Engine bearing gone?
 

Over the last few months I have noticed an engine rattle becoming worse. The car boosts and cruises without any issues, but at idle there is a rattle which gets worse as rpm drops (AC activated with manual idle control). Above about 2 k rpm the noise is not noticable. Water pump is not leaking and the is no shaft play or binding when free spinning. Alternator is new and no binding when spinning. Heat shields are tight. Turbos not noisy. Noise seems centered behind main pulley. I can feel the rattle if touching the engine. Belts were too tight for years. Rear engine oil seal started leaking recently. Does this sound like an engine bearing is starting to seize? Is there any way to confirm this is the problem? I will be filtering the oil tonight to see if there are any metal filings. Thanks for your input.

Mark

Does the pulley wobble? Check your engine oil for copper flakes...

No pulley wobble. No metal particles in the oil. What else could cause this noise?