Engine overheating is a serious problem that can cause catastrophic damage if not addressed immediately. Here’s what causes it, how to handle it safely, and how to fix the underlying problem.
What to Do When Your Engine Overheats
Do NOT keep driving. Pull over safely as soon as possible, turn off the engine, and let it cool for at least 30 minutes before opening the bonnet. Never open the radiator cap on a hot engine — the pressurised coolant can cause severe burns.
Most Common Causes
- Low coolant level — The most common cause. Check your coolant reservoir when the engine is cold.
- Coolant leak — Look for puddles under the car or white steam from the bonnet. Common leak points: radiator, hoses, water pump, head gasket.
- Faulty thermostat — If stuck closed, coolant can’t circulate. A replacement thermostat costs £10–£20 and is often DIY-friendly.
- Blocked radiator — Debris or scale buildup reduces cooling efficiency. A radiator flush can solve this.
- Failing water pump — The pump circulates coolant through the engine. If it fails, coolant stops moving.
- Blown head gasket — The most serious cause. Signs include white exhaust smoke, milky oil, and bubbles in the coolant reservoir.
Quick Checks You Can Do
Once the engine is cold, check the coolant level in the reservoir. If it’s low, top up with the correct coolant mix (50/50 antifreeze and distilled water). Check all visible hoses for cracks or loose clamps. If the problem persists after topping up, you have a leak that needs finding.
