Yanmar 1GM, Operation Manual

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[9-4.] Inspection of engine body
1) Retightening cylinder head nuts Retighten each nut with a torque wrench before starting a
new engine and after 50 hours of operation. Sequence for tightening the nuts is shown in the
figure.
1. For 1GM M10 bolts are used for main
2. Sub
3. Number shows tightening order
CYLINDER HEAD TIGHTENING TORQUE
1GM MAIN (M10) 7.5 kg-m
2GM, 3GMD MAIN (M12) 10 kg-m
SUB (M8) 2.5 kg-m
3HM MAIN (M12) 13 kg-m
SUB (M8) 3 kg-m
2) Exhaust/intake valve head clearance adjustment
The clearance of the valve will affect the overall performance
of the engine, so it is important that it be correctly adjusted.
Check the clearance before starting a new engine, whenever
assembling or disassembling and after 500 hours of
operation. Adjustment shall be done while the engine is cold.
2-a)
Remove the valve rocker arm cover and starter motor.