91 TOYOTA PICKUP 3VZE
MY truck keeps blowing power steering pumps they last for about two weeks then give up... I've put 3 pumps on so far and replaced the pulley the third time... Works fine until they blow what apears to be the rear seal. The last time my brakes started to make grinding noises just before it went out, but now that its out theres no noise...

 

Get your alignment checked.

 

There are 3 seals (O rings) that are the same size on that pump. The one on the back is a special compound, if you are using rebuilt units that may be your problem. If using Toy used or new, then not sure what could be going on.

 

Have you flushed the system?

 

I would say take it to a shop, where they can put a hydraulic pressure gauge on the system. They should be able to pin point the problem.
Your brakes were most likely grinding because the P/S provides power to the ABS system.
You may have a clog in the system that is causing the pump to build up excess pressure before the bypass valve.
Did the P/S work alright after you changed out the pump?