Small Engines (Lawn Mowers, etc.): john deere 318 lawnmower, john deere 318, piston rings

Question
I have a jd 318 onan with P218g engine serial no. J883450752 which began sucking oil into the breather. Put new valves, new valve guides and intake valve seals. Adjusted valves per tech. manual Intake at .005 and exhaust at .013. At mid rpm engine is still sucking oil into breather/filter compartment. No scoring or roughness noted in cylinders. Compression check was 130/134 prior to valve job. Help?

Answer
Most likely the cause is worn piston rings. They are not worn to the point of compression loss, however, they are worn enough to allow oil to blow by. Very common problem, especially on Onan motors. One thing to check, before you dig in too deep, is to make sure that the oil level is correct. Overfilling can cause this problem.