What Is a Radiator?
The radiator is a heat exchanger mounted at the front of the vehicle, designed to transfer heat from the hot coolant returning from the engine to the ambient air passing through it. It consists of a network of thin aluminium tubes and fins through which coolant flows, maximising the surface area exposed to airflow. Electric cooling fans assist airflow through the radiator at low speeds and when stationary. The radiator cap maintains system pressure, raising the boiling point of the coolant.
What Does the Radiator Do?
The radiator is the primary heat rejection component in the cooling system. Coolant heated by the engine passes through the narrow tubes of the radiator core, where it is cooled by airflow (aided by cooling fans when necessary) before returning to the engine. The efficiency of the radiator directly determines the maximum sustained heat rejection capacity of the cooling system and therefore the maximum sustained engine output.
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Get My Free Fault Scan →Symptoms of a Failing Radiator
Radiator failure or damage causes overheating, coolant leaks (visible as drips or steam from the front of the vehicle), reduced heating efficiency and discoloured coolant. Physical damage from stone strikes — particularly to plastic end tanks — is a common failure mode. Internal blockage from scale or corrosion reduces flow and cooling efficiency gradually.
When Should the Radiator Be Replaced?
Radiators are replaced on failure or significant damage. Radiator coolant should be changed every 3 to 5 years to prevent internal corrosion and maintain inhibitor effectiveness. Always use the correct specification coolant — mixing types can cause silicate precipitation and internal blockage.
If you are experiencing symptoms related to your radiator and are unsure whether it needs replacing, a free MotorLoom fault scan can help identify whether the component is likely at fault - giving you the most likely cause and estimated repair cost before you visit a garage.
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Related Parts
Other components that work alongside or are related to the radiator: