Green Fluid Leaking from Car (Causes & Fixes)

Jos Fallon
Green Fluid Leaking from Car

Green fluid leaking from a car is never a good sign. It could be a symptom of a severe problem that requires immediate attention.

The green fluid is the engine coolant, which regulates the engine’s temperature. This coolant may leak due to a faulty radiator cap, blown head gasket, or holes in the radiator, water pump, or hose. If your car leaks coolant, it can cause your engine to overheat, leading to costly repairs and severe engine damage.

This comprehensive guide will help you identify the source of the problem and provide you with the necessary steps to rectify it.

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6 Possible Causes Why a Car Leaks Green Fluid

As previously discussed, green fluid is essentially a coolant or antifreeze. The concern now is determining what causes it to escape from the system.

Radiator Cap

The following are six potential sources of green fluid leakage:

1. Faulty Radiator Cap

It doesn’t happen often, but a loose or faulty cap can cause coolant to leak out. 

The radiator cap serves as a pressure release valve for the cooling system. It maintains the correct pressure within the system and prevents coolant from boiling or escaping.

A faulty radiator cap may fail to maintain the proper pressure, allowing coolant to leak out of the system. This can lead to a green fluid leak and potential overheating issues, as the coolant is not adequately contained within the system.

car radiator

2. Hole in the Radiator

The radiator is the primary component of your car’s cooling system. It dissipates heat absorbed by the coolant as it circulates through the engine, helping to maintain the engine at the optimal temperature.

If the radiator bears a hole or crack, that becomes a safe passage for coolant to escape, resulting in a green fluid leak. This damage can occur due to road debris, corrosion, or simple wear and tear over time.

A leaking radiator can compromise the cooling system’s efficiency and lead to engine overheating. If the radiator is the culprit, you may witness severe bubbling from the radiator and engine overheating.

Blown Head Gasket

3. Blown Head Gasket

The head gasket is a seal between the engine block and the cylinder head. It prevents coolant, oil, and combustion gases from mixing and ensures that each fluid stays in its designated area.

Over time, due to engine overheating, manufacturing defects, or excessive engine wear, the gasket can blow out. This allows coolant to escape, causing a green fluid leak.

Additionally, it can result in coolant mixing with engine oil or entering the combustion chamber, leading to white smoke from the exhaust and potential engine damage.

4. Cracked Expansion Tank

Cracked Expansion Tank

The expansion tank, also known as the coolant reservoir, is a container that holds excess coolant. It allows for the expansion and contraction of coolant as it heats and cools, ensuring the cooling system maintains the correct fluid level.

A cracked expansion tank can result in a green fluid leak as the coolant escapes through the damaged area. Cracks usually develop due to excessive pressure in the cooling system, material fatigue, or impact damage from road debris.

5. Water Pump Failure

The water pump is responsible for circulating coolant throughout the engine. It ensures that the coolant flows through the various components, such as the radiator and the engine block, maintaining the engine’s temperature.

A water pump failure can lead to a green fluid leak as coolant escapes through damaged seals or a cracked pump housing.

The pump usually fails due to worn-out seals, bearing failure, or a damaged impeller, which can all lead to leaks and compromised coolant circulation.

car hose fixing

6. Worn Out Hoses

Coolant hoses transport coolant between the various cooling system components, such as the radiator, engine, and heater core.

Over time, coolant hoses can wear out and crack, allowing coolant to escape and cause a green fluid leak. Their deterioration results from exposure to heat, pressure, and the corrosive properties of coolant.

How to Fix a Car Leaking Green Fluid? [6 Possible Fixes]

Having identified the common causes of green fluid leaks in car engines, knowing how to address these issues is crucial.

Before fixing any of these issues, ensure the engine is cold and not running.

1. Replace the Faulty Radiator Cap

  1. Inspect the radiator cap. Is it loose, cracked, or has a corroded seal?
  2. If it does have, replace the faulty radiator cap with a new one that matches the specifications of your vehicle’s cooling system.
  3. Ensure the new cap is installed correctly and tightened to maintain the correct pressure within the cooling system.

2. Patch the hole in the Radiator

  1. Inspect the radiator for visible holes or cracks.
  2. Clean the area around the damage to ensure a proper seal.
  3. If the hole or crack is small, use a radiator repair kit to patch the damaged area according to the manufacturer’s instructions.
  4. If the damage is extensive or the radiator is severely corroded, replace the entire radiator.

3. Install a new Head Gasket

The gasket is a part of the cylinder head and to replace you may need to take apart the complex parts.

So, for this purpose, first, you need to consult a professional to confirm head gasket failure and then ask him for a replacement. The replacement will cost you somewhere between $1000 to $2000 on average.

4. Repair the Cracked Expansion Tank

  1. Drain the coolant from the expansion tank.
  2. Remove the damaged expansion tank from the vehicle.
  3. For a small crack, you can seal it with a plastic repair kit
  4. In case the expansion tank is severely damaged, replace it with a new one.
  5. Once you install a new expansion tank and refill the cooling system with fresh coolant.

5. Install a New Water Pump Failure

  1. Make sure the engine is cold.  Then, remove the battery terminals.
  2. From the bottom of the radiator, drain out all the anti-freeze.
  3. Locate the water pump; it is usually under the exhaust manifold. For precise location, consult the owner’s manual.
  4. Remove the old water pump, careful not to damage any surrounding components.
  5. Install a new water pump according to your vehicle’s specifications.
  6. Reconnect any hoses, belts, or other components removed during the water pump replacement.
  7. Refill the system with fresh coolant and bleed the system to remove any air pockets.

6. Replace the damaged Hoses

  1. Inspect all the coolant hoses for signs of wear, damage, or leaks.
  2. Drain the coolant from the radiator to prevent spills during hose replacement.
  3. Carefully loosen the clamps and fasteners and remove the damaged hose.
  4. Install a new hose that matches the dimensions of the hose you removed.
  5. Refill the system with fresh coolant and bleed it.

Frequently Asked Questions

Can I drive my car when green fluid is leaky?

Driving your car when green fluid (coolant) leaks is not advisable. A coolant leak can lead to engine overheating, which may cause severe engine damage.

How expensive are green coolant leaks?

The cost of repairing a green coolant leak varies depending on the cause of the leak and the extent of the damage. Minor repairs, such as replacing a hose or radiator cap, can be inexpensive (around $100). However, more extensive repairs, such as replacing a head gasket or radiator, can be costly ($1000-2000).

What is the green fluid leaking from my car?

The green fluid leaking from your car is likely coolant, also known as antifreeze. Coolant is a mixture of water and ethylene glycol, which helps regulate your car’s engine temperature.

Final Thoughts

Green fluid leaks can cause concern, but with proper knowledge and timely intervention, these issues can be resolved efficiently.

Though we have provided suitable solutions for each scenario, it is highly recommended to consult a professional if you are uncertain about the cause or feel uncomfortable attempting the repair on your own.

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