As the corrosion inhibitors in the antifreeze are gradually depleted over time, the alkalinity of the coolant changes allowing corrosion to start inside the radiator and cooling system. This condition can lead to leaks as well as restrictions. With conventional antifreeze, the coolant should be changed every 2 years or 30,000 miles. Long life coolants that can go up to 5 years or 100,000 miles can help reduce the need for maintenance while extending corrosion protection. Other causes of radiator failure include cracks from vibration and mechanical stress, and physical damage.
Excessive heat can be another cause of radiator failure.
Radiators with plastic end tanks can be damaged by steam erosion if the coolant level becomes low and the engine overheats. White deposits on the inside of the plastic tank would indicate steam damage. Replacement is usually more convenient and reliable than having an old radiator repaired. The replacement is usually the same type of metal as the original and designed for a perfect fit every time. Up until the 1980s, aluminum radiators were rare.