The color of the exhaust gases during engine start-up and during its further operation is a kind of indicator of the state of the power unit and systems. Various problems can cause the engine to smoke white, black, blue or gray exhaust. As a rule, on a serviceable engine, drivers briefly observe only white smoke when starting a diesel or gasoline engine.
Note that this phenomenon in some cases is not a malfunction, especially when the indicated smoke formation after the internal combustion engine warms up becomes less intense or completely disappears. If there is blue smoke when starting the engine or the driver notices black smoke when starting a cold engine, then this is a reason to check the power unit.
In this article, we will talk about the reasons why black smoke can appear when starting the engine in cold weather, what blue smoke indicates when starting a cold engine, and why white smoke comes out when starting the engine.
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Smoke from the exhaust pipe when starting the engine: white, black, blue color of the exhaust
As already mentioned, when starting the engine, the smoke from the exhaust system can be of different colors, and smoking is not always a cause for concern. Let's start with the white exhaust.
The fact is that after parking, condensate accumulates. After starting, the condensate begins to evaporate, and the amount of smoke and its density are also affected by the outside temperature and air humidity (the colder and wetter, the thicker and longer the white smoke will remain). In frosts, such smoke can be constant, that is, the installation smokes white, regardless of the degree of warming up of the internal combustion engine.
The situation requires increased attention when it is warm outside, and after starting the engine, a thick cloud of white smoke comes out of the exhaust pipe. In this case, there is a high probability that the working fluid (antifreeze or antifreeze) will get from the cooling system directly into the cylinders.
This malfunction appears as a result of engine overheating, breakdown or formation in those places where the channels of the internal combustion engine cooling jacket pass.
In such a situation, you will need to remove the head, if necessary, grind the mating surface, change the cylinder head gasket, check the head for leaks, repair cracks, etc.
- To confirm the diagnosis, unscrew the cap on the running engine. Seething and bubbles will clearly indicate a breakthrough of gases into the cooling system, while the coolant level may also increase. After stopping the internal combustion engine, the indicated level in the tank decreases, part of the coolant enters the cylinders.
- Note that the liquid will not always boil, especially in the case of microdefects. In such a situation, one should be guided only by color, condition and coolant level.
- The smell of burning, the presence of oil stains on the surface, a decrease in the level in the tank for no apparent reason, and a number of other indirect signs will indicate that liquid from the cooling system has entered the cylinders.
- Also, it will not be superfluous to get the oil dipstick and unscrew the oil filler cap. The fact is that with intensive penetration of the coolant into the combustion chamber, leaks occur from the over-piston space through the engine crankcase.
The result is a thinning and cloudiness of the engine oil, the appearance of a characteristic brownish emulsion. We add that with an intense accumulation of coolant in the space above the piston, an engine water hammer can occur. For these reasons, strong white smoke is an alarming symptom and requires immediate elimination. In other words, it is better to stop the operation of the internal combustion engine until the problem is fixed.
Black smoke when starting engine
The black color of exhaust gases often occurs when there are problems with the power supply system and the quality of the fuel-air mixture.
Such smoke is formed as a result of the fact that there is a strong enrichment of the working mixture of fuel and air in relation to a specific mode of operation of the internal combustion engine.
Enrichment should be understood as a large amount of fuel in relation to the amount of air. In this case, the following additional symptoms may appear:
- the engine turns easily from the starter, but starts with difficulty;
- often enough, even new or serviceable;
- after starting the engine "troit", the operation of the internal combustion engine is unstable;
- in and clap hard;
- the power unit loses power and consumes fuel;
- on the dashboard, the BC gives an error;
- in the exhaust there is a clear smell of gasoline or diesel fuel;
The shade of smoke can vary in different cases from gray to thick black. Blackening occurs from excess soot, which is formed as a result of incomplete combustion of the fuel charge.
The engine can smoke black both “on a cold” and after warming up, during gas recirculation, etc. If a persistent black exhaust is noted on a diesel engine, then a failed or other problem with the diesel particulate filter may be another cause.
