1997 Johnson/Evinrude EU 25, 35 HP 3-Cylinder outboards Service Manual, Page 152Get this manual
Thermostat Servicing Disassembly
rn 1Remove the thermostat assembly from the cylinder head]2Unscrew the thermostat cover from the thermostat housing Remove the relief springdiaphragm and cupwashervernathermand spring Remove the thermostat housing O-ring and thermostat cover O-ring CD
3Inspect the thermostat seal area in the cylinder headRepair any damaged surfaces before assembly
4Inspect the housing for cracks or heat damageReplace if necessary5Inspect the vernatherm, diaphragm and cup, and spring for signs of corrosion or heat damageReplace if necessaryAssembly