Small Engines (Lawn Mowers, etc.): Oil in Carburetor, briggs and stratton, vent tube

Question
QUESTION: I believe I am getting oil in my carburetor on a Sabre by John Deere 42" riding mower. I believe it is a 15.5hp Briggs and Stratton engine. I noticed when I changed the oil that is appeared to have gas in the oil as well.

ANSWER: Hi Bob
This is a common problem we see. What is happening is that the needle valve is not cutting off the gas flow when the engine is not running. The excess gas is draining into the crankcase which is causing a "overfill" situation. To repair this problem, replace the needle valve in the carb. Also be sure to drain the crankcase to remove any fuel that has contaminated the oil and replace with fresh oil. Hope this helps.

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QUESTION: Do you believe this can be causing the oil to show in my carburertor or might this be another issue? I am getting oil in the caburertor and burning a white smoke from the exhaust. The engine will run for a few minutes the die shooting a large puff of white smoke then will not start for about 1/2 hour. This is when I removed the sir filter and noticed the oil in the carb and around the air filter

Answer
Yes, this is causing the problem. When the crankcase is overfilled, The contaminated oil/gas mixture is being drawn into the carb through the crankcase vent tube instead of air. I forgot to mention after the repair, remove the spark plug and turn the engine over to blow out the gas/oil mixture from the cylinder.