Valve lash adjustment

**ywgbandit** · 11-07-2014

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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**Polaraco** · 11-07-2014

Yes that is true. However it's not the relationship that causes the noise as far as I know. It's the constant hydraulic pounding on the pump drive chain which causes thousandths in looseness in the pump drive train. I can't see where changing the relationship can matter.

I thought about that in the beginning of this. Don't remember if I said something or not.

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**Rockwerx** · 11-07-2014

Both of my 6.7s had a lot of clearance for the valves (way too much IMO and the specs were different for all of the valves...poor quaility control). I adjusted my deleted 2008 Ram 6.7 to 5.9 specs... I .010 and E.020. It was a lot quieter and it performed a lot better after the adjustment. I am going to do the same specs for my 2012 Ram as soon as I delete it.

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**ywgbandit** · 11-07-2014

I just completed my valve lash adjustment and it's no wonder it was making so much noise. Let's just say the clearances were generous from the factory. I went with .010" intake and .022" exhaust. on my deleted 6.7 and it's much quieter. Doing #6 is a *****!!!! Tomorrow I install the Edge Insight CS gauge with the pyrometer and get an idea as to how this baby is running.
Again, I would like to say thanks to all who made comments & observations....This is a very helpful forum and your assistance is appreciated!

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**ywgbandit** · 11-08-2014

Originally Posted by Polaraco

Yes that is true. However it's not the relationship that causes the noise as far as I know. It's the constant hydraulic pounding on the pump drive chain which causes thousandths in looseness in the pump drive train. I can't see where changing the relationship can matter.

I thought about that in the beginning of this. Don't remember if I said something or not.

On the other forum they said that moving the relationship of the pump drive to the crank 60 degrees almost always gets rid of the biggest part of the noise. If it doesn't they say to repeat the procedure another 60 degrees and it will. It gets rid of a harmonic that exaggerates the noise. It requires the use of a puller and barring the crank shaft, but it looks like tight quarters.

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