[Johnc]

Bill,
Your post is very clear & I understand the tensioner movement issue. I asked about tensioner replacement because on my Country Coach with the Cummins there was a mileage checking and replacement recommendation. I don't have the auto belt tensioner on my DD.

From Newell's generic PM sheet:

Every 12 months-
Check belts, hoses, engine, generator and blower motor".
Inspect fan idler pulley, hub and belt tension

Every 2 years- Change engine belts

Cat C-12 engines are very rare in Newell coaches. I can recall Ward Burton driving a Caterpillar supported race car in 2003, and Cat supplying us with a special C-12 engine for his coach (653). Fabick Cat would have provided all the engine accessories, as we were using Detroit Diesel as standard in 2003.

I have not seen any mileage recommendations for idler pulley replacement.