Car overheating? What to do (and what not to do)
Updated
Quick answer
Pull over somewhere safe as soon as you can and switch the engine off. Don't open the radiator or coolant cap while it's hot: the coolant is under pressure and can scald. Let it cool for at least 30 minutes. If it's lost coolant, or the warning comes straight back, don't keep driving: call for recovery.
The warning signs
- The temperature gauge climbing towards the red, or a red temperature warning light
- Steam or white smoke from under the bonnet
- A sweet, syrupy smell (that's coolant)
- Loss of power, or the engine running roughly
Getting to a safe place
If you're on a busy road and need a moment to reach a safe spot, turning the heater and fan to full hot can draw a little heat away from the engine. Then pull over somewhere safe, away from traffic, put your hazard lights on and switch the engine off.
On a motorway, follow the usual safety steps from our M11 breakdown guide: get behind the barrier first.
What never to do
- Don't open the radiator or coolant reservoir cap while the engine is hot. The coolant is under pressure and can cause serious burns.
- Don't pour cold water onto a hot engine.
- Don't keep driving with the gauge in the red: it can warp the cylinder head or blow the head gasket, which turns a cheap fix into a very expensive one.
Once it has cooled
After at least 30 minutes, check the coolant level in the expansion tank (the plastic bottle with MIN and MAX marks). If it's low and you have coolant, top it up to between the marks. In an emergency, clean water will do to get you somewhere safe, but have the system checked and refilled properly afterwards.
Look for obvious leaks under the car or a split hose. If you can see coolant pouring out, the warning comes straight back, or an oil warning light comes on, stop driving.
When to call us
If it keeps overheating, has lost coolant or there's any doubt, don't risk the engine. We'll load your car onto the flatbed and take it to your home or a garage of your choice. See vehicle recovery and our prices.