Kohler blowing oil--Long

I originally posted his on the garden tractor board but don't think it got many viewers there as the traffic is not a much as is on this site.

The engine is a single cylinder CV 15 S Kohler and it is about to drive me nuts. History: bought new on a JD 150 hydrostatic mower by a widow lady. Smoked from the beginning and she returned it to the dealer who did virtually nothing. Dealer sold out to mega store crowd and they pretty much told her they did not sell it so they didn't care. She took it to a couple of independent guys who did various things but no joy. She got disgusted and parked it and bought a new Sears mower. After a while she asked me if I wanted it, and of course I did. Well after putting it back together from the last tinkerer it ran but smoked and after a few minutes began smoking badly and almost shutting down. I pulled the air filter off and looked into the space and it had a large quantity of oil in it. I did some internet research and found that Kohler had some problems with rings not seating from the factory. so I removed the head and checked and sure enough the cylinder walls look like they were polished chrome. I checked for wear and found ~.003, so I honed the cylinder went back with Std rings, lapped the valves and replaced crank seals and all gaskets plus rebuilt the carburetor with a Kohler kit from John Deere. Put motor back on mower and it ran fine for a little while then began the same old mess of oil blowing out into breather tube. I changed the reed on the head for the crankcase vent system because it was standing about .002 of the seat and book says it should be flat, reassembled and started it up same old story. I then replaced the cylinder head with one from a running engine that was doing o k. No joy there also. When I did the crankcase vacuum test as per the Deere svc manual it was showing about 10 inches of pressure on the manometer instead of the 1-4 of vacuum as prescribed. I did a leakdown test and it seemed to hold ~90% of the air pressure introduced int the cylinder at 90 PSI and I could not hear any air passing through any where. The crankcase had the right amount of new 10-30,(Kohler recommended oil) wt H D oil and there is no gas smell indicating gasoline in the oil. The oil level in the crankcase drops with the running of it. The valve cover fills up and it pushes the oil through the felt of the breather tube vent oil separator at the top of the cover that is supposed to let the liquid oil drop back int the valve cover and return to the sump. I am about ready to take the proverbial BFH treatment to it and be done with it. Anybody have any Ideas?

The head should not fill up with oil. If it does, the drilling that draind the valve chamber may never been drilled. Or it could be drilled but not aligned with the hole or gasket or both. Jim

Seems youve been very thorough with your work. With good cylinder walls and new rings, Im leaning towards valves. You lapped the valves, but how are the guides and stems?

As a (fairly) young mechanic, these are the types of jobs I enjoy doing for myself at my own expense of time and money. Customer equipment, not so much fun. I have to agree with what Jim said, something doesn't seem to be correct and obviously causing oil to push out where it shouldn't. I'm guessing the valve guides are good?

Thanks for all the info. The valve guides are tight and as I lapped the valves I replaced the intake valve oil seal. This is the head off a running engine that broke a rod installed on it to see if it made a difference in things, but no difference so I will be tearing into it and looking at it with a magnifying glass in the next week or so.
Gene Davis Tennille, Ga.

Let us know what you find, this is interesting.

The single cyl John Deere Kohler engine I just gave up on sort of did the same thing. Long story short, I returned the tractor to the neighbor lady next door and told her it was not repairable. I have put 4 fuel pumps on it and every one filled the crankcase with gasoline. I gave it back to her and gave her the 5th fuel pump still in the box and bid her good luck.
See if the crankcase is over full with gasoline. That'll do it.
btw this one was a 212.