Hey all. I have a '14 2500CTD with 5,600 miles on it. Just over hte last few days it has started to tap in the morning when cold. It is most noticable @ 1,200 rpm and the tapping is linear with the RPMs...which has be thinking valve, injector or exhaust leak (really not sure...just guessing). Frankly, I'm afraid to take it to the dealer...they don't seems to know much about the truck. It's not the standard diesel clatter. Its a new noise and it goes away after 5 minutes when warmed up. No power loss; just a tapping noise (I don't think its the DEF pump either). Any thoughts or experience with this? Thanks.