The Causes and Treatment of White Smoke from Exhaust

The types of smoke that comes out of the exhaust pipes are varied and may be due to a variety reasons.

Every type of color, from white to blue, can indicate different issues with your vehicle.

It is important to understand what it means and how can you repair it. Let’s begin with a quick look at the signs to look for:

The Exhaust Pipe is the main cause of white smoke

Condensation from the exhaust system is the most likely cause of white smoke. You can also see white smoke from the exhaust system due to a leaky intake manifold gasket or bad EGR cooler.

You can see white smoke as vapor or light smoke. The white smoke coming from the exhaust pipes during acceleration, startup, idle or acceleration indicates that water or coolant is being vaporized.

You can also carefully smell the water or smoke from the exhaust; if it smells sweet, it’s most likely coolant, and in this case, you have a bigger problem.

Below is a list that explains the main causes of white smoke from an exhaust pipe.

1. Condensation

Condensed water, which is being vaporized, is the most likely reason behind white smoke coming from an exhaust pipe.

When your car is standing for a long time and hasn’t been used for a day or two, it will be condense created from the last time your car was driven.

This water will lay in the bottom of your exhaust, and once you start the car – the exhaust will get hot and then vaporize the condense.

If the white smoke is light and just coming for a short time after the startup moment at cold starts, there should be nothing to worry about because it’s most likely just condensation.

RELATED: Black Smoke From Exhaust (Causes & How to Fix it)

2. Gasket Leakage in Take Manifold Gasket

We now have a slightly more severe problem but it is not very serious. Your intake manifold controls the flow of air into your vehicle's combustion chambers.

Coolant fluid cools intake manifolds, so they often have a gasket that seals the manifold to the cylinder head. Sometimes, this gasket can become brittle and leak.

A bad intake manifold valve gasket can cause you to smell thick, sweet-smelling exhaust gases.

Read more about 5 Signs That Your Intake Manifold Gasket Is Not Working

3. Cooler to cool off bad EGR

If your exhaust smoke smells sweet, it’s most likely a condensed coolant you are facing.

Another common problem is cracks in EGR coolers. Although not all cars are equipped with EGR coolers and this is most common for European vehicles, it's worth checking.

Because there is no obvious sign outside of an engine, this can make it difficult to diagnose.

If the EGR cooler cracks, you will need to have it replaced. To diagnose if your EGR cooler may be defective, you will need to contact a professional mechanic.

Checking inside the cylinders of your car and checking for spark plugs is the best thing. It will also clean your cylinders if the engine is burning coolant. If one of the cylinders has not been cleaned but it is still burning coolant then the coolant must be sourced from within the combustion chambers.

4. Head Gasket

Head gaskets are gaskets that connect the engine block to the cylinder head. This gasket allows for the separation of combustion, oil, coolant and other fluids between these parts.

The coolant could leak from the combustion chambers if the head gasket becomes cracked or damaged.

This may cause engine coolant to ignite and can lead to heavy, white smoke. The size of the leak will determine the extent of your emission.

A blown head gasket can be very costly to fix because it requires you to take apart many pieces to replace.

Our other article, Bad Head Gasket Symptoms, will help you to diagnose bad headgaskets.

5. Broken Cylinder Head, or Block

Cracked cylinder heads or engine blocks are another thing that could cause white smoke to come out of your exhaust pipes. Both the cylinder block and engine block have many channels that allow coolant to flow through them.

If your luck is not in your favor, the block of the engine or the cylinder head could crack. In this case, coolant can flow into or out the exhaust.

It is uncommon, but it can occur after an overheating engine. This can occur, however, on certain engine types than on others.

These problems can be fixed by replacing the entire head/block, which requires a total disassembly.

6. Too Rich Fuel Mixture

A thing that is not directly causing white smoke from the exhaust – but can be mistaken for it is a too rich fuel mixture. It is not directly responsible for the formation of white smoke. However, it can cause gray smoke that could easily be confused with white smoke.

Grey smoke can result from a dense mixture. These are usually caused by fuel injector problems, MAF sensor failures or O2 sensor issues.

You can learn more about the different causes of a rich air-fuel mixture here: Engine Running Rich Causes & Symptoms

RELATED: Blue Smoke From The Exhaust (Causes & How to Fix it)

How to identify a car that has white smoke coming from its exhaust

You can diagnose white smoke in a car using many methods. Some methods may be faster and easier than others.

You can smell the smoke

First, smell or taste the smoke from the exhaust pipe. If it has a sweet smell, it’s coolant.

If the smoke doesn’t smell or taste anything more than water, it’s most likely condensation, and the smoke will go away after the car is heated up.

Make sure to use a pressure tester

Coolant pressure testers are the most reliable and effective way to check for internal coolant leakage. It can be attached to your radiator cap. Then, you will need to put some pressure into the coolant system and leave it for about an hour.

Check for coolant leaks in the combustion chamber by removing the glow or spark plugs. Coolant may be leaking into the combustion chamber if you have a crack in your cylinder head or your head gasket.

If you can’t find any coolant there, remove the pipes to the EGR pipes and check for any coolant signs inside of them. Coolant may be visible if there's a crack or leakage in your EGR cooler. Amazon has this kit: 8MILELAKE Universal Radiator Pressure Tester Kit

FAQs on White Exhaust Smoke