What’s the cause of that smoke?
UNDER normal circumstances the exhaust from your vehicle’s tailpipe should be clear. So if you realise that your car is smoking, auto mechanic and car enthusiast Roshane Holness said you should take note of the colour because this could help you to identify the source of the problem.
What does the colour smoke coming out of your tailpipe mean? Holness gives a break down.
White vapour
If your car is warming up and you notice white vapour coming from the tailpipe, don’t be alarmed; chances are as soon as the car is warmed up this will stop. However, Holness said that if it continues to give off white smoke even after the engine is warm, then you will need to get the cylinder checked because a cracked engine block, a cylinder head or a leaky head gasket that may be letting coolant into the engine is likely to be causing this.
Blue-grey or grey-white smoke
Blue-grey or grey-white smoke usually means that the vehicle (engine) is burning oil. This, depending the car that you drive, can mean several things. For example, if in the least likely case you are driving a turbocharged engine, then it could mean that a faulty turbo seal is causing it. However, if you are driving a vehicle with a regular engine then it could be one of several possible problems.
“For one, it could mean that oil is leaking into the combustion chambers and as such you may need to have your valve stem seals replaced or your engine rebuilt or replaced. There is also the possibility that there is too much oil in the engine; this usually happens if you recently changed your oil. To make sure that you do not have this happening, you can drive the car for a short distance and if you realise the oil level is above the full mark then you should address this,” Holness explained.
Another possible culprit is worn valve guides or seals. Holness said that this may allow engine oil to seep into the combustion chamber, resulting in bluish or greyish smoke from the tailpipe. To resolve the issue you will need to have the damaged parts replaced.
“Another problem may be that piston rings or cylinders are worn. Similar to the issue of broken seal, oil will get sucked into the combustion chambers and it will result in your vehicle giving off bluish-greyish smoke. When this happens, to resolve the issue, worn piston rings or cylinder walls should be rebuilt or replaced.
Black smoke
When there is black smoke coming from your tailpipe it means that the engine is burning too much fuel. Holness said that what happens is that there is too much gasoline going to the cylinders of your engine, and not enough air — that’s called a “rich” fuel mixture.
“To avoid this there should be a perfect blend of air and fuel being burnt in each chamber. This can be affected by a leaking fuel injector or a bad mass airflow sensor. Whether the fuel injector or the engine sensor is faulty they will both need to be replaced by a professional,” Holness advised.
He said that another culprit could be faulty fuel pressure regulators. The device is responsible for regulating fuel pressure to the engine by routing excess fuel back to the fuel tank.
“When it becomes faulty it can allow the engine to get more fuel than it needs, making it run rich. A restricted fuel return line can have the same effect. To rectify this problem, it is usually replaced or in the case of most returnless fuel systems the fuel pump assembly must be replaced,” Holness advised.
