Hello everyone, i have a question for all of you knowledgeable folks..
I have a 2001 F-250 7.3 Diesel.
It is an auto trans
It has 315,000 miles and i drive it every day.

So the other day i wad driving down the road, with my empty gooseneck, and a slight tick caught my ear. I kinda thought nothing of it, but by the time i had got home it turned into a full on knock. My truck has missed once in a wihle, so i was expecting a fuel injector to fail some time soon. I thought okay, time to fix this thing. I got a stethoscope (long stick) and put it all over my engine, and valve covers, and jammed it against my ear. I could hear that the knock was obviously coming from the drivers side, near the front of the engine. So yesterday, i pulled the valve cover on the drivers side, and started the truck. One by one i pulled the wires from the injectors. When i pulled the wire from the front injector the knock completely went away (it just missed, but no knock).
I thought allright, got it. I went down to the autoparts store, and bought a new injector. Slapped it in there, and bang, bang, bang, bang. I thought that maybe the injector still had air in it or something, so i let it run for a few minutes, and nothing changed at all.
I then assumed that possible i had purchased a dead injector, so i swapped the new one for one of the others, and same scenario. So.... I then pulled the rocker arms, both intake and exhast, and checked for obvious damage on the push rods, the rocker arm pockets etc.... Nothing, they still look new.
The only conclusion that i have come to is that there is a bad rod bearing, and when that cylinder is firing, it is causing the connecting rod to hammer on the crank. To me thats the only thing it could be... Im aware of what a ******* of a job getting the oil pan off can be. So im realling hoping im wrong. If anyone has any clue what it could be, let me know.

PS ive got brand new delo in there, new oil filter, new fuel filter, etc.

 

Yuck.

To me it sounds like you have nailed of down. For the life of me I can't think of anything else that would produce what you are describing other than something in the rotating assy. The fact it gos away when you kill that hole is pretty telling. We don't hear of bad rotating assembly's very often but that being said it's bound to happen eventually.

Any way you can get a video or even just audio of the knock and a video/audio with the injector unplugged so we can take a listen?

It could be a rod, or a broken piston wrist pin....

Just thinking out loud but if you have any amount of mileage on the oil maybe you want to pull a sample and send it to black stone. If it is a bearing it should show up as elevated wear metals.

 

It's not hopeless yet. The injectors are typically noisy after disrupting the fuel and oil from a stick pull. I use my AE to do a KOER test while in the driveway, and this does a good preliminary purge of air in the fuel lines (the test bumps the ICP to 2200 PSI). The truck still has to be driven about 50 miles to work out all the air, but it will likely quiet down on the first freeway onramp... but the starts will be "cranky" until you put the miles on.

The other possibility is a failing fuel pump, this makes all kinds of noise... so I would check the fuel pressure.

 

So if you were me... Would you put it back together and drive it a few miles? How do I check the fuel pressure? I really really don't feel like pulling the engine.

 

I would absolutely investigate further before condemning the engine.

You check fuel pressure at the filter housing. There are 2 ports one pre filter and one post filter if you do a search in this forum you will come up with detailed instructions. I imagine if your fuel pressure was right on the edge, as in enough fuel to run 7 cylinders and not 8, it could do what you are describing.

 

Compression test.

You arent getting the oilpan off without pulling the motor, so just plan for that to happen.
Figure out wether the knock is at crank speed, or cam speed.
Crank speed = 1 knock every crank rotation.
Cam speed = 1 knock every 2 crank rotations.

It really is not that big of an ordeal to get one of these heavy bastages out and on a stand.
Less of an ordeal and emotional event than finding a replacement truck anyway.