Thermostat - Mercury/Mariner 25 MARATHON Service Manual

POWERHEAD

Thermostat

Wash thermostat with clean water. Using a thermostat tester, similar to the one shown,
test thermostat as follows:
· Open thermostat valve, then insert a thread between valve and thermostat body.
Allow valve to close against thread.
· Suspend thermostat (from thread) and thermometer inside tester so that neither
touches the container. Bottom of thermometer must be even with bottom of ther-
mostat to obtain correct thermostat opening.
· Fill thermostat tester with water to cover thermostat.
· Plug tester into electrical outlet
· Observe temperature at which thermostat begins to open. Thermostat will drop off
thread when it starts to open. Thermostat must begin to open when temperature
reaches 5°F (3°C) above designated stamping on bottom of thermostat.
· Continue to heat water until thermostat is completely open.
· Unplug tester unit.
· Replace thermostat, if it fails to open at the specified temperature, or if it does not
fully open.
Page 4-34
51087
90-826883R2 JUNE 1998