I have an ~4 year old Murray push mower with a B&S 500 Series engine. Model 9P602 0019 F1. After the last mow, I noticed some oil dripping from under the air breather, but did not think anything of it. My next mow I looked down and there was a patch of brown sludge under the air breather. The inside of the breather tube was oily. What could be causing the oil to come out the air breather? I've cleaned up the breather tube and carb up a bit, but haven't tackled any further diagnosis.
90% of the time it is because the sump is over full
And about 95% of the time that is because the carb is leaking into engine due to the float needle not seating properly
I'll drain the oil and see if it's been overfilled. I don't recall putting any additional oil in since I changed it's oil. I kept the small oil bottle that they provided with the mower when it was new and marked where the fill line was so I can add back what it takes. Barring that being the issue I'll check the float needle on the carb, but being plastic we'll see how much fun that is. Luckily I had just replaced the head gasket and rebuilt the carb on my old push mower.
furt