I’m new here and I have some questions.

[Waterloo]

Your crank shaft damper too, Cummins recommends that be replaced every 500,000 miles. The damper is that big disc on the lower front of the motor. There is a viscous fluid in it, almost like a silicon jell, it hardens over time and looses its ability to properly balance out the crank shaft. When they start to fail, belts will pop off and components like the alternator and AC compressor can be damaged. There is no way to physically inspect or test one, it is just one of those parts that needs to be replaced at the recommended interval. And they can fail catastrophically, like blow apart. Don't let it get that far. There are photos here somewhere of one that did just that.