Radiator Overflow Tank?

The cooling system is one of the most important systems in the vehicle because it keeps the engine at a right temperature, allowing it to work efficiently. Since the engine takes charge of burning the air and fuel mixture, it produces large amount of heat that makes the parts so hot and vulnerable to damage. The cooling system prevents this to happen as it dissipates the heat from the engine and its parts through the coolant. This coolant absorbs the heat as it circulates around the engine and goes to the radiator where it transfers the heat to the cool air.

A coolant is a mixture of water and anti-freeze, which is a chemical solution, usually ethylene glycol and anticorrosion chemicals. When heated the coolant expands; thus, most cooling systems have expansion tank that provides storage space for the heated coolant. The expansion tank is usually plastic and is connected to the radiator through the overflow tube. It is also called as the radiator overflow tank, coolant-recovery tank, coolant reservoir, or simply overflow tank or canister. These names imply its function, which is to hold the overflowing coolant that absorbed the heat from the engine.

Not all vehicles have a radiator overflow tank; however, this part is helpful in the cooling system. Without it, the expanded or heated coolant would flow out of the overflow tube and eventually, out of the vehicle and out on the street. The expansion tank or radiator overflow tank provides additional space for the coolant to stay after it absorbed the heat from the engine. Also, the radiator overflow tank removes air bubbles from the coolant, thus, allowing it to absorb heat much faster. Furthermore, when a vehicle has an overflow tank, the radiator is always full.

Only enough amount of the heated coolant goes to the radiator for cooling and this goes back to the engine to absorb heat once again. When the engine cools, vacuum is created in the cooling system since it is a closed system. This causes the coolant in the radiator overflow tank to be sucked back into the cooling system.