Where would an engine thermostat most likely be found?

The engine thermostat is typically located at the engine end of the upper radiator hose. This positioning allows it to regulate the flow of coolant between the engine and the radiator. When the engine is cold, the thermostat remains closed, preventing coolant from flowing to the radiator. As the engine warms up and reaches the designated operating temperature, the thermostat opens, allowing heated coolant to flow through the radiator where it can be cooled before recirculating back to the engine. This cycle is crucial for maintaining optimal engine temperature and preventing overheating.

Other locations mentioned do not align with the standard design. For example, having the thermostat at the radiator end could disrupt the intended flow of coolant and the thermal regulation process necessary for effective engine cooling. Similarly, placing it at the engine end of the lower radiator hose would also interfere with the normal pathway for regulating coolant temperature, as that hose generally returns cooled coolant from the radiator back to the engine.