I had the same problem with my 2008 Dodge 2500 6.7

Every now and then no reason, engine sounded crazy, like a loud valve knocking.

Also had problems with the dpf, not regenerating.

several trips to the dealer, no fix.

My father is still driving a 1993 5.9 no prblems.

So after much research,

I deleted the DPF filter.

Smarty JR.
and straight pipe.

A totally different truck. More power and around 3-4 more mpgs, depending on how you drive it.

Hard part is staying off the pedal.