What are the Signs of Coolant Leak? | How to Fix Coolant Leak?

The efficient working of the engine is very important for the efficient operation of the vehicle. The engine coolant or antifreeze plays a big to prevent the engine from overheating and also maintains the normal temperature of the engine. The leaking or low level of the coolant is not a good thing. This article mainly explains the signs and causes of the coolant or antifreeze leak, coolant leak repair cost, and some other aspects.

What is a Coolant?

Coolant or antifreeze is an engine fluid designed to ensure the proper operation of the engine at normal operating temperature, whether it is protecting the engine from overheating or freezing. The coolant is also known as “antifreeze.”  

car engine coolant

The main function of an engine coolant is to absorb engine heat and prevent the engine from failure due to overheating and freezing.

It puts in the car radiator. It behaves differently in summer and winter. In winters, it acts as antifreeze and stops the radiator liquid from cracking and freezing. While in summers, it maintains the engine temperature and prevents your engine from overheating.

How to make an Engine Coolant?

The antifreeze is a mixture of silica and ethylene glycol. When this mixture is mixed with regular standard H2O, it makes a coolant that ensures the proper cooling of your vehicle engine and keeps warm enough in winter.

If your engine cooling system is not working properly, your engine will overheat very quickly, which may damage the engine parts or may cause complete engine failure. Therefore, proper maintenance and on-time exchange of the engine coolant are very important.

What Is a Coolant Leak?

The coolant or antifreeze leaks may cause due to multiple reasons such as a blown head gasket, damaged hose clamps, radiator hoses, and damaged heater core.

As the coolant leaks, the coolant level in the radiator becomes lower than the desired level, which can contaminate the engine oil, distort the cylinder head, overheat the engine, or failure of the engine.

Therefore, when you observe the symptoms of the coolant leak, immediately fix it, which may save you from an expansive repair. You must check the engine coolant level regularly.

Symptoms of Coolant Leak

The desired level of the engine coolant is very important for the efficient working of the cooling system. Sometimes, the coolant level goes down because of leaks and some other causes. As your car coolant level becomes low than normal, your car starts producing different symptoms.

Following are the symptoms of coolant leaks:

1) Visible fluid on your garage floor

The visible coolant on the garage floor (or where you park your vehicle) is a most common symptom of a coolant leak.

An healthy coolant has pink, orange, or light green color. It has a sweet smell. As you observe a coolant leak, you must first clean it because it is toxic to pets and humans.

2) Check the Temperature Gauge

The temperature gauge measures the engine temperature. It is located on the car dashboard. Very low fluctuations in the temperature gauge are normal, but sudden or large changes in temperature usually indicate a problem. Mostly this problem occurs when you have a low coolant level or your cooling doesn’t work properly.

3) Coolant level

To check for engine coolant leaks, check the coolant level in the expansion tank. Measure the coolant level; if it is low, it means your coolant may be leaking.

4) Coolant Smell

The smell of the healthy engine coolant is very sweet. It may sound strange, but smell it next time as you buy a coolant bottle. If your car leaks and smells like coolant will also start to discharge, it means you need to determine the source of the problem.

5) Puddle of Coolant/Antifreeze

When your car has a coolant leak, and you have parked it in one place for a long time, you may find a large puddle of coolant under the car. The flow of refrigerant leaks also plays an important role here.

This is a most common sign of a coolant leak that you may also observe when you remove your vehicle from a place after a long time.

6) Coolant Warning Light is Glowing

The latest cars have a coolant warning light. When the coolant level in the coolant tank goes down than the desired level, the coolant light starts glowing. This light is also installed on the car dashboard.

If your vehicle warning light is illuminating, it means you have a coolant leak; due to that, your coolant level has gone low.

7) Bubbles in Radiator

In normal condition, the coolant expansion tank and radiator pipe are well sealed. Therefore, air bubbles should be no there. In case of a coolant leak, combusted exhaust gases emitted by the engine can enter the radiator or expansion tank.

When the combusted gases enter the radiator, they generate bubbles inside the radiator.    As you see bubbles in your expansion tank or radiator, it means you have a coolant leak. When you observe air bubbles in your car’s coolant reservoir or radiator, you must immediately contact a professional.

