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Trouble with the rear main seal, Please Help

1990XJ4x4

1990XJ4x4

NAXJA Member #1158
Location
Louisville, KY
I'm in the middle of doing a whole bunch of work to my jeep and one of the items on the list is the Rear main seal. I pulled the bearing cap off and managed to get the lower chunk of the seal out of it, but now i'm on the top half. I can't seem to get the darned thing out of there. I have tried using a small brass punch to knock it out and i even attempted to put a bunch of extensions on a small torx bit and jack it up with a floor jack to act as a press.

I've been trying to get this one peice out for over an hour now and I'm open to any ideas.
 
You're on the right track with the brass punch - DO NOT use anything harder than brass, or you're re-cranking!

If you can't work it out easily, loosen the #5 and #6 main caps, which will give you a little freeplay to pop it loose.

When you install the new one, either soak it in clean engine oil for a half-hour or so, or rub it thoroughly with assembly lubricant. These things aren't usually fully-lubed when they're installed at the factory, so they can be sticky. When you lube the new one, it's usually easier to change the thing the second time around.

5-90
 
Thanks for the idea, that thing is REALLY stuck. I'm gonna go try loosening #5 and #6 to see if i can get er dun.

One other thing, to RTV or not to RTV. I have read mixed things about half say to use RTV and about half say not to.
 
It may be necessary to work your way all the way forward - I'd not loosen the cap bolts past about two turns. You don't need a lot of room.

For RTV - I've never used it for the rubber seals. The old SBC "rope" seals usually needed a little help, but as long as the rear main surface isn't grooved and the surface and lip are nice and clean, you're alright. I don't bother with RTV on 242 seals. The upper half sticks out just enough to get a good "crush" against the lower half, and seals nicely.

5-90
 
I finally popped mine out, by finding a punch that was as big as possible without hitting the edges, think it was 5 mm. If the punch is too small it will mushroom the gasket and not help much. Working it from both ends a little also seems to help.
I wouldn't RTV the top seal (liguid soap on the outside and a very light touch of grease on the lip). If you use RTV, try to keep as much as possible out of the mating surface of the cap to the block. I think the next time I do it, I'm gonna use a *very* light coat of RTV on the outside of the bottom half seal (in the bearing cap) it shouldn't be too hard to clean out again and the normal very small dab where the seal ends meet. If you use RTV, make sure it's completely oil free or you may be wasting your time.
What kind of seal are you using, I've had poor luck with Fel Pro.
Getting the punch exactly centered on the seal and giving it a sharp rap, can be difficult.
 
I think that I may have to wait until some hardware stores open in the morning, the only brass punch that I have is way really short and hard to hold up in there. I gotta get there as soon as they open so that I can get to work by 4 pm.

No wonder I have been putting this off for so long
 
You may be able to find a piece of brass brazing rod, I ended up using a big nail (with the end filed flat). Nails are pretty mild steel. The nail I found was almost a perfect fit. If you ding the edges, a set of keyhole files (about $5) with clean the dings up pretty quick, unless you get really carried away.
 
I used a brass plated zinc ("pot metal") curtain rod ground down to fit seal opening. Rod is ~18" long. Worked great for the rear oil seal and many other jobs requiring a "soft" metal punch with extra long reach.
 
When I did mine I had a brass punch attachment for a pneumatic chisel (after I had tried the old brass punch and hammer). One short burp from that and a half inch was sticking out the other side. I grabbed that with a huge pair of visegrips and it came right out.
 
ECKSJAY said:
When I did mine I had a brass punch attachment for a pneumatic chisel (after I had tried the old brass punch and hammer). One short burp from that and a half inch was sticking out the other side. I grabbed that with a huge pair of visegrips and it came right out.
Click to expand...

Where did you come up with an attachment like that. I cant find any stores here in town that have one. I think i may have to get a large brass drift and turn it down to fit the air chissel.
 
I'm out of ideas for removing it, but here are a few tips I found helpful for installation (most of which I learned the hard way):

-I used my grease gun and squirted grease directly into the upper seal's hole. Worked great and the seal went right in with very little effort! Much better than the other things I tried first.
-If you damage the upper seal in any way, stop and go get another.
-If you use RTV (and I used quite a bit), by all means WAIT until it has had time to cure before you fire up the engine. Over-night is best. Seems obvious enough, but after a long day of wrenching I sorta didn't think about that. :(
-The one piece rubber oil pan gasket is awesome! But I didn't use it when I did the rear main. I glued the cork gasket to the pan with RTV (but not the engine) and after letting it cure, it did just fine removing and installing it 5 times until I got everything right with the rear main seal. After a year though, the cork attached itself to the engine and yesterday it came apart when I dropped the pan for an inspection (trying to track down an intermittant noise). I bought a rubber gasket this time.
Jeep on!
--Pete
 
I take that back, I do have an idea. Can you spray any penetrating spray like PB blaster up into the seal at all?
Jeep on!
--Pete
 
Just thinking out loud, but I'd be tempted to drill a little into one end of the seal, a battery drill (or even an old fashioned had drill) would probably be best, then stick a brass rod in the hole (square slot) and wail on that. The brass will bend with the curve and there isn't really anything it can hurt.
I can't really remember exactly how big the square slot for the seal is, but 5 mm seems to stick in the old brain. Maybe try a 4.5 mm drill bit, I know the last seal I took out was really brittle, I could break it with my finger nails, so beating it to a powder is likely. A little pounding, then a little digging with an ice pick, then blow it out with a little air, you may be able to whittle enough off the ends that the middle will want to move. If you get in pretty deep, you may want to switch to a slightly smaller piece of brass rod.
Gasket removing spray and probably Gunk motor cleaner, will soften the seal if you keep soaking it, as a last attempt. I doubt it will melt it out of there, but will probably weaken it.
Old Man would probably be able to tell you which chemical will attack the seal, the most aggressively.
 
dude i had the same problem...I beat my hands up and the end of the gasket...Finally one of my buddies filed a steal rod down and wacked it out with a baby sledge.... It only took him one good shot...But we beat up the egdes pretty good in the process..

Good luck
 
8Mud said:
What kind of seal are you using, I've had poor luck with Fel Pro.
Click to expand...

what do you suggest to use? i am about to do mine for the second time around because it is leaking worse now than it was before i did the seal...thought i just didnt use enough RTV...but guess it could be my felpro. im dreading this job, gotta be the oiliest most PITA job on a jeep. and last time i did it i broke off the starter bolt in the bellhousing :rattle: i want to make this time around the last until i have to pull 'er out and morph it into a stroker
 
Well I couldnt find a brass punch for an air hammer anywhere, so I bought a big brass punch at harbor freight and made my own.
:D
475332360lgeOfn_ph.jpg
 
A common problem in changing a rear main is to not lube the seal good enough when you put the crank in. Also, pull the distributor and spin the oil pump with a drill to get oil up through the galleys. Starting a dry or poorly lubed seal will cause it to melt in about a half second, well before the oil gets up to it. Alternatively, you can pull the coil wire and crank it for a while, but it is still dry until the oil gets up there. It is much better to get the oil there first.

Oh, by the way, don't bother to ask how I know :laugh3:
 
ECKSJAY said:
When I did mine I had a brass punch attachment for a pneumatic chisel (after I had tried the old brass punch and hammer). One short burp from that and a half inch was sticking out the other side. I grabbed that with a huge pair of visegrips and it came right out.
Click to expand...


DUDE, thanks a million for the air chisel idea, I spent 2 hours on a lathe making a brass punch for mine and it only took one quick burp from it to knock the seal out.
 
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