COOLING AND LUBRICATION SYSTEM 6-11
THERMOSTAT
REMOVAL
• Remove the fuel tank cover. (#7-5)
• Drain a small amount of engine coolant. (#6-4)
• Place a rag under the thermostat case.
• Remove the thermostat case.
• Remove the thermostat.
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 satisfy the standard value.
$ Thermostat valve opening temperature
Standard: 73.5 – 76.5 °C (164 – 170 °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 3.0 mm
(0.12 in).
$ Thermostat valve lift
Standard: Over 3.0 mm at 90°C (Over 0.12 in at 194°F)
• A thermostat failing to satisfy either of the two requirements
(start-to-open temperature and valve lift) must be replaced.
INSTALLATION
• Install the thermostat in the reverse order of removal.
• Apply engine coolant to the rubber seal on the thermostat.
Thermostat
String
Stove Thermometer
Water
Valve lift
To Next Page
Loading...
