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Unread 02-15-2014, 03:34 PM   #1
Cobra21
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1989 YJ Wrangler 
 
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Rear main seal/ Oil pan gasket

Have an oil drip and looks like its coming from the rear main and also from the front of the oil pan. Trying to decide weather or not to pay a guy to do it or do it myself, with help of course. I know its a long and dirty job but don't really want to pay a guy 350 to do it. I have dropped the gas tank and replaced the fuel sender unit. Is it any harder than that? Also are there any tips or tricks for doing a job like this? Thanks

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Unread 02-15-2014, 04:19 PM   #2
92Islander
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rear main 89 yj

Good write up here:
http://www.lsjc.org/board/showthread...Rear-Main-Seal
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Unread 02-15-2014, 06:32 PM   #3
deathtrap
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$350 is a smokin deal. just sayin.
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Unread 02-15-2014, 08:43 PM   #4
Xzero117
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Quote:
Originally Posted by Cobra21 View Post
Have an oil drip and looks like its coming from the rear main and also from the front of the oil pan. Trying to decide weather or not to pay a guy to do it or do it myself, with help of course. I know its a long and dirty job but don't really want to pay a guy 350 to do it. I have dropped the gas tank and replaced the fuel sender unit. Is it any harder than that? Also are there any tips or tricks for doing a job like this? Thanks
agreed 350 for a guaranteed job that wont leak a drop of oil sounds like a steal
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Unread 02-15-2014, 08:46 PM   #5
gotswap
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350 to me seems like a ton of money to do the rear main.....maybe if they were planning on pulling the tranny but not for just an oil pan drop
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Unread 02-15-2014, 10:33 PM   #6
NonRubicon
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Quote:
Originally Posted by Cobra21 View Post
Have an oil drip and looks like its coming from the rear main and also from the front of the oil pan. Trying to decide weather or not to pay a guy to do it or do it myself, with help of course. I know its a long and dirty job but don't really want to pay a guy 350 to do it. I have dropped the gas tank and replaced the fuel sender unit. Is it any harder than that? Also are there any tips or tricks for doing a job like this? Thanks

Replacing the RMS:
  1. drain the oil
  2. drop the pan
  3. let the engine block drip dry overnight (optional, but if you don't let it drip clean you will need a face shield or sealing goggles, and you get covered in oil)
  4. remove the rear main bearing cap
  5. drive out the upper rear main seal (maybe requiring loosening other bearing caps along the crankshaft [this is to help relieve pressure on the seal, possibly making it easier to drive out]*)
  6. wrestle the new upper seal into place (being careful not to nick it)
  7. replace the lower rear main seal in the rear main bearing cap, using RTV on end tabs
  8. install the rear main bearing cap/tighten any caps you loosened
  9. install the oil pan with new seal
  10. refill with fresh oil
  11. run the engine and check the new seal for leaks
  12. If the new seal leaks, return to step one.

It may be a PITA to get the upper seal out. It will likely be stuck real good in the groove. You're going to want a small diameter brass punch or rod to get the upper seal out. I used a brass brazing rod, minus the flux on it, and a mallet. You may or may not need to loosen some of the other caps on the crankshaft to get enough clearance to get the old seal out and the new seal in. I had to loosen the next three bearing caps to get enough clearance. Be sure to retorque the caps in proper sequence and to spec.

Be careful when inserting the new seal into the block, you don't want to nick it or bend it. Expect it to be a PITA to get the new seal in, without nicking it. And considering you've never done a RMS before, expect it to take at least twice as long as you think it will.

Personally, I spent more time fighting with the upper seal than I did removing and installing the oil pan.

Last edited by NonRubicon; 02-17-2014 at 12:04 PM.. Reason: clarification* - not clearance, but pressure on the seal
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Unread 02-15-2014, 10:53 PM   #7
gotswap
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Quote:
Originally Posted by NonRubicon View Post

Personally, I spent more time fighting with the upper seal than I did removing and installing the oil pan.
this!!!
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Unread 02-15-2014, 11:15 PM   #8
imstillatwork
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Mine was on a motor stand, upside down and I STILL managed to mangle a new seal.
I would not want to do this job with motor in and no lift. Oh My, no.
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Unread 02-16-2014, 10:38 AM   #9
kahanabob
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check out these.....i am getting ready to do mine too.


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Unread 02-16-2014, 02:23 PM   #10
kahanabob
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Quote:
Originally Posted by imstillatwork View Post
Mine was on a motor stand, upside down and I STILL managed to mangle a new seal.
I would not want to do this job with motor in and no lift. Oh My, no.
i have been skid'ish about doing mine, after reading this i think i will pass. knowing me i will just get into a total goat rope!
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Unread 02-16-2014, 03:49 PM   #11
NonRubicon
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Quote:
Originally Posted by kahanabob View Post
i have been skid'ish about doing mine, after reading this i think i will pass. knowing me i will just get into a total goat rope!
I don't mean to scare anyone away from doing the RMS, it's just my thing to not sugar coat the task for the first-timer. It is totally doable for the home mechanic, who has some experience wrenching, the confidence to take on a repair they've never done before, and tenacity to pull through a job when it isn't going smoothly.

You get a great sense of accomplishment you get that first time you finish a RMS job and the seal doesn't leak.

