Engine overheating: What causes engine overheating and how to prevent it
Engine overheating: Causes and how to prevent it
Spotted a rising temperature gauge and a cloud of steam from the bonnet? It’s the issue no driver wants - an overheated engine. In this guide, we’ll explain what engine overheating really means, why it happens, and what you can do to keep your car engine cool and safe.
What does it mean if my car engine overheats?
Engine overheating happens when the temperature of your engine climbs beyond the normal operating range, typically above 105°C. When it gets too hot, vital components like the cylinder head, gaskets, and pistons can start to warp, crack or seize.
Left unchecked, an overheated engine can lead to catastrophic engine failure... And an expensive repair bill.
Why do car engines overheat?
Overheating isn’t always a sign of poor maintenance - sometimes, it’s just bad luck. Here are the most common reasons engines run too hot:
Coolant leaks or low coolant levels: Without enough coolant, your engine can’t regulate heat effectively.
Blocked radiator or cooling fan issues: A blocked radiator or a faulty fan either restricts coolant flow or airflow, which stops the system from releasing heat.
Broken water pump: This key component circulates coolant - if it fails, so does the cooling system.
Thermostat problems: If the thermostat is stuck closed, it blocks coolant flow; if stuck open, it prevents the engine from warming up properly.
Driving in extreme weather: Your car’s cooling system has to work harder to regulate temperature, and excessive heat or strain can overwhelm it.
Blockages or air in the cooling system: These stop coolant from moving freely, trapping heat in the engine.
Signs your car engine is overheating
Spotting the early warning signs can make all the difference. Look out for:
Temperature gauge outside of the normal range - or possibly unusually low.
Strange smells – a sweet smell could be coolant, and burnt smells could be burnt oil or engine components.
Warning lights flashing on the dashboard, or the car making strange noises.
What to do if your car engine overheats while you’re driving
Don’t ignore an overheating engine, and don’t keep driving. Here’s how to stay safe and minimise damage if your engine starts to overheat on the road.
Keep the AC on but set the temperature to hot. It sounds counterintuitive, but keeping the air conditioning on hot helps cool the radiator. The heater matrix is like a mini radiator, and uses the engine coolant to generate heat when air blows over it. Setting the heaters to hot and switching the fan to max helps reduce coolant temperature, drawing heat away from the engine using the heater core - and buying you time to pull over.
Pull over safely and switch off the engine.
Let the engine cool completely before opening the bonnet. This can take a few hours, especially in warm weather.
Only check coolant levels once the engine is cold – again, the engine can take several hours to cool down.
Call for roadside assistance if you're unsure or can’t fix the issue.
How to prevent your car engine overheating
A little forward planning can keep your engine cool and your journeys smooth:
Check the Vixa app to see if we’ve reported on any faults which could cause issues.
Check your coolant regularly - if it’s frequently low, there may be a leak.
Service your car regularly.
Avoid overloading your vehicle during heatwaves or in heavy traffic.
Is an overheated car engine dangerous?
Overheated engines can be dangerous, and in rare cases, they can even become a fire hazard. But they’re more likely to cause serious engine damage than burst into flame.
You might lose power steering or brake assistance if the engine cuts out, and there’s also a risk of being stranded in a hazardous location.
So if you spot steam, a rising gauge, or warning lights - pull over in a safe spot, turn off the engine, and let it cool before taking further steps.
Caring for your car engine with Vixa
We make car maintenance simple, so you can take care of your car and minimise the chances of your engine overheating. Vixa offers:
Real-time engine monitoring via your phone.
Proactive alerts if your engine's showing signs of trouble.
Fault information so you know more about what’s wrong.
Easy booking with one of our Mobile Mechanics or trusted AA approved garages.