Black Soot from Exhaust | Causes & Solutions

When you see black soot coming from exhaust you shouldn’t start panicking as this is a very normal phenomenon. 

Usually, this occurs because of a chemical reaction taking place in the car’s engine. This definitely doesn’t equate to your car breaking down.

The black soot coming out of the tailpipe of your vehicle is carbon dust, when carbon monoxide gets mixed with steam this results in the creation of steam. With further chemical reactions, this steam gets converted into black soot.

Let’s find out more about black soot, what causes it, and the impacts of it on your car.

What is Black Soot?

This is actually quite a normal and frequent problem seen in cars. The black smoke-like substance that you see coming out of a car’s tailpipe is black soot. 

The exhaust of the car consists of a colorless and odorless gas known as carbon monoxide. 

Steam is produced when this gas gets mixed with hot water and that moves to the catalytic convertor present in the exhaust system of the vehicle. Here, carbon monoxide gets converted into carbon dioxide and water with the help of oxygen.

Steam is produced and the molecules react with one another and exit the car through the tailpipe. The steam leaving the vehicle is known as black soot. 

The Causes of Black Soot and Smoke

Various things can lead to the formation of black soot and smoke. These are the three main reasons why:

Energy for Car’s Engine

Fuel has to be burned by the car’s engine in order to get energy for its operation. During your car’s acceleration air enters the engine’s cylinders. 

The more the acceleration, the more fuel is needed to be burnt. Because of this, the engine starts to overheat if a coolant isn’t flowing through it. Therefore, leading to black soot.

Exhaust Gets Burnt

As you accelerate the exhaust gets burnt as air gets into the cylinder if your vehicle goes faster than it usually does. 

Furthermore, the exhaust gets more burned when you’re on the move than in comparison to when you are stuck at a stop light.

Catalytic Converter

This component of the car is responsible for carrying the black smoke to the tailpipe and out of the car. 

Catalytic converters convert the harmful nitrogen oxide emissions into water vapor and carbon dioxide which are far less harmful than the former.

Although, the dangers of these components are less than carbon dioxide, at the end of the day, a greenhouse gas. Emission of it leads to depletion of the ozone layer and global warming.

Read Also: Car Exhaust Smells Sweet? Here’s The Reasons and How to Fix it!

Do You Have to Worry About Black Soot Coming from Exhaust?

The answer varies from one situation to the next. It is best if you take your car to a professional mechanic whenever you see black smoke coming out of your exhaust. 

The problem could be because of a broken fuel injector or even a cracked valve, both of which would need replacements.

Another reason could be oil leakage that would require immediate fixing. But if you see no indication of smoke coming out of your engine, you should not be worried at all.

Primarily, when you see black exhaust smoke it usually is an indicator of issues with a single component of the engine. This problem can be fixed by replacing the faulty part.

But if you see the issue still persisting and getting worse with time, then you might want to consider having a professional over to see what is wrong with your car.

What is the Cause of Soot

When there is incomplete oxidation or incomplete fuel burning soot is formed. It is indeed a very harmful byproduct and here are the reasons why its produced:

Faulty Fuel Injectors

If the fuel injectors are not working properly, the first sign that you will get is soot. When you see this happening, the first move would be to check out the filters. 

You have to replace the air filter once every 3 to 4 months. This will help prevent the buildup of dirt and dust on the injectors.

That way it will not get blocked or clogged with components such as soot or ash.

Leaking Valves

This is also one of the prime causes of soot formation in the exhaust of your vehicle. If you have a leaking valve, it could pose a great problem such as an increase in emissions. 

You should call a professional mechanic if you ever detect this issue occurring.

Worn Out Rings

If your car has worn-out spark plugs or rings, carbon deposits can build up in the combustion chamber and also the place where the pistol gets attached to the cylinder wall. 

Carbon builds up in those areas can lead to increased friction and, thus, form soot after fuel gets burned in the engine.

The issue with the Turbocharger

In order to enhance the engine’s power turbochargers are installed. Mainly, people who are into racing prefer cars with a good turbochargers. But if there is a failure or it or any issues with the fuel supply line, soot may get produced.

When you have doubts about your turbocharger, just take your car on a ride. After doing that, have a look at its exhaust and if you find deposits on the back of the exhaust, your turbochargers need to get work done.

Issues with EGR System 

The exhaust gas recirculation, EGR, has been made specifically so that the car operates more cleanly and forms less soot. How this system works by utilizing suction to suck in air and release the bad air.

Because of EGR, your car has better fuel-burning efficiency, and so will be able to generate more power without less energy.

It is a given that if there are any troubles with this sophisticated system, it will not function as it has been designed to. This will result in the formation of soot.

Related Post: Fuel Injector Stuck Open Symptoms – [Solutions Added]

Frequently Asked Questions [FAQs]

Is it safe to drive with black soot coming out of the exhaust?

It is not okay, as it means that there is something wrong with your car’s engine.

How to stop black soot from forming?

You should properly clean your combustion chamber and air filters. You can also use fuel additives.

What is the best cleaner for black soot?

You can use white vinegar as it can break down the molecules of soot quite easily.

Are soot particles harmful to humans?

Yes, it can cause illnesses such as heart disease, asthma, breathing issues, and in serious cases, cancer.

Final Words

If you notice black soot coming out of your exhaust, get it checked as soon as you can. While it may not cause a lot of problems initially, if you let it build up it may interfere with the performance of your car. 

Plus, black soot is harmful to the environment as well, so it’s best to get the problem solved sooner rather than later.