I have a pulley bearing noise coming from my 87 xj and one I'm trying to rule out the alternator. I had the alternator checked at O'Reilly and it was good.

Is it possible for the alternator pulley bearing to be bad if the alternator checks out as good?

 

Sure, when the belt was off did you check everything else? (grab on to everything with a pulley & spin it, try to get it move sideways, etc.)

 

Should the pulleys spin freely with no resistance or should there be some obvious resistance?

I noticed my idler pulley spins freely with no resistance while the alternator and a/c clutch seem to spin easily but feel firm/heavy.

Thanks!