Bad alternator OAD pulley bearing. Have someone shut the engine off while you watch the spinning windings inside the alternator. When the engine shuts off, the alternator pulley decouples and let's the alternator keep spinning. That's when this bearing starts spinning. The failing bearing is what's making the noise.

You should see the alternator speed and noise pitch match each other as it stops.

 

Bad alternator OAD pulley bearing. Have someone shut the engine off while you watch the spinning windings inside the alternator. When the engine shuts off, the alternator pulley decouples and let's the alternator keep spinning. That when this bearing starts spinning. Thee railing bearing is making noise.

I'll check it out, thanks. Could this potentially have been caused by the mechanic when they worked on the timing belt and water pump?

 

No I don't really think so. My failure was actually on a relatively new Alternator for no apparent reason....and timing belt job doesn't touch the alternator (though anything is possible).

If this IS YOUR PROBLEM and your alternator is newish, you can replace just the pulley following this thread: https://www.odyclub.com/threads/diy...-acura-oad-alternator-pulley-change-in-car.378249/?post_id=2596666#post-2596666

If your alternator is old, you may want to replace the entire thing (Denso remanufactured).

 

Don't replace the alt until you're sure that is the cause of the sound AND yes, if you do replace it use a Denso remanufactured one (or new one $$$$) as 94eg! suggested.
Buffalo4
PS: That is an unusual sound for me.
PPS: If it is the pulley, follow what 94eg! says in #4. (edit)

 

That wooshing sound is "normal"

Others have posted it here as well.

 

The sound at the end when the engines off is not normal

 

The woosh/sucking sound from the intake as the throttle looses vacuum is normal. However that other descending growl is exactly what my failing OAD pulley bearing sounded like.

The noise only appears when the engine stops, but the alternator is still spinning.

 

now you know what to do...

 

If you don't mind, I added a link to your video at the the beginning of my thread (crediting you of course).