Where is the engine thermostat located?

[WestonDella]

The engine thermostat is installed at the water pump's inlet to regulate fluctuations in engine coolant temperature. When the engine is cold, the thermostat's main valve closes the primary water passage, while the bypass valve opens the bypass channel. Coolant from the cylinder block flows out through the upper outlet, passes through the bypass pipe and valve, enters the water pump, and is then pumped back into the cylinder block, creating what is known as a small circulation cycle. The thermostat functions as a valve controlling coolant flow paths and serves as an automatic temperature-regulating device, typically containing a temperature-sensitive component that operates by expanding or contracting to open or close the flow of air, gas, or liquid.