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Car Leaking Antifreeze – What Could Be The Culprit?

Car Leaking Antifreeze

If you turned off your vehicle and noticed some weird sweet smell, it’s most likely your car leaking antifreeze.

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Whether it’s your antifreeze or any other fluid, your car needs these fluids to run properly without causing damages to the internal components. Thus, never ignore the fluid leak.

The antifreeze is very important for proper engine performance and to prevent its damage from overheating.

Ignoring antifreeze leaks problems result in significant damages that can get to a complete engine failure. Therefore, when your antifreeze leaks, you must stop driving your vehicle, consult a professional mechanic, and get the problem repaired promptly.

What happens when car leaking antifreeze?


The antifreeze is one of the most critical fluids in your vehicle. It’s part of the cooling system responsible for cooling down the engine as its temperature rises above the allowed limit.

Without the antifreeze, the engine’s temperature increases until a stage resulting in engine self-destruction.

Besides cooling down the engine, the antifreeze prevents the coolant’s water from freezing when the weather is cold. Usually, the coolant is made up of 50% water and 50% antifreeze. If the antifreeze started leaking, this ratio could affect the overall cooling system behavior.


How to tell if your car leaking antifreeze?

Your car has a lot of fluids that can potentially leak over time of use. It is important to understand how to differentiate between these fluids as they leak from your vehicle. 

You can look for several symptoms to confirm the antifreeze leaking, not water or other fluid in your vehicle.

  • A weird sweet smell


The first and most common sign of an antifreeze leak is smelling something sweet from your vehicle as you turn off your engine. 

The smell sometimes occurs around the wheels as well.

  • A green fluid puddle under the vehicle.

The antifreeze also is known for its lime-green like color.  However, some types of antifreeze come in different other colors like blue-green, orange, or pink.

Thus, if you noticed a puddle of fluid with these colors under your vehicle along with the sweet smell, now you have two proves of evidence; it’s the antifreeze leaking from your car.

  • Engine overheating

Engine overheating is one of the critical issues that you never want to ignore because it quickly leads to engine damage.

While engine overheating happens due to many other reasons, an antifreeze leak might be the culprit. 

Thus, if your car complained about increased engine temperature, stop driving immediately and look for the other antifreeze leak symptoms to confirm the culprit. 

Sometimes, if the antifreeze leak is very severe, you might not be able to drive the vehicle, and you must tow it to the nearest mechanic as soon as possible to prevent engine damage. 

Car leaking antifreeze – what might be the cause?


When your car leaks antifreeze, there are very common culprits you need to consider, including:

  • A blown head gasket

One of the first reasons for an antifreeze leak is a blown head gasket. If you don’t already know, the head gasket is a think plate between the engine’s block and the cylinders.

The head gasket is responsible for sealing the cylinders and preventing coolant and oil leaks to the cylinders. 

If the head gasket gets damaged for any reason, one of the first consequences is antifreeze leak inside the cylinders and outside the vehicle through the tailpipe.

  • Degraded radiator

Over time of use, the radiator’s connections might get brittle, causing potential cracks, leading to antifreeze leak to the other components and outside the vehicle. 

  • General cracks in cooling system connections 

The antifreeze is usually mixed with water to prepare a premixed coolant for the cooling system.

That been said, the antifreeze can leak from any worn out or broken connection around the cooling system. 

Repair costs can get higher if the leak is coming from unknown locations, forming internal leaks. 

Car leaking antifreeze – where is the leak coming from exactly?


Once you’ve confirmed, it’s an antifreeze leak, and now it’s the time to determine where the leak is coming from exactly.

Here is detailed step-by-step guidance on how to tell where the antifreeze leak is coming from:

  • Allow the engine to warm up for a little by driving your car before attempting to troubleshoot antifreeze leaks
  • After your vehicle is warmed up, never go and test for antifreeze leaks immediately. This is because the entire cooling system can be boiling, resulting in high potential of injury risk.
  • Locate both the radiator’s cap and the translucent plastic recovery tank caps under your vehicle’s hood. If you can’t locate them, refer to the vehicle’s owner’s manual for more details. If you don’t have a copy of the manual, you can download a soft copy from the internet or request a hard copy from your professional mechanic. 
  • As your vehicle is cooling down, perform a visual inspection, and look for signs of a green fluid puddle under the vehicle. 
  • Sometimes you might not see a clear puddle of antifreeze located under the car, especially in situations of small cracks. In that case, check for any sweet smell and look under the bottom of your car for signs of wet hoses or liquid dripping from them.
  • Once you locate any potential antifreeze puddle, check inside the engine’s bay for leak sources. 
  • You can also check for signs of a coolant leak around the radiator’s cap, connections, and hoses. The coolant is usually light-colored.
  • Sometimes the leak can be resolved by tightening some of the clamps or connections around the radiator.
  • If you noticed that the sweet smell is stronger when you are inside the car than when you are outside, the problem might also be related to the heaters. To confirm it’s the heater leaking, you can look for signs of foggy windows. Unfortunately, heater core leaks are not very easy to detect, and you might need to have a professional mechanic check it out and get it repaired. 

