Power steering noise

My '02 Explorer makes a grinding noise similar to a sound of a tire rub on a fender well only when the wheel is turned all the way in either direction and when the vehicle is not moving. The steering is still smooth and haven't lost any fluid. Am tending to think it it the pressure relief valve inside the pump. Any ideas?

Doctor, doctor, it hurts when I raise my left arm above my head! (doctor) Don't raise your left hand above your head. Not to be a wise guy, but why are you maxing your steering out if your not going anywhere. And yes, steering has its limits. It'll make noise to let you now.

To answer your question: Nothing is wrong with your steering, Its just your power steering letting you know that you cant turn any farther (in its own words) happens on most every vehicle