Engine coolant (c) Vauxhall

Engine coolant: the consequences of not topping up

Internal combustion engines produce massive amounts of heat. Alongside the burning of fuel the friction of moving parts – even when lubricated with the best modern oils – means if your vehicle’s motor weren’t cooled somehow, it’d simply destroy itself. At the most basic level, that’s why it’s important to keep an eye on your car’s coolant level.

Most modern engines are ‘water cooled’, which means a liquid is used to dissipate the heat built up within the bowels of the unit.

The cooling fluid is pumped round the engine using the water pump. This lowers temperatures in the cylinder block and ‘head’ (the main two component of the engine) drawing heat out of the metal.

As a result, this fluid then heats up, but with only a finite amount of coolant in the system – including the coolant reservoir – this also needs to be cooled.

This is where your car’s radiator comes in. The coolant is pumped through the radiator, which consists of many small tubes with extended fins to increase the surface area and therefore its temperature-reducing capability – this is placed at the front of the car directly in the airflow, which is used to take heat out of the coolant.

If you’ve ever heard your car’s radiator fan come on when in traffic, this is simulating the same thing, blowing air through the radiator to draw heat away from the liquid and keep your engine temperature constant.

While it might sound a simple principle, in practice it’s a complicated system. That’s why it’s vitally important to ensure your vehicle has an adequate amount of coolant.

You can check the level by locating the coolant expansion tank under the bonnet – this is usually a clear plastic reservoir filled with a coloured liquid. Check the fluid level against the ‘Min’ and ‘Max’ marks on the side of the tank. If it’s below or just above the minimum, top it up with pure, distilled water to ensure no foreign bodies or anything that could damage the engine can enter the water galleries.

Here’s a T W White & Sons top tip, too. If you need to add a large amount of water to the coolant tank (if it has been drained, for example), remember to add some anti-freeze at the right ratio as well. This is what gives the coolant it’s strange shade and stops the liquid freezing in winter, avoiding expensive engine damage.

Modern vehicles shouldn’t use much coolant, if any at all. But it’s still good practice to keep an eye on your coolant temperature gauge (usually somewhere on the instrument display) as well as the physical level in the tank.

If either of these two readings are outside of normal operating parameters, it could mean your engine isn’t working properly – be it a faulty water pump, a broken radiator, or even a small leak somewhere – and at risk of being damaged.

If your car overheats, it’s best to stop, turn the engine off and let it cool down. Do not remove the radiator cap when warm, as pressure in the system due to the coolant getting so hot it has boiled means hot steam and water could squirt out and burn you. Contact your breakdown service to be recovered to a safe place.

This potential pitfall can be avoided by simple routine maintenance, however. A few minutes running some simple checks, including examining your engine’s oil level, as well as the amount of brake fluid in your car, can avoid expensive repairs.

Despite that, it can be a problem that befalls some vehicles and a common occurrence for classic cars. Has your car ever overheated? What was the problem? Do you have any tips to share with the T W White & Sons community to help them avoid any of the above problems?

We want to hear from you, so join in the discussion below. Alternatively, tweet us @twwhiteandsons, or find our T W White & Sons page on Facebook and leave a comment.

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