1965 Evinrude SportFour Heavy Duty 60 HP Outboards Service Manual, 4204, Page 41Get this manual
CYLINDER
CHECKING MOTOR TEMPERATURE
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 possiblerun the motor in test tank
EXHAUST TUBE COOLING
for at least five minutes, at maximum speed of 3000 rpmMark the surface to be checked with the StikThe mark will appear dull and chalkyWhen the surface temperature reaches the temperature rating of the Stik, the mark will melt, becoming liquid and glossy in appearance On some painted surfaces on which the Stik will not leave mark, it will be necessary to hold the Stik against the surface See Figure 5-5
Figure 5-3Cooling System
Figure 5-5 Checking Motor Temperature Two Thermomelt Stiks are necessary to check motor125 FStikanda163 FStikWith the motor at operating temperature, the 125 mark should melt and the 163 mark should not meltIf the 125 mark does not melt after reasonable length of time, the thermostat is stuck open and the motor is running too coldIf the 163 mark also melts, the cooling system is not functioning properlyallowing the motor to overheatCheck for worn pump assembly, leaky water system, or malfunctioning thermostat0