Rear main seal/ Oil pan gasket - Page 2 - JeepForum.com

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post #16 of 24 Old 02-17-2014, 05:29 PM
bpounds
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It's a long way from the rear main cap to the transmission input bearing, and the trans shaft is slender. Pretty easy to get a little flex out of that. Just because you haven't found it necessary, doesn't mean it can't help.


Bill
Dodge did not build my Jeep.
1988 Wrangler,4.2L I-6, Howell EFI JP-1,GM HEI Ign, 5 Speed Peugeot, Zone 2.5" lift + 1/2" booms, BFG 31 x 10.5, Bestop.
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post #17 of 24 Old 02-17-2014, 08:38 PM
plym49
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Quote:
Originally Posted by bpounds View Post
It's a long way from the rear main cap to the transmission input bearing, and the trans shaft is slender. Pretty easy to get a little flex out of that. Just because you haven't found it necessary, doesn't mean it can't help.
Even if the crank does hang down a few thousandths, the seal does not grab the crank (the crank turns, the seal doesn't). The seal grabs the block and that is the connection you break as you punch the seal around to remove it.

No offense, but trying to get the crank to hang down in the way described sounds to me like drivers who tap their brakes in the middle of a turn, but do not change the speed of the vehicle at all. The brake tap is for their head, not anything else since the vehicle speed is unchanged.

Of course, if the crank is out it is crazy easy to get the seal out.
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post #18 of 24 Old 02-19-2014, 10:49 PM
NonRubicon
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plym49 -

I understand the skepticism. However, the crankshaft does put pressure on the seal. Loosening the bearing caps for even a few millimeters of droop will relieve this additional pressure and make it easier to break the seal loose from the groove and extract it. I tested this back and forth myself when the seal had broken loose, just to make sure what I was experiencing wasn't just in my head. Wanted to be sure I didn't fool myself in to thinking it actually worked like I expected it would, when all I may have done was "loosen the jar lid without realizing it".

After I loosened the caps enough, I was able to finally break the seal free, and with much less force than I was trying before. Thought "Hmm... might be in my head" (along the lines of your suspicions). So I tightened the caps back up to spec - now the seal was in there tight again and only the metal core would budge when I tried to drive the seal. Hmmm... Loosened the caps again and the seal was easily driven again. Loosening the caps had a direct effect on the pressure placed on the seal, and the friction the seal experienced in the groove. It can make a difference in ease of extraction of the old seal.

Is it necessary to loosen the other caps to replace the RMS? Certainly not, or it would be part of standard procedure. But it can make it easier all for the cost of turning a few more bolts. And considering all the freakin bolts on the oil pan, what's a few more bolts?

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post #19 of 24 Old 02-20-2014, 11:12 AM
bpounds
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It's clear to me why it would help. Having said that, there is always some risk involved when you disturb well run-in bearing caps. Try doing it the simple way first.

Bill
Dodge did not build my Jeep.
1988 Wrangler,4.2L I-6, Howell EFI JP-1,GM HEI Ign, 5 Speed Peugeot, Zone 2.5" lift + 1/2" booms, BFG 31 x 10.5, Bestop.
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post #20 of 24 Old 02-20-2014, 12:22 PM
kahanabob
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i would think it would help more when installing the new seal. from what i have read getting the new seal in is sometimes not easy and easily damaged. to get the old one out i would get a piece of PVC pipe the same or close diameter of the seal and cut a thin slice off then cut the thin slice in half and use that to push out the old seal until you can get on it and pull it out the rest of the way.
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post #21 of 24 Old 02-23-2014, 08:00 AM
sptrmike
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Quote:
Originally Posted by NonRubicon View Post
plym49 -

I understand the skepticism. However, the crankshaft does put pressure on the seal. Loosening the bearing caps for even a few millimeters of droop will relieve this additional pressure and make it easier to break the seal loose from the groove and extract it. I tested this back and forth myself when the seal had broken loose, just to make sure what I was experiencing wasn't just in my head. Wanted to be sure I didn't fool myself in to thinking it actually worked like I expected it would, when all I may have done was "loosen the jar lid without realizing it".

After I loosened the caps enough, I was able to finally break the seal free, and with much less force than I was trying before. Thought "Hmm... might be in my head" (along the lines of your suspicions). So I tightened the caps back up to spec - now the seal was in there tight again and only the metal core would budge when I tried to drive the seal. Hmmm... Loosened the caps again and the seal was easily driven again. Loosening the caps had a direct effect on the pressure placed on the seal, and the friction the seal experienced in the groove. It can make a difference in ease of extraction of the old seal.

Is it necessary to loosen the other caps to replace the RMS? Certainly not, or it would be part of standard procedure. But it can make it easier all for the cost of turning a few more bolts. And considering all the freakin bolts on the oil pan, what's a few more bolts?

There is no doubt that this works, exspecially when putting new one in. I have only had to loosen the cap closest to the rms though!
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post #22 of 24 Old 03-31-2014, 02:35 PM Thread Starter
Cobra21
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Ended up having a local shop handle the rear main seal as well as the seal where the transmission fluid was dripping. Doubt we could have done the transmission repair at home, so good decision on our part. Also the shop went over the vacuum lines. Apparently we had a few that were not correct after swapping in the Weber carb.

Now onto looking at putting a lift kit installed.
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post #23 of 24 Old 03-31-2014, 06:17 PM
gotswap
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Quote:
Originally Posted by Cobra21 View Post
Ended up having a local shop handle the rear main seal as well as the seal where the transmission fluid was dripping. Doubt we could have done the transmission repair at home, so good decision on our part. Also the shop went over the vacuum lines. Apparently we had a few that were not correct after swapping in the Weber carb.

Now onto looking at putting a lift kit installed.
That is weird, you only need a few vacuum lines after the nutter.
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post #24 of 24 Old 04-19-2014, 04:41 PM
Loosescrew79
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Great info on here. I just purchased a 91 YJ with an SOA lift and a leaky RMS. I am going to tackle this issue next weekend. I have plenty of room underneath and hope it goes smoothly.
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