Maintenance of Major Components
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5.1.2. Thermostat
General descriptions and main data
The thermostat maintains a constant
temperature of coolant and improves
thermal efficiency of the engine by
preventing heat loss.
Namely, when the temperature of
coolant is low, the thermostat valve is
closed to make the coolant bypass to
directly enter the water pump; when the
coolant temperature rises to open wide
the thermostat valve, the bypass circuit is
closed and the water passage to the
radiator is opened so that the coolant is
forced to flow into the radiator.
NOTE:
There are 2 kinds of thermostats according to surrounding and operating conditions.
One is named by 71 °C type and the other is 79 °C.
Inspecting
1) Check the wax pallet and spring for
damage.
2) Put the thermostat in a container of
water, then heat the water slowly and
check temperature with a
thermometer. If the valve lift is 0.1
mm (starting to open) at temperature
of 83 °C and 8 mm or more (full open)
at temperature of 95 °C, the
thermostat is normal.
EAMC002I
To radiator
Bypass
valve
From cooling
water pump
To bypass tube
Item
Specifications
In moderate climates In tropical climates
Type Wax-pallet type Wax-pallet type
Open at 79
°
C71
°
C
Open wide at 94
°
C85
°
C
Valve lift 8 mm or more 8 mm or more
EFM2055I
Thermometer
Wood plate
Ruler
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