- The list of reasons that lead to violations of fuel supply, mixture formation and combustion of the mixture is quite wide. On engines with a carburetor, it is necessary to start checking with the metering device itself, the float chamber and the fuel level in it, as well as air and fuel jets.
- More attention should be paid to the idle system. At the same time, it is recommended to check the ignition system on the injection and carburetor engines, since the failure of individual elements (spark plugs, high-voltage candle armor wires, coil, etc.) causes malfunctions in the internal combustion engine and can lead to misfires.
- Another point during the diagnosis is the intake system, since air filter contamination is a common cause of a too “rich” mixture.
- We add that on an internal combustion engine with an injector, malfunctions in the operation of sensors lead to an excess of the supplied fuel. Incorrect data is sent to, after which the controller initiates an increased fuel supply.
- In this case, check the throttle assembly, oxygen sensor and other elements. Relatively rare, but it is also possible for the electronic engine control unit itself to fail.
- As for the fuel system, the injectors themselves can become leaky and pour fuel into the cylinders. This problem is typical of both gasoline engines and diesel engines.
This may be due to severe contamination, wear or other defects in the injectors. On gasoline engines, the fuel rail and pressure regulator should also be checked.
The danger of this situation is that with a strong overflow of fuel, not only consumption increases, candles are flooded and other problems arise, but the oil film is washed off the cylinder walls with fuel. As a result, overall wear increases during start-up. If a lot of fuel gets into the cylinder that does not burn, then the fuel can also drain in excess into the engine crankcase.
To check, it will be enough to remove the oil dipstick and smell the engine oil, assess its condition. Strong dilution and a distinct smell of fuel will indicate a significant overflow. In such a situation, the engine needs in-depth diagnostics, cleaning, tuning or even replacing fuel injectors may be necessary.
Blue smoke after engine start
The blue color of the exhaust gases or a bluish tint is a sign that engine oil is actively entering the combustion chamber. Such smoke is bluish, oily and thick. Oil intrusion is easy to identify in a simple way.
It is enough to start the engine and lean a blank sheet of paper against the exhaust pipe. The presence of greasy stains that do not dry out will indicate grease particles in the exhaust system. An additional sign can be considered an increased oil consumption, which significantly exceeds the permissible figure for this type of internal combustion engine. Oil enters the combustion chamber for the following reasons:
- Significant wear of CPG elements.
- Faults.
In the first case, we are talking about the wear of the piston rings, the appearance of defects in the piston itself or the cylinder walls (seizure, ellipse, etc.). In the second case, the oil leaks because there is no proper seal in the area of the valve stem and valve guide.
At the initial stage, it may be enough to replace the valve seals (valve seals) for repair. The state of the CPG helps determine the measurement of compression in the engine.
If the decrease in compression in the cylinders is insignificant, then the engine may have a gray or blue exhaust only after starting and until the moment of warming up. The fact is that after warming up, the gaps between the parts decrease, the oil stops getting into the combustion chamber.
In the case of greatly enlarged gaps, oil diluted from heating will still enter the working chamber. If the car is equipped with a turbocharger, then blue smoke after starting the engine or during its operation may be due to malfunctions of this element.
In the event of wear on the turbine bearings, as well as rotor seals, oil will enter the exhaust system through the turbocharger and burn there. As a result, bluish smoke with grease particles comes out of the exhaust pipe.
Smoke from under the hood when starting the engine
This phenomenon can most often be found if there is an oil leak in any place (seals, gaskets). The lubricant enters the exhaust manifold and begins to burn out as the internal combustion engine warms up, and the driver sees smoke from the engine compartment.
Also, one should not exclude the possibility of foreign objects getting on the heated elements of the internal combustion engine or the exhaust system. A similar effect can be caused by fuel leakage, which occurs due to the loss of tightness of certain elements of the fuel supply system and fuel injection.
In both cases, the problem must be solved immediately, since the risk of fire and fire in the engine compartment is significantly increased. In parallel, leaks in the exhaust system or problems with turbocharging can also be the reason that smoke appeared from under the hood when starting the engine or smokes constantly during its operation.
