Coolant leaks - why do they happen and what should you do? | RAC Drive (2024)

It is necessary for all drivers to keep their vehicle running smoothly and as efficiently as possible. A crucial part of your car maintenance – the engine coolant – is often overlooked, yet vitally important.

Also known as antifreeze, the coolant plays a pivotal role in regulating your engine's temperature in both hot and cold weather. Therefore, no matter what time of year, it is something all drivers should be regularly checking.

This guide looks at what engine coolant does to your vehicle, what to look for it is leaking, and how to repair the problem.

Engine coolant, also known as antifreeze, is a fluid added to the engine that helps regulate its temperature.

It plays a vital role in maintaining the engine's temperature within the optimal range of the specific make and model, preventing it from overheating or freezing. It is something that helps keep a car in the best condition possible year-round.

The coolant is a mixture of water, ethylene glycol or propylene glycol – or a combination of the three.

Depending on where you live, the make and model of the vehicle, and type of engine, there are a variety of options for coolant.

If you are unsure what is the best coolant for your car, speak with your local garageor a mobile mechanic.

All drivers should regularly check coolant levels and top up as needed.

Always refer to the vehicle's owner's manual for specific recommendations regarding the type of coolant to use.

• Car leaking? How to identify liquid dripping from your car
• Car smells guide - causes and solutions
• Complete guide to car parts and what they do

The most common cause for coolant leak is poor vehicle maintenance. This highlighsthe importance of the annual MOT and regular servicing.

Although general wear and tear does cause coolant leaks, there are certain components that need to be checked for leaks on a regular basis.

Here are some of the most common reasons for a coolant leak:

• Check radiator hose, sealant, and connectors for cracks
• Blown radiator
• Damaged head gasket
• Small holes in the radiator caused by damage from other components or something getting into the engine
• Radiator cap broken or missing

These are the most common reasons, but not topping up your fluids can also lead to issues with the coolant.

Car ownership comes with many challenges, and regular maintenance is something everyone should be doing.

Not only does this keep your car as safe and road legal as possible - but will also save you from a much larger bill in the long run.

The primary function of engine coolant is to regulate the temperature of the engine while the vehicle is in motion.

During combustion, the engine generates a significant amount of heat, which the coolant absorbs and carries away from the engine to prevent it from overheating.

It also contains antifreeze properties, such as ethylene glycol or propylene glycol, which prevent the liquid from freezing in colder temperatures.

The fluid also helps maintain a healthy engine with corrosion inhibitors that protect the various components of the cooling system, such as the radiator, water pump, and engine.

By extending the life of these components, it will save the owner a large bill to fix these issues – which can end up being quite expensive.

Engine coolant circulates through the vehicle’s engine and absorbs heat generated during the combustion process, and the continued use of the engine throughout the length of the drive.

The fluid in the coolant system then carries the heat away to the radiator, where it dissipates into the air – therefore regulating the temperature and keeping the engine in optimal condition.

It also provides a safety feature of keeping the engine from overheating. This can lead to multiple, and more serious problems.

However, in colder, wintry weather, the anti-freeze part of the fluid prevents the coolant from freezing.

• Why is my car making that noise?
• What to do if my cart is overheating?
• Engine smoking - why is it happening and what should I do?

If you choose to drive with an engine coolant leak, there might not be any immediate danger – however, it will cause serious damage to your vehicle.

After the engine heats up, there is nothing to cool the components down.

This is when the danger can arise – and something drivers should avoid at all costs.

Knowing what to do if your car is overheating is important for all car owners.

• 12 essential car maintenance checks for all drivers
• Car running costs - a complete guide
• Head gasket guide - why does it fail and what to do next?

Although it is important for an experienced mechanic to fix your engine coolant leak, if you are confident to do so, it is quite simple.

Turn on the engine, and immediately open the bonnet.

Use radiator sealant on the areas where the leak is happening.

The engine must be running, but the coolant must be cold when you are carrying out the fix.

If this doesn’t fix the issue, then the radiator will need to be removed and either have more extensive work done on it – or it will need to be replaced.

Engine coolant leaks can be quite simple fixes – but can also be very expensive.

Prices can range from around £50 to £300, depending on the make, model, age, and type of vehicle.

If the radiator needs to be removed and have more extensive work carried out to fix the issue, then the bill could be more than £1,000.

Replacing a car radiator can range from £400 to more than £1,500.

If you have any questions about coolant, anti-freeze, car maintenance, or anything else, leave them in the comments section below.

If you are looking to top up the engine coolant in your car, then it is important to get the correct one for your vehicle.

Check your car owner’s manual, which will outline the types that your engine can use.

Find them here at RAC Shop.

More on this topic