Whistle coming from under hoop

hey guys so I’ve been driving my truck recently it’s a 2016 dcsb 4x4 with 40000 miles and there is a loud whistle coming from under the hood area... I got out and had someone rev the engine and it either seems internal or is the serpentine belt. Wondering if anyone can help?

 

Try releasing tensioner, and remove serpentine belt, then start up truck. This will tell you if it’s an accessory bearing issue/ tensioner/ idler pulley , our internal engine issue.

 

Can you make a video and post it on here?

 

Vacuum leak ?

 

I took a video and tried posting but it kept giving me an error