Why your engine is overheating: Causes, signs and what to do

Thursday 12th June 2025

Overheating engines might seem like a common issue in warmer weather or on longer drives, but they’re actually a huge warning sign. Ignoring the signals can cause major damage, expensive repairs, and an unsafe car to drive in. We’ll explain the common reasons your engine might overheat, how to spot the signs early, and what to do if it happens on the road. 

Need help fast? Find your nearest Formula One Autocentres garage and let our experts take care of it. 

Reasons your car engine overheats 

Whether you’re driving city-to-city or just caught in stop-start traffic, there are several issues which can cause your engine to overheat, especially as the summer months can heighten the risk of this happening. While you may want to head out to the nearest beach or have a picnic at the park, higher temperatures make our cars work harder.? 

Engine problems 

There are a few possibilities why your car’s engine could be the source of your car overheating. It’s the heart of your car and is intricately designed with belts, hoses, and other components, so you’ll need a professional to assess whether or not there are any engine issues. 

Low coolant levels 

Engine coolant is critical to keep your car at an optimal temperature and is usually the culprit if the engine’s overheating. If you need to top up your coolant after driving, you should wait at least 30 minutes before adding it.  

Coolant circulation failure 

If your car has sufficient coolant and your engine is still overheating, there could be a problem with the circulatory cooling system. This could be due to faulty radiator components, a mechanical fault, or a damaged expansion tank. You’ll need an experienced mechanic to discover the source of the issue, so speak to your local Formula One Autocentres garage to arrange an assessment. 

Low engine oil 

If your engine isn’t being effectively lubricated, it can cause it to overheat. Your engine oil’s role is to minimise friction and heat in the engine’s components, but insufficient levels can harm the operational process. You should check for any signs of a leak and also check the quality of the oil – if it’s dirty, gunky or discoloured, your oil needs changing.?  

Signs your engine is overheating while driving 

It’s vital to spot the signs of overheating early to avoid serious damage. Here are six warning signs your engine may be struggling: 

‘Overheating’ dashboard light 

The first warning sign that you might notice for an overheating engine is the temperature gauge on your dashboard. Every car model and make displays warning symbols in different locations on the dashboard, but these icons often include a thermometer symbol, which will illuminate red or orange when a critical rise in temperature is detected. Check the vehicle manual for confirmation that your car has this warning light and where it is located. A temperature spike to ‘H’ on the temperature gauge or any movement into the red zone is usually a sign that something isn’t right with your coolant supply, and you should head to your local Formula One Autocentres to get your engine assessed.? 

Knocking, clicking, or thumping noises 

These noises may indicate that your engine components aren’t sufficiently lubricated, and the noises are due to metal-on-metal friction. It’s crucial you get this investigated by a Formula One Autocentres technician as soon as you hear them, as continuing to drive your car with these issues can lead to further damage to your car’s components. 

Reduced power and performance 

An overheating engine will reduce performance as the engine and coolant system are working in overdrive to keep the car cool and running effectively. However, you may notice a dip or lag in power when driving because of this. If there are no other signs present, you should monitor the temperature gauge and warning symbols on your dashboard.? 

Smells like burning or butterscotch 

There are a range of smells which could be present if your engine overheats. If it’s sweet and syrupy, it could be an issue with your coolant. If it’s burning rubber, it could be the belts.?Hot oil and smoky smells also point to an overheated engine.? 

Smoke or steam from the bonnet 

Smoke and steam might look similar, but they indicate very different things. Extremely hot coolant escapes from the bonnet as steam, as it’s past the boiling point, while smoke is a sign of an oil or fuel leak. In both instances, you should pull over as soon as it’s safe to do so and let your car cool down. 

The bonnet is hot to touch 

Your car’s bonnet is likely going to be warmer than the rest of the exterior, but it shouldn’t be too hot to touch. If you aren’t able to touch the bonnet for longer than 10 seconds, it’s likely your engine is starting to overheat and preventative measures should be taken.? 

What to do if your car engine overheats

1. Pull over: Find somewhere safe to pull over as soon as you can and turn the engine off. If you’re on a motorway, leave at the next exit or head to a service station and put your hazards on. It’s important you don’t continue driving.? 
2. Let the car cool off: Park in a shaded area and let your car cool for roughly 30 minutes to an hour.? 
3. Observe and identify: Protect your hand in case the bonnet is still hot while you open it. See if anything seems out of the ordinary at first glance, then check the engine coolant levels and look to see if there are any leaks.? 
4. Don’t let the problem fester: You might be tempted to ignore the issue if your car cools down and starts working normally again. But if it happened once, it’s likely to happen again. Contact your local Formula One Autocentres for a mechanic to identify the source of the issue.?

Important things to note

• Wait until the engine has cooled before opening the radiator cap, as it’s pressurised and could cause severe steam burns. Open it slowly and protect your hands. 

• If your coolant tank is empty, this could signal a leak. Check under the car for any leakage or puddles. If you need to top up the coolant reservoir, use your usual coolant, or if it is an emergency, you can mix some distilled water with the coolant – but never use tap water or try to run the car with only distilled water in the reservoir. Drain this mixture as soon as possible and replace it with your recommended coolant.  

• If your coolant tank is full, this indicates a mechanical issue with your engine or coolant system. A professional technician needs to assess this.

How to prevent your car engine from overheating 

There are a handful of precautions which you can take to protect your engine. Not addressing any issues when they first arise can be extremely costly, so preventative action is key.? 

Regular maintenance checks 

This is necessary for a cool, operational, and safe car. Book servicing at your local Formula One Autocentres’ branch, or if your car is not due for a service, take advantage of our free safety checks. 

Park in the shade 

In warmer weather, it’s useful to keep your car cool and shaded as often as possible. You can also buy sun shades or screens and car covers to keep your interiors cool.? 

Regular oil servicing 

Follow your manufacturer’s recommendation for oil change frequency, but ideally every 3,000 miles should do the trick. 

Monitor coolant levels 

Check your coolant levels every other short journey and before any long journey, then top up as needed. 

Limit air con use 

It might feel essential to use your air conditioning when it’s hot outside, but if your temperature gauge is reading too high, open the windows instead. This improves airflow and avoids adding extra strain to the engine until the issue is fixed. 

Shift into neutral 

If you’re in traffic, put your car into neutral and rev the engine slightly to help draw air and water into the radiator. It’s better to crawl in slower-moving traffic than to successively brake, as it increases drag on the engine and raises its temperature.? 

How to keep your car cool with Formula One Autocentres 

Don’t wait until your engine is steaming. Book a free 10-point safety check or a full service today at your closest Formula One Autocentres for expert diagnostics, fast turnaround, and peace of mind with a functioning engine.?