Hi
I just replaced the alternator in my 87 4runner sr5 170k on the clock and now am have a whining sound coming from the engine when I accelerate. The belts are not too tight. After some research, I believe I found my problem. There is a bearing in one of the pulley's that is making the noise. Now I need to know how to find exactly which one it is. Do I have to take the belts off one at a time and go from there???
Here is a video of what it sounds like (not by me but same whine).

It's not that loud but still there.

 

You can pull one belt off at a time to find it that way. A mechanics stethoscope is cheap or use a long piece of tubing to listen to each bearing. Bearings can be easily replaced in the pulleys.

 

Might be the bearing in your rebuilt alternator.

You should not have to remove the belts just loosen them enough to get slack then feel all the bearings.

Loose belts will squeal as well

 

I know the bearings can be easily replaced, that's why I want to fix it. I wouldn't mind dropping the alternator, but I have to the drain the coolant again which I don't want to do plus it's my daily driver so I need the truck.