Small Engines (Lawn Mowers, etc.): 16 HP Vanguard B&S Blowing Smoke, head gasket, combustion chamber

Question
Hi I have a 16hp Vanguard Single OHV B&S motor MODEL 28Q777 that is getting oil into the air cleaner. Resulting in it blowing smoke. The Head Gasket has been replaced which made no difference. Would it be the valve clearances? Rings?. Or what else before I have it rebuilt/replaced. The motor at times blows no smoke at all for over 2 hours then next time it is used does. cheers

Answer
Scott, sometimes these type of diagnostics is difficult with the home owner type repair person. You see at the shop we use various gauges, and instruments to identify these types of problems with a engine. If I had the engine here first thing I would do, is after making sure the engine oil is not over full, and that the carburetor is not flooding during operation which will result in the gas passing by the rings, and thinning the oil to where it can make it's way back into the combustion chamber. (This is common) Smell the oil on the dipstick does it smell of fuel? Then making sure the breather is not blocked up under the flywheel. We would then move on to doing a compression test of the engine, giving us an idea of the condition of the rings. Then we would do a cylinder leak down test, this consists of filling the cylinder with pressure, and monitoring it for any loss of pressure, which then tells us the condition of, various internal components. So you see why I sometimes have problems solving certain problems being so far away?..........Tom