Small Engines (Lawn Mowers, etc.): 2000 cub cadet rider 15hp b.s vanguard motor, combustion chamber, oil consumption

Question
Hi Marc   I was cutting grass with the above described Lawn mower when a big cloud of blue smoke came out of the motor (not sure if it came out of the exaust) and it quit.   I let it cool down and started it again and it ran normal for about three minutes and the samething happened again, it will repeat this process as long as you let it cool down for a minute or two.   My first thoughts are a broken ring on the piston or a broken valve, but not sure due to the fact it starts and runs with good compression.  your thoughts     Thanks.   Leonard

Answer
Blue smoke, as you probably know, indicates oil consumption.  The first thing I would check is the oil level.  If it's excessively high and you are on a slope, oil can enter the combustion chamber via the PCV system.  Another thing to check  would require removal of the tappet cover(s).  It's possible that there is a piece of debris lodged in the oil return hole causing a build-up of oil around the valve stem(s) allowing oil to flow into the combustion chamber.  Then, as the engine sits, oil can slowly drain back to the crankcase.  Hope this helps.