I just traded a 2012 2500 with 83k miles for a 2017 3500 with 38k miles. I have had the new to me truck for a week now and I have noticed an engine clatter, while accelerating, that sounds a lot like valves clattering. It also does it at the beginning of a cold start for about second. I noticed when I got on it not only did it clatter loudly but seemed to not have the power the 2012 did. The 2012 has the 6.7, minus the DEF, and it never made this sound. I purchased a B to B warranty for this truck from the dealer. So I should be able to get this repaired at no cost, if it is actually a problem. I have done some research and it seems other folks on other forums have been told by their dealers that this is normal. Before I go through them pissing me off, I would like to ask around to see if anyone here has noticed this and if there is a fix. Other folks mentioned the FCA (fuel control actuator) but this was on 2nd generation 6.7 diesels. Any assistance would be greatly appreciated.