keep pushing the crank seal out

hi, i have a 91 b2600i and need some help.
i found a oil leak at the front crank seal so i replaced it and about 4 months later it leaked again. when i pulled the pulley off the seal came with it. i installed a new seal and now about 3 months later, its leaking again. what could this be? when i took the pulley off i noticed that it had some very minor grooves in it, not sure if that is what could be causing this. also, the motor has quite a bit of blow by, could this be causing it? i'm planning on rebuilding a motor on the side when i find one but i need this one to run in the mean time.
what can i do?
thank you

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if that doesnt work, try a little sealer on the crank seal. I know it's not recommended but it worked on my izuzu pickup. i would try replacing the seal again. i bought one before deciding to do my rebuild and the full gasket came with one also (different brands). they were just a teenie bit different in size, but enough to see. i doubt your oil pump's hole for it is too big, leaving the problem to lie with the seal....

haha, its funny you say that. thats what i did. hopefully it will stay until i can get another motor.
thanks for your help.

you prolly have a worn groove on your crank so when the seal gets broken in it leaks