1969 Evinrude 40 HP Big Twin, Big Twin Electric Lark Service Manual 4596, Page 45Get this manual
Figure 5-4Thermostat
Figure 5-5 Removing Heat Switch
TEMPERATURE SWITCH heat switch, installed in the head of the lower cylinder (electric start models only), is in series with warning light on the control panelShould an irregularity develop in the cooling system and cause abnormal water jacket temperatures, the switch closes the warning light circuitSee Figure 5-5The switch may be checked by submerging it in hot oilUsing test light to check the contacts and thermometer to check oil temperature, the contacts should be found to close at temperature of 211 and open at 175 7See Figure 5-6
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 5-7