Jimm 1/26/2013Most likely the issue is due to either; worn / stretched drive belt, faulty idler pulley, or faulty / worn belt tensioner.
Try the many on-line auto parts sources; such as, www.autopartswarehouse.com or www.rockauto.com for the replacement parts.
Check the 'How-To-Guides' feature on the AutoMD website for specific steps to check the belt tensioner and to replace the drive belt.
glhallowed 5/5/2013The real issue is that the tensioner pulley is completely smooth. This is acknowledged in the following link:
The video explains why it occurs so often and a permanent (but admittedly expensive) fix for the problem. I've dealt with this issue more times than I care to count. All the tow truck drivers I've talked to say this is actually common with minivans.