For example, a bent exhaust pipe flange or a burnt gasket will cause smoke to appear in the engine compartment. You should also pay attention to whether the car has a liquid pre-heater for the passenger compartment and the engine.
The appearance of smoke from under the hood in this case is more characteristic of diesel units, since preheating is more in demand on this type of engine. Simply put, the heater on a particular car may be.
Since the device burns fuel inside itself, an air supply is necessary for the combustion of a portion of the fuel, and a system for exhausting gases after combustion must also be implemented. In case of unqualified self-installation or for other reasons, the exhaust gas system from the heater can be removed so that the exhaust pipe goes into the engine compartment.
Normally, starting liquid heaters practically do not smoke, and combustion products are removed in the area of the front wing (behind the wheel). At the same time, certain malfunctions may well lead to the fact that smoke appears from under the hood. In this case, the installed system should be checked separately.
As you can see, in some cases it may be enough to replace the filters and clean the injector to eliminate the cause of the black, white or blue exhaust color. At the same time, for other engines, the only way out will be to replace worn-out elements of the CPG, timing, or even overhaul the engine.
We add that if the engine suddenly began to smoke with black exhaust at startup for no apparent reason, then it is recommended to change the fuel at the very beginning. Refueling with low-quality fuel or fuel with a high content of additives and impurities often leads to difficulties in igniting the mixture and changing the color of the exhaust gases.
We should not forget that the stability of the unit and the usefulness of the combustion of the fuel-air mixture directly depend on the valve timing, the quality of the valve adjustment and the normally set ignition. The timing belt (if any) must be set strictly according to the marks, the thermal clearance of the valves must be carefully adjusted.
Note that in the process of conducting primary diagnostics, it is possible, the color of soot on the electrodes and the threaded part. For example, wet spark plugs or black oily deposits will further indicate the cause and severity of the problem. Finally, we add that in order to quickly troubleshoot an injection gasoline or diesel engine, it is recommended to immediately conduct a complete computer diagnostics of the engine.
Given the low cost of this operation at the service station, it is possible to identify malfunctions and malfunctions in the operation of individual ECM sensors. You can also check the internal combustion engine for errors yourself using the diagnostic adapter in.
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Black diesel exhaust. Soot from the exhaust pipe of a diesel engine, the cause of incomplete combustion of fuel. Identification of major faults.
Significantly different from gasoline. But the problems with them are almost the same as with gasoline units. Having read automotive forums, you can see a lot of all sorts of topics where certain problems are discussed. But especially often you can see topics where motorists complain that diesel engines periodically emit black smoke from the exhaust. Let's see what the problem is, why this phenomenon occurs. Let's also see how this problem can be solved.
We make a diagnosis by the colors of the exhaust
Diesel engines, like gasoline engines, can have exhausts of various colors. More often it is white, gray, gray and black smoke.
Let's start with white. Often referred to as white smoke with a bluish tint. This happens when the turbine collapses, and the lubricant gets straight into the intake tract. In such a situation, bluish-colored smoke comes out of the chimney. But an inexperienced motorist will completely take him for white smoke. And if you also smell it, then it is immediately clear and understandable what is the reason for its appearance.
Many in the kitchen at least once, but burned vegetable or butter in a pan. The smell is about the same. Such smoke can also be confused with steam, which is more often observed in the winter months from the exhaust of not only diesel cars. It's all because of the water that appears as a result of combustion.
Later, after the engine warms up, steam will not be noticeable, although this can be easily checked. You just need to put your palms on the exhaust. The palm will be slightly damp. This steam causes significant inconvenience when tuning the engine, and especially in winter. For high-quality tuning, it takes a long time to heat the unit. And in cold weather, the adjustment may not work at all.
White smoke is a signal of a serious problem
If the smoke from your diesel is not steam, then it is definitely coolant that enters the combustion chambers. Usually a cylinder that has been flooded with coolant mixtures does not have the ability to idle. Therefore, the motor can troit.
