Bought a truck from A big fleet.

Aren't we all conduits for money, with the government at the receiving end?

 

An idler pulley locking up will make noise for all of 10 seconds while it seizes and burns through the belt. If you're pulling a hill or yakking on the CB, you could easily miss it. Last (and only!) time I had it happen was on a Detroit Series 60, and my only tip off was the temp gauge skyrocketing into the red giving me enough time to get off the road from the granny lane before the warning light came on. Entirely plausible, can't catch in a pretrip without slacking the belt and fooling with the pulley by hand, and unless you carry a spare tensioner and belt it'll sit you down waiting for road repair or a parts runner for a few hours.

That being said, I'd be extremely wary of buying a truck where maintenance records were unavailable or refused, unless I was buying a project or an antique. A working truck, no records no sale. I want to see what else was done by whom, and when.

 

While my series 60 has v-belts and therefore no tensioner, it is an important and integral part of my pre-trip to start the engine before I close the hood. That way I can inspect and listen to all of the whirly bits whilst they're whirling so I can spot or hear any major issues or leaks. Even if you don't unload the tensioner to inspect it, you can see and hear that it's got problems long before it gives up for good.