8) Engine Overheating

As we discussed above, the main function of the coolant is to prevent the engine from overheating. If your car engine is overheating, it means you don’t have sufficient coolant due to that your cooling system is not working properly and engine overheating.

9) Quick reduction in coolant level

If you notice a sudden drop in the coolant level, it is 100% certain that you have coolant leaking.

Read More: How to Add Oil to Car Engine?

Causes of Coolant Leaks

The coolant leak can be caused because of many reasons, such as a blown head gasket, radiator cap leak, hoses leaks, and many other factors. Let’s have a look at the causes of the coolant leaks:

  1. Hole In the Radiator
  2. Damaged Hoses
  3. Leaky Radiator Cap
  4. Blown Head Gasket
  5. Water Pump Failure
  6. Problem with Expansion Tank
  7. Damaged Heater Core
1) Hole In the Radiator

As we know, an engine generates extreme heat. Therefore, car engine parts have to withstand a lot of wear and tear and extreme temperatures and pressure.

With the passage of time, the hose gets weaker, debris and contamination can build up inside the hoses. When the debris makes contact with the radiator water, it may produce corrosion inside the radiator. This corrosion may create a hole in the radiator and cause coolant leaks.  

coolant leak due to hole in radiator

Solution: Continuously inspect the radiator and prevent it from corrosion. As you see corrosion build-up, immediately remove it so that you can save your radiator from an expansive repair.

2) Cracked or Damaged Hoses

The hoses play a big role in the cooling system. They connect the water pump to the engine and the engine to the radiator. The coolant flows inside the hoses. They are installed under the hood of the vehicle. 

With time, the hoses become stiff and brittle. A cracked or damaged hose can cause of coolant leak.

coolant leaking from DAMAGED HOSE

Solution: Inspect the vehicle hoses before driving the vehicle. Ensures the proper maintenance of your car hoses and replaces them on time. 

3) Leaky Radiator Cap

Your car radiator has a small cap, but it performs a big role. The radiator is under extremely high pressure, and the cap serves to create a tight seal that maintains the appropriate pressure of the cooling system. With time, the radiator cap seal becomes weaker, or the springs can wear out, leading to coolant leaks.


Solution: You must continuously inspect the radiator cap and replace it immediately in case of a worn or damaged cap.

Read More: Working of Cooling System

4) Blown Head Gasket

A head gasket plays a vital role in the efficient working of the engine. It installs in between the engine block and the cylinder head.

It provides an efficient seal between the engine block and cylinder head as well as stops the leakage of engine oil and coolant. It has the ability to bear extreme temperature and pressure.


The head gasket has the responsibility to maintain desired temperature and pressures inside the engine. The main function of the head gasket is to maintain the separation of the coolant and engine oil.

As the head gasket is burned or blown, it may cause of coolant leak. Due to the blown gasket, engine oil and coolant cannot be separated. The coolant will mix with engine oil and burn into the combustion chamber, which may cause engine failure.

Solution: Regular inspect the head gasket of your engine and replace it before its expiry date.

Read More: Working and Function of Head Gasket

5) Water Pump Failure

A water pump is also a most important part of the engine cooling system. It ensures proper coolant circulation throughout the cooling system. The engine power uses to drive it.

water pump

As the water pump fails, it doesn’t properly circulate the coolant due to that engine overheats.  

Solution: Check the pump before driving the car. If your car has a failed pump, firstly replace it and then drive the vehicle.

6) Problem with Expansion Tank

An expansion tank uses to transfer coolant to the car radiator. It is made of plastic. A rubber hose uses to connect it to the radiator. It transfers or gets coolant to and from the radiator as the engine cools down or warms up.

coolant leak due to EXPANSION TANK

With time, the plastic of the tank becomes weak, and the parts attached to it also weaks. Due to this weakness, the tank or cap may crank, which may cause of coolant leak.

Solution: Inspect the expansion tank regularly and ensure its proper maintenance.

7) Damaged Heater Core

The heater core gets heat from the radiator coolant and transfer this heat inside the car. This heater core may also cause of coolant leak. In such conditions, there may be liquid in the plastic case at the heater’s core bottom.


Solution: Regularly check and maintain the heater core.

Read More: Working of Heater Core

How to Find a Coolant Leak?

