LetMeTLYouAStory

Hi Folks,
2010 TL w/Tech, FWD.

I think I've got bad alternator bearings. But....
History:
Heard a funny noise. It doesn't QUITE match any noise anyone has posted online for any normal thing.
I posted about it. (I'm starting a new post because the old one is too old and too many red herrings to be useful now.)
Consensus reply was bad tensioner pulley. I replaced that--same noise.
With the serpentine belt off, the noise disappears. Back on? Noise.
With a long screwdriver pressed to the alternator housing, it feels/sounds like the smoking gun, but I'm not an expert.
No problems seen with the electrical system; no noticeable effects of any kind other than the noise.
I'll take any opinions, but I do have a specific question.
Many people seem to say if the alternator bearings are making a noise like that (i.e., failing), if I remove the belt and turn the alternator pulley with my hand, I should be able to hear something, or feel something a little rough, sticky, or grinding.
But no, it's as smooth and quiet as can be. Nothing.
If the alternator bearings are going, would I necessarily be able to detect it by turning the pulley?
Put another way, how likely or unlikely is it that it could really be the alternator bearings despite my NOT noticing anything when I turn the alternator pulley by hand?
Thanks!

csmeance

when you turn the bearing by hand there is no lateral load. The belt has a lot of tension and load on the bearing so that may be enough to cause the issue.

LetMeTLYouAStory

So I think you're saying that if it walks like a duck and talks like a duck, you don't necessarily have to notice an obvious problem when turning the alternator pulley by hand to know it's still very probably a duck. Right?

asb32952

I replaced the rectifier a few months ago and I have a little bit of a whining noise. Battery is charging fine though. Guy who owns the auto electric shop told me because the unit is so close to the exhaust manifold which obviously has a heat shroud around it it's not designed for the high amperage you can check my other post. So don't know if I have to go back into it and hope this helps you with your situation because heat is a killer. My 2001 CL still has the original alternator in it with no problem but it's half the amperage. He said the high amperage with the same basic outside housing was a bad call on the engineers Go figure they're both denso oem. Please follow up on your thoughts and what you did.
Larry's Auto Electric. Melbourne, Florida. Good dude don't abuse him.

LetMeTLYouAStory

Yes, in the end it was the alternator. Had the local mechanic replace it w/new Denso OEM. Noise gone, problem solved. Thanks everyone.