Investigation: "new" engine sound

So I fixed my initial problem a few days ago after waiting to fix it for weeks (actually a few months due to being busy with other things) where my engine was giving off a high-pitched squeal:
https://www.tundras.com/threads/engine-whine-especially-when-revving-up-low-voltage-meter.9960/
..the problem was a bad supercharger idler pulley bearing.

Now, I'm onto the next sound, which I honestly don't remember being there or not before the squeal started. It only happens when I shut off the engine. Here's a video of what it sounds like..

https://www.youtube.com/watch?v=j0yEQtJUffU&feature=youtu.be

Again, the sound isn't audible with the engine running and the hood popped.

 

Sounds like the fan clutch or bearings bud

 

I'm leaning fan clutch assembly/bearings...only because that thing still spins pretty good (3-4 seconds)after engine shut down

 

Mine has been doing that since I drove off the lot.

 

Mine does the exact same thing. Normal.

 

Mine doesn't do that....but my secondary air injection pumps have been disabled. I suspect that's what you're all hearing. See if you can localize it in the front passenger fender.

 

Mine makes this noise and it only has 400 miles on it. My wife's 4Runner also has made this noise since new.