Talk me out of going deeper in this motor

[Shadetreemechanic]

My 87 cab and chassis has had an engine tick for several years now. Motor is not original and I have no idea of miles. the tick is not consistent, sometimes loud and sometimes almost inaudible. On a couple occasions I have turned the motor off while in gear on the highway and have thought I could still hear it some so I have assumed its in the top end of the motor.
Last month after an extended interstate run the noise change and got more metallic. I got worried that something was about to let loose, so today started checking it out.
I pulled all injectors and did a compression test. Min cylinder 300, max 350. Not great, but a runner for sure. Most cylinders were around 325.
I pulled the valve covers and the rockers seem tight. I barred the motor over and checked again, and again, and again until I had run through a complete revolution. Nothing seemed out of whack. One rocker had a few thousanths of slop in it when the lobe was down, but nothing that a lifer wouldn't take care of.
I also had my son turn the motor over with the starter with injectors out and valve covers off. Everything appears tight with no odd noises.
EVERYTHING SEEMS FINE.
I was also given an injector tester recently so I tested the injectors. Only 6 would test because the PO cross threaded two, pop pressures were all over the place, as were spray patterns. Two that I could test just dribbled after 1400psi.
I had planned to pull the intake and the valley pan to double check the pushrods and inspect the lifters, but I am wondering now whether it was just injector knock the whole time.
Is there anything else I should be looking at? I am tempted to put it back together with some rebuilt injectors I have on the shelf, but I am deep enough now that I could pull the valley pan. Anyone care to advise whether its worth my effort?

 

[Shadetreemechanic]

One more thing making me wonder about going deeper is that the exhaust has always sounded great on this truck, never a miss, pop, or tap. I thought I could hear the difference between valves and injector knocks, but now I am not sure.

 

[79jasper]

You sure it's in the engine? Not exhaust or flywheel/trans?

Sent from my SM-N960U using Tapatalk

 

[IDIBRONCO]

Why not try putting in some good injectors and then seeing what happens? You have to replace them anyway, so it seems like a good place to start to me.

 

[Shadetreemechanic]

Why not try putting in some good injectors and then seeing what happens? You have to replace them anyway, so it seems like a good place to start to me.

This is what I woke up thinking. I WAS sure it was in the engine, only way to find out is to put it back together I guess.
I have replaced the entire exhaust since purchasing including the downpipe. I have also put a clutch in it with all the associated goodies and had the single mass flywheel resurfaced.Non of that changed the sound.
If it turns out to be injectors this will be the worst injector knock I have ever heard. I now wish I had videoed it so I could upload.
Oh well, I will video it once its back together. Hopefully it will sound like a new one.

 

[IDIBRONCO]

I've seen several people swear that an injector knock was a rod knocking. They both have a different pitch of knocks.

 

[nelstomlinson]

Look for a junkyard engine to rebuild and have on the shelf. In the meantime, run this one. It sounds like it's in much better shape than my daily driver!

 

[Shadetreemechanic]

Look for a junkyard engine to rebuild and have on the shelf. In the meantime, run this one. It sounds like it's in much better shape than my daily driver!

I have a 6.9 sitting in another cab and chassis that is "mothballed" in my back yard. My issue is too many projects. I tend to do what it takes to keep them on the road when I need them, and never get far past that stage. The 87 I am working on right now has a 12 foot pto dump on it so its a very useful truck. Extended downtime maintenance on it is rare. I need it going again by hay season.
The mothballed truck only needs a power steering pump, but the work involved in putting the dump bed on it would be extensive, plus it is a 5 speed so I would need to source a new PTO box since the one on the t-19 is apparently wont fit on the zf-5.

 

[Oledirtypearl86]

Talk ya out of it. Hell you got another parts motor put a set of injectors in the truck and run it till it comes apart then take the weekend and do the swap my two cents worth

 

[nelstomlinson]

If you have an engine rebuilt and 100% ready to swap in, you can use this one up. Not much downtime involved, compared to finding an engine, getting it half-assed ready in a hurry, then the swap.

 

[Shadetreemechanic]

Injector pop testers are cool. Someone gave me one a couple months ago and this is the first time I have spent any time using it. My set of rebuilt injectors were part of the uhaul inventory sold on ebay several years ago. As others said at the time they are not great. Many leaked and had poor spray pattern. I ended up poking around the shop and came up with 48 injectors. From that I managed to find 8 that popped or could be shimmed to pop at 1800 psi and had good patterns.
Unfortunately my pump is bad. The advance piston had been dripping, when I looked closely I realized it is jammed and does not move.
I guess I will have a whole new fuel system by the time this is over with. I'll be bummed if the tick is still there, but as crappy as the injection system was, it should at least run better.

 

[Shadetreemechanic]

Well, the good news is I really do know what an engine tick sounds like, bad news is after new pump and injectors, the noise is still there. It does run better. I got it timed and took it out on the road and made a video. It take any guesses as to what the noise is. I have never posted videos to this site before so let me know if it doesn't work.
https://photos.app.goo.gl/Mgj1sTPebxemuMFE8
https://photos.app.goo.gl/fnhApnHJ1sNAvJyt6

 

[IDIBRONCO]

Both videos worked. I couldn't hear it at all in the second one. Now I'm just throwing out possibilities here. Since you mentioned that you don't know how many miles are on the engine, did you check for rocker arm wear? How about broken valve springs? It could be something in a lifter. The noise goes away with higher RPMs so maybe oil pressure has something to do with it?

 

[Shadetreemechanic]

I probably should have looked deeper. I grabbed and tried to move all rockers and pushrods and rotated it all the way through the rotation doing that. I probably should have removed the rockers, but when I couldn't hear it with glow plugs and valve covers off I jumped to the injector conclusion.
Good news is it runs much better now timed with pump and injectors. Hay season is about to start so I will be running it all summer as long as it will go.

 

[Shadetreemechanic]

I was using truck today at work and one of the guys was a diesel mechanic. He listened to it and said wrist pin.
It always has sounded like it was coming from the driver's side lower part of the engine, but I assumed the issue was with an exhaust valve and I was just hearing it there because it was near the manifold. I have read on here that bottom issues were rare in these motors, but quickly deadly.
Is there any way to do diagnostics on that other than an oil test?