What are the Symptoms of Coolant leak? | How to stop a Coolant Leak

Coolant or antifreeze is present in the car engine to maintain its optimal operating temperature range. Usually, it is in blue, green, or pink color and is made with the chemical composition of Ethylene Glycol or Propylene. A coolant leak is not dangerous, but sometimes it can create an unpleasant situation. With the reduced amount of coolant, your car engine can get overheated while driving and cause some damage. This article explains the causes, repair costs, and symptoms of a coolant leak.

What is a Coolant?

Coolant is a gas or a liquid that uses to normalize the temperature of the car’s engine. The ideal coolant has a low cost, low viscosity, non-toxic, chemically inert, and higher thermal capacity. It should not generate corrosion inside the cooling system. In advanced cars, the coolant also acts as an electrical insulator.


A coolant is a protective fluid that protects the car engine from overheating and freezing. It expels excessive heat from the engine to maintain the optimal temperature. In the absence of coolant, the engine may get overheated in minutes and cause serious damage. 

Therefore, you must continuously inspect the coolant leak and its level to improve your car engine’s service life and performance.

Symptoms of Coolant Leak

The coolant leak produces one of the below-given symptoms:

  1. Engine Overheating
  2. Minimum Coolant Level
  3. Temperature Gauge
  4. Coolant warning light
  5. Sweet Smell
  6. Radiator with Bubbles
  7. Puddle of Coolant
  8. Quick reduction in coolant level

1) Engine Overheating

The primary function of the coolant is to maintain temperature and protect your car’s engine from overheating. The engine overheating is the main symptom of the coolant leak. If the engine is overheated, it depicts that your radiator doesn’t have sufficient antifreeze.

2) Minimum Coolant Level

Inspect the expansion tank. If it has a lower coolant level than the desired level, you probably have a coolant leak.  

3) Temperature Gauge

A temperature gauge is used to measure the engine’s temperature. This gauge is installed on the vehicle dashboard.

A slight deviation of heat level from the optimal temperature is acceptable, but if the deviation is too high, then the temperature gauge starts illuminating. Most commonly, the temperature gauge illuminates due to insufficient coolant.  

4) Coolant warning light

Every car has some warning lights and a coolant warning light too. When the antifreeze level gets down, the light starts illuminating and hence display a warning of low coolant level in your car.

In such a situation, you need to refill the coolant. So, if the light is frequently glowing, it is a clear symptom that your car’s coolant is leaking, and you must figure out the problem.

5) Sweet Smell

The healthy coolant fluid comes with a very sweet smell. You should smell the antifreeze whenever you buy it. If you observe a sweet coolant smell coming from your car, it means your car has a coolant leak issue.

6) Radiator with Bubbles

The radiator pipe and the expansion tank are very firmly attached and sealed. So usually there is not any chance of air bubbles. But if there is a coolant leak, the combustion gasses may enter the expansion tank or the radiator.

Whenever the combustion gasses go into the radiator, the bubbles start generating. It is a strong symbol of the antifreeze leak. In case of bubbles from the radiator, you should consult a mechanic.

Read More: Bad Radiator Causes and Symptoms

7) Puddle of Coolant

If your car is at rest for so long, then there may appear a puddle of coolant at the bottom of the car. This is the coolant fluid that leaked out during this stay.

8) Quick reduction in coolant level

If you have a sudden drop in the antifreeze level, it is 100% sure that you have antifreeze leaking issues.

Causes of Coolant Leak

There are numerous causes of the coolant leak. Below, we have listed some major causes of a coolant leak:

  1. Damaged Heater Core
  2. Gusted Head Gasket
  3. Damaged Hose
  4. Issues with Expansion tank
  5. Bad Water Pump
  6. Damaged Radiator
  7. Leakage in Radiator Cap

1) Damage in Heater Core

A heater core is a small radiator that dispenses the heat in the passenger cabin of your vehicle. A damaged heater core is one of the major causes of the heater core.

