Pulley noise and replacement

So during a couple particular cold days I noticed that I would hear a vibration for just a few seconds, just long enough to notice it and begin pop the hood. Sounded like the front of the engine… like a pulley vibrating. I’m thinking possibly the tensioner or idler pulleys. It only lasted about 15 seconds each time then went away, so almost impossible to tell for sure what it was. Hasn’t done it since the temp has started to come up. It wasn’t a metal-metal sound, but more of a fast vibration… hard to describe… like “VVVVVVVVVVVVV…’ lol

I’m thinking of buying one of each, just to have in case… the way supply chain is anymore, I’m buying anything reasonable just to have, along with brake pads, rotors, etc.

Any brands I should look for? I see Delco professional..Dayco, a few others. Any thoughts welcome…

 

Get a mechanics stethoscope. I thought my pulley bearings were going out-turned out it's the alternator bearings.

 

100% the tensioner...buy OEM...the aftermarket versions are not worth having unless you enjoy doing the work yourself due to warranty claims...I've gone thru x3 AM in the last 20k miles and it seemed it always was exactly 1 year into install life...OEM (Dayco) is best...but they are not as cheap. God's speed...I'd buy several if you do AMb nothing wrong with that decision as long as you understand you'll get good at doing it yourself to not pay $150 in labotlr only...