1972 Evinrude StarFlire 125 HP Outboards Service Manual, PN 4822, Page 50Get 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 temperatureTwo Thermomelt Stiks are necessary to check motor100FStik and 130FStikWith the motor at operating temperature, the 100 mark should melt and the 130 mark should not meltThe motor is best checked when operating on boatIf this is not possible, run the motor in test tank for few minutes, at speed' between 3000 and 4000 rpmMark the top of both cylinder heads with the Thermomelt StiksThe marks will appear dull and chalky When the surface temperature reaches the temperature ratings of the Stiks, the marks will melt, becoming liquid and glossy in appearanceOn some painted surfaces on which the Stik will not leave mark, it will be necessary to hold the Stik against the surfaceSee Figure 5-7If the 100 mark does not melt after reasonable length of time, the thermostat is stuck open and the motor is running too coldIf the 130
Figure 5-7Checking Motor Temperature