Does this sound like a bad alternator?

[Aleman]

Only after more than a half hour of driving, the engine starts making this loud grinding noise, and I suspect it's the alternator. Before removing it, I'd like to get your opinion. Maybe you've heard this before, and it turned out to be something else. I'm 99% sure it's not the water pump or power steering pump. I used a mechanic's stethoscope to listen to various components under the hood, and it seems to be the alternator.

Are you aware of a way I can diagnose the alternator w/o taking it out? The thing that's really throwing me off is that doesn't make noise till the engine has been at full operating temp for quite a long while.

Give a listen:

https://www.youtube.com/watch?v=wGXJqjJzwKE

THANKS for the help!

[roguetoaster]

Sounds like a bearing making noise.

As far as diagnosis, I'd drive around with no PS belt for a bit to rule that out, then I'd return home with the car at op temp and remove the main V belt and run the car for a very short duration to see if it is in fact related to a belt driven accessory.

Only realistic thing I can think of would be expansion causing a bearing to get wobbly, but it seems like a very long duration for that scenario.

[Aleman]

Sounds like a bearing making noise.

As far as diagnosis, I'd drive around with no PS belt for a bit to rule that out, then I'd return home with the car at op temp and remove the main V belt and run the car for a very short duration to see if it is in fact related to a belt driven accessory.

Only realistic thing I can think of would be expansion causing a bearing to get wobbly, but it seems like a very long duration for that scenario.

Thanks! I'll give that a shot next time the noise happens.

[varg]

If you can, pop the accessory belts off one by one when the engine is hot and making the noise to make sure it isn't the timing belt tensioner.