Hey everyone. I keep getting a rattling noise coming from the area of my serpentine belt tensioner when it is moving back and forth under the hood when the engine is running. Does this mean that the tensioner is about to fail? How hard/expensive is that to replace? Could it also be the water pump causing it? The belt was replaced 2/2009 and is still in good shape. I am not losing antifreeze and the car doesn't get near the notch before 210. Thanks.