My 2009 Acadia now makes a noise that is very similar to the idler pulley and power steering pump noises I previously fixed. Sounds kind of like a whine or growl. I investigated all of the belt driven pulleys then ran the engine with the belt off and the noise is still there. It sounds as if it is low on the front end just behind the crankshaft pulley. I don't have any oil pressure issues, no knocking noises, no check engine light, its not overheating. It runs pretty smoothly for an engine with 170k and gets the same gas mileage as before. Has anyone had this problem, what is it?