1990 Johnson Evinrude 120 thru 140, 185 thru 225, 300 HP, P/N 507875, Page 205Get this manual
Thermostat Servicing Disassembly
Remove four screws retaining thermostat coverRemove cover and diaphragm with thermostat assemblyInspect the thermostat seal in the cylinder head.10911
4If the seal is damaged, remove the cup and seal and replaceLightly coat outside diameter of new cup with OMC Gasket Sealing CompoundDo not allow sealer to contact the sealThe cup's lip must face outPress cup until it seats in the cylinder head5Remove the thermostat assembly from the diaphragm1sl 6Inspect the diaphragmIt should be pliable and free of EJ cracks or abrasionsThe vent hole must be open7Unscrew the two halves of the thermostat housingRemove the vernatherm and spring8Inspect the housing for cracks or heat damageReplace if necessary9Inspect the vernatherm and spring for signs of corrosion or heat damageReplace if necessaryAssembly f61 1Insert the pin into the vernatherm with the convex end of the pin facing out10910