Finally Scored...

[Billrog]

Had an injector knock develop on my dump truck sounded like a rod hammering was told to take the fuel filter off fill it 1/2 full of sea foam so gave it a try and the hammering stopped. Also added reslone to the oil because the hammering started right after an oil change with shell rotella ( which I won't be buying again) though many seem to swear by it.

 

[Plongson]

Another thought, with the apparently new injector pump, there must'a been something going on...Could/Can someone screw up the install/timing to get a symptom like i'm seeing...like it was one tooth off? that would cause this hammering.

Listening to it, it sounds like it's from the top end...It's more high frequency rather than a dull "THUD" like a FU'd rod. I recorded the sound but it's difficult to discern from the video...

I'll post the video later...

 

[check]

Sometimes detonation can sound like metal to metal. Like someone left a socket in the cylinder. The cylinder that's knocking can be the next one in the firing order carrying the load which the weak cylinder dropped. You can also take a large screwdriver and hold the handle to your ear and touch the tip against each cylinder and injector to get clues.

It can be tricky to locate problems by sound in person and harder on the internet. One time I told a friend his truck sounded like it swallowed a valve. It turned out a piece of exhaust gasket at the exhaust port fell out and the exhaust hammered a piece of tin heat deflector, LOL.

 

[Plongson]

Hard to tell anything from this YouTube, but here it is anyway...

https://www.youtube.com/watch?v=cdQpE_U5A78

 

[Plongson]

Ok, Cracking the fuel lines to each injector they 2-4 made the engine slow with a noticeable change. The front cylinder had no change at all. Pulled the injector and will get it tested tomorrow, anything else to consider?

Wish I had a bore scope to look down the hole...

 

[Oliver W D]

Ok, Cracking the fuel lines to each injector they 2-4 made the engine slow with a noticeable change. The front cylinder had no change at all. Pulled the injector and will get it tested tomorrow, anything else to consider?

Wish I had a bore scope to look down the hole...

Google "android borescope" works with smart phones and around $25

 

[lantraxco]

Or Harbor Freight, they sell some inexpensive ones.

 

[check]

Ok, Cracking the fuel lines to each injector they 2-4 made the engine slow with a noticeable change. The front cylinder had no change at all. Pulled the injector and will get it tested tomorrow, anything else to consider?

Wish I had a bore scope to look down the hole...

You could also swap injectors into different cylinders and see if the problem follows the injector.

 

[Dirtdauber]

If the plastic bushings are worn out and missing from the hydraulic pump coupler at the front of the engine, the noise you will hear is easy to mistake for a bad engine. I know of one tractor that was sold for that reason. May not be your problem but might be worth looking at anyway.
I really couldn't tell much from the video.

 

[Plongson]

Google "android borescope" works with smart phones and around $25

Huh, I had no idea that was available. Pretty cool and cheap, I'll probably order one!

On a side note, I'm heading the the JD dealer for an injector but I brought the piston up TDC and hit it with air and it pushed the piston down, so that's a good thing...At least there isn't a hole in the piston...

Really counting on this being a fuel/injector problem...and not a rod! I'll give a follow up later.

 

[lantraxco]

Those engines I believe have balancer shafts with bolt on weights, could be something there coming loose and wanting to get out also? If the injector doesn't help it's probably time to pull the pan off and look around.

 

[Plongson]

Ughh, no injector...they had to order it, be in on Wednesday. Oh, they tested the injector and it was firing and dribbling at 3200 psi. Spec is 3600.

 

[lantraxco]

Dribbling is bad, cross our fingers this is your problem! :yup