I've been hearing a funny sound when i crank up lately. only thing I physically see is that my tensioner pulley is kinda shaky. I took a vid.



listen for it and you'll hear it. and you can see the tensioner shaking

 

Heres an easy test solution,, loosen the tension of the belt off that tensioner pulley and while the belt is`nt touching spin that pulley by hand and also try to move it side to side listen for noise or any movement, the bearing inside of them can go bad mine did, and the pulley is available at "advanceauto"... Good luck with it.

 

tensioner should have some shake to it as its spring loaded, take the belt off and spin all the pullies by hand, feel for play and rough rolling resistance.

 

Could also be coming from the alternator or compressor bearings but I would suspect a pulley.

 

It's the tensioner or idler or compressor pulley bearings. Take belt loose and spin them. If they 'sing' and have any wobble at all replace them.
The Compressor pulley, I suggest replacing entire clutch assy. Big can of worms if you havent done it before.. and not worth trying to save the 80 bucks difference, becuase the clutch does wear and prone to crack when it's over 100k. Been there.

 

Dude you video is a good way to loose a couple fingers!!!!

If you blip the throttle/cable cable and rev the engine and the tensioner "dances" after it returns to idle, the tensioner has reached it's life span.
those things last 30k miles....at least from the auto parts stores...

 

start replacing... easy fix... yank the two pulleys and see if its still there after you replace them....