COOLING AND LUBRICATION SYSTEM 5-11
THERMOSTAT
REMOVAL
• Drain engine coolant. (!2-17)
• Place a rag under the thermostat case.
• Remove the thermostat case.
• Remove the thermostat
1.
INSPECTION
Inspect the thermostat pellet for signs of cracking.
Test the thermostat at the bench for control action, in the follow-
ing manner.
• Pass a string between flange, as shown in the photograph.
• Immerse the thermostat in the water contained in a beaker, as
shown in the illustration. Note that the immersed thermostat is
in suspension. Heat the water by placing the beaker on a
stove and observe the rising temperature on a thermometer.
• Read the thermometer just when opening the thermostat. This
reading, which is the temperature level at which the thermo-
stat valve begins to open, should be within the standard
value.
" Thermostat valve opening temperature
Standard: Approx. 88 °C (190 °F)
• Keep on heating the water to raise its temperature.
• Just when the water temperature reaches specified value, the
thermostat valve should have lifted by at least 8.0 mm
(0.31 in).
" Thermostat valve lift
Standard:
Over 8.0 mm at 100 °C (Over 0.31 in at 212 °F)
• A thermostat failing to satisfy either of the two requirements
(start-to-open temperature and valve lift) must be replaced.
1
Stove
2
Thermometer
Water
Valve lift
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