1965 Evinrude 90 HP StarFlite Service Manual, PN 4206, Page 47Get this manual
CHECKING ENGINE TEMPERATURE The Markal Thermomelt Stik, heat sensitive stick similar to crayon which melts on contact with surface at specific temperature, is used to measure power head temperatureThe motor is best checked when operating on boatIf this is not possible, run the motor in test tank for at least five mi nutes, at maximum speed of 3000 rpmMark the surface to be checked with the StikThe mark will appear dull and chalkyWhen the su rface temperatu reaches the temperature rating of the Stik, the mark will meltbecoming liquid and glossy in appearanceOn some painted
Figure 5-7Checking Motor Temperature su rfaces on which the Stik will not leave mark, it will be necessary to hold the Stik against the surfaceSee Figure 5-7Two Thermomelt Stiks are necessary che ck motor125 FStik and 163 StikWith th motor at -operating temperature, the 125 mark should me lt and the 163 mark should not eltmark does not elt after reasonable length of time, the th rmostat stuck open and the motor is running too coldIf the 163 mark also melts, the cooling system is not functi oning properly, llowing the motor to overheatChe ck for worn pump assembly, leaky water system, or malfunctioning hermostat0