How coolant protects your engine
Tom Vondrasek | 30 June 2024 | 3 minutes to read
Whether you have a diesel or petrol engine, the combustion process they use to run creates heat as a byproduct. If this heat is not controlled these engines will usually sieze, because the metal expands due to overheating.
While the engine still has oil in it to lubricate the moving parts, the coolant does the heavy lifting when it comes to controlling engine heat. It has help from the water pump to circulate the coolant and the radiator to dissipate the heat from the coolant while a thermostat helps regulate the temperature.
Our dive into coolants covers:
What is in a Coolant?
Coolant is a mix of water and ethylene glycol/propylene glycol as well as additives to stop corrosion, lubricate the water pump, and stop the build-up of sludge in your cooling system. Ethylene glycol dissipates heat far better than propylene glycol, though propylene is far less toxic than ethylene.
Having all these items in the coolant mix makes the freezing point lower and the boiling point higher than if it were simply plain water.
Pressurised System
The other piece of the puzzle that helps cooling is having the entire cooling system sealed. If it was open, the coolant would evaporate. Naturally, when heated, it will pressurise. This has the added benefit of increasing the coolant boiling point. The radiator cap is the release valve if the pressure gets too great. Ideally, the system is designed so it doesn’t get to this point unless there is a problem.
Coolant's Main Function
The coolant's main role is to take the heat away from the cylinder head and top of the engine block where combustion takes place. It constantly flows through the engine so any heat it picks up along the way, it releases it as it flows through the radiator. Once done the process keeps repeating itself.
Corrosion Protection
This is a big deal as with all the different metals, plastics, and rubber pieces that make up a cooling system, you don’t want the coolant to be corrosive and damage the system from the inside. This is what a lot of the additives do. They provide protection so corrosion and wear are kept to a minimum.
Another important role is stopping the build up of sludge that can restrict coolant flow and make it less efficient. The coolant can suspend or break up the particles to keep things flowing.
Maintenance
The job coolant has is quite demanding and, just like engine oil, it degrades and needs to be changed every so often as part of your vehicle maintenance schedule. The vehicle manufacturer will have recommended change intervals for the coolant.
What is important is making sure you get the correct coolant for your vehicle. With the complexities of modern engines all coolants are not the same and putting the wrong one into your engine can cause expensive problems.
Coolant Top Ups
The same thing goes when topping up coolant when it is under the low level mark in the cooling system. If you use plain water it will dilute the coolant making it less effective. Top it up with the recommended coolant for your vehicle to maintain the coolant's integrity.
For top ups, use a pre-mix coolant which is already correctly diluted, not the concentrate. Concentrates are best used when changing over all the coolant.
If you look after your coolant by checking the levels regularly and changing it when required, it helps your vehicle avoid breaking down from overheating.
