Prevent Overheating

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Thanks to the hard work that your engine does burning fuel, heat becomes a by product of driving. Heat is handy for keeping your car warm in the winter months, but it's important to manage the exposure that the rest of your car's components have to high temperatures.

As the cost of living continues to increase, we’re all trying to avoid unexpected bills, but if your engine gets too hot then it can cause expensive damage, so it's critical to ensure that your car has enough coolant.

If your engine gets too hot, then it can cause expensive damage, so it's critical to ensure that your car has enough coolant.

Engine coolant, usually called antifreeze thanks to additional properties that mean it won't freeze in low temperatures, is a liquid that moves around various areas of your engine, helping to dissipate some of the heat created by fuel being burned and moving parts working together to create friction. Antifreeze does this by picking up some of the engine's excess heat and moving it away from hot areas, helping to maintain a manageable temperature that won't cause long-term damage.

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.

Car overheating signs

If you notice any of the following, then your car may be overheating - stop driving immediately and either top up your coolant, or head to your nearest Halfords and we'll do it for you.

  • Visible or audible warning on the dashboard that shows the temperature gauge going above the normal running temperature
  • Reduced performance or sluggishness
  • Engine fan running at maximum capacity (it will be very loud)
  • Burning smells
  • Steam or water vapour escaping from engine bay in extreme cases

If your car is constantly overheating, then you may have a leak in your cooling system. It's best to get a mechanic to check this over as leaks can get worse, so head to a Halfords store as soon as you can if your car's temperature gauge keeps going above normal levels even after you've topped up your antifreeze.

How to stop car overheating

Although there are lots of quick fixes to cool your engine down, the only safe and long-term solution is to top up or replace your antifreeze. Here's a quick guide to topping up antifreeze so your car's temperature gauge won't be constantly in the red.


  • Coolant (antifreeze) suitable for your vehicle and weather conditions (check your vehicle handbook or Haynes manual for details, or ask a member of staff at Halfords/check online)
  • Clean water, ideally boiled (not needed for pre-mixed coolant)
  • Funnel or jug
  • Protective goggles and gloves
  • Clean cloth or rag

If you aren't sure which antifreeze you need, check out our selection of coolant and antifreeze products online. We also stock a variety of other cooling products and replacement cooling and ventilation parts if you're overhauling your vehicle's cooling system entirely.

Shop Antifreeze Online

Important Safety warnings

Never undo the coolant filler cap while the engine is hot, as the system may still be under pressure and boiling coolant may spray from the filling tube, causing severe burns or scalding.

Once the engine has cooled (leave several hours), put on some protective goggles and a pair of protective gloves and place a rag or cloth over the cap. Unscrew it slowly to allow pressure to escape, keeping pressure down on the cap as you turn.

If you get any coolant on your skin at any point, wash it off immediately, as it is both corrosive and detrimental to health. If you manage to swallow coolant or get any in your eyes, seek medical attention immediately.

Try to keep coolant away from your car's bodywork too, as it can be corrosive to paint and plastics.

Step 1 - Check Coolant Level

Most cars have a coolant reservoir with minimum and maximum level marks. With the engine cold, the coolant level should be between the two marks.

Step 2 - Top up Coolant

If your coolant level is too low (below or near the lower mark), top it up using a 50/50 mixture of water and antifreeze (for normal driving conditions), or pour pre-mixed antifreeze straight into the reservoir. You can use clean tap water in an emergency, but antifreeze should be added as soon as possible. DO NOT overfill, as this could damage the entire cooling system when the antifreeze gets hot.

Step 3 - Refit Cap

Refit the cap tightly afterwards and mop up any spills.

How to replace 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:

  1. 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.
  2. 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.
  3. 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.

Other top tips for cooler engines

  • Leaking coolant hose? Sometimes they can be patched up with a hose bandage until a new hose can be fitted. You could also add a leak-sealing compound to the coolant reservoir as a short-term fix.
  • A clogged radiator can cause overheating. Try using a cooling system flushing compound to clear it.
  • If the engine starts to overheat whilst you're driving but you can't stop immediately, put the heater on maximum heat and highest blower speed to disperse some heat.

Antifreeze top up and replacement at Halfords

If you've never topped up or changed antifreeze or don't have the time/confidence to do it, remember Halfords can do it for you. For a small fee, we'll happily top up/replace engine coolant and even carry out a free a safety check while we're at it. Just ask in store or select 'click and collect' when buying antifreeze online and ask us to fill up for you when you pick your antifreeze up.

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