Why is my car overheating?

An overheated car can be a stressful experience and you may be unsure of what to do should the situation arise. It's essential to act quickly if your car is overheating to avoid further damage to your car engine and keep yourself safe.

Keep reading to discover why a car overheats and what to do if it happens.

Car overheating causes

There are numerous reasons why your car might overheat such as:

  • Issues with your car’s cooling system.
  • A faulty cooling fan.
  • A faulty coolant pump.
  • A blocked radiator inlet.
  • Faulty head gasket.

What should I do if my car is overheating?

If your car is overheating, you may experience several of these things:

  • Temperature gauge reading higher than normal and / or a warning light may appear on your dashboard.
  • Steam coming from your car bonnet.
  • Clicking or clanking noises.
  • Leaking engine coolant.
  • Burning smell coming from the engine.
  • Poor engine performance.

Pull over

If any of these signs occur, pull over to a safe place, turn off your engine and ensure you and all passengers vacate the vehicle and are away from the road.

Leave engine to cool

If you can, open the bonnet but be wary that steam may be released and will be extremely hot. Try and leave the engine to cool for at least half an hour.

Check the coolant tank

Under no circumstances should you remove the radiator or expansion tank cap if your car has overheated as this can lead to steam burns. If you can open the cap once the engine has cooled down, make sure you open it slowly. You can then check the coolant tank once the engine has cooled. If the tank is empty, check for signs of a possible leak such as a puddle.

Based on what you see, there are two options on what to do next:

Top up your coolant

You may need to top up the tank with coolant – try not to use straight water, particularly cold water, as this can damage the engine. If it’s an emergency, you can top up with water to help you drive to the closest garage but keep a close eye on your temperature gauge or warning lamp.

Visit a garage

If the coolant level is full, then there’s likely to be a more serious underlying issue with the engine. If this is the case, you’ll need to speak to a garage or call your breakdown service as soon as possible.

How to check engine coolant

If you need to check or manually top up your engine coolant, follow these steps:

  • Locate your expansion tank. If you’re unsure, check your vehicle handbook.
  • Check the coolant level – this should be between the minimum and maximum marks.
  • Check hoses – wet or any colour-stained hoses could indicate further issues.
  • If you need to top up, do so when the engine is cool.
  • If the coolant level has suddenly dropped, get this checked by a garage.

What is engine coolant?

Engine coolant usually consists of anti-freeze and water. It can prevent your car engine from freezing when it’s cold while also preventing it from overheating. There are different types of anti-freeze, so it’s essential that you use the right kind for your vehicle. For more advice, check out our article on which antifreeze should I use for my car.

As antifreeze degrades over time, its effectiveness naturally reduces, meaning your engine won't be able to stay cool as efficiently. Over time, this can create problems, meaning you'll be paying much more than the cost of a new bottle of coolant.

Antifreeze should be replaced every 3-5 years depending on how often and how far you drive your car, its age, and the temperature of where you usually drive. Extra care needs to be taken in the summer months, especially if it's a hot day, so make sure you check your coolant levels before the start of the summer.

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How to replace engine coolant/antifreeze

If it has been a while since you completely replaced your antifreeze, or if you've never done it, then you'll need to renew your antifreeze rather than replace it. Here's how:

  • Step 1 - Drain the system: Once your engine is cool, put on protective gloves and goggles and open the radiator drain tap, or disconnect the bottom hose.
  • Step 2 - Flush the system: If there is a cylinder block drain plug, unscrew it, then flush the system with clean water, or a flushing compound if recommended in your car owner's manual.
  • Step 3 - Refill the system: Close the drains and refit any hoses, then refill the system with the correct water/antifreeze/pre-mixed antifreeze mixture.

Note: Some cars have bleed screws that must be opened when refilling to avoid airlocks. Check your vehicle handbook or Haynes manual for details.

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What if my temperature warning light comes on?

The temperature warning light on your dashboard looks like a little thermometer. If this comes on, it usually means that your engine coolant levels are low and or that your engine is overheating. Leave the engine to cool down for 30 minutes and top up your coolant if necessary. If the temperature warning light is still on, you’ll need to take it to a garage as soon as possible as this signifies a more serious issue with the cooling system.

How long does it take for a car to cool down?

It’s recommended that you leave your car for at least 30 minutes to cool down but preferably an hour, if possible, to allow it to cool down fully.

How to prevent a car from overheating

If you’re concerned about your car overheating, there are a variety of steps you can take to reduce the likelihood of this happening.

  • Regularly check your temperature gauge and coolant levels.
  • Keep coolant in your vehicle to allow you to top up if necessary.
  • Have your coolant replaced in accordance with the manufacturer recommendations.

What happens to the engine if a car overheats?

If your car does overheat, it may not impact the engine too much, providing that the issue is addressed quickly, and you speak to a garage if necessary.

However, failing to address issues with your cooling system could result in further damage and could cost a substantial amount to repair further down the line.

Can I drive if my car is overheating?

You should never continue driving if your car is overheating as this could place further strain on the engine, which is not only unsafe but can also be incredibly costly to fix. You should pull over to a safe place as soon as possible if your car does overheat.

If you’re concerned about your car engine, head to your local Halfords Autocentre to get it checked out. If any repairs are necessary, we’ll provide you with a no obligation quote before carrying out any work.

We also stock 1000’s of car parts online with free next working day delivery available.

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