How does coolant get into the cylinders?
Coolant enters the cylinders due to the poor condition of the intake manifold gaskets. Also, the cause may be a burnt cylinder head gasket, and for diesel engines, most often it may be a cracked block head. In the cylinder head crack, the tank, often full of liquid, also completely goes into the pipe.
Repair
If you find a cylinder head crack, then here you can only recommend replacing the head. However, prices ... Therefore, many motorists do not disdain contract details. These are used parts from Europe.
Cracked cylinder heads can be repaired, but we will not recommend this technology, because during such repairs a hole is drilled that will fall on the crack, and then a copper bar is pressed into the hole. There will be no gas breakthrough here, however, one of the cooling valves will be blocked by half. Such a head will have a significantly reduced resource.
Blue smokes
For those with diesel smoke, the sight of blue smoke made them nervous.
Blue, and on some engines it can be gray, on a working engine it is often caused by late injection. This problem has been said more than once, many motorists have managed to discuss this topic up and down.
Experts say that blue smoke is not scary. In most cases, the problem of late injection is associated with the natural process of wear of the injection pump, of course, if no one touched the pump.
Causes of blue smoke
The fuel pump in our conditions works as follows. A set of parts in this assembly constantly rotates, works, rubs. And lubrication is provided by a pumped diesel. While the diesel is moderately oily, the pump in this mode can work for a very long time. But when the cold comes, winter diesel fuel is poured into the fuel tanks of diesel engines. Everything in it is excellent, but the lubricating fractions are completely absent. Well, almost none. All its fat content, along with various paraffins, was removed at the refinery.
So, when winter comes, most high-pressure fuel pumps on diesel engines run without lubrication and are subject to severe wear. Due to this completely natural, but already too fast and increased wear, the injection advance is reduced. Diesel fuel stops heating up, and the cylinder stops working normally. The engine twitches, shakes. Fuel that does not have time to burn, as a result, turns into blue smoke. Some engines have black smoke coming out of the exhaust. If the engine warms up, then it will stop smoking, or at least the amount of exhaust will decrease. In this case, the fuel has time to warm up and ignite.
If the power unit has low compression characteristics, then the temperature in the combustion chambers is less than necessary. And the fuel will not ignite. If the unit is equipped with a pair of cylinders with good compression, the one with the lower compression will not work.
This picture often happens in parking lots. Cars are trying to start, and the entire area is filled with blue smoke. But sometimes diesel emits black smoke from the exhaust pipe. After warming up, the smoke will disappear. After all, the temperature in the engine is growing, and the temperature increase, even in worn cylinders, will be enough to ignite.
A case from one's life
Mechanics on this subject tell one story. The cylinder head gasket was replaced on the unit. After the motor was assembled, they found a strong shaking at idle. After a couple of kilometers, these vibrations stopped, and after a couple of minutes of work again at idle, the shaking reappeared.
The mechanics analyzed this situation and found out that the new gasket is slightly thicker. Until the diesel engine warmed up to operating temperature, it did not work smoothly.
So, the main cause of blue smoke is late fuel injection and poor compression performance. Many modern engines have a device that injects a little earlier. Cars work harder, but the fuel in the cylinders heats up and burns without smoke, that is, at all. Then the unit heats up, the coolant heats the actuators, and they return the injection advance piston to its rightful place. The motor runs smoother and smoother.
How to remove blue smoke
If the engine shakes and releases diesel black smoke from the exhaust pipe, well, or blue, then you can safely tuck the injection pump. But first you need to see if there is enough fuel. If the pump does not have enough fuel, then the pressure decreases, and this allows the spring to move the timer to late injection. This will cause shaking.
Black smoke
Such smoke can be observed if the fuel does not burn completely. This happens if too much fuel is supplied or the wrong combustible mixture is supplied. If too little air is supplied to the engine, there will be the same effect as if fuel was supplied in excess.
Why is black smoke coming out of a diesel exhaust?
