Rear Main Seal, Replacement?

[Duckman]

I have had alot of people tell me to replace the rear main seal to stop the leaking on my 88 G-WAG. I have a chilton manual and I can't find anything on that. Does anyone have any do's and dont's that may save time and make the job easier?

[joe]

Look in the /tech/ section of this site. You'll have to dig around as I don't remember the sub-heading but the proceedure is in there.

[Rande]

A definite rite of passage here! You have fun with this one, ok?
Be certain your brother sits there making smartGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley remarks and drinking beer while you work.
I couldn't get the oil pan out so I just moved it off to the side and had enough room to work. You will need a brass rod to use as a drift to push the upper half out. It will usually be stuck and take a few whacks to move. Be certain you insert the new seal the right way. Lube it up good before you install it or the crank will burn it before enough oil gets to it.
After replacing mine, it still leaked. I figured I would have to do it again. I couldn't stay at my brother's any longer (it was Sunday afternoon). I had to go home (100 miles). About 30 miles out, I stopped and checked the oil level, down a quart. Filled it up and kept going. 30 miles later I stopped again, just a bit low. Checked again when I got home, now it was a quart low again. Haven't lost any again since. So, if it still leaks a bit afterwards, it may just need to "seat" a bit. Give it time before tearing into it again.
Its not really difficult but its certainly no fun either. Give your self the whole day to do it so you don't get rushed. I have heard of some guys having to remove the main bearing caps, dropping the crank down a bit to drive that top half out. Hope it doesn't come to that for you.
Good luck...

[Rogue]

i was replacing a two piece seal on a 64 chevy the seal was soo dry rotted that i had to heat the block ( i pulled the trans for a rebuild ) with a torch before i could get it out. not trying to talk you out of it just plan for the unexpected. if this is your daily driver start friday night so that you have all day sat and sun to make parts store runs etc etc if necessary like rande said its not fun but not too hard either, good luck Jeff

[Duckman]

Thanks for the replys guy's. Rande, did you say that you were able to do it without dropping the crank down? I would like to hear more about that. I was under the impression it was required. I have still not been able to find the procedure in the tech section? Maybe it is gone now. Good advice on starting it early and being ready to go to the parts store alot. I definately have the smartGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley brother in law part taken care of, every time I slip a wrench and bust my nuckles he just pops another beer and tells me he has a good mechanic down the street!
:D

[Ernzo]

http://www.ifsja.org/tech/motors/rearmainseal.shtml

[Rande]

I just loosened the main caps to releive the pressure on the seal. I only removed the rear one, which, of course, has to come out. What I read from others here made me think they had actually removed the other caps and pulled the crank down some to get at the seal. I moved mine maybe 1/8"-1/4" down and was able to drive it out.
It hasn't leaked since the drive home. Of course, the front one is now spitting oil out. That's this weeks job.

[Duckman]

Thanks Ernzo and andy. That was exactly what I was looking for.

[PAJEEPER]

Try it with just the rear cap removed first. I've never had to loosen the rest of them.

[Duckman]

Thanks for all the input guys, I have good news and bad. I may not have to do the rear main seal. I think I have located the source of the oil. It seems to be coming from somewhere near the starter? Is that good or would that still be the seal? I have the seal sitting in the garage, it laughs at me every time I walk by it :D I also noticed a bad ticking noise coming from the bottom right rear of the motor. It is a ticking noise, what the heck is that?

[Sambo]

but what do you do when you pull the rear main cap and the darn thing looks gaulded right through the middle of the main bearing?
time to build the 401? and replace the 360? :confused:

[Duckman]

Thanks so far guy's I my wallet really appreciates the advice. Here is the dilemma, I replaced the valve cover gaskets and tightened the oil pan. neither of which seem to be leaking. I have oil pooling on top of the manifold and dripping steadily on the ground. There also seems to be oil running from up on top of the starter down to the bottom of the motor in front of the tranny. I don't want to replace the rear main if that is not the problem. Thanks again for the help.

[Hump]

That's the same problem I am experiencing. Crazy Jeepman said that the intake manifold gasket was probably bad, so it looks like you will have to redo your valve cover gaskets. As for the leak by the starter, I think that is the rear main like you thought before.

If you're fixing it before me, keep me posted. I'll let you do the dirty work first. :D

[Duckman]

Come on Hump! You're the engineer, you go first :D I may do the intake today? There is oil everywhere, I think I will spray the whole motor down with degreaser then powerwash it. After that I will try to wipe it as clean as possible, start her up and stand back see what erupts first! I guess I will just plug one leak at a time tongue.gif

[fitron74]

Duckman,
Get a Haynes Manual for the full-size jeeps from an auto-parts store. That's what I used when I changed the rear main seal on my '87 GW. Mine didn't leak a drop afterwards. I followed the instructions in the manual carefully and had no problems. Make sure you have a 1/2" drive torque wrench for properly torqueing down the bearing cap bolts when you re-tighten them. Have fun.
Fitron74

[Rogue]

don't forget to check your pcv valve as this will cause oil leaks if it is plugged up

[Ernzo]

Hey, how long a job is this at home for a reasonable home wrench?? One day?

E

[jasonthomasfrance]

Which job? The rear main seal? The intake manifold? Or the valve covers? RogueStar stated you should start Friday night if you're asking about the rear main. The intake shouldn't take more than a couple hours... And valves are just annoying, but pretty easy.

[Rogue]

HEY FITRON I see you're from my HOMETOWN. what's up?!?!?!