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Discussion Starter #1
I have been having (as many others have) an annoying engine knock. Mine occured only at idle and only after the engine warmed up. I read on another site that there has been success in getting rid of the noise by retiming the cp3. I tried it and I am happy to say it seems to work. :woot:

First off there are different causes for an engine knock, mine was a metallic sounding knock from the front left side of the engine. To change the timing is pretty simple. First remove the belt from in front of the access hole on the timing cover in front of the CP3. This will give you access to the nut that locks the timing gear to the CP3. Remove the nut and washer behind it(being carefull not to drop either inside, doing so will require much more work). Next you need a puller, steering wheel puller or small T bar will work to pull the gear loose from the CP3. Depending on how much dexterity you have you may or may not need to remove the upper radiator hose and bracket under it, in order to attach the puller to the gear. The fan is in the way of a standard length pusher bolt so I cut mine off, if you dont want to do that you can remove the fan. With puller installed and pusher bolt in place remove the gear from the cp3. The gear is a taper fit with no key way, so once the gear is loose all you have to do is rotate the engine to retime the cp3 in relation to the engine. I did mine twice before I found the magic spot, but it ended up about 60 degrees from where it was. Once you have rotated the engine re-install the washer and nut and torque to 77ftlbs(I used a ratchet on a dampener bolt to keep the engine from turning). Pictures are available in the service manual and will give you a good idea what is involved. It took me about 30 minutes to perform this procedure and I'm happy with the results.

Why does it work, well it seems that the cp3 being a piston pump behaves just like an engine, it takes force to push the piston on a compression stroke, and then after TDC it tries to spin faster(or easier) until the next compression stroke. When the engine is doing its compression stroke at the same time the CP3 is on its return stroke it can cause the gear teeth driving the cp3 to loosen and then slap back into contact causing noise. :CRY:
 

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That's very interesting :popcorn:
 

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Ive been trying to figure out, what the hell was making that hollow rap (knocking ) sound for months.
Ill put that on my list of things to.
thanks ,doug
 

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Hmm, anyone else try this? May help many with the "mystery knock" that seems so common but isn't injectors etc.
 

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Discussion Starter #7
I'm not saying it's everyone's fix, but it certainly fixed mine. On a side note you might be able to turn the pump instead of the engine, but that would most likely require removing the upper radiator hose in order to get a good enough grip on the pump shaft, I could barely get 2 fingers on the end of the shaft so I didnt even try to turn the pump itself.
 

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my truck makes this same knock. i plan on doing this tonight. i had a new cp3 put on by the dealer and i am thinking they did not get the pump and motor in time with each other. the very night i picked it up, my truck made this knocking noise, called the next day and they said a diesel knocks normally. basically they didnt understand that it was a different knock than normal and it started the night i picked it up with the new pump on it.
 

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I have noted the same sounds but blamed it on the ulsd fuel. noise started at the same time. sounds like I need to check
 

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MTHISGUY, can you provide use with more detailed destructions on this topic please. it would be much apprietiated:thumbsup
 

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Discussion Starter #11

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thanks. but how do you know when you are at 30-60 degrees. or is it when you can start the motor and the knocking is gone. sorry for my lack of intelligence.

The link does not work also.
 

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Discussion Starter #13
Dont know why the link is messed up, but it's in the 3rd gen tech forum. Perhaps you need someone to help you do it. Or pay the dealer to do it for u, shouldnt take more than 1 hour.
 

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It is an event issue, the CP3 contains pistons and springs, as it is a rotary pump, the sound is backlash from the timing gears. You will be putting the injection pump into a preloaded relationship, in reference to the timing gears. This works and will make the tapping noise disappear!
 

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I did this to mine and no more knock. engine sounds a lot quieter at idle now.
Thanks mthisguy for posting this.
 

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Discussion Starter #16
Glad I could help.
 

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I assuming that you guys are eye balling the degree's. Can there be any ill effects if you only move it 5-10 degree's ?
 

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Discussion Starter #18
No the timing only changes the amount of backlash in the drive gears, doesnt change the engine operation at all.
 

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I understand that it doesn't change the timing of the pump. Why do you have to rotate it 30 degrees ? Why can't you just move it 10 ? I haven't had a chance to try this yet but how much play is there in the gears ? .015- .020" of an inch ? Is there any way just to turn the gear until the teeth of the gears are in constant contact to get rid of the play ? I asssuming that if you rotate more then 60 degree's you can't hurt anything. Thanks.
 
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