What Causes An Engine To Produce A Lot Of Smoke?

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A vehicle’s engine will produce a lot of smoke due to a collection of electromechanical issues. The issues can be visually distinguished if one pays attention to the color of the exhaust smoke coming out of a vehicle’s tailpipe! Vehicle exhaust smoke is broadly differentiated into 4 colors –Black, Blue, White & Grey. We will talk about that in this blog. But before that.

A Crash Course On An Internal Combustion Engine!

Suck, squeeze, bang, blow – quirky as it sounds, these are the four phases inside an internal combustion engine when running.

When Do Things Get Problematic?

While this process is intended to produce smoke, if your vehicle starts releasing abnormally large amounts of exhaust, it signals underlying problems that demand prompt attention.

In this context, remember that by observing the color of the exhaust smoke emitted from the tailpipe of a vehicle, one can gauge what is possibly wrong with it.

This blog will cover the different colors of exhaust smoke, their causes, and what you should do in each case in the following sections.

Let’s begin the discussion.

Black Exhaust Smoke

Black exhaust smoke emanates from the tailpipe of a vehicle when its engine has too much fuel and a small quantity of air in its combustion chamber. This state is known as a ‘rich cycle’.

Causes of Black Exhaust Smoke

Clogged Air Filter

A clogged air filter restricts the flow of atmospheric air into the combustion chamber of an engine, thus reducing the air in the air-fuel mixture within the combustion chamber of the motor.

Bad Fuel Injectors

A malfunctioning or leaking fuel injector(s) can also unnecessarily increase the amount of fuel inside the combustion chamber of an engine, thereby making it run rich! This is an issue mostly found in pre-owned cars, which is why it is best to check vehicle history of a pre-owned car that has caught your eye!

Faulty Fuel Pressure Regulator & Sensor

A bad fuel pressure regulator or a mass airflow sensor that has seen better days can also lead an engine to run rich and produce a lot of black smoke.

A clogged Diesel Particulate Filter

In case of diesel vehicles, if the Diesel Particulate Filter is clogged, which prevents it from cleaning itself; it can result in the vehicle emitting a lot of thick black smoke!

What should you do?

Seek expert assistance—simple as that. The causes are many, and, as a typical car owner, accurately diagnosing or repairing them yourself is nearly impossible.

Blue Exhaust Smoke

A car whose core engine components, such as piston rings, valve seals, or turbocharger, are not doing their job as intended, which ultimately gives way to engine lubricating oil to enter the combustion chamber and burn alongside the air-fuel mixture, results in blue smoke emanating out the tail pipe!

Damages to the core components of a car’s engine can happen if it has been in a serious accident or if it has not been maintained on time. In case you are planning to buy a pre-owned car, ensure that the vehicle has no accident history.

Causes of Blue Exhaust Smoke

Worn Piston Rings

Piston rings that are at the end of their operational lives cannot form a tight seal between the piston walls and the walls of the combustion chamber, which is the perfect condition for engine oil to enter the chamber and be burnt alongside the air-fuel mixture.

Faulty Valve Seals

Worn or leaking valve seals can make enough room for engine oil to seep into the combustion chamber – especially when the engine is cold-starting or is idling.

Damage to Cylinder Walls

If the walls of the combustion chamber are damaged, then, yet again, the piston rings won’t have an even surface to form a seal. Ultimately, this allows engine oil to enter the combustion cycle.

Malfunctioning Turbocharger

In turbochargers, there are oil seals that keep engine oil, which is used to cool and lubricate turbochargers. If these seals break, oil can enter the system and result in the car emitting a ton of blue exhaust smoke from its tailpipe.

Overfilling Oil

One has to ensure that the right amount of oil is put inside an engine. Overfilling engine oil can force the excess oil inside the combustion chamber, ultimately leading to the emission of blue smoke!

What should you do?

Stop driving the car, call a flatbed truck, and take the car to the nearest OEM service center so that the experts there can diagnose the issue(s) and fix them accordingly.

White exhaust smoke

Thin white exhaust smoke is a normal phenomenon, especially for petrol/gasoline engines, on cool days, as in this way, excess moisture is being vented out from the engine. But, if this white smoke is thick, then it can mean that coolant is leaking into the combustion chamber, getting turned into steam, and then is being vented out!

Causes of White Exhaust Smoke

Blown head gasket

The primary cause of thick white smoke emanating out of a vehicle’s tailpipe is a blown head gasket – the component that seals the engine block.

Cracked engine block or cylinder head

If the cylinder heads or the engine block itself is cracked, then coolant can easily find its way into the combustion chamber. – This ultimately results in thick white smoke coming out of the tailpipe.

What should you do?

The moment you see that your car is emitting a lot of thick white smoke, pull over to the side of the road and turn off the engine. Call for a tow and take the car to the nearest OEM service center so that the experts can diagnose the problem in a bid to fix it.

In case you are planning to buy a pre-owned car that emits a sweet smell whenever you turn its engine on, get a car history report for the vehicle from a reputable entity that offers such services. In this way, you will end up buying a used car that is not a lemon!

Grey Exhaust Smoke

Here’s the deal - grey exhaust smoke means that the engine of your vehicle or its transmission has suffered irreversible damage or has some underlying issues.

Causes of Grey Exhaust Smoke

Faulty PCV valve

An end-of-operational-life PCV valve can let engine oil enter the combustion chamber of the engine, leading to it emitting grey smoke from the vehicle’s tailpipe.

Excess Air

If a turbocharged engine’s turbocharger is nearing its operational life, it can let an excess of air into the combustion chamber, which results in the formation of grey smoke.

Transmission Fluid Leak

In vehicles with older automatic transmissions, if the transmission fluid somehow enters the combustion chamber of the engine, especially through a faulty vacuum modulator, then the production of thick grey smoke is the natural outcome.

What should you do?

Stop using the vehicle, avoid ignoring the symptoms, and take the vehicle to the nearest OEM service center before things get out of hand!

A Smoking Engine Is Not Good!

To sum it all up, if your vehicle’s engine is emitting unusually large quantities of smoke through its tailpipe, then its overall electromechanical health is poor!

If you want to continue enjoying your vehicle ownership days seamlessly, then invest in a thorough vehicle health report offered by a revered entity today!

After acquiring the health report, take it along with your vehicle to an OEM service center and get the document as well as the vehicle inspected for the best results!