Foamy Antifreeze? What Does It Mean?

Why is my antifreeze foamy? What could be the reason behind foamy antifreeze? Can it be harmful to my car? How can I stop my coolant from foaming? Answers to all this and more, coming up!

White foaming in the coolant or the antifreeze can mean that your gasket is about to start when the engine hits its combustion cycle. 

The foaming of the coolant could also mean that the antifreeze is heating up. This article will learn about the possible reasons for the antifreeze to get foamy and how you should tackle it. 

Foamy Antifreeze

What Does A Foamy Antifreeze Mean? 

A foamy antifreeze could mean that the coolant has oil in it. You can remove the oil cap on the coolant to check the coolant level. If you see white foam on the coolant, it indicates a problem. In most cases, foam in the coolant is just the residue or crap getting stirred up in the flush or the filter tank. If you think that your head gasket is blown, you can check that by following a few simple steps. These steps are:-

  • Suppose you see the coolant leaking externally or from below the exhaust. This is a sign of the head gasket being blown away. 
  • If there is visible white smoke from the exhaust pipe, it indicates a faulty gasket. 
  • Bubbles in the radiator tank of your car are also not suitable for high performance. 
  • If your vehicle is experiencing overheating of the engine, then you should not take it lightly. You should either replace the coolant or get the problem fixed by a mechanic. 
  • The formation of a milky white oil-like substance on the coolant is also an indicator of something wrong with the coolant. 
  • Some faulty or fouled spark plugs in the car can also indicate a defective gasket in your vehicle. 
  • If you are experiencing low cooling system integrity, you should consider replacing the coolant. 

Foamy Antifreeze

How Can You Stop Your Coolant From Foaming? 

  • Coolant foaming can be a very annoying issue. Without a properly functioning coolant, the car’s engine would heat up, resulting in an engine failure. 
  • You add a small amount of calcium carbonate or calcium acetate to your coolant solution. When the foam disappears, then you can stop. You can repeat this process until you notice the foam disappearing. 
  • Using distilled water as a base for the coolant can also stop the coolant from foaming in the tank. 

What Are The Causes For Foam Build-Up In The Antifreeze? 

  • The primary or root cause of the antifreeze’s foaming is the presence of air bubbles in the coolant. These tiny air bubbles can get into the coolant because of a leakage somewhere in the coolant system. 
  • Some other causes for foaming of the antifreeze can also be because of the lack of lubricating oil in the system. If there is an inadequate lubricating oil level in the system, the coolant can become agitated and start to get foamy. 
  • Some sort of contamination in the coolant can also be responsible for forming foam in the coolant. Foaming can often be a sign of an underlying condition most of the time. 

How Do You Determine The Issue With The Foaming Problem? 

You can use a simple and easy test to determine whether the foaming issue is caused by a mechanical or because of the coolant. 

  • Firstly you’ll need to collect a sample of the clean bottle with a lid. 
  • You can then fill the bottle halfway with the cooling liquid. Then you need to close the cover of the cooling tank. 
  • Then wait for all the bubbles inside the tank to collapse. There should be no visible foam on top of the fluid. 
  • After that, keep the bottle on a flat and solid surface.


You might also like to read: How Long Does It Take Antifreeze To Circulate?


What Does a Milky and Brown Antifreeze Mean? 

A milky-appearing coolant always has some contamination in it. If your vehicle has a milky antifreeze, a foreign liquid is also mixed with the coolant. You will have to identify where this liquid is coming from and repair the leak. 

The time taken by the coolant to turn milky is more, so it means that the coolant is already contaminated by now, and you will have to replace it. It would help if you got a new cooling liquid when your old coolant turns milky. 

If your coolant is brown, it could mean the head gasket in your vehicle has blown. The oil from the blown gasket will mix with the coolant, and it will create a brown liquid resembling a chocolate milkshake. 

Does milky coolant always mean head gasket?

A milky coolant doesn’t always mean that you have a blown head gasket. Milkiness can be a sign of various other problems, such as it could mean that there is some oil leaking in the oil pan. If your vehicle has a milky coolant, then the chances that you have a head gasket issue are scarce.

If you are mixing some additional components into the coolant, it could disturb the original viscosity and concentration of the actual solution. Due to this reason, sometimes your coolant appears to be slimy, milky, or muddy. 

Foamy Antifreeze

Frequently Asked Questions.

#1. How do you fix foamy coolant?

The best solution for fixing a foamy coolant is to replace the coolant. Suppose you are looking for a temporary solution to the foam problem on the coolant tank. You should be sure where the leak is coming from and rectify the situation. Then you can also add defoamers to the coolant tank—some of the defoamers available on the market help the tank emulsify the oil leak. Oil leaks are food for all types of bacteria. Therefore using a defoamer is not a long-term solution to this problem. 

#2. Why is my coolant or antifreeze boiling?

The coolant or antifreeze in your can reach boiling temperatures if there is some leak in the car’s cooling system. 

You might experience the pressure on the liquid to drop suddenly. Due to this pressure drop, the temperature of the coolant rises. Ultimately as you drive your car around, the coolant temperature will reach boiling point. 

If you can stop the leak and maintain the ideal amount of pressure in the tank and the engine, the coolant temperature will start dropping, soon reaching its average temperature. 


You might like to read: Will Antifreeze Melt Ice?


#3. Is it normal for coolant to bubble?

Yes, it is very typical for coolant to bubble because of the air pockets formed inside it. You’ll find these air pockets created when the radiator is partially filled or incomplete. These air pockets in a coolant are responsible for improper flushing procedures. 

Air pockets inside a coolant will result in creating a lower coolant volume. This will create the operating temperature of the coolant to rise higher than average. You can check whether your coolant tank has air bubbles by seeing the coolant through the inlet valve. 

A Few Final Words

A foamy antifreeze is not ideal for the peak performance of your vehicle. If your car is functioning on foamy antifreeze, then it will cause damage to the internal sections of the car. 

We also talked about the significant reasons why the coolant would turn foamy. And mentioned some remedies for the same in the above article. You should solve the antifreeze foaming issue as soon as possible for your car. 

If there are some severe issues, consider taking your car to a professional. They can easily diagnose the problem and solve it. Thank you for reading the article. If you have more doubts and questions about the color and form of your antifreeze, do drop us a word and we will get back to you quickly.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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