My tensioner rattles at very low rpms(1000-1200 or so). I can see that the 2 metal pieces that stick out to prevent the tensioner from going to far are hitting each other at low rpms putting out this horrible rattling noise. it's especially nice when you go through the drive-thru at mcdonalds. anyway I've taken it off, jammed things between it, I don't know how to fix it. A tighter belt would make it worse I've figured out. maybe the tensioner is just shot. chevy wants like 65tomatoes for it. I'd rather turn up the bass.