Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Is oil over full from gas contamination?
If gas is not thinned from gas contamination, then engine has too much blowby. Oil is pushed out the engine vent tube into the air inlet, or into the cylinders, into the exhaust. Has engine been run low on oil?
Oil can get thinned from gas getting into the oil, caused by a leaking carburetor needle valve. Causing the contamination.
Blow by is the compression, getting by the rings. Causing high crankcase pressure, blowing out breather and exhaust.
I would try changing the oil and running it to test. That might be all it needs!
If oil is thin, or smells of gas, yes,clean the carb.