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Junior Member
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8 Posts
Discussion Starter #1
Okay guys. My 02 is giving me the run around with a knocking sound. Everyone swears it is an injector stuck open and what I was hearing was fuel knock (loud). I have done a lot looking to fix this sound. I can unplug the #3 injector and the knock goes 70% away. Unable to really hear if from an open valve cover or the top of the motor. Plug it back in and the sound comes back to full volume. It seems like I have narrowed to cyl #3 but NOT the injector (replaced it anyway...twice). It isn't loud enough to be a rod knock (doesn't sound like someone hitting the engine with a hammer...) What can be my problem when there is combustion the noise is louder than when there is no fuel being added to that cyl???? Anything will help. Probably have tried it but?
 

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Senior Member
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101 Posts
could be a lifter, but that's more of a tapping sound idk though worth a shot.
 

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Junior Member
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8 Posts
Discussion Starter #3
are the lifters in the head? Wouldn't any other problem other than piston, rings, etc be in the head? So if I found a good head somewhere and changed them, that would be valves, rods, rockers etc. I am about at that point. This noise drives me crazy. IT runs great. I have never changed a head. I would probably have someone do that....
 

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Junior Member
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8 Posts
Discussion Starter #5
That is true. But the noise mostly went away when I unplugged the injector while the truck was running. I even changed the injector....again.
 

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Junior Member
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Discussion Starter #7
hayjay.. I would think that would be a louder knock and get louder with RPMs. My knock is the same volume and eventually you can't hear it because the engine is too loud.
 

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Junior Member
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3 Posts
Okay guys. My 02 is giving me the run around with a knocking sound. Everyone swears it is an injector stuck open and what I was hearing was fuel knock (loud). I have done a lot looking to fix this sound. I can unplug the #3 injector and the knock goes 70% away. Unable to really hear if from an open valve cover or the top of the motor. Plug it back in and the sound comes back to full volume. It seems like I have narrowed to cyl #3 but NOT the injector (replaced it anyway...twice). It isn't loud enough to be a rod knock (doesn't sound like someone hitting the engine with a hammer...) What can be my problem when there is combustion the noise is louder than when there is no fuel being added to that cyl???? Anything will help. Probably have tried it but?
Have you figured out where the knock is coming from? I have a 2003 7.3L that is experiencing the exact same knock you are describing. My shop narrowed it down to number 4 cylinder. Compression test reveals 380psi for suspect cylinder and 390-400 for others. They replaced my #4 injector and I still have a knock in motor. I still and not convinced of bearing issues because i drove 600-800 miles on the truck so far, I even pulled a fully loaded 6-horse trailer from Virginia to New Jersey and no change in the knock.
 
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