I have similar noise. I had about the same reading for pressure. I put a BB behind the regulator spring to bump up the fuel pressure and a lot of the noise went away.


After removing VCs I found one injector returning more oil than the rest. Going to try orings first before investing in injectors.


I read there should only be 1.5v across IPR coil at idle and any more means an oil leak somewhere under VC, im going to see what mine reads before I pull the injector for reference

 

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Thanks for the help by the way!

Ok, I looked under the valve covers and don't see anything wrong on inspection. I put a straight edge on the injectors and they are all the same height. I checked for loose injector bolts as well.

Then I ran the engine to see if there was anything obvious wrong. Some injectors squirt more oil than others but over the course of the engine warming up the amount they would squirt changed. So this didn't really reveal anything I don't think.

I'm going to do some compression tests because I'm curious if I have engine wear since my turbo compressor wheel is so mangled. (See this thread: https://www.ford-trucks.com/forums/1...mer-video.html). I ran out of time so I will continue next week. Here's where I stand right now:

Engine Warm but not up to temp, 5-7 seconds of cranking, Fuse 22 pulled
Cyl 3: 420 psi
Cyl 4: 420 psi
Cyl 5: 440 psi

Take a look, anyone notice anything that doesn't look right?

 

Ok, I completed the tests. I'm not sure what to think of the results. I guess I need to sleep on it. I did 2 tests. A running compression test and a cranking compression test:

CRANKING:
-----------
7 - 440, 8 - 460
5 - 420, 6 - 440
3 - 430, 4 - 430
1 - 440, 2 - 440

RUNNING:
-----------
7 - 490, 8 - 490
5 - 490, 6 - 500
3 - 500, 4 - 490
1 - 500, 2 - 510

When looking at the cranking compression tests, I feel like these are pretty typical numbers based on the web searches I've made.

I couldn't find too much info about a running compression test numbers. This is the video that prompted me to do one:
I was concerned my rings were bad because of the crazy wear on the turbo. Now this video is a SuperDuty 7.3L so I'm not sure this applys to my 1996 7.3L. But in the video the good cylinders hit 600-650psi on the running compression tests. Mine don't go near that, so I'm not sure if ALL of my rings have worn equally (something that probably wouldn't happen) or if my numbers are normal for the model/year.

Ok, so this all circles back to the very beginning post. What is that knocking sound? I still don't know. I unplugged each injector individually and ran the truck to try and isolate the noise to a cylinder. Each one unplugged made the truck misfire and run rough. The noise didn't seem to change.

So what does this mean? I think it means the knocking noise has nothing to do with a specific cylinder. Which, to me, means it could be a mechanical knock. Like a rod, wrist pin, or piston slap? Honestly, I don't know at this point.

I'd appreciate any feedback on what to try next!

 

add a BB to the fuel regulator and see if it gets better, only take 5 min


then if it knock more on one side you will have to move injectors around to isolate the bad one, noisy one moves from one side of motor to other side


the pressure vid showed a drop below 40 at the 12 second mark, that seems a bit low when revving it

 

I'll give that a try. Would this mean that something is worn out if my fuel pressure isn't high enough?

 

Could have a restriction on suction side that lowers it. Fuel filter clogged?. The Regulator is the last item so anything in front can cause low pressure.

A flow test when cranking could tell you if pump isn't up to snuff. I don't know the specs on it but will be looking for my self soon. I just ordered all fuel orings and hoses. Going to give mine a good looking through.

 

Found the knock!

https://ibb.co/kmz68w
https://ibb.co/d03cFb

 

WOW!!! Thats one broken piston skirt, what caused it to fail like that?

 

No idea! I don't see anything obvious.

 

Thanks for the update, but what caused that piston damage

 

So are you going to rebuild the whole thing, or hone that cylinder out a little and put in new piston? I'd rebuild when I had it down that far but have seen guy just change the piston. Cylinder really doesn't look that bad. I'd be afraid of metal in the rest of the motor.

 

I have some stock pistons.if you need to just patch it.back up

 

That reminds me, I need to make a hitch adapter for my two rods and pistons to dangle off the rear.



OP, That wasn't what I was thinking was wrong. ouch