Smoke from vehicles: What’s it telling you?

Have you ever seen a blue, black, grey or white smoke from car exhaust when accelerating? Well, it doesn't really affect you directly if the car in question is not yours. However, you should take things more seriously in case you find black, grey, white or blue smoke from exhaust of your car. Here, we tell you about the typical causes of smoke from vehicles exhaust system.

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Smoke from Vehicles - What causes Black, Grey, Blue or White smoke from exhaust?

Diagnosing a smokey exhaust: what to look for

Most Internal Combustion (IC) engines derive power through combustion of petrol, diesel or CNG in a closed chamber that emits harmful gases and noise during the process. These gases can cause a lot of pollution if they are released in the environment without treatment. This is exactly where exhaust systems come to play. Simply speaking, they reduce the harmful effect of these gases to a large extent. This is done through treatment of these gases and finally release them in the form of smoke.

All's well if the release smoke from exhaust of cars is colourless or slightly white. However, things are certainly going wrong if you see blue, black, grey or white smoke from exhaust when accelerating or even when the engine is in idle. Our little guide here should help you figure out what causes, white, black, grey or blue smoke from exhaust of your car.

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Types of Smoke from Vehicles:

1. White smoke from exhaust of car

• A thick white smoke from exhaust indicates coolant burning in the combustion chamber of the nine. On seeing this even after your. engine has warmed up, you should immediately visit the workshop. This phenomenon occurs only when the coolant leaks into the engine, thereby lowering coolant level and overheating the engine.
• Another common reason from white smoke from exhaust is a blown head gasket. But a coolant leak can even happen from a damaged cylinder head or cracked engine block.
• So, if you see white smoke from car exhaust, it's a sure-shot sign of trouble. On seeing this, simply turn off the engine and call a technician.

1. Blue smoke from exhaust of car

• A major cause of blue smoke from exhaust is the engine oil entering the combustion chamber and burning along with the fuel.
• Blue smoke from exhaust of car is a clear indication of the engine oil being burning. This happens if the piston rings or the valve guide seals are worn out or cracked.
• It's not an immediate danger but blue smoke from car exhaust indicates that the engine is reaching the fag end of its lifecycle and/or the oil levels are fast reducing.
• If you see blue smoke from exhaust of your car, book an appointment with a technician immediately.

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1. Grey smoke from exhaust

• Grey smoke is a clear sign of excessive engine oil burning in the engine.
• A reason for this could be a faulty Positive Crankcase Ventilation (PCV) valve that helps with emission control.
• PVC draws unburnt fuel from the lower part of the engine to the top part. This is done to reduce emissions when the engine is cold and not burning fuel in an optimised manner. Failure of PVC results in grey smoke.
• Another reason for grey smoke from the exhaust of automatic cars could be transmission fluid entering the engine through a leak.

1. Black smoke from the exhaust

• Black smoke from car exhaust is caused by incomplete fuel combustion due to excess fuel reaching the combustion chamber.
• Black smoke from car exhaust is mostly due to an imbalance in the air-fuel-ration (AFR). This is either due to excess air or excess fuel.
• Over-feeling or a rich AFR could happen due to a clogged air filter.
• Another reason for black smoke from exhaust of car is a fuel injector leak due to a worn out nozzle.
• Other two less common reasons include a damaged sensor or a faulty fuel-pressure regulator.
• This is not an immediate danger to the engine but it will certainly reduced the longevity of the motor if not addressed.

So, these were the reasons for blue, grey, black and white smoke from your car's exhaust. IF you notice such a smoke from exhaust of your vehicle, you should head to your mechanic and get the issue resolved at the earliest.

Conclusion

Under normal operation, the smoke from vehicles is colourless or a faint shade of white. However, blue, grey, black and white smoke from your car's exhaust is a definite sign of concern. It's also a sign of poor maintenance and should be noted seriously in case you plan to buy a used car. Regular maintenance and an understanding of engine behaviour in case of malfunction can help you minimise the chances of engine damage. Remember, the colour of the smoke from vehicles is an important sign of the health of the engine.

FAQs

Q. What problems can we have from smoke coming out of vehicles?

A. In normal conditions, smoke from vehicles is colourless or translucent. However, in case you see blue, black, grey or white smoke from car exhaust when accelerating or even on idle, it's a sign of worry. Based on the colour of smoke, the problem with the engine could range from anything from a coolant leak to an incorrect Air-Fuel-Ratio. Whatever the case, you should visit a workshop at the earliest and get the issue resolved.

Q. How do I fix white smoke from exhaust pipe?

A. White smoke from car exhaust system is a clear sign of coolant burning int eh combustion chamber. This happens due to coolant leaking into the engine chamber. If you see white smoke from exhaust, pull over, switch off the engine and call a mechanic. Alternatively, you can drive down to a nearby workshop.

Q. How do I fix black smoke from the exhaust pipe?

A. Black smoke from car exhaust is caused by incomplete combustion or fuel reaching the combustion chamber. This leads to a lot of unburnt fuel in the exhaust pipe. In case you see black smoke from your car's exhaust, do not neglect it. Leaving this issue unaddressed might lead to a reduction in the longevity of the engine.

Q. How do I fix blue smoke from the exhaust pipe?

A. Blue smoke from exhaust is a sure-shot sign of burning of engine oil due to oil leaking into the combustion chamber. This could be a clear indication of the engine nearing the end of its lifecycle or the oil levels being too low. In either case, a serious repair work is required at the earliest.

Q. What are the types of smoke in the engine?

A. In normal circumstances, the smoke from vehicles is colourless or translucent. However, blue, black, grey or white smoke from vehicles exhaust is a sign of requirement of maintenance work. Basis the colour of smoke, the issue with the engine could be anything from a coolant leak to an incorrect Air-Fuel-Ratio. Regardless of the case, one should head to a reliable workshop as soon as possible to avoid permanent damage to the engine.