1999 F53 Rear axle seal

Axles take some care when installing. The shafts have sharp splines on the inside end and they're kind of heavy and rough cast. If the installer stuffs them in the hole and slides them along the seal they won't last. Even big machines take finesse to assemble properly, I'd bet you ran into a couple of "mechanics" who don't understand that. You said the last mechanic saw damage on the previous seal.

thanks Neil, I'll certainly check the vent

Blown out, yeah you need to check that rear axle vent.
If the vent has a hose, check the end of that, because those dirt dobber bees just love a small hole like that to build their nest in & then the rear end cant vent off the pressure once hot.

Maybe check where the hose goes through something, like a pull tye holding a bunch of hoses, wires & tubes together. Ol hose get hot & close up & then not vent.
Neil

Thank for the suggestions. I'll check all the things you guys mentioned......Just got it back from the original installer with a new seal. He said the only damage he saw was from the second installer. Of course that doesn't account for the failure of the original installer. First installation was completely blown in less than 200 mile. Second installation was only leaking slightly at over 300 miles. I think I getting the run around. I guess we'll see. Thanks again for the assistance.

Just had mine done on our 1994 Pace arrow. My ace mechanic told me there are 2 levels of seals. You may have had the lesser level of seal installed.

Is the vent plugged? Is there a burr on the axle? Is there a groove worn into the axle where the seal rides? (any reputable mechanic should have checked the last two)

Doug