A larger volume of fuel supplied is usually a signal of either incorrect adjustment of the injection pump, or wear of the injectors, or wear of the speed controller in the pump.
Any fuel pump is equipped with a special adjusting screw. With the help of it, the volume of fuel supplied is adjusted. This screw can only roughly adjust the volume. If this screw is tightened, then the volumes increase. And where there is an increase in volumes, there is also an increase in idle speed. But the turnover can be significantly reduced. Then you can increase the power. But driving diesel black smoke from the exhaust pipe will continue further. If the adjusting screw on the injection pump is screwed even more than it should be, the unit will practically stop reducing speed.
Nozzle wear
Here we can assume that the needle does not fit tightly enough into its seat. And the level of pressure that this needle should raise is reduced. This leads to the fact that excess fuel enters the combustion chambers. It is superfluous, if only because it is supplied not in spray form, but in drops. These drops take a long time to heat up and ignite. Hence the black smoke from the exhaust pipe, and increased fuel consumption (diesel).
the saddest thing
One of the saddest breakdowns that lie in wait for diesel owners is the inevitable wear of the fuel pump. As already mentioned, the giblets inside the pump work without lubrication. If in the summer the diesel still lubricates something, then in the winter it does not. And domestic fuel is generally of poor quality. This is where the internals of the pump wear out.
When the gas pedal is pressed very sharply, for example, in order to quickly move off, the injection pump lever is transferred to increase the volume of fuel supply. This lever will rest on the support. And the position of this very support is already adjusted by the regulator. Therefore, it will not work too sharply to increase the volume. So, pressing the pedal, the driver only wants to give more fuel. And it’s not at all a fact that this will lead to an increase in turnover. It depends directly on how worn out the speed controller is. If it is in good condition, then the car will start with gray smoke. If the wear is large, then the diesel will spit black smoke from the exhaust pipe in a large club.
About lack of air
Also, dark gases from the pipe can sometimes be caused by a lack of air. But in this case, the exhaust will not be black, but rather gray or dark gray. There is also a decrease in power.
This can be caused by a clogged air supply filter. This is by no means a rare case, and this happens to everyone from time to time. Already not 10 or 100 times it has been proven by bitter experience that only 15 minutes will be enough in a traffic jam in front of a KamAZ, which has black smoke from the exhaust pipe. Diesel is on fire, and the new filter of the one in the back can now be thrown into a landfill. But this happens if KamAZ is incorrectly adjusted, although someone has it adjusted.
Also, a lack of air can be observed due to incorrect operation of the EGR and throttle, incorrect clearances in the timing valves. Also, among the reasons may be incorrectly set gas distribution marks, turbine malfunctions.
When a car is turbocharged and you see black smoke coming out of a diesel-turbo exhaust, it's worth checking the boost. Most likely, it is in him. It is also worth looking for cracks in the pipes of the fuel or air system.
One of the car owners poured cleaning for the fuel system into the car. Having traveled a bit, at high speeds when driving uphill, the car puffed black smoke. But after a little puffing, the smoke disappeared and has not reappeared since. At the same time, he checked all the above reasons. He believes that the additive helped. The car didn't smoke anymore. So, it is possible that the cause of smoke in this case may simply be soot from the fuel system, especially if the diesel is equipped with a converter. Sometimes the filter needs to be cleaned from time to time.
Another reason for black smoke from a diesel exhaust pipe
At one of the owners of a diesel car, the engine suddenly began to smoke. At autopsy, nothing intelligible could be found. But after reading all kinds of forums, talking with other diesel owners, it turned out that the problem was in the ignition.
After re-opening the control valve was found on the ignition unit. He was advised to hit the adjusting bolt. After that, the car stopped smoking. It turned out that it was the ignition angle.
When the ignition is turned on, a good sensor crackles. What to do if there is black smoke from the exhaust pipe (diesel)? No matter what ignition it appears, the sensor should be removed. If the motor has stopped smoking, and the machine is running smoothly, then it's time to change this element.
Black smoke and cold start
A study of the forums has shown that many complain about the smoke from a diesel engine. Some people say that this is a high pressure fuel pump, but more experienced motorists say that this is not so.
