This truck can in very low compresas cylinder 4 and 6. They were at zero compression, number 5 was at 63%. It’s always important to check compression before and after your valve adjustment.

We have seen a few intake manifold gaskets blown out due to excessive pressure because of valves not being adjusted regularly. I recommend valves be checked and adjusted if necessary at every 100K to 150K miles for the DD13 and DD15 engine. These are definitely not your Series 60 engines. We need to adapt to keep these engines running longer.