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rear main (upper installation)

4

4Doors

NAXJA Forum User
Location
FL Panhandle
I've done a ton of searching and it seems that everyone asks how to get the thing out....but I haven't found anyone looking for advice on getting the blasted thing IN! I did one a few years ago on my old '91 and I really don't remember it being so difficult to get the new seal back in. On my current '92 however, it's been quite difficult and I ruined my first seal. I couldn't find info on any forum so I searched google and actually found this site where the guy got the following advice from 4Wheelers Supply.

The primary reason for new rear main seals leaking is (after installation) the torn backside of the seal. Because there is a pre-load on the (upper half) seal when installed, it is all too easy to cut/tear the rubber off the back side of the seal where it meets the sharp machined edge of the back of the block (thereby creating gap and/or unequal pressure along surface).

Solution:

A thin piece of plastic (ie. the stuff used to package stuff...credit card would work, but is a little thick). Cut the plastic so that it has an ear the width of the seal journal and about 1/4 inch long. Insert the ear into backside of the journal (you are using it as you would a shoe horn to cover the sharp edge) Cover back side of seal with LIGHT coat of RTV (acts as lubricant during installation and seal when done). Seal will slide in like a greased pig on hard ice (as opposed to having to tap in with hammer). SMALL dab of RTV on mating surface (ends) of seal... DO NOT put RTV on mating surface of bearing cap; this will destroy proper bearing clearance.
Click to expand...

It wasn't until after I messed up my first attempt that I found this advice, so I decided to practice with the bad seal (no RTV on my practice runs) and found that the above advice does very well to get the thing started, but I still could not push the seal all the way around, so I'm turning to you guys. Any more advice on how to push the seal around the crank? I think I read somewhere that you can loosen the bearing caps and allow the crank to drop ever so slightly, is this true? ANY help would be much appreciated!
 
Put it in some warm oil first, or assembly lube. Then loosen the first bearing cap or two and see if it helps somewhat. That's what I've read, though I haven't done mine as it turned out my oil leak was from a badly rusted pan, not a rear main seal. Still need to get around to fixing that, for now I just park on an incline so oil doesn't sit over the pinhole.
 
btam13 said:
Tap it in with a wooden dowel and a hammer. Be careful not to shave off to much on the bearing journal.
Click to expand...
I'm only getting about half of it in, so I'm not at the point where I can even tap it the rest of the way. I've considered wrapping some forceps with a paper towel, clamping the seal and trying to push it in, but I'm still concerned about damage to the seal. I've got all the bearing caps loose and I'll try soaking it in warm oil for a bit. Hopefully I'll get to work on it this afternoon.
 
As an aside, make sure you use a torque wrench to put the bearing caps back on with the right amount of torque.
 
When I replaced my rear main I had to loosen three bearing caps to be able to slide the upper half in without damaging it. I had the same problem as you so I just started with the closest cap and worked my way down the line until I could get it in.
 
rotate the crank (have someone spin it via the harmonic balancer bolt) while you feed it in.

Jeff
 
To get it in the same way it came out, lube it in oil, stick it to the bottom of the crankshaft and rotate it back in carefully as not to peel/tear the new seal. Not sure I'd use RTV as he described though. You only use a dab of RTV where the timing cover meets the block and where the rea main bearing cap meets the block after it's installed.

I did my rear main/oil pan gasket in the campground at Moab one year.
 
Last edited:
I ended up getting the new one in with no difficulties. The idea in my original post about making the little shoe horn out of thin plastic was great. After loosening some bearing caps, I kept practicing with the new seal that I had already damaged and kept having difficulty. Then I decided to get a small medicine dropper and shoot oil in the passage just to make sure it was lubed up, and then the seal went in perfectly with no difficulty at all. I pulled that one out and got my newest new one out of the dish of oil that it had been soaking in and the thing slid in with hardly any pressure at all. Thanks for all the help.
 
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