My 96 Impala SS's belt tensioner bearings would go every 10K.
This is actually do in fact to a slight misaligment GM made when they designed the alternator brackets...... Thats GM for ya! :P
The bearings would go premature... but the sound was masked by the chirping noise the belt would start making. The GM dealer would always replace the tensioner and the belts to remove the problem under warrenty.
I doubt you are having the same problem, but perhaps my little story will give you some new trains of thought on the matter.
1996- BMW 328IS
<img src='http://img.photobucket.com/albums/v242/gws226/TEX/neverleanedsig.jpg' border='0' alt='user posted image' />
Performance: Zimmerman Cross Drilled Rotors-- PBR Deluxes-- Cosmos CAI---- Turner Pulley Kit--- Fan Delete mod---
Beauty: 18 polished M-Parallel replicas, Inpro Euros w/ Enchanced Angel eye kit, 20% tint
Clear corners/sidemarkers ---- Eurospec (Depos)
To do list:
UUC System U TDM- 3/05
M50 manifold converstion 3/05
off to the tuning shop for custom software 4/05
Cams/lightened flywheel, throttlebody........ well lets see what happens