Small Engines (Lawn Mowers, etc.): Craftman 18hp briggs & stratton, air filter element, air filter assembly

Question
recently replaced battery and upon starting tractor for the 1st time in approx. 1 yr, it starts runs fine until engine warms up. then it starts to blow thick white smoke out the exhaust, back fires, and stalls. just bought it last year, it's a few years old, only used it a few times last year but it ran fine with no problems. other than the dead battery no other maintenance has been done.

thank you,

tom

Answer
Is the oil level increasing?  If it iis fuel is runn from the carberator to the chankcase.  It runs fime on the gas  in the bowl fut by then the crankcase is pumping oil anbd gas into the air filter assembly vis the breather.  Fix it by installing a carburator kit.  The needel is not seating.  Clean fuel system very well ysing tag wire to clean passages.  Tag wire can be the wire from a twist tie.  Blow out with compressed air.  If you do not have a compressor use the can of air used to clean computer keyboards.  Replace all gaskets and filters.

If that is not it you have an air leak in the crankcase causing it to pump oil out the breather.  Checl O ring on dipstick.  Check where  the oil fill tube goes into the crankcase.  Is the gasket leaking at the crankcase halves.  Remove the breather clean throughly put a new gasket in.  

The usual cause of white smoke is fuel black or blue smoke is oil.  If you haven't already change the oil and put a new air filter element in it. If there is any old fuel, 90 days, in it drain it out and replace with fresh.  Put the old in your car when the tank is 3/4 full it will delute.  Once fixed you will have to run it a while to get it burned out.  You may have to install new spark plug(s) too.

Good Luck on your project.