6A-10 - SEAWATER COOLING MODELS 90-823225--1 1096
Testing
1. Clean thermostat in soap and water to remove
any deposits or debris.
2. Inspect thermostat for corrosion or other visible
damage.
7180172674
a
b
a - Brass Thermostat
b - Stainless Steel Thermostat
3. If thermostat is suspected of producing insuffi-
cient engine temperature, check thermostat for
leakage by holding it up to a lighted background.
Light leakage around the thermostat valve indi-
cates that thermostat is not closing completely
and should be replaced. (A small amount of leak-
age at one or two points around the valve perime-
ter is acceptable.)
72717
a
Brass Thermostat Shown (Stainless Similar)
a - Check for Light Leakage Around Perimeter of Valve
4. Check opening and closing temperature of ther-
mostat (using a tester similar to the one shown)
as follows:
a. Fill tester to within 1 in. (25mm) of top with tap
water. Do not use distilled water.
b. Open thermostat valve and insert nylon
string. Position thermostat on string so that it
will be just below water level when sus-
pended, then allow valve to close. Suspend
thermostat in water.
c. Place thermometer in container and position
so that bottom of thermometer is even with
bottom of thermostat. Do not allow thermom-
eter to touch container.
72675
b
c
a
a - Thermometer
b - Nylon String
c - Thermostat (Typical)
IMPORTANT: When performing procedures
“d”-“f,” water must be agitated thoroughly to ob-
tain accurate results.
d. Plug in tester and observe temperature at
which thermostat opens (thermostat drops off
thread). Thermostat must open at specified
temperature stamped on thermostat.
e. Continue to heat water until a temperature
25°F (14°C) above temperature specified on
thermostat is obtained. Thermostat valve
must be completely open at this temperature.
f. Unplug tester and allow water to cool to a
temperature 10°F (5°C) below specified tem-
perature on thermostat. Thermostat must be
completely closed at this temperature.
g. Replace a thermostat that fails to meet all of
the preceding tests.
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