I noticed that when the noise comes on the serpentime belt between the top two pulleys is vibrating almost 1/3 of an inch from the neutral position. As the RPM's go up the vibration on the belt goes away and it runs smooth. Is this excessive play and resulting noise likely the tensioner or there is something else going on that is causing the belt to vibrate so much.Is there a way to tell which of the two it might be. I am not likely to be able to see much from the underside of the car.
Thanks.