Rear axle seal keeps leaking

The right rear axle seal on my 1991 Toyota 2wd pickup keeps leaking. I’ve had it replaced 3 times in the last 7 years and now it needs replacing again. Last time I had it replaced (January 07) I asked the mechanic (Toyota dealership) to see if there’s a reason why it keeps blowing. He wrote “no marking or scoring of the hub, all appears to be OK. Suggest for customer to check the differential bleeder at times to make sure it’s free so the pressure doesn’t blow out the seal”. I’ll admit, I haven’t checked the differential bleeder (I didn’t even know it had a bleeder). Besides checking the differential bleeder, is there something else that could be wrong? It costs over $200 every time I get the seal replaced which seems to be every time I have my annual inspection now. I can’t do it myself because it requires special tools and a hydraulic press. Thanks for any advice.

All components that contains a fluid that gets hot must have a way to vent to the atmosphere. Otherwise the pressure in that component can build where it blows out seals.

Other things that can cause seals to leak are worn axle bearings, and a groove worn in the axle shaft where the seal rides.

Tester

If the seal keeps leaking then the axle bearing needs to be replaced.

find a shop that gives lifetime warr and keep taking it back some places give a years warr on work . are you towing to much weight or running threw water. puting a strain on axle,s are they bent. next time buy after market seals may be the dealer seals are old.you maybe their only customer and they order your new set and the seals are on the shelf for three years.