The thermostat helps an engine to warm up. It’s found in different positions on different engines.
It is a valve that operates according to coolant temperature. When coolant is cold, a spring holds the valve closed.
When a cold engine starts, coolant circulates within the engine block and cylinder head and through a coolant bypass to the water pump inlet. It can’t get to the radiator.
As the engine warms up, the coolant in the engine gets hotter and hotter.
This thermostat has a wax-like substance that expands as the engine nears its operating temperature. This starts to open the valve. Coolant starts to flow to the radiator.
Thermostats have a small hole or valve to let out air that was trapped in the engine block.
Heated coolant is pumped from an outlet in the cylinder head. It goes into the upper radiator hose, then to the radiator.
