The cooling system is a system of parts and fluid that work together to control an engine’s operating temperature for optimal performance. The system is made up of passages inside the engine block and heads, a water pump and drive belt to circulate the coolant, a thermostat to control the temperature of the coolant, a radiator to cool the coolant, a radiator cap to control the pressure in the system, and hoses to transfer the coolant from the engine to the radiator.
The liquid that flows through a cooling system, antifreeze, or commonly referred to as coolant, withstands extreme hot and cold temperatures and contains rust inhibitors and lubricants to keep the system running smoothly.
Coolant follows a circulation path that begins with the water pump. The water pump’s impeller uses centrifugal force to draw coolant from the radiator and push it into the engine block. Pumps are usually fan, serpentine timing belt, or timing chain driven. Nowadays, they may even be driven electrically. If the water pump experiences a leak from the seal, a cracked housing, broken impeller or a bearing malfunction, it can compromise the entire cooling system, causing the vehicle to overheat.
As coolant flows through the system, it picks up heat from the engine before arriving at the thermostat. The thermostat is a valve that measures the temperature of the coolant and opens to allow hot fluid to travel to the radiator. If the thermostat becomes ‘stuck’ and quits working, it will affect the entire cooling system.
Once released by the thermostat, hot coolant travels through a hose to be cooled by the radiator. The antifreeze passes through thin tubes in the radiator. It is cooled as air flow is passed over the outside of the tubes. Depending upon the speed of the vehicle, airflow is provided by the vehicle’s movement down the road (ram air effect) and/or cooling fans. Radiator restrictions can compromise its ability to transfer heat. These can be either external air flow or internal coolant flow restrictions. A malfunctioning electric cooling fan or fan clutch can limit air flow across the radiator. Check/replace the fan clutch…the life expectancy of water pumps and fan clutches are about the same and share a common shaft. A failed fan clutch can cause severe damage to the water pump.
As coolant temperature increases, so does the pressure in the cooling system. This pressure is regulated by the radiator cap. Correct system pressure is required for proper water pump seal lubrication. Increasing the cooling system pressure raises the boiling point of the coolant. Each one pound of increased pressure raises the boiling point by 3˚F. If the pressure builds up higher than the set pressure point, a spring-loaded valve in the cap will release the pressure. If an engine has overheated, the radiator cap and thermostat should be replaced.
It is important to regularly inspect the condition of your cooling system’s belts and hoses. Soft hoses, oil soaked belts or cracked belts and hoses can have dire effects on the entire cooling system. Proper belt tension is also important.
Always refer to your manufacturer’s manual to determine the recommended coolant type for your vehicle. This and the proper mixture of coolant and distilled water are the lifeblood towards keeping your system running cool. Most parts retailers now offer a solution of premixed coolant and distilled water. While it may seem like an unnecessary added expense, the cleanliness of the premixed solution will pay off over time.
Mineral deposits and sediments from corroded or malfunctioning parts accumulate in the cooling system. Before performing a cooling system repair, it is recommended to flush the cooling system prior to installing any new parts. This is a task made even easier by using a flush-fill kit. Failure to flush the system will contaminate the new parts being installed and could lead to premature component failure.