SERVICE
BULLETIN
1
13
INFORMATIONAL
ISSUED:
September1987
REVISED: June1995
SUBJECT: Analysisof 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
warranty coverage for any valve defect, however, carbon buildup alone will not be considered a warrantable
reason for exhaust valve replacement.
Should the valve be burned, pitted or refaced, it then becomes necessary to complete a proper valve job. The valve
seat must be recut whenever a new or refaced valve is installed into the engine. Proper procedure for valve, seat
refacing and setting valve lash can be found in the Mechanic’s Manual.
