Uncommon transmission leak

[Loren]

I had a split case transmission rebuilt and was finally able to install it. After a few days I noticed an oil spot on the ground and thought it was the backing plate, but there wasn't any oil on the backing plate or drum. After a closer inspection I found the oil was coming from the pin that holds the end casting to the axle tube and oil was leaking from the back side of the end casting. No oil is leaking from the bottom of the locking pin, but I suspect the powder coating must be creating a seal to prevent that. Has any one come across this type of leak before? How do I get it to stop. All I can think of is knocking out the lock pin to see if there is a wear hole in the indent to index the lock pin. Maybe putting some sealant on the lock pin and reinstalling it will fix it?

It's hard to see, but oil keeps seeping from the back of the end casting.

Again, it's hard to see, but the top of the lock pin is wet with oil

[Zwitterkafer]

Haven't had that exact leak, but if the end of the axle tube pressed into the end casting is distorted, undersized, or grooved with scratches, oil could conceivably wick back up to the pin area. It should be possible to stop such a weeping leak with sealant, since the oil shouldn't be under significant pressure. (Transmission vent must be clear)
Ideally the axle tube ends should be masked off before powder coating, since removing powder coat from the junction area could introduce scratches. Before pressing axle tube into end casting, a very light application of sealant near the ends might be a good precaution. End castings can crack and leak too. Have yet to see a pin bore through to the inside of an axle tube, but never say never. Good luck!
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"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[esde]

I would attack that leak from the other end, but it will be a bit oof disassembly.
Remove the brakes, backing plate and wheel bearing. You will be looking into the axle casting at the end of the tube that is pressed in. Jack the axle up so the gear oil isn't running out, and clean the seam between the tube and casting as clean as you can. Go around the corner with a pick, and get it surgically clean. Then, there is a loctite product, sleeve retainer that is thin, and works on assemblies that are already assembled. Get it into the groove, and hope it wicks into whatever void is causing the leak. Some heat usually helps it flow into small voids, but the powder coating is an issue.
The pin is really tight, I don't think I've ever had one that didn't need at least a 5lb hammer, and a solid surface backing the casting up. I'm doubtful you can get it out under the car.
Good luck!
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[wagen19]