update Kohler Blowing oil--long

Up date on this mess. The problem turns out to be a camshaft with the exhaust lobe almost worn off. I measured
it against a good one and it was .110 of an inch lower than the lobe on a good cam. The exhaust valve was barely
opening and the engine when running was taking in more air through the intake valve than could go out through the
exhaust so the excess was passing back by the rings into the crankcase as blow by and there fore pressurizing the
crankcase thus forcing oil into the air cleaner elbow through the vent tube from the rocker arm cover.

Original post----

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 shut down. I pulled the air filter off and looked into the space and it had 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 leak down 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 hammer treatment to it and be done
with it.

Woof. So are you waiting for a cam, or is it fixed. Replacing the lifter is also recommended as that one is likely to be rounded in a way not in spec. and with a scored finish. Jim

Good find. Didn't let it beat you! Sounds like it beat a bunch of other mechanics. Time to crow!

Good job, Gene. Hard one to figure out, but not for an Earthmaster man.

Garry

Now you need to figure out why a low hour engine had a cam lobe worn that bad. Was it a faulty cam or an oiling issue? Something caused the early failure and you don't want a repeat.

Yep, I am the proud owner of 3 Earthmasters. 1 running, 1 partially restored that I know all the history of and 1
more for a parts donor.

The camshaft must have been soft/defective from the start as this started pretty soon, maybe six months after the lady bought it she said. She was dependent on the local Deere dealer for keeping it up and doing oil changes and such. Apparently no one there looked at the used oil they drained out to see if metal shavings or particles were in it, It had many oil changes before I got it so I did not see any of the evidence of wear in the oil. That dealer sold out to retire and the new mega dealer doesn't have anyone that really seems to care one way or the other.
At that time there was no reputable small engine repair shop here in the county, just shade tree tinkerers. She is the secretary/bookkeeper at one of the parts houses I frequent and asked me one day if I was interested in it. She had bought a new one from Sears and was through with it. Of course I was and she told me that it was at a guy's house who had been dabbling with it if I would just pick it from there I could have it. He had replaced the head gasket because he thought it was blown, but it did no good. So the engine was in pieces when I got it.
It took me a while and several tries to figure this one out and honestly I was not expecting it to be a cam problem. On the third try out of desperation I was looking everything over again and was checking everything closely and noticed the valve lift on the exhaust valve was very little so I took the cam out and it was immediately obvious to me. The exhaust lobe was almost round but the intake lobe showed very little wear. I have not seen this on a Kohler engine before. This usually happened on Chevrolet especially the older 305 engines. This was a classic case of inheriting someone else mess. When I start on something like this I like to practice the old Indian guide's way, look for signs first.

I have a camshaft ordered and will replace the lifters as well. BTW they are interchangeable with SB Chevrolet lifter which are about 1/3 the price of OEM from Kohler.

As for the end of this story. I told the lady about it and asked if she wanted it back for the price of the repair and she said, I don't want it back at any price,I have had enough of it.

While the cam was worn and it was a good catch to find it . I am not 100% certain that is going to reduce the blow by up into the air cleaner .
Wondering if there is a 2nd factor . It would be interesting to connect an old spark plug shell to an airline . Then wedge the flywheel and test for blowby with the piston at TDC , halfway and BDC.
I will admit this one has me curious.