Keep blowing axle seals

I'm about to pull my hair out with this thing. I keep blowing the left side rear axle seals. I've ran new vents replaced with good parts, no burs on anything and after a few hundred miles there they go again. It's always the same ones. Any thoughts or issues I may be overlooking?

Are you sealing the keyway when replacing these seals?

Yes. I use a piece of cork.

Are you putting silicone on outside of seal.

Since you have repeated problems with one hub I would consider replacing it. There may be an issue you can't see causing it to leak.

Do your series of 5 tons have vent valves on the axle housings like the M35`s? If they are blocked or stuck, the heat from driving them will expand the oil, and the weakest point in an axle would be the flexible wheel seals. My 2 cents.

Are you backing the hub nut off to much? Do not back it off the bearing preload more then 1/4" turn.

I'm thinking I'll change out that hub. But on the plus side I can do them in my sleep, I think I'll start timing myself

Check the sealing surface on the axle for the inner bearing seal. The M51 series had a replaceable bushing as this area wore rapidly due to abrasive. I remember they needed heating in oil to install.

I appreciate all the info on this guys. Once I get her apart which won't be for a while I will report back with pictures

I floated the idea or installing Stemco seals on the rear of my truck awhile back. https://www.steelsoldiers.com/showthread.php?148996-Stemco-Seals/page2&highlight=stemco I never got around to doing it and my hubs are dry and cool running even after long runs at road speed. If the inner surface of you hubs look normal and the axle is within specification, it might be the solution for you. I certainly think it'd be cheaper than purchasing a hub and you might end up having something to share with the rest of us.

M35A2-AZ said:

Are you backing the hub nut off to much? Do not back it off the bearing preload more then 1/4" turn.

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Agreed. From what I have seen the back off is very important. If I remember it goes, take up the bearing to 100/150 fp. Back off then tighten to 50fp then back off 1/4. The problem I have see is way to much back off. On stuff that does not run our outer seal it calls for the same 1/4 back off so when I do any military with greased hubs I only back off 1/8.
Next time you decide to open up the leaking axle try this. When you get the outer jam nut off instead of removing the inner nut try and tighten it and see how far backed off it really is. I have found one that was just done by a mechanic and leaking that was one whole turn backed off not even close to 1/4 1/8.