SERVIC E   BULLETI N   1 13   INFORMATI ONAL   ISSUED :   September19 87   REVISED: June1995   SUBJEC T:   Analysi sof  FieldFailureExhaustValves   Tecumseh has recommended the use of unleaded gasoline for many years to reduce carbon build-up. Since July 1,   1 984 all production engines have used an austenitic steel exhaust valve.   An evaluation of field returned exhaust valves, found that majority of the valves had carbon build-up only. The   valve could have been cleaned and placed back into the engine. The valve seat must also be cleaned and inspected   and recut if necessary.   The quality and durability of the austenitic steel exhaust valves have increased valve life significantly. When   performing valve service be sure to clean and inspect the valve carefully. Tecumseh will continue to provide