If you own a diesel-powered vehicle and you see black smoke coming out of the exhaust, it’s a sign that something is wrong. We will look for an answer to the question of what is the reason for the release of black smoke from the diesel engine exhaust.
If environmental pollution is involved, diesel engines are the things that have the worst reputations in this regard. The car with a diesel engine provides 4 times more emission output than a gasoline engine. This leads to much more pollution of our environment and the atmosphere. In addition, in the past 10 years, many diesel engine manufacturers, especially Volkswagen, have faced scandalous events. Unable to cope with the contamination of diesel, Europe and America have now abolished the use of diesel engines altogether. As of July 2023, diesel cars will no longer be available for sale in Europe.
Just because a diesel car blows black smoke from the exhaust doesn’t mean it harms the environment. Because harmful gases are mostly evident under the UV / infrared camera. Still, today’s diesel engines shouldn’t produce black smoke. If you see black smoke coming out of the exhaust, this is a sign of a malfunction.
Causes of Black Smoke from Diesel Engine Exhaust
In a diesel engine, black smoke usually indicates higher fuel consumption. Because the order required for the efficient and performance operation of the engine is broken.
1- Clogged and Dirty Air Filter
Diesel engines operate with a much more precise air/fuel mixing ratio than gasoline engines. For this reason, the air filter spoils this mixture even when it is not completely clogged. This causes black smoke to be expelled from the exhaust.
2- Injector Failure or Blocked Injectors
In today’s Comman-rail Diesel engines, fuel is sprayed by injectors. However, since the fuel quality is generally low in our country, the small outlet ends of the injectors may be clogged. It can also cause the injectors to fail. As a result, you can see black smoke coming out of the exhaust.
3- Blocked or Defective EGR Valve
The diesel exhaust gases are reused by the EGR valve before they leave and then sent back to the exhaust system. This reduces fuel emissions and makes the engine work more economically. However, when the EGR valve is full and clogged, it fails. As a result, your vehicle’s exhaust emits black smoke.
4- Faulty Mass Air Flow Sensor (MAF Sensor)
We have already said that diesel engines work as a result of a very delicate mixture. The mass air flow sensor, also known as the MAF sensor, continuously measures the flow rate of air entering the engine. If the MAF sensor fails, the air/fuel mixing ratio is impaired. Since the engine works with a richer mixture, it emits black smoke.
5- Soot Bonding of the Inside of the Engine
Since diesel is an oily fuel, it leaves some black soot as a result of the combustion process. This soot constantly accumulates in the piston head or combustion chamber. As a result, it causes black smoke to come out of the exhaust. This is the reason why older diesel cars emit much more black smoke.
6- Fuel Pump Failure
The diesel fuel pump operates at a much more precise setting than gasoline engines. At the slightest malfunction can cause the engine to absorb excess fuel. Among the causes of the outflow of black smoke from the exhaust can be a pump failure.
7- Glow plugs are obsolete
Diesel engines operate with a very high compression ratio. To put it briefly, when you turn the ignition of your vehicle one turn, the glow plugs sign first lights up. As soon as you start pressing the car’s starter, the air is compressed in the combustion chamber. The trapped air heats up. At this time, fuel is sprayed into the hot air by injectors. But this is not enough temperature for ignition. Here the glow plugs come into play and provide ignition. However, if the heating plugs fail, they cannot fully ignite the fuel and cause it to be thrown out of the exhaust without burning. This is called working with rich mixing. The color of the rich exhaust fumes is black.
Source: The Reason for Black Smoke from Diesel Engine Exhaust