I posted this on a differand site
A few weeks ago I was readng a thread about a tapping sound coming from the top of the engine. I had the same problem!

So I tryed most of the sugestions, use injector cleaner (4 tanks of fuel ) no change. As one of the guys said to clean the deposits from the injectios to drive it like I stole it still no help. The noise now has went from a tap to a rattle in about 1300M.

Drove from Houstion TX to South AL(600+M) while there took it by the D/S they said it needed a valve adjustment. After adjusting the valves the rattle was still there they said it could be a bad injector and couldn't check it due to equipment problems.

Drove back to Houston (600+M) took it by a Cummins dealer to busy to lissen to it. #@$%!Drove home to South LA. (300M) now the rattle is now a clatter/knock. I have family that work for Southland Dodge in Houma LA in the race shop. So I took it there the head mechanic is the diesel diagonostic tec and checked the valves and injectors all was OK. He used a listening device they have on the block and come back with bad news. The noise was coming form the wrist pin or a rod bearing. The cost for the repair was going to be around 4500. 00 to 5500. 00:--) :shocked:if the cylinder and crank was OK. Not wanting to spin that much money on an 03 truck I traded for a 08 2500 6. 7. So far I have have driven the new druck aboud 3000m and happy with it but I sure wanted to keep my 03 it was paid for. :{ Now I trying to find out what mod's I can do to the with out busting my warrenty The stuff I had on the my 03 don't fit the 08
For all ya'll with engine noise tick or tap Good Luck!!!