I remember on the ambulances, swapping a different tensioner in with a big damper on it.
I'll get a pic of it later today so you guys can see what it looks like. I can make a short vid of it running too. My belt is all bobbly now. I may have a new one in the garage still.
A shorter belt seems to have solved the problem.
All pulleys measured close to spec and are aligned as close as I can get them.
The tensioner is the updated one.
I can't figure out what makes my serpentine drive want a shorter belt but that's what I'm running.
The indicator pointer is where it should be so.....