Small Engines (Lawn Mowers, etc.): Lawn Tractor - smoking, sears craftsman lawn tractor, craftsman lawn tractor

Question
Hi Eric, I have a 1997 Sears Craftsman Lawn Tractor model # 917.258513 with a 14.5 HP IC engine ( Briggs & Stratton mod # 287707 , type # 0255-01). 5 years ago the engine started smoking real bad - I found the head gasket blown, so I replaced the gasket.I also noticed that the cylinder block that the head gasket presses up against had a small groove in it.  Now 5 years later the engine is smoking real bad again. (same symptoms - intermittent thick smoke) But this time I did not find the head gasket blown. I did not notice with my eye that the cyl block was grooved. I replaced the head gasket hoping this would fix it. It still smokes intermittently usually after it warms up a few minutes. Any idea what would cause it to smoke intermittently with white smoke. ( eng oil level ok, eng oil replaced every 25 hours. Any help would be appreciated.
Bob  

Answer
The engine is getting old so it may just be engine wear causing the problem.  Do you have a cylinder leak down tester to test the internal condition of the engine?

If not, I would start by replacing the upper and lower dipstick seals/o-rings.  Briggs has had some trouble in the past with the upper o-ring leaking on the dipstick causing a vacuum loss and burning some oil.

Also, check the valve breather.  It should rattle like a baby rattle.  If the breather is sticking then again you will have some vacuum leak which could lead to oil getting past the rings causing some oil to burn.

Is the smoke bluish/white in color?  Does the engine use oil?  Is the spark plug tip black and sootie with soft deposits on it?
Let me know.
Eric