Power Steering Problems?

I am having power steering problems. I replaced my pump about a month ago, and had no issues for about two weeks. My wife was driving my son to school and she heard a loud noise and she was unable to make her next turn. I took the truck, put it on jacks and turned the wheels to the left and right to get the air out, and it improved. Since then I have started driving and I am hearing a loud noise while driving and it is silent at nuetral. I have no sign of leaks anywhere, I replaced the serpentine belt, and my rack and pinion seems to still be functioning because my wheel still rotates back to center after completing a turn. Could this be a result of a faulty new pump or is there something else triggering this?