So I read on another forum that this CP3 "knock" is fairly common on the 6.7 and it can be quite loud. It is in fact a harmonic between the CP3 pump piston and the engine. Apparently there is a procedure for removing the pulley from the pump and rotating the crank shaft 60 degrees and reinstalling the pulley: Here is the info from the other forum:
Cliff notes version:You are not timing or changing the timing of anything. Well, not as most people refer to timing on engines anyway. What you are doing is changing the relationship of the CP3's plunger stroke to the engine's piston stroke. You will not change injector timing by doing this. The injectors are not timed by the CP3. The CP3 just feeds fuel to the rail, and it will happily do it with its plungers in any relation to the engine's pistons. Actually, it's that relationship that causes the noise. I do not know what situation in that relationship causes the noise but in certain circumstances, the noise occurs...
So my question now, is it just a harmless harmonic noise that is irritating, or is it a potentially damaging vibration that will take it's toll on the CP3 over time and needs to be addressed?
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