after car has run a while around town i get a groning sound when i turn my wheel on 2001 Ford Mustang

it only does it when car car has been driven a while not when it is cold also it only does it atlow speeds not fast i put a rebiult power sterring a year ago could it be getting bad or could the rack on the sterring causing the trouble it not hard to turn ond drives well only makes that noise it almost sounds like when the ball jionts make niose .i had a mechanic check he cant find ant problem.

Asked by for the 2001 Ford Mustang
Sound like your power steering fluid has air in it. I would replace the P/S reservoir, which has a filter that gets plugged, and then flush out your system. Also be sure that your P/S belt is properly tensioned.