Which device in the cooling system determines whether jacket water goes to the engine or through the cooler?

Which device in the cooling system determines whether jacket water goes to the engine or through the cooler?

• A. Flow meter
• B. Thermostatically controlled bypass valve
• C. Thermostat
• D. Water pump

Answer: (B)

The device that controls whether jacket water goes to the engine or through the cooler is the thermostatically controlled bypass valve. This valve creates two paths: a bypass that keeps coolant circulating through the engine when it’s cold, and a radiator path that sends coolant through the cooler once the system warms up. In cold conditions, you want fast warming of the engine, so the valve closes the radiator path and routes flow back to the engine. When the coolant temperature rises, the valve opens the route to the cooler to shed excess heat. The other components don’t decide the routing: a flow meter only measures flow, a thermostat mainly regulates when coolant is allowed to circulate through the radiator, and the water pump just moves the coolant through the system.

The device that controls whether jacket water goes to the engine or through the cooler is the thermostatically controlled bypass valve. This valve creates two paths: a bypass that keeps coolant circulating through the engine when it’s cold, and a radiator path that sends coolant through the cooler once the system warms up. In cold conditions, you want fast warming of the engine, so the valve closes the radiator path and routes flow back to the engine. When the coolant temperature rises, the valve opens the route to the cooler to shed excess heat. The other components don’t decide the routing: a flow meter only measures flow, a thermostat mainly regulates when coolant is allowed to circulate through the radiator, and the water pump just moves the coolant through the system.