Where is the car thermostat installed?
2 Answers
The car thermostat is installed at the upper water outlet of the engine, and it can be seen by removing the engine water pipe. The car thermostat is a valve that controls the flow path of the coolant, serving as an automatic temperature-regulating device. Its function is to automatically adjust the amount of water entering the radiator based on the coolant temperature, change the circulation range of the water, regulate the cooling system's heat dissipation capacity, and ensure the engine operates within an appropriate temperature range. The working principle of the car thermostat is: 1. When the coolant temperature is below the specified value, the paraffin in the thermostat's temperature-sensing body remains in a solid state, and the thermostat valve closes the channel between the engine and the radiator under the action of the spring. The coolant returns to the engine via the water pump, performing a small circulation within the engine. 2. When the coolant temperature reaches the specified value, the paraffin begins to melt and gradually turns into a liquid, expanding in volume and compressing the rubber tube, causing it to contract. As the rubber tube contracts, it exerts an upward thrust on the push rod, which in turn applies a downward counter-thrust on the valve, opening it. The coolant then flows from the radiator and the thermostat valve, returning to the engine via the water pump, performing a large circulation.
The thermostat in a car is typically installed at a critical location in the engine cooling system. Specifically, it is positioned in the outlet pipe at the front of the engine cylinder head, connecting the engine block to the water pump inlet. For example, in older Japanese cars, it is often located at the engine's upper hose connection, while in German cars, it might be hidden near the water pump inlet. To locate it, you need to open the hood and follow the thick coolant hose—it resembles a metal or plastic disc with a valve. This placement allows the thermostat to promptly sense changes in engine temperature. Once the coolant overheats, the valve opens to direct the coolant to the radiator for cooling. When replacing it, you must first drain the antifreeze, and after installation, you need to bleed the air bubbles from the system; otherwise, cooling efficiency will be compromised. I once encountered a stuck thermostat while helping a friend repair their car—the temperature gauge shot up alarmingly while driving.