It is believed that this phenomenon is quite normal. It is usually short lived. This can be explained by the fact that during a cold start, a re-enriched mixture is supplied to the cylinders. Hence the black smoke from the exhaust pipe. Diesel "cold" often does this. Therefore, do not panic about this.
The situation with the Kia Sorento
Let's take a concrete example. One of the owners of this car when you press the accelerator pedal thick, black smoke. In motion, the car is very reluctant to gain momentum.
A scan was performed for possible errors in the electronic system, but there are no errors. Analysis of the parameters of work also did not give the desired result. There is simply no defect at first glance. The balance of the nozzles is in a normal state, no serious deviations were noticed, the turbine produces a normal pressure level, but at the same time, the Kia Sorento diesel engine still gave out black smoke from the exhaust pipe. When measuring the readings, they thought about the USR. This is a valve that regulates exhaust gases.
After examining it, they found serious deposits of soot behind the throttle. After removing the exhaust pipe, soot and oil were also found in the intake tract. In the end, everything was removed and cleaned. But a more detailed examination of the valve itself revealed damage to its seat. The valve was eventually replaced.
As a result, there is no smoke, and the car rides noticeably better.
common rail system
Here, too, problems of the same kind are noticeable. Many complain about black smoke from the exhaust pipe - the Comon Rail diesel engine successfully provides such a result during a cold start. Motorists say that this may be due to low-quality fuel or problematic injectors. So, the fuel is not sprayed, but poured. Therefore, black soot. And when the engine warms up, the injectors pump fuel in normal mode.
As a conclusion
We found out the common and popular causes of smoke. Also, when starting "cold", a little black smoke for a diesel is the norm. Most problems can be easily fixed on your own. However, the problem is that all symptoms are suitable for black smoke, and it is not clear what to treat. Therefore, if you have black smoke from the exhaust pipe, diesel troit and twitches, it is better not to tempt fate. In this case, you should give the car for diagnostics to experienced specialists.
So, we found out why black smoke is coming out of the exhaust pipe. Diesel is a complex thing, so these cars need constant care.
A familiar picture: they started the engine after a long stop and thick smoke poured out of the exhaust pipe. It is possible that after warming up, it will decrease, and during the trip it will completely disappear. But more often it is different. The smoke continues and clearly shows that there are some problems in the motor. Long inaction served as a kind of impetus for their sharp manifestation.
Exhaust smoke can be white, black, or anything in between. Color is an important diagnostic feature. The operation of the engine with increased smoke is often accompanied by other deviations from the norm, although sometimes subtle. They must be caught and noted in order to more accurately assess the situation.
Usually, the appearance of smoke is associated with malfunctions of the following working parts of the engine: control systems (mainly fuel supply), cooling systems, mechanical parts (piston group, distribution mechanism, etc.). In accordance with this, smoke occurs either due to incomplete or “improper” combustion of fuel, or coolant entering the cylinders, or oil entering there. The presence of oil, coolant, or excess fuel during combustion in the cylinders gives the characteristic color to the exhaust gases.
If we analyze possible malfunctions, it turns out that in many situations the smoke is the same in color, although it has a different nature. Another circumstance: often a malfunction of one system, which turns out to be a source of smoke, occurs due to malfunctions and defects in another. Here is a typical example: poor performance of the cooling system leads to overheating of the engine and, accordingly, burning of the piston rings. As a result, oil enters the cylinders and causes smoke, the cause of which is essentially secondary.
It is better to start the search for the cause of smoke by comparing all the recorded circumstances: the nature of the smoke itself, observed accompanying phenomena, and possible external influences. We will talk about the characteristic combinations of these factors.White smoke.
