Coolant Flow - Segway SNARLER ATV 2021 Series Service Manual

COOLING SYSTEM

Coolant Flow

Select 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 wax particle type, which opens or closes with the change of the coolant
temperature. 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 and the radiator fan works. When there is not enough airfl ow (for
example, at low speeds). The radiator fan sucks 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 working 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 storage tank back to the radiator.
The radiator cover 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/c ㎡ ,
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/
c ㎡ , 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.
6 - 3