As we discussed above, the coolant leaks may occur due to different reasons. If your car coolant is also leaked and you want to find the leakage reason then follow the below-given steps to find it:

  1. Run the Vehicle: To find leaks, first run the vehicle until it is fully warm and then park it on a clean area.
  2. Leave the engine for cooling: Switch off the vehicle engine and wait for a few minutes until it fully cools. The engine and coolant have very high temperatures and pressures when the vehicle runs. If you remove the radiator cap or recovery tank cap in warm engine condition, the hot coolant may severely harm your skin.
  3. Find the Coolant Puddle: After parking the vehicle, wait up to 14 minutes, look underneath the vehicle for a fresh puddle of coolant. If you don’t see a puddle and you are still smelling the sweet odor of antifreeze, climb down and look under the vehicle to see if it’s wet or not.

Note: The air conditioner also produces condensation that can seep onto the floor, but pure, clear water drips out of the air conditioner.

  1. Engine Compartment Inspection: If you observe stains or a small puddle of antifreeze underneath the vehicle near the vehicle front, open the hood and inspect the engine compartment. During this inspection, you should also smell around to find if you can spot where the coolant smell is coming from.
  2. Inspect the complete system: Check the hose connected to the engine compartment (inspect the hose ends from where they connect to other parts), the area around the radiator cap, and the internal side of the radiator to find the signs of coolant. If there are no clear signs of coolant leaks, inspect the entire engine compartment. This leak may have come from anywhere under the hood.
  3. Heater Core Leak: If the antifreeze smell is more inside the car than the outside, it means that problem is with your car heater. The heater uses a “core” like a radiator to deliver heat inside the car. If your car carpet is humid or there is moisture on the windows, it means that your car has a leaking heater core. Since the heater is part of the air conditioning system and is integrated behind the dashboard. Therefore, a leak in the heater core is very tough to find and even harder to repair. In such a condition, you should contact a technician for repair.
  4. Hose Inspection: You can check the condition of the hose to see if there is a leak around the hose. Bad hoses can also cause coolant leaks. If you find that the hose is leaking near the clamp, use a screwdriver to tighten the clamp.

How To Fix a Coolant Leak

The coolant or antifreeze is not much hard to fix. As we discussed, your radiator antifreeze may leak because of different reasons. Therefore, here we are going to discuss different methods to fix the coolant leaks:

1) Use Eggs

If you are on the way and your radiator coolant has been leaked, first try to search the nearest repair workshop. If there is no nearest workshop and your radiator is leaking coolant quickly then buy some eggs and put them into the radiator.

This option is only suggested if no other option is available.

  1. Stop your vehicle on the side of the road and turn off the engine.
  2. Wait for 6 to 15 minutes until your engine cools.
  3. Lift the hood and remove the cap of the radiator.
  4. Crack and put three eggs inside the radiator reservoir.
  5. Now inspect the leak, whether it has been stopped or not. If leakage is not stopped, crack more eggs into the reservoir until it blocks.

2) Replace the Old or Damaged Hose Clamps

Sometimes, antifreeze or coolant may leak due to old, worn, or damaged hose clamps. In such a case, you need to replace your vehicle hose clamps.

To replace a hose clamp, follow the below-given steps:

  1. Turn off the car engine and wait for 6 to 15 minutes until your engine cools.
  2. Lift the hood and unscrew the radiator cap.
  3. Find the worn or damaged hose clamp.
  4. According to the hose clamp location, you may need to drain some antifreeze. Put the vessel under the hose and drain as much fluid as needed to access the hose and clamp.
  5. Unscrew the worm or damaged clamp. If you can’t unscrew it, you may also cut it.
  6. Install the new clamp onto the untied hose.
  7. Tightly screw the hose clamp. 
  8. Add the new antifreeze into the radiator reservoir and reinstall the radiator cap.

3) Replace the Radiator Hose 

The hose is the most vital part of the engine cooling system that connects the parts of the engine. With time, the vehicle hoses damage or worm. In such conditions, they may cause of coolant leak, and you may need to replace them to fix the coolant leak.

To replace a hose, follow the below-given steps:

  1. Turn off the car engine and wait for 6 to 15 minutes until your engine cools.
  2. Lift the hood and unscrew the radiator cap.
  3. Find the worn or damaged hose clamp.
  4. According to the hose location, you may need to discharge some antifreeze. Put the vessel under the hose and discharge as much fluid as needed to access the hose and clamp.
  5. Remove the hose clamp on both ends of the hose.
  6. After clamps removal, remove the old or damaged hose.
  7. Install the new hose and tightly screw the hose clamps on its both ends.
  8. Add new antifreeze into the radiator reservoir and reinstall the radiator cap.
  9. Now inspect and ensure that coolant is not leaking.

