2006 SD Johnson 4 Stroke 9.9-15HP Outboards Service Manual, Page 171Get this manual
POWERHEAD COOLING SYSTEM
COOLING SYSTEM
Operation
The cooling system consists of: Water pump, in the lower unit Water tube, between lower unit and powerhead Thermostat, in the powerhead If overheating occurs, check cooling system parts for blockage, corrosion buildup, or damageRefer to WATER PUMP on p202Refer to driveshaft housing Cleaning and Inspection on p183
Inspection
If salt deposits, corrosion, wear, or other damage are foundclean or replaceCheck thermostat opening temperature as follows: Insert length of thread between thermostat valvebody, and suspend thermostat in container of water Place thermometer in container and heat water Observe water temperature when thermostat valve opens and releases thread