Cadillac Repair: loud bearing noise, pulley diameter, tensioner pulley

Question
I drive a '94 STS which is in great shape. A couple of weeks ago I thought I would spray belt dressing on the serpentine to clear an occasional squeak. Since then and about 500 km the tension pulley bearing makes a very loud rattling noise. I can cure it temporarily by spraying it with oil. Any ideas would be appreciated. thanks  

Answer
Hi Gary, Sometimes it is better to replace a squeaking belt than put belt dressing on it which is only a temporary fix anyway. In my experriance the GM belt isn't as likely to squeak as the aftermarket belts are that you get in the pats stores. So what I would do is get the GM belt from the dealer, remove the old belt and spray brake clean on all the pulleys where the belt rides to get rid of the belt dressing. Then install the new belt and you might fix the rattle also. If a pulley is cocked or out of alignment with the others it can cause noises. If you still get the rattle noise then replace the tensioner pulley assembly don't try to oil it up. Cadillac has had problems with belt noises on the NorthStar engine and came out with a pulley diameter change along with a differant length belt. Maybe you could benefit from this change if it hasn't been done yet. Hope that helps. Bill