1. Maintenance Is Optional THE FAILURE OF LAWNMOWER ENGINES

3. Several Engines Compared Negative Features - Grass/ oil mixture on restricting airflow - Lack of oil - Grass/ oil contaminated air filter - Broken breather tube - Bad maintenance 5 engines compared - failure - 2 failed engines - 2 working engines Positive Features - Over-Speed Protection - Positive Oil Pump - Metal cam shafts and gears - All had engine brakes - Structural Webbing - AlSi con rods (hypoeutectic) - AlSi crank case (hypoeutectic) - Easy Start (Compression/ Release Feature)

4. Lubricated cap Non-lubricated cap

5. Fracture surface (SEM) Galled surface Hypoeutectic AlSi

6. Conclusion Basically good engine but old Poor materials choice for breather tube Causes: –Lack of maintenance No oil - Breather tube system Solutions: –Engine doesn’t work when low oil LED light turns on