I don't know if your vehicle has one or not, but on one of my old cars there was an "idler pulley". The purpose of the idler pulley was to be able to tension the belts or something, I am really not sure. But in any case, it was a pullet that the belt went over but wasn't part of an actual device on the car. was just a pulley by itself. This caused the same type of noise on mine, so if you have one, check it out. Good luck.