Of course, if you can find a good deal on having a shop replace it for you, you can save yourself some time and frustration if you aren't really gung-ho about doing repairs yourself.
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Unread 02-16-2014, 11:08 PM   #12
plym49
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Quote:
Originally Posted by NonRubicon View Post
Replacing the RMS:
  1. drain the oil
  2. drop the pan
  3. let the engine block drip dry overnight (optional, but if you don't let it drip clean you will need a face shield or sealing goggles, and you get covered in oil)
  4. remove the rear main bearing cap
  5. drive out the upper rear main seal (maybe requiring loosening other bearing caps along the crankshaft until you get enough clearance)
  6. wrestle the new upper seal into place (being careful not to nick it)
  7. replace the lower rear main seal in the rear main bearing cap, using RTV on end tabs
  8. install the rear main bearing cap/tighten any caps you loosened
  9. install the oil pan with new seal
  10. refill with fresh oil
  11. run the engine and check the new seal for leaks
  12. If the new seal leaks, return to step one.

It may be a PITA to get the upper seal out. It will likely be stuck real good in the groove. You're going to want a small diameter brass punch or rod to get the upper seal out. I used a brass brazing rod, minus the flux on it, and a mallet. You may or may not need to loosen some of the other caps on the crankshaft to get enough clearance to get the old seal out and the new seal in. I had to loosen the next three bearing caps to get enough clearance. Be sure to retorque the caps in proper sequence and to spec.

Be careful when inserting the new seal into the block, you don't want to nick it or bend it. Expect it to be a PITA to get the new seal in, without nicking it. And considering you've never done a RMS before, expect it to take at least twice as long as you think it will.

Personally, I spent more time fighting with the upper seal than I did removing and installing the oil pan.
There is no need for step #3.

There is no need to remove the other main bearing caps. Even if there were, think about it for a minute. The crank is supported by the transmission input shaft and the front seal at the timing cover. It does not droop, certainly not far enough to release the RMS.

The upper seal always comes out with good technique. Use a long punch with a flat point that is small enough to fit in the groove and large enough to catch the stiff metal wire embedded inside the seal. Also remember that the upper seal does not drop out, it rotates out right on the rear crank journal. Think in circles as you tap it out.
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Unread 02-17-2014, 12:01 PM   #13
NonRubicon
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I know #3 isn't necessary, hence why I said it was optional. It's just a matter of preference if you want to get dripped on by oil or not.

Regarding step #5 - I don't think I expressed myself clearly (I'll go back and clarify it).

Loosening additional bearing caps will droop the crankshaft a little and help relieve pressure on the seal, making it easier to break the seal loose and extract it. It certainly helped for me. Prior to loosening the caps I fought with the RMS for over half an hour and only managed to drive the metal core from one side to the other - the rubber seal held fast to the engine block - didn't matter that the brass rod I was using as a punch covered both the rod and nearly all the seal. So, following advice I came across elsewhere I loosened the bearing caps gradually to let the crankshaft droop some then tried punching out the seal. Moved a couple of millimeters, but still really tight and stubborn, so I loosed another cap to let the crankshaft droop some more and tried again. A little more movement, and just a little easier, but still really tight. With enough crankshaft droop the seal came out very easy-peasy.

While it is certainly doable without messing with the other bearing caps to droop the crankshaft (after all, standard procedure only has you remove the rear main cap), it is likely going to be less of a struggle with the seal if you do allow the crankshaft to droop some and get pressure off the seal.
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Unread 02-17-2014, 12:59 PM   #14
Cobra21
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Gave it to a guy this morning. I also had a small drip from where the transfer case and transmission meet that the shop is going to look at. For the 350 to fix the leak and probably a little more to fix the transmission to tcase I decided to go that way.
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Unread 02-17-2014, 02:47 PM   #15
plym49
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Quote:
Originally Posted by NonRubicon View Post
I know #3 isn't necessary, hence why I said it was optional. It's just a matter of preference if you want to get dripped on by oil or not.

Regarding step #5 - I don't think I expressed myself clearly (I'll go back and clarify it).

Loosening additional bearing caps will droop the crankshaft a little and help relieve pressure on the seal, making it easier to break the seal loose and extract it. It certainly helped for me. Prior to loosening the caps I fought with the RMS for over half an hour and only managed to drive the metal core from one side to the other - the rubber seal held fast to the engine block - didn't matter that the brass rod I was using as a punch covered both the rod and nearly all the seal. So, following advice I came across elsewhere I loosened the bearing caps gradually to let the crankshaft droop some then tried punching out the seal. Moved a couple of millimeters, but still really tight and stubborn, so I loosed another cap to let the crankshaft droop some more and tried again. A little more movement, and just a little easier, but still really tight. With enough crankshaft droop the seal came out very easy-peasy.

While it is certainly doable without messing with the other bearing caps to droop the crankshaft (after all, standard procedure only has you remove the rear main cap), it is likely going to be less of a struggle with the seal if you do allow the crankshaft to droop some and get pressure off the seal.
The crank will not drop a couple of millimeters unless your transmission input shaft bearing is toast.

What probably happened is that you felt more confident.

You have to be purposeful to drive the upper main seal out; actually, just to get it moving. Once it breaks free they spin out the rest of the way quite easily.

You need good, confident technique for you want to smack it smartly without hitting cast iron - cast iron chips and dents easily.

I suspect you were frustrated and it was more Hawthorne effect after you loosened the caps. You might even have been in a more comfortable position underneath, permitting you to swing the hammer a bit better.
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