Coolant in any vehicle is extremely important because it works to create the needed conditions for the engine to work properly. If the coolant is low or of bad quality, the engine may overheat and this will result in extremely unwanted consequences.
Now, you should know if coolant expands when hot because this will affect its level and you should understand how much space to leave in the reservoir for this. Actually, manufacturers have already thought about this and made some min/max lines on that reservoir, but it wouldn't make it worse if you knew some basic facts.
So, does coolant expand when hot?
We've seen different answers to this question. But we've gone to coolant manufacturers and asked them. Most of them replied that the high-quality coolant will expand to about 6% of its total volume when heated to 212 degrees Fahrenheit.
Also, experts say that the total expansion will depend on the type of antifreeze. Some kinds of coolant may expand to 8-12 percent under the same temperature of 212 degrees F. This is not just because of the quality, but also because of the original contents and ingredients of the coolant. It doesn't always mean that the coolant is bad.
Some modern types of coolant tend to expand to only 1-2% even under greater temperatures. This is achieved thanks to more expensive chemical components that are used during the manufacturing of this coolant.
But overall, it doesn't play a really important role in how the coolant works. So, now you know that the expansion of the coolant in your vehicle may be from 1% to 12% under the temperature of 212 degrees F. Let's see why it is so important to know this.
What should you know about the expansion of coolant?
When your engine gets hot, it transfers part of its heat to the coolant. Antifreeze then flows to the radiator to get cooled. But within the system it's still quite hot - sometimes even hotter than you can imagine. So, it can expand. And if the system of antifreeze circulation was closed, it would just explode because of the pressure that builds up when the liquid is expanding.
Well, thank goodness we have those coolant reservoirs in our vehicles. Those reservoirs have min and max marks and if you ask a car mechanic, they will tell you that you should keep the antifreeze level right in the middle between those marks. When the coolant becomes cold, it may reduce in volume a little and move closer to the min mark in the reservoir. When it gets hot, it may expand a little and move closer to the max mark.
But what happens if you fill the reservoir with coolant higher than the max mark? It will still expand and eventually hit the coolant reservoir cap. After that, pressure will start building up in the system. If it heats up even more, the system will obviously have a leak. And you will end up having no coolant in the system because of this leak.
What to do to avoid problems because of expanding properties of coolant?
You may do a couple of things to prevent these problems from happening:
- First of all, always buy the type of coolant which suits your vehicle. The wrong type of coolant may act weirdly in your car and lead to problems.
- Also, never fill up the coolant reservoir to the max line or above it. This may lead to problems when the coolant gets hot.
- Make sure the cooling system in your vehicle works well and doesn't have any leaks.
- Also, pay attention to the thermostat. If it malfunctions, the engine may overheat and the coolant will overheat, too.
- Avoid overheating. If you see the engine temperature going up, just turn off the engine and let it cool down before you continue driving.
- From time to time, check the coolant level in your vehicle to avoid issues like low or high levels of antifreeze.
By following these simple rules, you will make sure there are no problems and bad surprises when you are driving your car. Also, you'll know for sure that your vehicle is in optimal condition and doesn't develop any serious issues with the cooling system.
About the authors
The CarAraC research team is composed of seasoned auto mechanics and automotive industry professionals, including individuals with advanced degrees and certifications in their field. Our team members boast prestigious credentials, reflecting their extensive knowledge and skills. These qualifications include: IMI: Institute of the Motor Industry, ASE-Certified Master Automobile Technicians; Coventry University, Graduate of MA in Automotive Journalism; Politecnico di Torino, Italy, MS Automotive Engineering; Ss. Cyril and Methodius University in Skopje, Mechanical University in Skopje; TOC Automotive College; DHA Suffa University, Department of Mechanical Engineering
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