This is a Briggs and Stratton 14HP 28N777 engine issue. Single cylinder OHV 4 stroke, with horizontal piston.
The nearer I top the sump up with oil to the full mark, the more likely the issue is to occur. Problem is it blows lots of oil out via its engine breather system, which then vents into the centre of the air filter to be ingested into the intake via the carb.
Yesterday I pulled the carb off and the breather system, to investigate. Cast into the upper side of the engine is a rectangular socket for the breather unit, fixed with two bolts and sealed against the socket. It has a larger hole at the top, a smaller one at the bottom (drain?)
Breather unit is a rectangular metal box mounted vertically in the above socket. It has a large hole to match the above at one side, which contains a one way valve, then a second hole on the outside, to match a rubber pipe, between and inside the box, there appears to be a baffle plate. Rubber pipe runs along and up to the intake side of the air filter.
Yesterday the box was filled with oil, as was the socket it fitted in plus some in the rubber pipe. Once drained and all cleaned out of oil, the engine started and ran fine for 30 minutes. I poked some wire down what I had assumed was the drain hole in the casting, but is seemed to be clear. Today I topped it up to the full mark, resulting in rough running and lots of smoke from the burning oil drawn into the intake from the breather.
Compression seems good. Not a lot of pressure if the dipstick is removed with engine running, but lots of oil thrown up via the long dipstick tube.
My initial thought was that the dipstick might be the wrong one, too short, hence setting the oil level too high, but no it is the correct length.
I am wondering if the breather unit, ought to have a small hole at the bottom, on the engine side, to allow that to drain?
Any ideas welcome please?
I have tried posting to the B&S problems forum, but B&S simply deleted my post without explanation.