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Why Is Coolant Coming Out of Exhaust? (Explained)

Updated: Jan 9

Coolant coming out of the exhaust is a serious issue that can cause significant damage to a vehicle if left unaddressed. There are several potential reasons for this problem, and it is important to diagnose and fix the issue as soon as possible to avoid further damage.


Coolant coming out of the exhaust is most typically caused by a blown head gasket, it could also mean your vehicle has a cracked intake manifold or radiator leak which is leaking coolant into your exhaust system.

 

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white smoke coming out of exhaust pipe on car

Is It Coolant Coming Out of Exhaust?

Be sure the liquid is coolant and not just condensation and water coming out of the exhaust. To determine whether the substance coming out of your exhaust pipe is coolant you should drive the car until it reaches operating temperature (about 20 minutes).


You will notice any usual condensation and water has boiled away and any liquid or vapour coming from the exhaust system will likely be coolant.


Coolant typically has a sweet flavour and smell, while water, which is a normal part of the exhaust process, will have no particular taste or flavour. If you can smell exhaust which has a sweeter taste and smell it'll likely be coolant rather than water and condensation.


Never inhale or directly smell exhaust fumes as they are toxic.

Causes of Coolant Coming Out of the Exhaust System

If you confirm that the liquid is coolant, you may also have noticed a cloud of dense white smoke coming from the exhaust tailpipe. This indicates it could be any of the following.


  • A blown head gasket

  • A cracked intake manifold, cylinder head or block

  • A radiator leak


These issues can cause coolant to enter into the exhaust system. It is important to address any of these issues promptly to avoid further damage to your vehicle.


Blown Head Gasket

One possible cause of coolant coming out of the exhaust is a blown head gasket. The head gasket is a seal that sits between the engine block and the cylinder head, and its primary function is to prevent coolant and oil from mixing.


If the head gasket fails, coolant can leak into the cylinder and be burned off through the exhaust, resulting in coolant coming out of the exhaust pipe.


Cracked Intake Manifold, Cylinder Head & Block

Another potential cause of coolant coming out of the exhaust is a cracked cylinder head, engine block, or intake manifold. These components are subjected to high levels of heat and pressure, and over time they can become damaged or fatigued.


f a crack develops, coolant can leak out and be burned off through the exhaust.


Radiator Leak

A third possibility of coolant coming out of the exhaust is a faulty or leaking radiator.


The radiator is responsible for keeping the engine cool, and if it is not functioning properly, the engine can overheat. This can cause the coolant to boil and vaporise, which can then be expelled through the exhaust.


Fixing Coolant Leaking Through Exhaust

Regardless of the cause, it is important to address the issue as soon as possible to avoid further damage to the vehicle.


In some cases, the problem can be fixed with a simple repair, such as replacing a faulty radiator or blown head gasket. In more severe cases, however, the engine may need to be completely replaced, such as if the cylinder head is cracked.


It is also important to note that coolant coming out of the exhaust can be a sign of other underlying issues.


Why Does My Exhaust Smell Like Coolant?

Coolant has a sweet taste and smell in comparison to water which has no taste or smell. If your exhaust smells like coolant it could be that your vehicle has a blown had gasket, a cracked cylinder head, cracked cylinder liner/block, cracked intake manifold, or even leaking radiator.


How Do I Know if My Head Gasket Is Leaking Coolant?

There are several signs that your head gasket may be leaking coolant. Some of the most common symptoms include the following.


  1. Overheating: If your engine is consistently overheating, it may be a sign that coolant is leaking from the head gasket.

  2. White smoke from the exhaust: If you notice white smoke coming out of the exhaust, it could be a sign that coolant is being burned off through the exhaust.

  3. Low coolant levels: If you consistently have to refill the coolant in your vehicle, it could be a sign that there is a leak somewhere in the system.

  4. Milky oil: If you notice that the oil in your vehicle has become milky in color, it could be a sign that coolant is mixing with the oil, which could indicate a head gasket leak.

  5. Coolant in the oil: If you notice that there is coolant present in the oil when you check the levels, it could be a sign that the head gasket is leaking.