06 N62 E53 keeps eating drive belts

[johngrefe]

I can't imagine the extra 2mm making a big difference with the spring loaded tensioner, but maybe it does have an arch while running.

I've basically overhauled the Truck. It was used as a company vehicle and serviced by an indie that really didn't know much about much.

So i've done
Coil Packs
Plugs
Valve Stem Seals
Gaskets
Fuel Pump and Filter
Heater hoses
Water Pump and Thermostat.

When I took the skid plate off there was some curled up bands of drive belt. I have a 6pk1548 that I took off at the start of the job with one rib missing that seems to run fine. I used it to idle the car for about 45 mins bleeding the cooling system today.

I ate one 6pk1550 with about 2 mins of run time, and figured the failure was due to a bad idler wheel on the alt. Replaced idlers and got another 6pk1550 in. This one lasted just about an 1/8th of a mile and back. The AC drive belt is happy, so I'm thinking the crank pulley isn't wobbling, will inspect surfaces of other pulleys for wobble / knarling obstruction as suggested right now.

Thanks!