5.9 magnum knock on startup

[Gharve88]

Hey guys new to the forum.
So ive been having this issue for quite awhile now and cant pinpoint the problem. I have a 97 ram 2500 with 5.9 magnum, when its cold and i start it, it knocks for a couple seconds then goes away. Its pretty loud also. I cant tell if its valves, rod bearings, or something with the plemum. Any advice would be appreciated
Thanks

 

[AK12MN]

Have you tried thinner oil? Sounds like its taking a while to coat the lifters.

 

[dapepper9]

Don't run thinner oil. If anything, run a cleaner like a half quart of Marvel Mystery Oil through for 3-500 miles and then change the oil