Small Engines (Lawn Mowers, etc.): Tecumseh HH-60, troy built tiller, piston movement

Question
I have a Troy Built tiller with the Tecumseh HH60 engine.
I runs quite well but when filled with oil the to correct level, it badly blows oil out of the vent tube until the oil level barely shows on the dip stick. Then it runs perfectly. There is no smoke coming from the vent tube but a lot of pulsing air is coming out. Is this air normal due to the piston movement or is something else causing this, like valve misadjustment?
I don't like running the engine with low oil level oil even if it does run good. A lawnmower repair shop told me I had too much oil in it.

Answer
Hello Bill, I hope I can be of some service to you. The air that is coming out of your vent tube is because of piston movement. However, I've been doing some research on this. What is happening is that you are experiencing blowby. Blowby is caused by any leakage or loss of compression past the piston rings. Often accompanied by oil from the crankcase passing through into the compression chamber. It might even be a valve seal. I hope this helps!