2) Gusted Head Gasket

The cylinder head and engine block are both sealed with the help of the vehicle’s head gasket. When the heat gasket is damaged or blown, the antifreeze and the engine oil may mix. That causes the antifreeze to start leaking from the bottom of the engine onto the ground.

3) Damaged Hose

Hoses are the main components of your car’s cooling system. These hoses connect the water pump to the radiator through the engine. Coolant runs through these hoses, and they are installed under the hood of your car. So, whenever these hoses are damaged or cracked, they lead to a coolant leak.

4) Issues with Expansion tank

An expansion tank in the car helps to supply coolant to the radiator. It is the plastic container that is placed beside the car’s engine. This tank connects to a radiator with the help of a rubber hose. When there is any change in the engine’s temperature, the expansion tank starts to feed the coolant into and from the radiator.

With the passage of time and fluctuation in the temperature, the plastic body of the tank may damage or get cracks which may lead to a coolant leak.

5) Bad Water Pump

The water pump helps in the circulation of the antifreeze in the whole cooling system. It is one of the important parts of the cooling system.

As the pump goes bad, it doesn’t circulate antifreeze properly throughout the cooling system, which leads to an antifreeze leak.

Read More: Function of Water Pump

6) Damaged Radiator

Nowadays, advanced coolants have some anti-corrosive chemicals that help prevent the radiator from corrosion and protect the radiator. But still, the radiator may get some holes that can be noticed from the front of the engine.

 7) Leakage in Radiator Cap

Due to the high pressure in the radiator, the radiator cap seals the radiator tightly. Hereafter this seal keeps the cooling system at the right optimal pressure. With time due to the deterioration in the seal, the spring inside the cap can wear out and cause the coolant to leak.

Read More: Symptoms and Causes of damaged Radiator Cap 

How To Fix a Coolant Leak?

Fixing the coolant leak is not a difficult task. We have discussed the causes of the coolant leak; now, we will learn some effective methods and hacks on how to fix the coolant leakage:

Follow the below-given steps to fix the coolant leak:

1) Usage of Eggs

If your car coolant is leaked on the way, and there is no nearby workshop, then use eggs to stop it. The easiest way to fix the coolant leak is to put some eggs in the radiator. But this hack is only recommended if you cannot find any other method to fix the antifreeze leak for your car.

Follow the below-given steps to fix the coolant leak using eggs:

  • Stop the car and shut off your engine
  • Please wait until the engine gets cool; it may take about 5 to 13 minutes
  • As the engine cools then, open the hood of your car and remove the radiator cap
  • Crack the eggs and put them into the radiator
  • Check if the leak has stopped or if it is still spilling out
  • In case of leakage, crack some more eggs and put them in the radiator until the leakage gets fixed
2) Replacement of damaged hose clamps

In some cases, the coolant may leak due to problems in the hose clamps. So, the only solution is to replace the hose clamps.

Follow these steps to replace the hose clamp of your car:

  • Turn off the car and wait until the engines get cooled down
  • Lift the hood and open the radiator cap
  • Search for the damaged hose clamp
  • You can drain some coolant to access the hose and clamps
  • Unscrew or cut down the damaged hose clamp
  • Deploy the new clamp onto the untied hose
  • Now, screw back the hose clamp tightly
  • Add some new coolant into the radiator and screw the radiator cap and ensure the perfect seal
3) Replacing Radiator Hose

Hose connects the different parts of the engine and plays a significant role in the cooling system of your car. It may damage or wear out with time, so the only solution is to replace that damaged hose.

