[Richard]

So my very best helper, @"RussWhite", leaves for the day, and 5 minutes later, white not black smoke starts pouring out of the stack. 

OH NO! Well maybe I expressed it a bit differently. But nonetheless. 

It’s almost dark, so I have to quit for the night. Needless to say my noodle was working OT to try to figure this out. 

Cranked it again in the morning with the same pattern. Engine exhaust is crystal clear until the engine runs about 15 minutes and then LOTS of white smoke is coming from the exhaust. 

My diagnostics before cranking the engine a second time were:
Turn the engine with breaker bar to see if I feel or hear anything unusual. Nothing
Open coolant cap to look for oil or diesel indicating blown or leaking head gasket. Nothing. 
Drain a sample of oil into clear container to see if coolant is in the oil. Have to wait for that to settle over nite. 
Hmmm, if it were an injector or compression problem it would manifest itself when the engine was first cranked, so I kind of eliminated that. 
Lot’s of internet chatter on what to lube new rings with to ensure good break in. The only consensus is DON’T use assembly lube like I did. Lovely. 
Now that I am confident, that nothing catastrophic is going on, I decide to let it run for a couple of hours to see if the mystery smoke will clear. After all it could be all the junk built up in the exhaust system from years of smoking. 
While it’s running, I take a ladder to the roof and let the exhaust run onto a white rag for 30 minutes to sniff it and feel it. Maybe this will give a clue. Curious enough the white smoke does not have a distinct odor. It does not smell like diesel. It does not smell like burned diesel. It does not smell like burning engine oil. In fact I don’t smell anything. And not much of anything except flecks of carbon are collecting on the white rag. But it is still smoking like crazy. And it doesn’t show any signs of getting better after two hours. 

So either I have an unknown contaminant, or the new rings are not seating. 

Sigh. 

I then look at the oil sample collected a couple of hours ago. Something has settled to the bottom. But the sample is small, and the settled liquid sample is too small to really evaluate. It is coolant, is it water, is it kryptonite? Who knows. 

But this gets me thinking. It could be water. After all, you did pour gallons of water into the open engine block, perhaps it hid somewhere and has contaminated the oil. If there is water in oil, it will emulsify, and water is being smeared on the cylinder walls with the lubricating oil. The film of water is turning into steam. A ha, that’s why it has no smell. 

I had planned on doing an oil change a few hours after break in anyway, so I went ahead and change oil and filter. I collected a much larger sample of the old oil this time. The first pic is a shot of the clear container while holding it at angle to produce a low spot. The second pic is a closeup of the same thing. Looks like about a teaspoon of water has settled out of the oil.
       

Cranked the gen with the fresh oil. NO SMOKE. Loaded it up with amperage. NO SMOKE.

What an adventure, but I won’t be embarrassed in campgrounds about the coach being on fire. 

I would like to thank @bestgenman for his excellent guidance and sage wisdom on this project. 
I would like to thank @Russwhite for helping me put the thing back together, there were times when five hands were needed. 

So, what should you take away from this, besides that dude is bonkers. 
Take the time, maybe a couple of times per month if you are using the coach regularly, to turn on everything till you pull some serious amps, and let the motor burn the carbon out of it. It’s nice that Newell puts a monster genset in there, but the light use we give it is not good for the Diesel engine. 

And should you need a compression tester for the Yanmar, or a Flexhone for the cylinders, I know where one can be obtained.