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Replacing rear main seal... How hard??

CJ-8_Jim

CJ-8_Jim

Scrambler Junkie
Lifetime Member
City
NW Chicago Suburb
State
IL
Hi,
It looks like the Scrambler I bought a week ago needs a rear main seal. From what I've read, I need to:

1) Remove starter (disconnect battery first)
2) Remove oil pan (easy, except the right engine mount needs to be loosened and the engine lifted to provide access to one of the oil pan nuts)
3) Remove rear bearing cap
4) Loosen all other bear caps
5) Remove top piece of rear main seal
6) Re-install top rear seal (this requires strategic placement of cement, oil and dishsoap)
7) Re-install bottom rear seal (this requires strategic placement of cement, oil and dishsoap)
8) Install rear bearing cap
9) Tighten all bearing caps
10) Install oil pan (with new gasket)
11) Reinstall starter and reconnect battery

My questions are:
a) How tough is it to remove the top rear seal?
b) If installation of the top rear seal (with the strategic placement of oil, cement and dishsoap) is not 100% perfect, will it still leak
d) Do I run the risk of tearing the seal?
c) Does it go in easily?

THE BIG QUESTION: I bet this is a $600 job at a shop... should I just pay someone to do it if it is easy to screw-up?

Any thoughts are appreciated!!!
 
I did mine this summer, but had the luxury of having the engine out at the time since I was swapping it to my new frame. I would say the hardest part about the whole job is getting the top section out. I ended up using a punch to pound it through. You have to be VERY careful not to score anything while doing this though. It really isn't all that hard to do, just take your time and becareful... having done it myself, I would NEVER pay a shop that much to do it (if it does indeed cost that much).

The only things I would add to your list are to drain the oil (maybe obvious maybe not) before you start and that I would also clean the sludge out of the oil pan while you have it off. You'll also need to pick up a new oil pan gasket and cement, don't forget that when you pick up your rear main seal.

Let me know if you have any specific questions.

Good luck,

Kyle
 
oil seal

I would also like to add, remove the bar that mounts to both sides of the frame under the oil pan. When I did mine I removed the motor mount and frame adapter. It gave me alot more room.One more thing, change the oil pump unless you have good oil pressure. Clay
 
I did this in January, the worst part was all the oil under there! I was told to use a Brass or Aluminum drift to punch the top half out but I couldn't find any the right size. I just used a punch and was careful not to gouge anything. The new one went in easily, just make sure you put it in facing the right direction.

Ben
 
I've done 2 rear mains in the past couple months (different scramblers, not a redo! :)

I didn't have to loosen the other bearing caps... Just remove the main bearing cap, you'll just end up wasting some time and putting more wear and tear on your torque wrench. And yes, make sure you have a torque wrench so you don't over or under tighten the main cap. That's a real good way to invite a leak. Needless to say, everything else sounds good. Instead of removing the engine mount, I just loosened it and jacked up the tranny a bit. If you don't have a lift this will allow you to have more room to put the oil pan back on. A definate plus!

Good luck! It will probably take you a good 6 - 8 hours seeing you've never done one. And also, buy a couple rear main seals... they're like 8 bucks a piece, but it will save you a trip to the parts store if you ruin one. The bottom part of the seal is a pain in the rear. (No pun intended)
 
Thanks

Thanks guys.... I really appreciate the tips and moral support.
I'm definately going to tackle this myself on the next rainy weekend day.

By the way, all along I've been assuming (and I think correctly) that it is the rear main seal that is leaking. It's definitely NOT leaking from around the oil pan and it is definitely motor oil.

The "weird thing" is that there is NO oil running down the rear of the oil pan (from where the rear main seal would be).

Instead it is leaking from inside the leading edge of the bell housing. There is a flat metal cover that encloses the flywheel on the leading edge of the B.H..... it's from there where the oil is dripping.... errrr... more like draining out.

Another "weird thing" is that this is an ATK remanufactured long block with 5,000 miles on it.

It's not worth the hassle to get compensated on $15 of gaskets and my time, but I just hope that the problem is with the rear seal and not with the crankshaft surface or rear bearing surface (race).

Thanks again!
Jim
 
FYI- that's where mine was leaking too. Rear main seal replacement took care of it. Now just a small seep coming from the valve cover.

Ben
 
Firetruck41 said:
FYI- that's where mine was leaking too. Rear main seal replacement took care of it. Now just a small seep coming from the valve cover.

Ben
Click to expand...

Same with mine :)
 
Rea Main Seal

Someone told me they make a little tool, like a grabber, that you can use to take out the top piece with. Good Luck - Dwain
 
Last edited:
rear main seal

With the new one piece rubber oil pan gaskets do you need to use silicone with them?

Shawn
 
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