Why does my car overheat?
An overheating engine is a serious problem that can cause expensive damage very quickly — including a blown head gasket if you continue driving. Pull over safely and switch off the engine as soon as the temperature gauge enters the red. Let the engine cool for at least 30 minutes before opening the bonnet. Do not open the radiator cap when hot. The most common causes are low coolant, thermostat failure, water pump failure, or a blocked radiator.
Likely causes
Low coolant level or coolant leak
Check for puddles under the car, coolant smell, or white exhaust smoke
Thermostat stuck closed
Coolant cannot circulate to the radiator — engine temperature rises quickly
Water pump failure
Coolant stops circulating — often accompanied by a whining or grinding noise from the pump
Blocked or damaged radiator
Blocked radiator cannot dissipate heat — more common on older vehicles
Head gasket failure
Serious — often a consequence of overheating rather than a cause. Look for white exhaust smoke, bubbles in coolant reservoir, or mayonnaise under the oil cap
Repairs you may need
Typical cost range: £80–£1500 — Thermostat: £80–220. Water pump: £150–350. Radiator: £200–500. Head gasket: £700–1,500+. Coolant top-up: minimal.
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