(By Doug Gregory) – We all know nitro is a heartless mistress and will inflict whatever damage to expensive engines she chooses. Gasoline can be the bratty little sister who will also have her way with our stuff.
Here we have what used to be a Kawasaki V-twin vertical shaft air cooled engine, mounted on a Ferris zero turn mower. They rely on a fan on the flywheel to blow cooling air over the fins on the cylinders and heads. This unit got a bunch of grass packed into the fins, causing it to overheat. This resulted in the exhaust valve guide on one cylinder to seize to the valve stem, but the valve kept operating, the guide now flopping around in the head…for a while. At some point the valve dropped and contacted the piston, beating up the piston and breaking the rod. The crank end of the rod stayed on the crank, so the low oil pressure sensor didn’t kill the still functioning other cylinder which just kept inflicting damage on the dead cylinder. Finally the fatally windowed block allowed enough oil to spill that it seized.
Wouldn’t someone notice all the racket? Probably, but it’s a rental unit and it was still sorta working. The new engine has cleanout ports in the blower housing to blow out debris from the fins, so this was likely not the first time this happened.
Thank you to master small engine mechanic Wayne Kipper for the photos.
Something regularly checked on my Clubbed Cadet mower. Had enough issues with axle seals on my Tuff Luck diff. Don’t need anything else to go wrong other than the usual.