I hope that some one might be able to offer some insight. I have a 12.5 HP Kawasaki engine that is on a 36" John Deere commercial walkbehind lawn mower. The age of the engine is unknown, maybe 7 years old? I have noticed that some thing is trying to break out of the aluminum Engine case. There is a tear or puncture begining and it seems to extend 1/4 of an inch. The tear is located at the true back side tword the operator or transmission. The engine starts and runs well. Motor does run a little high on RPM. All insite and ideas are welcome.