L275 engine issues

[LeadHead]

So I finally found another L275 which was missing some parts (injector pump, injectors, lines, hydraulic pump, intake manifold, etc...) and I brought it home as a parts machine for mine which threw part of rod #1 through the block before I bought it. Supposedly the engine on this donor tractor had "been rebuilt" shortly before the parts were "stolen" off of it, but after swapping the engine over to my tractor and finally getting it to fire up and seeing all the smoke it's blowing, my suspicion is that someone sold some parts off of it to recoup some money from a tractor that needed an engine rebuild. When we had the head off we noticed that the cylinder sleeves were not scored but a couple of them had been exposed to some moisture at some point, so that's surely why it's smoking. They feel pretty smooth, so I'm hoping we can lightly hone the sleeves to clean them up, and replace the rings.
After FINALLY getting the engine to start (it's tough to get going), it has a noticeable knock from cylinder #1 until it runs for 5-7 seconds, then it smooths out. While the starter is cranking, the engine "pauses" or at least slows down on every 3rd cylinder stroke with a very audible "clack" sound. We've not yet had the chance to pull the oil pan and check things out in the bottom end, but is this likely rod bearings or a head clearance issue?
Also, after the engine started I noticed some fuel seepage at the base of the fuel injector on cylinder #1, and to a lesser extent, cylinder #2 where they thread into the head. Is there supposed to be a copper washer to seal that area or not?
Pretty depressed. Any suggestions would be appreciated.

 

[LeadHead]

Also, how sensitive are these engines to having the proper amount of air:fuel mixture? It seems to start easier when, if the air cleaner is off, the intake is partially obstructed to reduce the air being sucked into the engine. Is this normal? We don't have the front axle reattached yet, so the air cleaner is not easily mountable.

 

[284 International]

I would speculate you have a bent rod or two, probably from water in the engine when cranking. I would pull the head off and check that before spending any more money or time on things.

 

[LeadHead]

Maybe this is a dumb question, but why would the knock go away within a few seconds if it were a bent rod?
As for water, the intake was left off the engine for some time and it appears that moisture accumulated in a couple of the cylinders during storage. We did not crank it over with water in the cylinders.

 

[Stumpy]

Nothing you've described really screams one problem or another to me. A slightly bent rod is as good a guess as a valve crash at this point. There's just too many things that clack could be but one thing I'll bet money on is you've got a leak somewhere on that cylinder hence the misfire til it spinning. It might be rings, the rod could be bent, you could have a problem with the valves but I think you'll need to do some digging. I'd invest in a diesel compression tester, you can get em reasonably priced on Amazon, and hook that to an air compressor and listen for where it's leaking.

Before doing that it might be prudent to swap injectors with another cylinder and see if the problem moves. I'll scan the page out of my manual for you concerning the injectors.

Click each image for the full resolution.