How much does it cost to repair a car leaking antifreeze?


I was repairing a car leaking antifreeze ranges from $90 to $115. The exact number depends on your vehicle’s make, model, year, and the severity of the leak.

While this range is expected to repair the antifreeze leak, sometimes the price can increase significantly depending on the problem source.

For instance, if the cause of your antifreeze leak is due to a blown head gasket, you might need to pay up to $2,000 depending on your car’s type.

Similarly, if your antifreeze leak is coming from a degraded radiator, you might need to replace the entire part for up to $700.

Another example is when your antifreeze leak is happening due to a water pump problem, it will cost you about $500 on average to get the water pump replaced.

Finally, if your vehicle’s expansion tank is causing the antifreeze leak, expect to pay up to $200. 

Can I drive while my car leaking antifreeze?


It is never recommended to drive you when your car is leaking antifreeze. This is because of the potential engine failure risk.

Therefore, automotive experts suggest repairing any antifreeze as soon as possible; the problem will not be resolved independently; you must act and repair it. It is the other way around; ignoring an antifreeze leak gets worse, and worse, the more you leave the problem or ignore it. 

When it comes to how long you can drive your car leaking antifreeze, the answer depends heavily on the leak's severity.

 For example, if your car only has a slow leak during summer days, you might be able to drive it up to a couple of days while ensuring adding the missing amount of coolant each time you drive. 

On the other hand, if a car leaking antifreeze heavily, you must not drive your car and need to be inspected and repaired by a professional mechanic. 

DIY to repair your car leaking antifreeze!


As we mentioned earlier, if you suspect your car is leaking antifreeze, you must not ignore the problem.

Usually, repairing antifreeze leaks can be costly; however, automotive experts and manufacturers came up with some simple products that you can use to repair your car leaking antifreeze by yourself. 

These products usually work for small leaks resulting from very small cracks around the cooling system. Therefore, if you noticed a big puddle of antifreeze leak under your car, you need to get the problem inspected and resolved by a professional repair shop.

Here are some of the top cooling system repair products that you can use to stop antifreeze leaks: 

  • K-Seal Multi-Purpose One Step Permanent Coolant Leak Repair


K-Seal is one of the tops suggested brands for cooling system repairs. It is very straightforward and doesn’t require any mechanical skills.

All you need to do is follow the instructions and pour the coolant leak repair in the radiator to get the problem resolved. 

According to customers’ reviews, the K-seal doesn’t result in future antifreeze leaks from the cooling system, indicating that it is very effective. 

One of the biggest drawbacks of this cooling system repair product is that it is at the high end when it comes to price, and it might cause some clogs in the cooling system. 

  • Bar’s Leaks Liquid Aluminum Stop Leak

Bar’s is another big name in the cooling system repair industry. It is known for the effectiveness of its products. 

Bar’s is not only used to repair car leaks; many people in some home leaks also use it.

This type of cooling system repair product doesn’t need you to flush it out of the cooling system; you can leave it there and drive without any problem. 

Like any other cooling system repair product, Bar’s has its drawbacks, including the high cost and the long waiting time before seeing results 

  • ATP AT-205 RE-Seal Stops Leak


The last big name we would like to highlight here is the ATP AT-205. 

The most important feature of this product is that you can use it on any engine type, including diesel and gasoline engines. 

You also can use this product to seal leaks anywhere around your vehicle, not necessarily in your cooling system.

The main drawback of the ATP AT-205 cooling system repair is that you might deal with future leaks and cracks. Furthermore, it is not the best choice for plastic pipes.

  • Other cooling system repair products


Here is a list of other less common cooling system repair products that you can use for your vehicle:

  • Bar's Leaks 1196 Radiator Stop Leak
  • GUNK Aluminum Cooling System Stop Leak
  • AlumAseal Radiator Stop Leak Powder Blister Card
  • Prestone AS145 Radiator Sealer Stop Leak
  • J-B Weld DS-114 Radiator Stop Leak
  • Liqui Moly Radiator Stop Leak




Your vehicle’s antifreeze is one of the vital fluids in your car’s systems. Without the required amount of antifreeze, your engine might get damaged in a very short period. 

Antifreeze leaks usually happen due to a blown head gasket, a degraded radiator, or any worn out connections or pipes in the cooling system.

You can determine if your car leaking antifreeze by visually inspecting a lime-green like fluid and smelling some weird sweet smell coming from the inside or outside of your vehicle. 

While you can drive you when your car leaks antifreeze with small amounts, it is never recommended to continue driving in this situation as the problem worsens over time. 

Therefore, if you confirmed its antifreeze leaking from your car, you must have your vehicle inspected and repaired by a professional mechanic. 

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