Small Engines (Lawn Mowers, etc.): 18hp twin cylinder vanguard 2004, valve stems, lawn sprayer

Question
  I was pulling my lawn sprayer last night, and the motor smoked, and would not run flat.  I changed the fuel filter-----nothing.  i then pulled it in the shop and took off the air cleaner.  It was soaked with oil.  there is a rubber tube that comes into the area for the air cleaner, and it was shooting oil into the carb.  This looks serious to me---do you have any ideas what to look for.  this motor has always been a little quirky.  please resopons asap!   Thanks  Jeff Kumpf  

Answer
Hi Jeff,

Sorry for my delay.
If the oil level is not overfull, then I would suspect something is causing the crankcase to become pressurized.  Either combustion pressure leaking by the rings or valve stems or a clogged crankcase vent.

Let me know what you find.
Michael