When the engine was first started, I could hear a rattle coming from the supercharger. The supercharger on this engine is a Eaton M45, that is common to many vehicles throughout the years (mini cooper s, pontiac gran prix/am?, etc.) From my reading online, there are two general causes of the rattle. Those are failing bearings (which there are many in the supercharger) and worn coupler. For general diagnosis, with the supercharger belt off, turn the snout pully, if there is play when rotating back and forth, the coupler is likely worn, if it is rough and grindy, bearings are likely the problem. On mine there was play when rotating, but it rotated smoothly, implicating a worn coupler. Lucky for me, this is the easiest of fixes. Drain supercharger fluid, remove snout, replace coupler, reinstall snout, fill with new fluid, done. I purchased kit similar to those found on this site (http://www.superchargersonline.com/index.php?main_page=page&id=57). From what I’ve seen online, replacing bearings requires more care and expensive tools (presses, etc).