How do you know when your car needs coolant?

Written by: Simon Pavey, Last updated:28th February 2022

Close up of car engine, hands pouring coolant into the system

Keeping your engine cool is a critical factor in ensuring your vehicle runs efficiently and does not face the risk of overheating and causing potential damage to vital components that can be extremely costly to repair.

As a result, knowing when to add additional coolant to your engine is a must for all motorists. There are some tell-tale signs that your vehicle may be running low on coolant, so take the time to read our handy top tips below.

What is car coolant?

Coolant is quite simply a liquid substance that is used to keep the water in your engine at an optimal temperature. If the water gets too hot, or reaches freezing point, it could cause permanent damage to a car engine – and so coolant is designed to prevent this.

The coolant liquid is circulated through your car’s engine via a cooling system, which absorbs heat from the engine while constantly monitoring its temperature to keep it at safe levels.

What is antifreeze?

You may also hear antifreeze mentioned in discussions around car coolant. Virtually all coolants that are commercially available in today’s market comprise antifreeze mixed with water, at around a 50:50 ratio- which yields a coolant liquid capable of protecting your vehicle from excessive temperatures.

When should I top up my coolant?

So, how do you know whether you need to top up your coolant levels?

Most new cars will have automatic systems to detect excessive heat due to a lack of engine cooling, but for older models, drivers must keep a close eye on their engine and ensure regular maintenance to top up any engine fluids.

A dashboard warning light will illuminate to warn the driver that water/coolant levels are getting low, while a rise in the temperature gauge is also a first sign that there might be a problem. Billowing steam, a hot bonnet, and a lack of control over the interior heating are also signs of temperature issues with the engine.

For newer vehicles

An automatic engine cut-off is installed in most new vehicles, which is designed to prevent damage to key engine parts when temperatures spike. However, if your car is not fitted with this type of system, the onus is on the driver to keep coolant levels effectively topped up.

When you fail to recognise the warning signs that your car has inadequate cooling, you risk damaging some of the most important parts of your vehicle’s engine.

Symptoms of engine damage caused by heat

Due to the high temperatures created by a car engine running, poor cooling can result in severe damage to the water pump, head gasket, cylinder and piston timing, cylinder head, warped or bent connector rods, or even crank failure.

Failure to properly maintain your vehicle can even result in the car becoming a write-off, so vigilance is key when it comes to topping up coolant.

How to top up coolant for your car engine

The process of topping up your engine’s coolant is straightforward, and the steps are as follows:

  1. Ensure the engine is cold, the handbrake is applied, and the vehicle is in first gear.
  2. Raise the front of the vehicle on jacks and ensure the back wheels are chocked (locked in place and restricted) to prevent any movement.
  3. Place a container below the engine’s radiator and undo the drain valve and remove the filler cap.
  4. Flush the system as many times as necessary to ensure it is completely empty.
  5. Locate and remove the reserve coolant tank from the vehicle and drain any remaining fluid, then replace the tank securely and close the drain valve.
  6. Refill the system to the base of the filler neck with the correct coolant for your vehicle (specifications can often be found in your vehicle handbook).
  7. Finally, bleed the system of all air by briefly running the engine, turning it off and topping up once more. Repeat this process until the coolant level remains static when the engine has been turned over. Securely replace the radiator cap to complete the process.

How can fuel card services help?

It’s crucial that all drivers put in place a good habit of conducting maintenance checks on their vehicles to keep everything running in order – which could help avoid costly repairs in future.

For drivers using company cars, and operators of commercial fleets, it’s crucial that these issues are resolved quickly- given the sheer number of miles these vehicles cover.

Fuel Card Services offer MyService.Expert; a vehicle maintenance service that offers subscribers access to a network of garages across the UK that make fleet maintenance easy. What’s more, the service grants access to pre-negotiated rates at thousands of UK garages, enabling businesses to make considerable savings on vehicle maintenance – with discounts of up to 25 per cent on all parts and labour.