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Discussion Starter #1
Hi this is my first post on Diesel Place. I recently purchased a 2003 Silverado Duramax. The engine has 130000 miles on it. It appears the previous owner did a good job as far as service goes. The truck never had a tune on it. I have all the service documents and when I replaced the injectors the internals of the engine was spotless. I replaced the injectors not long after I bought the truck due to the haze coming out of the exhaust as well as mileage on the truck with original injectors. The problem came after I replaced the injectors. The engine developed a knock ranging from a tick to very noticeable and annoying while driving on the highway. I recently borrowed a friends EFI Live and discovered the knock was coming from the #8 cylinder. What is most likely to create this knock? I am trying to determine if the most probable cause would maybe be the copper washer not sealing properly (cup was very clean when injector was installed). Or maybe injector failure or etc. I have another injector on the way but if someone could tell me it is most likely not the injector and to look at something else I would consider this before buying the injector. The engine did not knock prior to changing injectors.
 

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You didn't use Pensacola remans did you, It sounds like you have a bad injector....
 

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No I did not use Pensacola. I used one of the more reputable vendors mentioned on several sites and they are working with me but I do not want to get into any names. I just want any thoughts as to if everyone thinks it is most likely the injector or possibly something else.
 

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It does sound like a injector in my opinion. Let us know what you find.
 

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put your finger on the injector lines with it running. you should feel the line jumping up and down if the injector is loose it sounds like you describe. any combustion gasses in the crank case? that would be a dead give away.
 

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Discussion Starter #6
Last weekend I received a new injector. However when I pulled the #8 injector out it felt like the hold down clamp bolt was somewhat loose (at least not 37 ft/lbs tight). When I removed the injector and inspected the copper washer it was evident that there was some leakage across the washer due to color. Therefore I cleaned the cup out put on a new copper washer torqued hold down bolt to 40 ft/lbs and rechecked torque on the other 3 then reinstalled the existing injector. I did not get to drive it any before my brother inlaw called and I had to make a 200 mile each way road trip to get his truck. When we started out the truck did seem quieter but once we got on the highway I could here the noise again. About half way home with his truck loaded (total weight around 13000 lbs) and a 20 - 30 mph head wind the noise all of a sudden stopped. I did not drive the truck again until this morning and it is much quieter but the noise is still there. I am going to put the EFI Live on it again to make sure it is still #8. If so I will change out the injector this time. I did have some blow by but do not remember what it was like before replacing the injectors so I have nothing to base it off of. Thanks for all of your input. I will let you know what I find.
 
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