Small Engines (Lawn Mowers, etc.): smoke from my craftsman riding mower, craftsman riding lawn mower, craftsman riding mower

Question
I have a Craftsman Riding Lawn Mower  15.5 ohv turbo cooled engine...model 917.270654. I have had this mower for approx 8 years....have changed oil occasionally. Tonight I was mowing my lawn, when all of a sudden, a large puff of heavy white smoke came from the exhaust...then the engine stopped. I let it sit for a short while...then started it again....still a fair amount of white smoke came out of the exhaust. I let it sit for a while again, started it and drove it up to my garage where it now sits. I checked the oil..it was full. Can you tell me what happened and what I copuld do about it.

Answer
Any knocking sound in the engine?

It's very difficult to tell with out some testing.  Do you have a cylinder leak down tester?  I'm guessing not since these are pretty expensive tools but this tool would tell if you have a bad compession component.

Try changing the engine oil.  Does the engine still run smooth?

Eric