An internal combustion engine works via the combustion of fuel. In the heart of the engine sits the block and the cylinder head, two components that are fixed together and which house the cylinders where the ignition of fuel takes place. This ignition occurs thousands of times every minute, with the small explosions forcing the pistons within the cylinders to move at tremendous speeds. The stress, pressure and heat created through this process is, not surprisingly, incredibly intense and a way to control the temperature within the engine is required so that it does not suffer catastrophic damage.
The cooling system is designed to do this job and it comprises of several components that work together to ensure that a liquid coolant can flow smoothly through channels and passageways within the block and cylinder head, drawing heat away from the engine and keeping it working at an optimum temperature.
The components that make up the cooling system are:
- Radiator: Coolant that has drawn heat from the engine is cooled when it flows through the radiator.
- Radiator cap: Keeps the cooling system under pressure.
- Water pump: Pumps coolant through the system. It is powered by the engine timing belt.
- Radiator fans: While the radiator is placed at the front of the vehicle and receives cooling air through the vehicle grille, fans are also used to provide quality airflow.
- Reserve tank: The cooling system is a closed, sealed system. As coolant heats up, it expands and increases the pressure in the system. The reserve tank is used to contain the expanding coolant.
- Timing/Drive belts: Because the timing/drive belts drive the water pump, they can be considered part of the cooling system. If they fail, the water pump will not be driven and the cooling system itself will fail.
- Thermostat: Essentially a valve that measures coolant temperature and diverts it through a bypass system and back into the engine while the engine is still cold. This allows the engine to heat up to its optimum operating temperature more quickly. Once the engine (and consequently the coolant) has heated up, the thermostat opens and the coolant flows to the radiator.
- Heater core: A small component that looks like a mini radiator, the heater core is used when the heating feature of the system is required to warm up the cabin. Hot coolant is diverted through the core and the air that passes over it absorbs the heat and is blown into the cabin.
- Hoses: The rubber tubes used to connect the various cooling system components and direct the flow of coolant.
SYMPTOMS OF A FAILING COOLING SYSTEM
There are a few obvious signs that a cooling system is in trouble.
- Temperature gauge: Prominent amongst the many indicators and warning signals on a vehicle’s dashboard is the temperature gauge. If this rises above the norm, perhaps even into the red, then clearly something is amiss.
- Steam from the engine: Steam escaping from under the bonnet is another very clear sign that the engine is overheating and that the cooling system has failed.
- White exhaust smoke: Smoke of any kind coming from the tailpipe is almost always a sign of trouble. White smoke is an indication that coolant has leaked into the engine’s combustion chamber and is being burnt along with the fuel. This is likely due to cracked or broken seal.
- Coolant level: Every vehicle has a recommended amount of coolant within the system. If it is low or has fallen below the minimum required level, then there is almost certainly a leak in the system that needs to be repaired. Checking the coolant level is a basic maintenance check that every owner should carry out on a regular basis.
- Coolant leak: Notice a green (or whatever colour of the coolant in your vehicle) puddle under the vehicle? Then the coolant is leaking.
The cooling system is vital to the performance and health of a vehicle. A coolant leak or a failing component within the system will lead to the engine overheating and that can lead to very serious damage to any number of critical components within the engine proper. In the worst-case scenario it could even lead to a cracked block and that could result in the engine needing to be replaced – a very expensive prospect.
Regular checks of the coolant level, replacing the coolant at the recommended interval, keeping to the vehicle’s recommended service schedule, and always using the correct coolant specified by the vehicle manufacturer, should ensure that any problems are discovered early (which is always good for the wallet), and that the system is kept in tip-top shape.
WANT TO LEARN MORE?
MTA Queensland’s Vehicle Maintenance course is designed for those who are interested in gaining valuable information and learning good practices for everyday vehicle use. The result: a safer journey with fewer breakdowns and repairs. If you have ever wanted to learn how to carry out preventative maintenance, then this course is for you.
5 February 2020
Please note the information contained on this page is general in nature and does not take into account your specific needs or circumstances. You should consider whether the information is appropriate to your needs, and where appropriate, seek professional advice.