Lemme guess, you got a metal impeller water pump.
Seems the metal impeller pumps are prone to seal failure - I don't know why.
The only pumps that seem to have few problems are the white plastic impeller pumps. Try on of those. I'm approaching 70k miles on mine - no problems. I've seen posts from several guys that have more than 100k on their original white impeller pumps without problems. I've seen very few posts about white impeller pump failures.
