Onan Micro light

[bowmaga]

Hey guys, its been awhile since i hounded you guys for answers.  Here my questions and issues.

When we had super Betty, we put a Onan Microlite 4000 watt genny in her. We had bought it the year before.  Stuck it in SB before our first trip to the race in MIS in June, hooking it up to the house batteries for charge etc.  Anyway, used it all weekend and she worked great.  Got Betty back home, parked her and kept working on her.  2 weeks after the first trip, getting ready for the second and casually fired the genny up to "make sure" everything was working and it fired and died, then i hit the starter again and it began puking out thick blue smoke.  Puzzled i let loose of the switch, stared at it, then hit it again, same result, thick blue smoke.  Now.....very bad thoughts are running through my mind at this point...along with hundreds of swear words and dollar signs.   I figured i broke a ring and had nice slices up and down the cylinder wall.  With no time before the next trip, and needing a genny I got lucky and eBay, 25 minuted from my house was an exact twin....but that one ran.  1100 dollars later a case of beer and a few miles on my truck, the replacement was in super Betty and you all know the story...super Betty is gone to a new happier home in NC.  Anyway, left behind is the old genny....still doing the same, but the rings are fine, cylinder is fine, can actually still see the crosshatching from having it honed out...rings are not oblong or out of shape, seals are good, valves are fine......WTF is wrong with it?  anyone else have any of these issues with an onan genny?  sorry for the long explanation....but i haven't bus talked in a while. 

[Chopper Scott]

Did you change the breakin oil? In fact if you read the owner's manual (I never do either!) a lot of times they require an oil change after only a few hours on a new engine. Just a shot in the dark but you could change the oil and filter and see what happens. If it works you owe me a case of beer!!   Later

[TomC]

While the valves may look alright, you may have a valve guide that is cracked allowing oil from the rocker arms down into the combustion chamber.  I'd first check the intake valve guide-which involves disassembling the valve train.  Good luck, TomC

[junkman42]

Blocked crankcase vent,maybe mud daubbers or faulty vent valve or filter?  john