2002 Chevrolet Venture

Engine Mechanical problem
2002 Chevy Venture 6 cyl Front Wheel Drive Automatic

my serpentine belt on my 3.4 liter Chevy Venture rubs slightly against the back of the belt tensioner. Both belt and tensioner are new. It rubbed worse on the old one, but the new one has a larger dia. Pulley, by about an 1/8 of an inch. It seems that the belt should be slightly bigger, or the pulley on the alternator should be smaller. Both the belt and tensioner are to factory specs (checked twice). Do you think that as the new belt wears in, and streches a bit, that the problem will rectify it's self? Or should I try a longer belt, or new alt. Any sugestions would be greatly appreciated. Thanks!
November 28, 2009.

I am surprised that it is bigger in diameter if it is the exact one. Did the dealer tell you GM changed it for a reason?

As far as your question, are the belt's splins lined up with the pulley? If not, are you able to adjust it where it belongs? What is the belt rubbing on?

Let me know. Also, if you could get a picture and upload it for me, it would be helpful. Finally, make sure all of the other pulleys are lined up with the tensionier.