Engine coolant has a primary function of convective heat transfer for internal combustion engines. The correct coolant mixture and quality will prevent freezing in winter, prevent boiling in summer, prevent rust and corrosion of metal parts, become a good conductor of heat, and aid in preventing electrolysis.
A cooling system works by circulating liquid coolant through passages in the engine block and cylinder head(s). As the coolant flows through these passages, heat is transferred from the engine components to the coolant. The heated coolant then makes its way through a rubber hose to the radiator in the front of the engine compartment. As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air flow entering the engine compartment through the grill in front of the vehicle. Once the fluid is cooled, it returns to the engine to absorb more heat. The water pump has the job of keeping the fluid circulating through the system when the engine is running.