Is this the sound of a bad alternator?

no that is still the sound of the belts... specifically the alt belt i had that same sound after i replaced my alt and didnt notice the belt was not sitting on 1 of the pulleys correctly which was causing that chirp
 
If that isn't the bearing inside the alt you may not have the belts tight enough. I hate the belt tensioner setup on these cars, they are too easy to over-tighten and ruin bearings. A normal tensioner is so much easier to work with
 
Yeah, has me missing the tensioner setup on my old Celica for sure. I'll try tightening it up.
 
I'm on my fourth alternator in four years. The bearing crapped out on two of them,... the guys at the garage over tightened it. The alts. were replaced under warranty but they charged me $180 each time for labor. I do my own labor now and keep my belts as loose as I can. The belt still squeals once in awhile at startup but I turn off all electrical loads until it stops, then turn stuff back on again.

The alt pulley is really small and the belt doesn't make much contact with it. I've seen cars using idler pullies to wrap the belt around the alt. pulley better,.. much better design.

A squealing belt can become glazed and start squealing even worse. New belts are nice and grippy. A lot of people here like gatorback belts.
 
Yeah, this vid is with brand new gatorbacks on... Why I was suspecting the alternator bearing.
 
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The easiest way to check your belt is to reach in half way between the alt. and water pump pulleys and twist the belt. You should be able to turn it upside down. If you can only twist it sideways or less, it's too tight. It's too damn tight in there to try to see a ruler while trying to judge 20 pounds of pressure.

New belts always stretch,... there's different specs for new and used.

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if u didnt have the noise before belt change then like i said earlier recheck the belt and make sure it is sitting on the pulley correctly in my case it was the waterpump pulley it was not sitting on corectly.. it was off by 1 groove
 
Well I was able to just turn the belt over with effort when I installed them and that's roughly where it still was. But I went ahead and tightened it up a little more and the squeak is gone.(yippy) Now it's more like 3/4 of a turn over with some effort. If the space wasn't so cramped or I had smaller hands it probably would be a full turn though.

The engineer in me really loves such a precise measurement method lol.
 
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Just an FYI,....

I have found that if I've used anything electric on the car with the engine off, the belt will squeal the next time I start it up. Even just putting my windows up and down a few times or having the radio on for a while is enough to cause a squeal at startup.

I have found that if I turn off any unnecessary electrical loads (radio, rear defog, interior fan, etc.) a few minutes before I intend to be shutting of my car then the battery is in a fully charged state when I shut it off. Then the car is a lot less likely to squeal at the next startup. It also helps to turn off electrical stuff before starting the car then waiting half a minute or so before turning them on.

If the battery is a bit low at startup, it can draw enough current from the alternator to cause a squeal.

I also did this "mod" to help keep the battery topped up. It's wired into the interior dome light. (one power wire in the light switch has constant 12V so the solar panel will charge with the key out)

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I could just tighten up the belt a bit more but I'm really hesitant to do that after going through two alternator bearings.
 
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