Questioni have been given a lawn mower in good physical shape, starts fine but oil is coming out the exhaust. pulled the dip stick out and it is over full.pulled the head off the cylinder looks good. could it be that the crankcase has been over filled and is now forcing oil out the exhaust? or would the valve seals be gone?just wondering. corey.yardman 5.5 hp. mtd. model #11a 108d501. serial #1d089is0062 lawn mower.
Answer Hello Corey
Check the Crankcase vent. If the engine was over filled with oil the oil has filled up this vent and is stopping it from working or it may be bad (unlikely).
Follow the vent tube from the breather to the vent.
Remove the vent and wash the oil out of the vent.
There are no seals on the valves but excessive wear will allow the oil to follow the exhaust valve stem to the exhaust port and be blown out the exhaust.
More than likely your problem is as stated above, the vent is full of oil.
If this is not the case you will have to have valve work performed on this engine to cure the problem. ie new valve guide and seat.
Respectfully
John
