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How to check the coolant level in a car

| Insurance

Your car’s engine can reach very high temperatures and coolant is needed to prevent it from overheating. Find out how to check the coolant level here.

Ever wondered why your dashboard has an engine temperature gauge or how, on a freezing cold day, the vents produce heat to keep you warm? It’s because your car’s engine produces a lot of heat when it burns petrol or diesel. As these fuels are burned, molecules present inside the petrol or diesel split apart and create a lot of heat. This process is known as combustion. The heat energy that is produced can be turned into mechanical energy, allowing your car to run.

However, if the engine becomes too hot, you can run into serious problems. For example, this can cause damage to the water pump, head gasket and cylinder head. If you drive a modern car, the engine might cut out altogether to protect it from damage. This is why it’s so important to check your car’s coolant level regularly and make sure that it’s topped up.

How to check coolant levels 

Follow our basic steps below to locate your coolant tank and fill it up. Just keep in mind that every vehicle is different, so if you’re struggling to find the tank, check your vehicle’s handbook.

Let the engine cool down 

Before you check your vehicle’s coolant levels, it’s imperative that you wait for the engine to cool down before looking under the bonnet. The coolant solution could be very hot and the tank is usually pressurised. This means that if you open the cap before the engine has cooled, the hot liquid could burst out and scald you. If you’ve recently been driving, wait at least an hour or two.

Find the expansion tank 

The expansion tank is there so that when the coolant heats up and expands, it has somewhere to go, reducing the pressure in the engine. You will need to locate the tank so that you can take a level reading.

Check the coolant level

On the side of the tank there should be an imprinted scale that shows the maximum and minimum levels of coolant. Have a look to see what the current level is. If it’s nearly down to or below the minimum level, it should be topped up.

Fill up your coolant

To fill up the coolant, remove the cap on the tank and pour the fluid in until it reaches the maximum mark. Make sure that you are using the right type of antifreeze and the right ratio of antifreeze to water. If you’re unsure what that should be, check your vehicle’s manual. Tighten the cap to seal the tank.

How often should you check your coolant

A leak could cause your engine to overheat, and this is why it’s so important to check your coolant regularly. If there is a small leak, the coolant level will have dropped underneath the ‘max’ band on the tank. You may also be able to spot an issue with your coolant if you notice your dashboard thermometer registering a temperature higher than 90℃. Spotting these problems quickly could prevent an accident occurring in the future. For example, If you were to break down in an unsafe place because your engine overheated, you could cause an accident and may need to claim on your insurance.

You should check your coolant levels at least twice a year - once in summer and once in winter. The coolant should maintain a constant level as it runs around a closed system. The only reason the level will drop is if there’s a leak. If you do notice a slight dip, check your coolant more frequently to monitor the levels. A hose may have come loose, so ensure that the hoses are inserted fully. If you cannot find a reason for the leak yourself, then take your car to a garage.

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Can you drive a car without coolant?

Without coolant, your car would quickly overheat and this can cause serious damage to the engine, particularly the head gasket, the cylinder head and the water pump. The longer you drive an overheated vehicle, the more damage you will cause. This makes coolant a necessity.

If you ever run out of coolant, you should pull over safely as quickly as possible and allow your engine to cool down. If there isn’t a safe place to pull over for some distance, turning the air con off  might help decrease the load on the engine.

Can you use water as coolant?

Water can be a good temporary substitute for coolant, however it has a much lower boiling point than antifreeze. This means that water can be good if your engine is overheating or you notice that your car’s coolant is a little on the low side, however it can heat up quickly and become inefficient at cooling the engine down. This makes water a temporary fix - it will work to get you home or to a garage but, without the anti-freeze, the water can heat up and may no longer cool your engine down. In some cases, it may boil over.

You might also find that you have the opposite problem in winter. The water can freeze and crack the radiator. Avoid using water if the overnight temperature is due to drop below zero.

Another reason why water should only be a temporary solution is because it contains lots of different minerals. Over time, these minerals can build up and cause deposits to form within your radiator. Excessive amounts could prevent the radiator from working properly. Your radiator and engine will run much more smoothly if you use the correct antifreeze solution.

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