A little into the engine:
The heads on these things are freakin HEAVY!
Oh no! Found the problem:
Looks like the injector on #4 was leaky and washed oil off the cylinder till the piston went. What's the cylinder look like?
The awesome thing is that the cylinder measures well within specs. Got a ball hone - she'll clean right up. Just shy of 200K and you can still see the cross hatching!
Well. That's where I am now. I just ordered the engine rebuild parts yesterday! Now comes the fun!