Differential / axle tube leak

[Anime]

The rear diff has been leaking for some time now (probably years) on the right side, all around the axle tube. While it's not much of a problem and is hardly any fluid (looks worse than it is with the thin film of gear oil spread out), I'd like to fix this. I've been planning on welding the diff to the tubes to prevent spinning anyway, but would that be a fix or is there another possible issue? I don't see any cracks on the diff or tube, I don't think theres a seal other than the press fit of the tubes into the diff, and all the factory plugs are still intact, with no seals leaking, either. Also, when welding the diff, since it's cast iron, do I really HAVE to use hi-nickel rods to do the job right, or will a wire welder with flux-core wire do the trick? Suggestions and advice appreciated.

 

[IZwack]

Are you saying the axle tube is leaking at the part where it enters the casted differential housing?

Cauz typically they leak at the end of the tubes, near the brakes. If they are leaking towards the center, then that might mean that the axle assembly is crooked.

 

[Anime]

Yes, it's leaking at the diff housing/axle tube.

I'm aware of the tube end seal leaks on newer models, which is all the info I came across in searching for rear axle leaks. The axle sure doesn't *seem* crooked, it's as straight and level as can be going by measuring and inspection. Guess I'd have to take the axle off to see if theres any wobble in the diff/tube connection.

 

[IZwack]

You're sure the oil isnt leaking from say the pinion seal and just spreading?

Its hard for the axle tube to leak at the center .. I dont think even Rick's rig's axle tubes leaked even after spinning cauz the tubes are that hard pressed on.

But if everything is fine (no cracks or whatever), then welding it up would require a hi-nickel electrode. A flux core weld will crack -- you'll actually hear the cracks form as one side of the metal cools a lot faster than the other side.

 

[Anime]

I realize it's unique, I've yet to find another report of this kind of leak anywhere, but I've cleaned it up several times, and the leak is definitely only around the axle tube.

 

[IZwack]

One thing you could do is try like JB-weld or something. If the leak is indeed from the interface between the tube and the differential housing, then JB-Weld should stop the leak.

 

[Anime]

JB weld probably isn't strong enough to stop the diff from spinning on the axle tubes like a hi-nickel rod weld, is it?

 

[IZwack]

I dont think you'll ever spin those tubes unless you have high gear ratios and large tires. The JB weld is more to stop the leak.

 

[4x4junkie]

I've had just a teeny spot of oil right there on the rear plug weld on the 8.8 in my Ranger for a number of years now, it hasn't gotten any worse.

My guess is not every single axle is 100% oil-tight when put together. it only takes a super-microscopic ("nanoscopic"? lol) leak for the oil to eventually appear there after awhile.
The Ford service books infact do make mention of possible leaks at the plug welds, and tells how to go about fixing them (they say to use "epoxy sealer" (JB Weld will work) and shows a diagram of that area on the axle).