Fix it now. The passenger side balance shaft chain drives the oil pump as well, and if shifting the adjuster didn't quiet it, something is worn out. Kind of nasty to change yourself (lots of stuff to move) and hard to seal up tight, but it can be done ok by one guy who knows how or where to ask. Take out the radiator for working room and to protect it, and while it's out, have it flow tested and rodded. Best $100 you'll spend on the truck. Spokesperson owns no equity or debt interest in any radiator industry member....


Not responsible for advice not taken...