Coolant Flow - Segway VILLIAN SSV Series Service Manual

COOLING SYSTEM

COOLANT FLOW

Choose permanent antifreeze as the coolant to prevent rust and corrosion of the cooling system. When
the engine starts, the water pump rotates and the coolant circulates.
The thermostat is a type of wax pellets, which opens or closes as the temperature of the coolant
changes. The thermostat continuously changes its valve opening to keep the coolant temperature at
an appropriate level. When the coolant temperature is lower than 79 ~ 82℃ (174.2 ~ 179.6℉), the
thermostat is closed. Therefore, the fl ow of coolant through the exhaust hole is restricted, which makes
the engine warm up faster. When the coolant temperature exceeds 79 ~ 82℃ (174.2 ~ 1179.6 ℉), the
thermostat will open and the coolant will fl ow. When the coolant temperature reaches 88℃ (190.4℉),
the radiator fan switch is turned on,
The radiator fan is working. When there is not enough airfl ow (for example, at low speeds). The radiator
fan draws in air through the radiator core. This increases the cooling eff ect of the radiator. When the
temperature is lower than 83 ℃(181.4℉), the fan switch is turned off and the radiator fan stops working.
In this way, the system controls the engine temperature within the narrow range of engine operation.
Even if the engine load changes, the engine has the highest operating effi ciency.
The system is pressurized through the radiator cap to suppress boiling and the resulting bubbles that
may cause the engine to overheat. When the engine warms up, the coolant in the radiator and water
circuit expands. The excess coolant fl ows into the water storage tank through the radiator cover and
hoses. Conversely, when the engine cools, the coolant in the radiator and water circuit shrinks, and the
stored coolant fl ows from the water tank back to the radiator.
The radiator cap has two valves. One is a pressure valve, which maintains the pressure in the system
when the engine is running. When the pressure exceeds 93 ~ 123kPa (0.95 ~ 1.25 kgf/cm², 14 ~ 18psi),
the pressure valve opens and releases the pressure to the water storage tank. Once the pressure
overfl ows, the valve is closed and the pressure is maintained at 93 ~ 123kPa (0.95 ~ 1.25kgf/cm², 14
~ 18psi). After the engine has cooled down, another small valve (vacuum valve) on the cover opens.
When the coolant cools, the coolant shrinks, creating a vacuum in the system. The vacuum valve opens
and allows the coolant to enter the radiator from the storage tank.
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