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Smoke from car exhaust pipe – reasons

Smoke from car chimney: blue, black, white

  • Blue – oil burns.
  • Black – unstable engine operation.
  • White – engine not warmed up.

As you know, new vehicles cost significantly more than used cars even in very good condition. Therefore, most potential salon customers eventually decide in favor of buying used car.

At the same time, the issue of evaluating the state of the car comes to the fore. Correct diagnosis helps to determine the amount of future costs of the service station and, accordingly, make a considered purchase. In addition, at least a general knowledge of some of the symptoms of breakdowns is very useful to all drivers and, especially, for car’s appraisers. This article deals with the description of breakdowns that are accompanied by the emission of smoke from the exhaust pipe.

White, blue, and in the worst case – black. If you notice smoke rising in such colors, you need to do something urgently. Otherwise, something bad will soon is going to happen with your car.

Whether you have a car running on a gasoline engine or a diesel engine, increased smoke from the exhaust pipe, this signal that you need to look under the hood of the car. After the appearance of smoke, you can pre-diagnose the cause of the defect by its color and evaluate the possible costs for future repairs.

White smoke

The most common cause of white smoke from exhaust pipe is a gasket failure. The cylinder head may also have cracked. In this case, the first symptoms are rapid decomposition of the fluid in the cooling system. Antifreeze flows from under the head to the combustion chamber. The result of this process is visible to the naked eye as white color smoke. In the case of such signs experts advise to urgently contact a mechanic. The faster you start troubleshooting, the cheaper it will be to repair the cooling system. White smoke occasionally appears during engine start and gas addition.

Blue smoke

The most common cause of this color exhaust is entering the combustion chamber of motor oil. Noise effects in the exhaust manifold can also be a frequent side effect. Another side symptom is the constant lowering of the level of motor oil and the need for its regular addition. The reason for this effect are valve seals (while falling from high revs), piston rings or cylinder ribs (when increasing idle speed). In diesel engines, the fault may also be due to an oil pump or incorrect injection angle.

Black smoke

In the case of diesel engines, the result of serious failure of mechanical components can be the production of black smoke. The most common defects in this case are: the injection system (nozzle tips and injection pump), the system responsible for the combustion process of the fuel-air mixture or the exhaust gas purification system and therefore the exhaust gas recirculation. This results in accumulation of deposits or leaks in the vacuum or vapour lines. In particular, old, worn-out self-ignition units are prone to these problems.

Often the problem lies in the incorrect operation of the fuel supply system. It is worth checking the oil and air filters first. However, the problem of ensuring the correct dosage of air can be elsewhere, due to poor valve control or damaged turbocharger.

Black smoke is also visible in modern diesel engines based on Common Rail nozzles or injectors. It should be noted, however, that short and low black smoke is normal in new diesel engines. This is mainly due to the design of such an engine and usually occurs during high load. Each diesel engine has an appropriate smoke limit – according to all standards. Therefore, during a sharp acceleration you can notice smoke coming out of the exhaust pipe. Smoke limit is usually different in engines of different manufacturers.