Engine knock white and or black smoke under moderate to heavy load

Hello,

Engine/diesel knock accompanied with white or black smoke usually points towards bad diesel injectors. Possible sticky injector nozzle.

I would suggest to first trying some good quality diesel fuel additive, this could help clean the injectors and possibly reduce/stop the knock and smoke. As the engine only seems to knock under load while driving it will be difficult to establish which cylinder/s is the culprit

Cummins has officially endorsed a fuel additive, recommending two Power Service products, Diesel Kleen + Cetane Boost and Diesel Fuel Supplement + Cetane Boost. See picture below

The Diesel Kleen + Cetane boost is their injector cleaner, available from Amazon and local parts stores.

Please let us know if this helps.

Cheers, Boris