Unread 10-16-2003, 11:32 PM   #6
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Quote:
Originally Posted by XJMark
You'll have to keep changing them only if you use the wrong parts. Getting a plain seal will get you a seal intended for a fresh rebuilt engine with a smooth crank.

The groove happens because the oil makes the seal turn hard as a rock. This in turn causes the seal to groove the crank seal surface. There is supposed to be a problem solver type rear main seal that has a double lip that fixes leaks due to grooves. The second lip makes contact with the fresh ungrooved surface of the crank, if I'm not mistaken it also has a tad more depth for a better fit against a now smaller crank diameter.


Mark
I am interested in this main seal. Do you have any idea where I can get one? I wouldn't mind doing it again if it will stop my leak.
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Unread 10-17-2003, 01:47 AM   #7
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Stealership for sure (not that big a price difference). The double lip is designed for replacing the stock hard as a rock single lip that caused the leak. It seals in two places that are offset from the original seal area.

You may be able to get it at NAPA or another well stocked outlet also. It will be listed as a "supersedes part#nnnn" probably under the Chicago rawhide or Fel-Pro brands.

Mark
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Unread 10-17-2003, 06:41 AM   #8
Tumbleweed
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Great info, thanks. I heard of the double lip seal but wasn't sure what it was for.
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Unread 10-18-2003, 04:11 PM   #9
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i know exactly what you mean about it seeping out onto the exhaust, i was smokin so bad but i thought it was kinda funny, this is the only mod that i didnt have time for seeing as how i go to school, job and football so i took it into the shop, so its actually in there right now, its coming out tomorrow. im gunna ask the mechanic about the work done tho so i can get a good idea for it. hes actually fixing my door and a relay in my heater too. so my xj is gunna be ship shape
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Unread 05-26-2010, 07:01 PM   #10
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looks different...

I am working on my '96 XJ and while doing the RMS I found a plate attached to all the crank bearing caps.

Can I remove it without messing up the other caps??

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Unread 05-26-2010, 08:44 PM   #11
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Nice thread revival

Wanna come by Golden and show me a thing or two about replacing mine?
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Unread 05-27-2010, 08:29 AM   #12
xjbrian
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Yes. You have to remove it. I did mine a couple of months ago.
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Unread 12-06-2011, 09:18 PM   #13
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This is my first step towards reviving my 2001 4.0 liter manual. I have numerous issues, but this is the easiest and first one to take care of, in my mind. Thanks to all who have provided information in this thread over the years.

All I need now are part numbers for:
Mopar OEM double lipped rear main seals
oil pan gasket for 2001 TJ
special OEM gasket sealant for oil pan gasket.
Thanks,

Mike
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Unread 12-07-2011, 08:54 PM   #14
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Quote:
Originally Posted by logem View Post
All I need now are part numbers for:
Mopar OEM double lipped rear main seals
Not sure the part number but its probably the same one as the '00 and '01 XJs which is different than the earlier ones. I found that for this particular seal it was cheaper to get the Mopar seal from the dealer than the Felpro seal was at Oreilly's.
Quote:
oil pan gasket for 2001 TJ
Felpro one-piece seal at any parts store
Quote:
special OEM gasket sealant for oil pan gasket.
Not sure on that one as I used RTV instead. It worked fine for me.
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