White smoke from the exhaust pipe is quite normal during cold engine warm-ups. It's not just smoke, it's steam. Vaporized water is a natural product of fuel combustion. In an unheated exhaust system, this vapor partially condenses and becomes visible, and water usually appears at the end of the exhaust pipe. As the system warms up, condensation decreases. The colder the environment, the denser and whiter the steam will be. At temperatures below -100 C, white steam is also formed on a well-heated engine, and at a frost of minus 20-25 degrees it acquires a thick white color with a bluish tint. Humidity also affects the color and saturation of steam: the higher it is, the thicker the steam.
White smoke in warm weather and on a well-heated engine is most often associated with coolant entering the cylinders (for example, through a leaky head gasket). The water contained in the coolant does not have time to completely evaporate during the combustion of the fuel and forms a rather thick white smoke (in fact, again, steam). Its shade depends on the composition of the coolant, the weather and the light outside. Sometimes it looks bluish, resembling "oily" smoke. Distinguishing water vapor is easy: it immediately dissipates, and after the “oil” smoke, a bluish fog remains in the air for a long time.
To make sure that the cooling system is at fault, a series of targeted checks will be required. It is easy to clarify that water is indeed emitted from the exhaust pipe, and not oil. To do this, on a well-heated engine, briefly cover the exhaust pipe opening with a sheet of paper. Drops of water from the leaf will gradually evaporate and will not leave obvious greasy marks, and they will not be greasy to the touch.
Further, the search must be coordinated with the design of the engine. Fluid can enter the cylinder due not only to gasket damage, but also to cracks in the cylinder head or block. All these defects during engine operation cause exhaust gases to enter the cooling system (sometimes even a gas plug forms there), which serves as the basis for recognition.
By opening the cap of the radiator or expansion tank, it is easy to notice the smell of exhaust gases and an oil film on the surface of the coolant. Yes, the fluid level will be low. It is characteristic that in such cases, after starting a cold engine, the pressure in the cooling system immediately rises (it is easy to feel it with your hand by squeezing the upper radiator hose), and the liquid level in the expansion tank also increases rapidly. Moreover, this level is unstable and in the tank you can notice the release of gas bubbles, sometimes with a periodic release of coolant from the tank.
If the engine is stopped, the picture will change. Fluid begins to flow into the cylinder. Gradually, it passes through the piston rings and enters the oil, into the oil pan. At the next start, the oil mixes with the liquid, forms an emulsion and changes color - it becomes opaque and lighter. Circulating through the lubrication system, such an emulsion leaves a characteristic light yellow-brown foam on the head cover and oil filler cap.
This is checked by removing the dipstick and opening the filler cap, but if the defect (crack, burnout) is small, then there may not be any changes (it happens that the oil remains clean, although foam forms on the plug). On the contrary, if the leakage in the cylinder is significant, then the liquid, accumulating above the piston, even prevents the crankshaft from turning by the starter at the first moment when starting. In especially severe cases, water hammer in the cylinder, deformation and breakage of the connecting rod are possible.
Sometimes it is possible to determine the location of the defect. Once in the cylinder, the coolant actively "cleans" everything it comes into contact with, so the spark plug will look completely fresh. If air under pressure is supplied to the cylinder through the spark plug hole (for example, through an adapter with a hose or a special leak tester), the liquid level in the expansion tank will begin to rise (when checking, it is necessary to turn the crankshaft to a position in which both valves are closed, put the car on brake and shift into gear).
Further checks are only possible with the block head removed. Assess the condition of the gasket, head and block planes. Gasket burnout is often accompanied by deformation of the head plane, especially if the defect was preceded by engine overheating (for example, due to a malfunction of the thermostat, fan, and other reasons). Worse, if obvious defects are not found. Then it is necessary to check the head for tightness under pressure; it is most likely that a crack will be found on the wall of the combustion chamber (more often near the exhaust valve seat). You should also carefully inspect the cylinder, lowering the piston to bottom dead center. A crack in the cylinder is a rare defect, but if it is, it is not difficult to detect it. The edges of the crack diverge (the walls "breathe") and often turn out to be polished piston rings.
