I have a ride on mower with a 17HP Briggs and Stratton Intek OHV engine.
The mower is 10 years old.
Earlier this year, prior to the start of the cutting season I replaced oil, oil filter and air filter. Oil (SAE30) was filled to the correct level.
During the second cut of the year, whilst mowing up a short slope, (10 yards long), the exhaust blew out a lot of black smoke. I got the mower to a level section and let it cool down. It started OK, with no repeat of the smoking incident.
However, over this cutting season I have noticed oil is getting burnt, and I am having to top up every cut.
The engine pulls well and does not falter.
I have checked the rubber breather tube between air filter and breather unit and it is not blocked.
I removed the breather valve on the side of the engine and checked that there is no blockage from the breather valve mounting recess into the crank case.
The spring loaded valve in the inner face of the breather does open when light air pressure is applied.
After reassembly, the engine is still burning oil.
Should I replace the crank case breather assembly, or is it rings or blown head gasket?.