The cooling system keeps our engine from overheating. Its job is to move heat away from the engine. Let’s talk about the various components of the system and how they work to accomplish this.
The radiator is the part most everyone associates with the cooling system. Coolant flows through the radiator which has fine cooling fins that draw the heat out of the coolant and dissipate it into the air. To make sure there’s enough airflow over the radiator, a fan pulls air over the cooling fins even when the car is idling.
In some vehicles, the fan is powered by the serpentine belt. On others, an electric motor runs the fan. Electric fans turn on and off as needed. You may have heard the fan kick on shortly after you turn your car off. The sensor has determined that the engine needs a little help cooling down to a safe temperature.
A hose connects the radiator to the water pump. The water pump pushes the water into the engine block. Now the engine block and cylinder heads have passages for the coolant to pass through without getting into the oil or the combustion chamber. These passages are referred to as the “water jacket”.
While the coolant is passing through the water jacket, it absorbs heat from the engine on its way to the radiator for cooling. Between the engine and the radiator is a gatekeeper called the thermostat. The thermostat’s job is to regulate the temperature of the engine just like your home thermostat regulates the temperature of your house. It gets your engine up to the correct operating temperature and then keeps it from overheating.
When your first start the engine, it’s very cold and needs to warm up. So the thermostat blocks the flow of coolant to the radiator. As the engine warms up, the thermostat starts to let coolant flow through the system.
The final component I want to talk about is the overflow reservoir. This bottle is designed to hold some of the coolant. It’ll have a mark that indicates whether or not you have enough coolant. This is where you should add coolant if you just need to top it off.
Caution: never open the reservoir or the radiator cap when the car’s hot. The cooling system is pressurized and opening them while it’s hot can cause hot coolant and steam to escape resulting in serious burns.
Cooling system failure is the most common mechanical failure in vehicles. Your service center can do a periodic inspection of the components for leaks, loose connections and weakening hoses.
Your manufacturer has also specified a cooling system service interval. With a cooling system service, the old coolant is replaced with correct clean fluid that contains the additives required to prevent corrosion. The additives are depleted over time and you need fresh fluid for adequate protection. Your radiator pressure cap should be replaced at this service as well.