Categories: Auto

For what reasons the diesel smokes blue or blue smoke

The diesel engine can produce white, blue and black smoke from the exhaust pipe, as well as numerous shades of these colors, which are clearly visible in the exhaust. If the diesel smokes blue or blue smoke "cold" and / or "hot", then the failure of the power unit is quite obvious. The appearance of blue diesel exhaust often indicates two problems:

violation of fuel efficiency;
engine oil enters the cylinders of the diesel engine;

We also recommend reading the article about it, why the diesel engine smokes a white exhaust in the mode of warming up and after an exit to working temperature. In this article you will learn about possible faults, indicated by white diesel smoke.

Diagnosis and localization of the problem

In the first case, the exhaust is blue, caustic, has a pungent odor. The reason is, that only well-dispersed diesel fuel burns in the cylinder. Drops of unburned diesel fuel fly out of the exhaust pipe in a vaporous state. The rest of the drops burn inside the cylinder, but already on the piston. This causes the piston to overheat, which may cause it to melt or burn.

The culprit of the malfunction is the fuel equipment of the diesel engine. Most often the problem lies in the pump and diesel injectors. Smoky blue exhaust at the time of heating the diesel indicates a malfunction of the glow plugs or a drop in compression in the cylinders.

In the second case, the exhaust turns from whitish blue to dark blue. The color of the exhaust directly depends on the amount of oil entering the combustion chamber, the mode of operation of the internal combustion engine and the degree of warm-up of the motor. The smell of exhaust with lots of oil burned, such smoke dissipates in the air for a long time.

The following method will help to distinguish white-blue smoke with burnt oil from water vapor in the exhaust.. It is enough to attach a sheet of white paper to the exhaust pipe of a heated diesel engine. As a result, stains will appear on the paper. If stains from water, then they evaporate, leaving no obvious traces on the sheet. Oily stains will indicate the presence of oil in the engine exhaust.

The appearance of oil smoke is accompanied by an increase in engine oil consumption. During the operation of the internal combustion engine in transient modes, the smoke with impurities of burnt oil is thicker. Catalyst (catalytic converter) Gasoline engines clean the exhaust of oil even at high consumption. On diesel engines, the oil exhaust is more noticeable.

Blue smoke: wear of the cylinder-piston group

The most common reason for this, that diesel smokes blue smoke, there is wear of the cylinder-piston group and timing parts. The ingress of oil into the combustion chamber may be due to increased clearances of the piston rings, gaps between the valve stems and guide bushings. Damage can be to the cylinder liners, possible destruction of the rings, piston grooves, etc.. d.

The presence of strong gaps in the piston grooves cause the oil to be "sucked" into the combustion chamber. This happens even taking into account the normal condition of the oil rings. Additionally, the shape of the cylinder may change, which significantly reduces sealing with rings. The cylinders can take the shape of an ellipse, resulting in lumens. LNG wear causes loss of compression, crankcase gas pressure also increases. When measuring compression must be taken into account, that the oil in the cylinders is able to seal the gaps. It turns out, the compression in the faulty cylinder will be inflated. To obtain accurate results of the assessment of compression and the state of the CNG, it is necessary to comply with certain requirements.

If the CHP is not severely worn, then the blue smoke is clearly visible in the process of warming up the engine. After reaching the operating temperature, the smoke intensity decreases or the blue smoke of the diesel disappears completely. This is due to the expansion of the parts as a result of heating, which causes the sealing of gaps. An example is that, that diesel starts badly "on cold", but re-hot start is no problem.

Heavy wear of LPG causes more active smoke "hot". Heated oil becomes less viscous and easily gets into the cylinders of the internal combustion engine, and the thermal expansion of the parts of the cylinder-piston group is no longer able to compensate for too large gaps.

Oil consumption increases as a result of breakage of jumpers between piston grooves. An increase in engine oil consumption leads to ring breakage due to wear or overheating of the diesel engine. The use of low quality oil and its untimely replacement leads to the occurrence of piston rings. The rings "stick" in the grooves of the piston, at the same time their mobility is completely lost.

We also recommend reading the article on how to increase the power of a diesel engine with the help of tuning - boxing. In this article you will learn about the main types of such devices, their main advantages and disadvantages, as well as the installation of modules to increase the power of the diesel engine and the impact of devices on its life.

Direct lines help to detect oil ingress into the cylinders due to LPG wear (oil consumption) and indirect signs. The second group includes: the appearance of noise from the motor, various knocks with change of turns and loading on the engine are found out, the intensity of smoking with blue or bluish smoke changes as the engine warms up, noticeable unstable operation of the diesel engine when running "cold".

Timing failure and other causes of bluish exhaust

Oil smoke and increased oil consumption may also be associated with timing:

burnout or destruction of the valve plate;
wear of valve rods and guide bushings;
there are defects in oil caps;

Answer the question, why diesel smokes blue smoke after warming up, can be based on the dilution of the oil after increasing the temperature of the internal combustion engine. In the course of work of the engine at idle speeds and at the moment of braking by the engine oil flows down on rods of valves, a film is formed on the part, its accumulation in the exhaust system is observed. When the driver presses on the gas, a thick cloud of blue oil exhaust suddenly appears from the exhaust pipe.

Faults in the fuel supply process (early angle of advance of injection) or lack of proper valve tightness can also cause blue diesel exhaust. Burnout of the valve causes the exhaust to turn white and blue. This defect with the valves is due to a strong reduction in compression in the faulty cylinder. Diesel glow plugs can also be covered with black soot and deposits, which will further point to this problem.

Turbocharged diesel engine (turbodiesel) may also have increased oil consumption and blue smoke as a result of turbocharger problems. This occurs as a result of bearing wear, violation of rotor seals, etc.. P.

Turbine malfunctions can be a symptom of a problem with oil caps. For reliability, it is necessary to inspect the turbocharger pipes for oil. Problems with the turbocharger seal are harder to detect, as the oil enters the exhaust system, where it burns out.

Other causes of blue exhaust can be crankcase ventilation, ignition gaps in the cylinder. Blue exhaust is often accompanied by loss of traction of the diesel engine, atmospheric or turbodiesel may have a rich flow of oil seals, etc.. d.

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