What Damage Occurs When a Car Overheats?

When a car overheats due to some problem or failure in the cooling system, excessive temperatures can damage parts of the engine, such as the head gasket, engine block and cylinder heads. Engines that have aluminum, as well as iron components, are more vulnerable to damage by overheating, compared to older engines that are made entirely of iron or aluminum. Bi-metal engine components will expand at different rates, which causes warping.

Cracked Head Gasket

If the head gasket cracks from overheating, its sealing ability fails and coolant can then leak into a cylinder or into the crankcase, according to AA1Car.com. If the oil in the crankcase becomes sufficiently diluted, it will lose its lubricating ability, leading to potentially serious engine damage. A damaged head gasket is the most common cause of internal coolant leaks, which can cause persistent overheating.

Cylinder Problems

If the cylinder heads become warped, they may have to be resurfaced. If the damage is severe, they will need to be replaced, according to NewCarBuyingGuide.com. If coolant leaks into a cylinder, it can dilute the oil on its walls, damaging the piston and piston rings. The coolant can also foul the spark plug, interfering with combustion. Green antifreeze contains silicates, which can foul the oxygen sensor and catalytic converter.

Additional Information

Repeated overheating can damage the radiator camp, so that it can no longer hold pressure. This may result in the coolant in the radiator boiling over. Checking for overheating problems typically starts with examining the radiator, thermostat, fan and water pump.