I have found it to usually be a belt problem, just the brand. If you cannot see any alignment problems, if you have checked it carefully any alignment trouble can be seen fairly easily, there was a service bulletin involving the 3.3L tensioner, not for damaging belts, for internal failures causing complte failure and throwing it right off, if the rest of the belt looks ok, and there were no nicks or dirt on any pulleys keep an eye on it, change the adjuster(tensioner) if the idler and all the others are tight as you try to move them with belt off.
If it was my van, I would change the tensioner if it has never been done before, hundreds came in with that problem, on new belts but didn't fall off. It's 8 years old, I would change it.
Wednesday, January 6th, 2010 AT 7:04 PM