Why Do Diesel Engines Produce Black Smoke — Reasons And Causes

So why does a diesel engine emit black smoke? Do all diesel engines emit black smoke? Here are the answers to your questions. All diesel engine do not emit black smoke. Only those diesel engines which haven't been maintained well put out the black soot.

What Is The Black Smoke Coming Out From The Tailpipe Of A Diesel Engine?

The black smoke coming out of your vehicle's tailpipe is unburnt diesel. Diesel engines work on the compression ignition principle and the diesel entering the cylinder itself is responsible for combustion.

When the diesel enters the cylinder and yet remains unburnt when the exhaust stroke happens, it comes out as black soot. If main engine components were properly maintained, it would have burned inside the engine itself.

Why Is My Diesel Car Emitting Black Smoke?

The primary reason for any diesel-powered car to emit black smoke is - A messed up air-to-fuel ratio. It could be either too much diesel entering the cylinders or too much air. The result of both is, emission of black smoke.

What Are The Causes For My Diesel Engine To Have Bad Air-To-Fuel Ratio?

Clogged Fuel Injectors

When the fuel injectors in a diesel engine are clogged, enough diesel is not injected into the engine. This makes the engine run lean and emit black smoke.

Blocked Air Filter or Air Intake

When the air intake system is blocked, the fuel injectors keep spraying the amount of fuel needed, but the engine is not being able to take in enough air. This makes the engine run rich and spew black soot, as unburnt diesel comes out of the tailpipe.

Contaminated Fuel

If the fuel being used is contaminated in any way and the diesel tank has grit in it, it will automatically cause the engine to emit black smoke.

Blocked Fuel Pump

A blocked fuel pump too can cause black smoke to be emitted from an engine. A fuel pump can fail after being used for a long time in an area where good diesel is not available. It can also fail with the one time use of contaminated diesel.

Modifications

Most diesel engines with an engine remap to produce more power end up producing a lot of black smoke. These engine remaps end up pushing more fuel into the cylinders and this in turn leads to production of excessive smoke.

DriveSpark Thinks!

Diesel engines are known for their excellent drive-ability and ability to produce high amounts of torque. With such characteristics, diesel engines also require more maintenance.

Diesel engines are not as dirty as one assumes them to be, because the black smoke is emitted due to improper maintenance of the engine. Also, find out why diesel engines produce more torque compared to petrol engines.