What to Do When Your Car Overheats

Pull over as soon as it's safe, switch off the air conditioning, and turn on the heater to draw heat away from the engine block. Switch on your hazard lights if you're stopping on the roadside, and choose a spot away from moving traffic rather than the nearest gap. Turn off the engine once you're stopped and let it cool for at least 15 minutes before opening the bonnet. Watch the temperature gauge rather than waiting for a warning light, since not every car shows one until the engine is already significantly hot. Do not keep driving to reach home or the workshop — a few more kilometres on an overheating engine can turn a coolant top-up into a head gasket repair.

No. A hot cooling system is pressurised, and opening the radiator cap while the engine is still warm can release scalding coolant and a burst of steam straight at your face and hands. Some radiator caps have a two-stage release that lets built-up pressure escape gradually rather than all at once, but it still isn't something to test while the engine is hot. Wait until the engine is cool to the touch, at least 15 to 20 minutes after stopping, before touching the cap or checking the coolant level. If you need to add coolant or plain water on the roadside as a temporary measure, pour it in slowly with the engine switched off, and treat it as a reason to get the system checked rather than a fix on its own.

Running the air conditioning puts extra load on the engine, and the aircond condenser sits directly in front of the radiator under the bonnet. A blocked or failing aircond system can restrict airflow through to the coolant radiator behind it, which raises engine temperature especially at low speed or in traffic. If cooling fades once you're stuck in traffic or the air wasn't cold to begin with, it's worth checking how often car aircond should be serviced, since a system overdue for service is more likely to be running poorly and adding heat under the bonnet rather than just blowing warm air. Ignoring a struggling aircond system for months tends to make both problems — cooling and comfort — worse together, since the condenser and radiator effectively share the same airflow.

If you've separately noticed the steering wheel shaking under braking or clunking over bumps on rough road, mention it when you book the overheating check — it won't be related to the cooling fault, but flagging it now saves a second visit later. Vibration under braking can point to worn pads, scored rotors, tyres, or suspension components, and unusual noises or a car that pulls to one side are common symptoms of worn suspension worth flagging at the same time so both can be looked at in one visit. None of this changes the priority of sorting out the overheating first, but a single visit that covers everything noticed is more efficient than several separate ones.

Note when the overheating happened — at idle, in traffic, or at highway speed — and whether the warning light came on before or after you noticed steam or smell. Mention if you've topped up coolant yourself and what you used, since mixing coolant types can affect the diagnosis. This is especially useful if the overheating has only happened once and hasn't been reproduced yet, since the workshop can plan the inspection around trying to catch it. Send the car model and these details on WhatsApp before you arrive, so the workshop can confirm whether it's a diagnostic slot or a longer booking.