I have a 2007 XC 90 with 146K. I have a constant rattling noise at idle that turns into a whirling rattling noise during acceleration.
I removed the drive belt and started the the engine and it runs smooth and quiet. I replaced the idler pulley and the tensioner pulley, and checked
the compressor it was fine, reinstalled belt noise is still there. Any suggestions?

 

I would check all other pulleys, like the ones on the alternator, crank, etc. It seems the noise is related there somewhere since it was gone when the belt was off. Check the alternator housing as well, it may seem weird but when I replaced an alternator on a 850 the housing was very loose and held in by 1 loose bolt.

Also, do a new belt while you have it off if you haven't already.