Which component is NOT typically a part of an engine's cooling system?

The piston is not typically part of an engine's cooling system. Instead, pistons are integral components of the engine's combustion system, where they convert the energy from combustion into mechanical work. The cooling system is responsible for regulating the engine's temperature and preventing overheating, and it consists of several key components such as the radiator, thermostat, and water pump.

The radiator dissipates heat from the coolant, allowing it to cool before circulating back into the engine. The thermostat controls the flow of coolant based on the engine's temperature, ensuring that the engine operates within a safe temperature range. The water pump circulates the coolant throughout the system, maintaining adequate flow to absorb and disperse heat effectively.

In contrast, since the piston is involved in the internal processes of combustion and is located within the engine block, it does not contribute to the cooling of the engine, making it the component that does not belong to the cooling system.