I've noticed a whining noise comming from the engine of my 01 5.4 screw, It sounds like the powersteering, but theirs plenty of fluid in there. I cant seem to pinpoint what part of the engine its coming from exactly. But it does quite down when I turn the wheel and then goes back to the whinning sound when you stop turning it.
I dont hear anything while driving, just when idiling.
Any ideas??

 

My 94' Maxima had the same problem. It seeemed to always be full. But it would always make a noise when I turned the wheel when Idling. Then it seemed to even out when I got going.

Turns out it was the powersteering, but the hose had cracked, down where you couldn't see it. Had it replaced, and installed the hose too close to the manifold. Yet again it was doing it again because the manifold burned through the hose. So this time, I think I got it fixed.

So yeah... Probably Your Power Steering Hose...