shadowwar

Ok my 2.4 2006 hhr developed a noise a week ago from the front passenger side. It only starts at about 2500 rpm and is constant and louder upfrom there up through the rpm band. It currently has 47000 miles on it. I took the belt off today and drove it and the noise is still there. To me it sounds like a tensioner pulley bearing going bad but eliminating the belt eliminated the tensioner, ac or alternator as the culprit. Could it be a timing chain or guide issue? It doesnt matter what road speed it does it in all gears only about 2500 rpm