Hey Scotty! I've got a 2008 Toyota Yaris Sedan with about 100,000 miles on it. I've recently replaced the original OEM serpentine belt with a new one from Toyota. This one does not squeal but when I accelerate from idle into first to second gear, there's an audible growling noise coming from the pulley system. When I shift into second gear the noise goes away and it goes back to normal. Also the serpentine belt pulley system does not have an automatic tensioner.
do you get the noise if you rev up your engine in park?
No, it only happens when I am in Drive
then it's drivetrain related, not belt or engine
I don't believe it is a drivetrain issue. That sound did not happen before I replaced the serpentine belt and I distinctly remember it being one of the first sounds I heard when I changed the belt to a new OEM Toyota belt. Possible bad bearing maybe?
take off the belt and you will see right away