I have 'oil' spewing out of the breather pipe of a Briggs and Stratton 11.5hp MTD RH115b mower engine( type 1119-E1). I found this after I had been unable to start the mower. I then removed the air filter assembly and tried re-starting the engine. It fired OK but within 30 seconds what appeared to be 'oil' bubbled up thru' the air breather pipe. I switched off and have not dared to try again. Please can anyone tell me how to sort this out?

Hi,
Something is causing the crankcase to create a n incorrect pressure differential. Candidates are the sump gasket, head gasket or bad O-ring on dipstick tube. They could have ruined the breather as well. Try spraying something non flammable ta these areas with a warm engine and running to see what reaction happens(water is NOT suitable.)
Peace,
Clarke