If the temperature gauge climbs, switch off the air conditioning, turn the heater to maximum to pull heat out of the engine, and pull over as soon as it is safe. Continuing to drive an overheating engine is how a modest cooling repair becomes a head gasket.
Is it safe to open the radiator cap when the engine is hot?
A cooling system is pressurised, which raises the coolant's boiling point above 100 degrees.Releasing that pressure while hot causes the coolant to flash to steam instantly and ejectthrough the opening. This causes serious burns every summer and is entirely avoidable: waituntil the engine is cool to the touch before opening anything.
What usually causes a car to overheat?
- Low coolant, which means a leak somewhere rather than consumption.
- A failed cooling fan, which shows up as overheating in traffic but not at speed.
- A stuck thermostat, often causing a rapid climb shortly after starting.
- A failing water pump, sometimes preceded by a whine or a weep from the pump housing.
When Your Car Overheats: Questions
What should I do if my car overheats in traffic?
If your car overheats, switch off the air conditioning, turn the heater to maximum, and pull over as soon as it is safe.
Can I open the radiator cap to check?
No. A hot cooling system is under pressure and can spray scalding coolant. Wait until the engine has cooled.
What usually causes it?
Low coolant from a leak, a failed fan, a stuck thermostat or a failing water pump are the usual causes.

