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Discussion Starter #1
I have a knock in my 94 idi turbo truck that I cannot locate. I have replaced the injectors with new BB code injectors. I have used a mechanics stethoscope and anywhere I touch on the motor with the exception of the oil pan I hear the knock.

Truck is a 94 IDI factory turbo with 169000 miles with a rebuilt injector pump and new injectors.

http://youtu.be/5J-JXwmphE8
 

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"new" injectors? From where? I've gotten new before and it made my truck knock worse then running the old pair. I'd pop test them
 

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Discussion Starter #3
I got the new injectors from fleabay still in the box and plastic. Should I crack the injectors again. I have noticed that I make more power with the new injectors than before. Also I noticed that when the truck is cold the knock is not as noticeable but when it warms up or the rpms come much above idle the knock comes back.
 

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because its not a "knock". Its just diesel ping, which is normal and probably more noticeable because of the new fuel system. You can retard the timing a little bit to try and make it go away if it bothers you that much, but it sounds completely normal to me. Also, fuel treatment like Power service will help get rid of any pinging being caused by poor fuel.
 

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to save yourself all sorts of problems diagnosing... loosen your pump nuts up, and with it idling, retard the timing and see if the "knock" disappears. My bet is that it will.
 

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Have you checked your flex plate? When they crack they sound and knock similar to a bad bottom end. Also changing the timing when it is running can and will put the pump gear out of line this is no gasser. It can also damage the internals of the injection pump as I've been told by my local stanadyne injection shop. So only adjust timing when its off.
 

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Also changing the timing when it is running can and will put the pump gear out of line this is no gasser. It can also damage the internals of the injection pump as I've been told by my local stanadyne injection shop. So only adjust timing when its off.
Please do not take this personal, but that is complete rubbish.

Is it possible to cause this damage? Yes, but you would have to try to mess it up.

The local stanadyne shop is going to tell you this because there is people out that are probably dumb enough, or mechanically impaired enough to do this.

loosen bottom two nuts, then you loosen the top nut just enough so the pump can rotate. This holds the pump perfectly in place so the gear does not wonder back and forth. I think that is pretty obvious that you would not want to loosen the nuts to the point that the pump can wobble, which even if you did pull the nuts that loose, would be difficult because the seal does a very good job of holding it, as well as the injection lines.

As for rotating it while running being able to cause damage to the internals, impossible if done the way I just described.

I get it, you're posting "by the book", but there is nothing wrong, or dangerous about adjusting it while running. Its much quicker to tune it by ear this way, and it allows you to observe real time visual and audible differences when tuning by ear and eye.
 

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Discussion Starter #10
Here is a link to my truck running when warm after retarding the timing a dimes width. This puts my timing back to the factory marks. From behind the truck you can really hear the knock.

http://youtu.be/1xddI3U7lRg
 

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Discussion Starter #12
this was the reason for changing the knock. It may be a little louder now with the new injectors. Maybe I am more sensitive to the sound. It has me worried.
 

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I think you're over thinking it... it sounds completely normal to me.

Are you having any smoke issues?
 

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Discussion Starter #14
it does put out a puff of black smoke when starting now. It did not smoke when starting before the injectors. It also smokes less at WOT now that I have retarded my timing with the new injectors. My pump is turned up two flats.
 

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Discussion Starter #16
no there is no smoke at idle. The one thing I have noticed at idle when starting the truck now it is a little rough for a few seconds like maybe an injector is leaking off a little. Before the new injectors it always started smooth and never idled rough.
 

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I hear the knock, the part that gets me is how loud it is at idle. As for the injectors, iirc you got them off fleabay, i would have them pop / leak down tested.
 

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Discussion Starter #18
Before I changed the injectors it sounded about the same and the injectors had 168000 miles on them. I think I will pull them and have them tested. The only thing is I don't know who to take them to.
 

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i would think that any local diesel shop would be able to do that for you. I think its like 10-12 bucks and injector.
 

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My truck has had a similar sounding noise for 100k or better. I finally diagnosed mine as oil getting into one cylinder via cdr. Try running a rdt for awhile and see if the sound clears up.
 
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