1996 Mercury Force 25 HP Service Manual 90-830894 895, Page 62Get this manual
Thermostat Wash thermostat with clean waterUsing thermostat tester, similar to the one shown, test thermostat as follows: 1Open thermostat valve, then insert thread between valve and thermostat bodyAllow valve to close against thread 2Suspend thermostat (from thread) and thermometer inside tester so that neither touches the containerBottom of thermometer must be even with bottom of thermostat to obtain correct thermostat opening3Fill thermostat tester with water to cover thermostat4Plug tester into electrical outlet5Observe temperature at which thermostat begins to openThermostat will drop off thread when it starts to openThermostat must begin to open when temperature reaches (30 C) above designated stamping on bottom of thermostat6Continue to heat water until thermostat is completelyopen7Unplug tester unit8Replace thermostat, if it fails to open at the specified temperature, or if it does not fully open