Follow these simple steps and learn how to replace the radiator hose:

  • Stop the car at some side and turn off your engine
  • Wait until the engine gets cool; it may take about 6 to 15 minutes
  • Open the hood of your car and remove the radiator cap
  • Find the damaged hose in the radiator
  • To access the damaged hose, you may drain out the coolant as much as you need in a bucket
  • Unscrew the clamps of the hose
  • Now slide both clamps and place the new clamp
  • Again, tighten the clamps
  • Add an optimal amount of fluid and again seal the radiator with the cap
  • Start the engine and see if there is any kind of leakage.
  • If not, then you are done!
4) Radiator replacement

Sometimes the radiator needs to get replaced. Follow these steps to replace the radiator of your car by yourself:

  • Stop the car at some side and turn off your engine
  • Wait until the engine gets cool; it may take about 6 to 15 minutes
  • Open the hood of your car, find a radiator and remove the radiator cap
  • Disconnect the battery
  • Drain all the coolant from the radiator with the help of the hose clamps by losing them and unscrew the plug of the drain
  • Once the coolant has drained out completely from the radiator, remove the hose
  • Locate the thermostat and remove it
  • Some cars may have fans placed with radiators. In such a case, you must disconnect the fan.
  • Find out the brackets that hold the radiator and remove its nuts and bolts from the bottom.
  • Now, remove the fan bracketry
  • Install that fan bracketry to the new radiator
  • Place the new radiator and bolt it accordingly
  • Reinstall the fans
  • Remove the tape from the old thermostat and place it with the new one
  • It’s time to connect all the hoses with the new radiator
  • Fill the coolant fluid in the radiator
  • Reconnect the battery
  • Do not cap the radiator and start the car to remove excess air bubbles by squeezing the hoses.
  • With its stop bubbling, search out for the leakage. If it’s clear, Put the cap back to the radiator and take it to test drive
  • If the car stays at its normal temperature, then congratulation, you are succeeded in replacing the radiator by yourself!

Coolant Leak Repair Cost

Coolant leak fixing or repair cost depends on the issue your car is facing. The average fixing cost of the coolant leak is from $110 to $3100. Some eggs, a new clamp, or a hose cannot cost you a lot, but in the case of radiator replacement, that be costly from $310 to $1400. More by Including labor and head gasket repair, it may cost up to $2000 or more.

FAQ Section

What is a coolant leak?

A coolant leak is leaking the coolant or anti-freezing fluid from your car. In the absence of coolant, the engine may get overheated in minutes and cause serious damage. A blown radiator hose, a defective hose clamp, and a warped head gasket are just a few causes of coolant/antifreeze leaks.

Are coolant and antifreeze the same product?

Though antifreeze and engine coolant are similar, but not the same. Antifreeze is made of ethylene glycol or propylene glycol and is the basic ingredient, but it has to be mixed with water to create coolant, which is the cocktail you will find in the cooling systems of all “water-cooled” vehicles.

What are major causes of low coolant?

  1. Hole in the heater core
  2. Gusted head gasket
  3. Damaged hose
  4. Issues with expansion tank
  5. Failure in the water pump
  6. Damaged radiator
  7. Leaky radiator cap
  8. Improperly tightened hose clamps
  9. Old hoses

What are the Symptoms of Low Coolant?

Following are the symptoms of low coolant:

  1. Engine Overheating
  2. Minimum Coolant Level
  3. Temperature Gauge
  4. Coolant warning light
  5. Sweet Smell
  6. Radiator with Bubbles
  7. Puddle of Coolant

Can you mix coolant and antifreeze?

Mixing antifreeze is a huge mistake and can result in expensive repairs. When combined, they can form a thick, jelly-like substance that will clog your vehicle’s cooling system. This entirely stops all coolant flow, which can cause overheating. Other problems that may occur include a water pump and radiator damage.

What happens if coolant is low?

Coolant helps pull heat away from the engine. So, without enough coolant, the engine could overheat or seize up. Continued use of an overheated engine could lead to permanent damage, such as pistons welding to the cylinders.

What is the color of Coolant?

Fresh coolant is a clear brightly colored liquid, usually violet, yellow, green, blue, red, or orange but this will vary depending on the manufacturer’s formulation. Over time, your coolant will become dirty losing its color and becoming darker, often an oxidized shade of brown.

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