another engine knock post with video
 

yeah its knocking, bought it this way so i changed the injectors and swapped them around also delivery valves cleaned, swapped around and even swapped one from another vehicle, vac pump removed and bearings replaced, diesel purge and checked prechamber for ball in place i also adjusted the valves twice. next i guess is remove chamber and scope the cylinder.
any other ideas?

Steve

oh the video https://youtu.be/V2LBAhjPZQs

could be a loose crank pulley

bolts can loosen up on it

happened on my 240D and it made a similar noise

i will check when i can...thank you

Steve

Sounds like something internal to me. Since you've narrowed it down to #1 cylinder, if you drop the oil pan you'll be able to check the main and connecting rod bearings.

As another poster mentioned, it sounds like a connecting rod bearing that is going bad. Good luck!!

here is the prechamber in the cylinder making the knock after wet blasting for inspection, no plugged holes before blasting