excellent, same result as mineDealer removed aux belt and thump was eliminated. GM service bulletin authorizes no repair. So, Friday I will match the OEM aux belt to a Gates Greenstripe at NAPA. If no result, will replace tensioner. Til then.
or the geometry of the belt path -- multiple short, tight runs and a few runs that in comparison are quite longOn my truck, it is either the aux belt, the tensioner, or both making the thumping sound at idle.
I thought you knew that. Apologies if I didn't make that clear.