Black Soot Coming From Exhaust: Is That Normal? (Explained)

A lot of car drivers are complaining about black soot that is coming from their tailpipes. This black soot can be an unburnt fuel. This occurrence will happen if there is not enough oxygen in the combustion chamber. 

So is it normal to have a black soot coming out of the exhaust? No, it is not normal. If the exhaust is from your vehicle’s tailpipe, this can be because your engine is overworked. You should have your vehicle checked for damages. 

This will also happen if there is too much fuel being fed into the combustion chamber. So if you want to avoid these issues and wonder if these issues are typical, you are on the right page. It is essential to know about this issue because if these issues continue, it can cause a misfire, and in the long run, you will likely have an engine failure. 

Black soot is not normal, therefore, you should always check your vehicle so that you will know if there is anything that needs to be repaired. Repairs are done to resolve the problem.

With that, this article is made to address these issues. This article will discuss why there is black soot coming out of your exhaust and if this occurrence is typical. Let us get started.

Black Soot Coming From Exhaust

Why Is Black Soot Coming From The Exhaust?

If you are driving your vehicle with an exhaust system, you might experience soot coming out of your exhaust system. If the exhaust is from your vehicle’s tailpipe, this can be because your engine is overworked. This black soot will come out of the fuel source and the tree’s chemical reactions if the same fuel burns to power your vehicle. 

This will begin from the look of white vapor. Later on, it will then turn black due to the combustion byproducts like carbon monoxide and some unburned hydrocarbons. Some reasons can also be when you park when the vegetation reaches up from under the vehicle like trees or maybe grass, there can be some mud on the tires or the grasses, and it will then come into your exhaust system. 

The first is that your engine will be needing an overhaul. This will then need to be replaced, or it will just do some cleaning. Another possibility is that a dirty air filter causes the coot. 

Car drivers can clean this. You can use compressed air or do some replacement with one from an auto parts store. Soot in your exhaust can also be because of a lack of oxygen. 

If your engine is running, the fuel and the air mixture will enter the cylinder, and it will not have sufficient oxygen to burn completely. This will have some slightly burned hydrocarbons as soot in the inside of your tailpipe or muffler. So if you drive more, there will be more carbon deposits. 

There are a lot of types of fuels that are available for the internal combustion engine. However, all of them are produced in some level of soot in the exhaust, and this is because of incomplete combustion when they are burned with insufficient oxygen levels.

Is Black Soot Coming From The Exhaust Normal?

The danger level, according to some experts, is medium. If your exhaust is blowing out black soot, it can be because of the air mixture or the too-rich fuel. Proper combustion will need a precise mixture of fuel and air for your engine. 

Too much fuel or too little air makes the mixture rich. If this is the case, you might need to have your Subaru taken to an authorized service center. Many things can make a rich fuel or air ratio, including a dirty engine air filter, clogged fuel injectors, or a fuel pressure regulator. 

What To Do When Black Soot Is Coming From Your Exhaust?

Having black soot coming from your exhaust is never a good thing. But it is not the worst also. First, you need to know what type of engine you have. After knowing, proceed to the troubleshooting section. 

The black soot might look really serious and very bad, but it is not hard to clean. It is just a carbon deposit coming from your engine. This is just water vapor that is mixed with unburned hydrocarbons from the engine. 

So if you have black soot from your exhaust, this is what you can do. You will need dish soap, water, vinegar, containers that have lids, rag or cloth, and some elbow grease. You need to fill one of the containers with two cups of hot water. 

And then mix it with one-half cup of dish soap. After that, add another half cup of vinegar. Use this mixture as your primary cleaning for your exhaust pipe. 

Scrub it properly and remove all signs of soot from the surface area. Rinse the area well. Take the aluminum on the microfiber towel and then wipe the place so that it will brighten. 

Rotate the bowl if it becomes dirty. Put some protection in the exhaust tip using a metal coating so that it will be cleared. 

Black Soot From The Exhaust At Startup: Is That Ok?

If your vehicle is blowing off black soot at startup, this is not a regular occurrence. The cause can be a worn valve guide. With that, this is not okay. 

This means that you have to do some maintenance of your vehicle. If your engine is running, the oil will circulate over the valves, and the oil will keep these valves lubricated. If the engine stops, the top of the cylinder head where the valve is located will be covered in oil. 

With that, the valve guides will be worn out, and the oil will drip down into the combustion chamber. The oil will then turn into smoke if the vehicle starts.

Heavy Black Soot From The Exhaust: Is That Ok?

It is not okay. Black soot can come from a severe problem. But black soot might mean that your engine is burning a lot of fuel. 

Your engine will need oxygen and fuel so that it can burn. If there’s too much fuel in your combustion chamber, there will not be enough oxygen to burn it with, and it can cause black soot from your exhaust. 

Black Watery Soot From The Exhaust: Is That Ok?

It can just be a condensation that has been building in the motor or the exhaust piping. It is common for some people in their hometown. As long as it is not antifreeze or oil, you are fine. If you do not misfire, it is okay too.


In summary, black soot can come from your exhaust, and many people are experiencing this situation. Of course, black soot might be from something serious. 

But most of the time, black soot from your exhaust is not severe. You can clean the soot if you can find one from your exhaust.

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Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more