4) Replace the Radiator

A radiator is a place that bears extreme pressure and temperature. Sometimes, the coolant leak occurs due to a damaged or old radiator. In such a condition, you need to replace it immediately.

What is the color of the car engine coolant?

The engine coolant has the following different colors:

Si-OAT (Silicated HOAT)Silicates & Organic AcidsPURPLEPorsche, VW, Audi, Mercedes-Benz, others
P-HOAT (Phosphated HOAT)Phosphates & Organic AcidsPINK / BLUEHyundai, Honda,  Nissan, Toyota, KIA & other Asian vehicles
HOAT (Hybrid OAT, Phosphate-free)NAP FreeTURQUOISEMini, Tesla, Volvo, BMW, others
HOAT (Hybrid OAT)Silicates & Organic AcidsYELLOWEuropean, Chrysler, Ford
OAT (Organic Acid Technology)Organic AcidsORANGEVW, Saab, GM
IAT (Inorganic Additive Technology)SilicatesGREENOlder Vehicles

How much does it cost to fix a coolant leak?

The cost of an engine coolant leak fix depends on many factors, such as the nature of the leak and the area where you live.

The average cost of a coolant leak fix is from $500 to $800. If you notice the leak early on, then the fixing cost will be low, and you may need to pay from $80 to $150

The below-given table represents the cost of the coolant leak fix for different workshops:

Auto CenterPrice
Amazon$ 100 to $230
Midas$120 to $590
NAPA$210 to $850
Mr Tire$130 to $660
Your Mechanic$150 to $910
Walmart$90 to $250

FAQ Section

What is the function of the Engine Coolant?

The main function of the engine coolant is to prevent the engine from overheating and maintain its normal temperature. It ensures the proper operation of the vehicle cooling system.

Can I Drive My Car with a Coolant Leak?

Yes, you can drive, but it is suggested that you shouldn’t drive your vehicle in case of a coolant leak. The main function of the car engine coolant is to prevent the engine from overheating and maintain its normal temperature. If your car coolant leaks and you continue driving, soon your engine will be overheated, which may lead to parts or complete failure of the engine.

How long does a coolant leak take to fix?

The time to fix a coolant leak depends on the type of leak. The small fixing completes within 25 to 30 minutes. However, the replacement of the gasket or radiator may take a long time.

What are the signs of Antifreeze Leak?

The antifreeze or coolant leaks have the following major signs:

  1. Quick reduction in coolant level
  2. Visible fluid on the garage floor
  3. Glowing Warning Temperature Gauge
  4. Engine Overheating
  5. Bubbles in Radiator
  6. Low coolant level
  7. Antifreeze smell
  8. Puddle of coolant
  9. Coolant warning light is glowing

Why is my car leaking coolant?

The car coolant leaking may cause due to multiple reasons. Following are the most common causes of coolant leaks:

  1. Old or Damaged Hose
  2. Water Pump Failure
  3. Hole In the Radiator
  4. Damaged Heater Core
  5. Leaky Radiator Cap
  6. Problem with Expansion Tank
  7. Blown Head Gasket
  8. Cooling system failure

How to stop a coolant leak?

The coolant leaks are caused because of different reasons. Therefore, there are different methods to fix the coolant leaks. Follow the below-given methods according to the nature of the leak:

  1. Use Eggs: Pour eggs into the radiator if there is no other option.
  2. Replace the Damaged Hose Clamps: Replace the clamps if coolant is leaking due to old or damaged hose clamps.
  3. Replace the Hose: If the hose is leaking, replace it with the new one.
  4. Replace the Radiator: If your entire radiator system has been failed then replace the radiator.
  5. Replace the water pump: If your water is not pumping antifreeze properly then replace it.
  6. Replace the expansion tank: If leaking occurs due to a damaged expansion tank, then buy a new one and replace it.
Read More
  1. Different types of Car Engines
  2. Signs and reasons of Cooling System Failure
  3. BMW Coolant Cost
  4. A list of Car Internal Parts

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