It also happens that coolant enters the cylinder through the intake system - for example, due to leaks in the intake manifold gasket (if it simultaneously seals the collector heating channels with coolant). In such cases, the pressure in the cooling system does not increase, there is no smell of exhaust gases in it, but the oil turns into an emulsion, and the coolant level quickly decreases. These signs, as a rule, are enough to find a defect and not confuse it with the one described above, otherwise the block head will be removed in vain.
All problems associated with white smoke from the exhaust pipe require not only the elimination of direct causes. Since defects are usually caused by engine overheating, it is necessary to check and eliminate malfunctions in the cooling system - it is possible that the thermostat, switch-on sensor, clutch or fan itself are not working, the radiator, its plug, hoses or connections are leaking.
If white smoke and its accompanying defects are noticed, then the car cannot be operated. First, defects progress rapidly. And secondly, the operation of the motor on an oil-in-water emulsion dramatically accelerates the wear of parts, and after several hundred kilometers, it is most likely impossible to do without a major overhaul.Blue or gray smoke
The main reason for the appearance of blue smoke is the ingress of oil into the engine cylinders. "Oil" smoke can have different shades - from transparent blue to thick white-blue, which depends on the mode of operation of the engine, the degree of its warming up and the amount of oil entering the cylinders, as well as illumination and other factors. Characteristically, oil smoke, unlike steam, does not quickly dissipate in the air, and the paper test mentioned above gives greasy droplets that fly out of the pipe along with the exhaust gases.
It is also clear that oil smoke is accompanied by increased oil consumption. So, at a flow rate of about 0.5 l / 100 km, blue smoke appears mainly in transient modes, and when it reaches 1.0 l / 100 km, it also appears in uniform motion modes. By the way, in the latter case, in transient conditions, the oil smoke becomes thick blue-white. True, the owners of the most modern cars should be aware of the possible presence of a converter that can clean the exhaust gases from oil even at fairly high costs.
Oil enters the cylinders (more precisely, into the combustion chambers) in two ways - either from below, through the piston rings, or from above, through the gaps between the valve stems and guide bushings.
Wear of parts of the cylinder-piston group is one of the most common causes of oil smoke. The upper compression rings show wear not only on the outer surface in contact with the cylinder, but also on the end planes that perceive the pressure of gases in the cylinder. The grooves of these rings in the pistons may also be worn out. Large gaps in the grooves create a pumping effect. Even if the oil scraper rings are still normal, oil still enters the cylinders, since the upper rings continuously "pump" it from the bottom up.
Cylinders wear out most of all in the stop zone of the upper ring when the piston is at top dead center, and in the middle part they often acquire an oval shape. The deviation of the cylinder shape from the circumference worsens the sealing properties of the rings. Gaps usually form in the zone of locks, but their appearance in other places of the circumference is not excluded.
There are frequent cases when, with a relatively decent condition of the rings and pistons, the surface of the cylinder is damaged. This happens, for example, with poor oil filtration, when abrasive particles get between the piston skirt and the cylinder. Then there are scratches on the cylinder.
A similar situation is real after a long parking of the car, when corrosion centers may appear on the surface of the cylinders and rings. It will take a significant amount of time to smooth out these defects and the mutual running-in of parts (if they can run in at all).
The same effect often occurs when the engine repair technology is violated, if the surface of the repaired cylinder is too rough or the cylinder has an irregular shape, or poor-quality pistons and piston rings are used. In such cases, as a rule, one cannot count on normal running-in at all.
The wear of parts of the cylinder-piston group is often accompanied by a loss of compression and an increase in the pressure of crankcase gases, which is determined by the appropriate instruments (compressometer, leak tester, etc.). However, it should be remembered that a large amount of oil entering the cylinders seals the gaps in the mating parts well. If they are not too high, then the result of the compression evaluation may be quite normal, sometimes even closer to the upper limit. It is this circumstance that confuses the search for a specific cause of blue oil smoke.
One more note about characteristic circumstances. When there are no large wear parts, then blue or blue-white smoke is clearly observed only when the engine is warmed up, gradually decreasing and even disappearing. The reason is simple: when heated, the parts take shape and take up space in which they better fit together. With excessively high wear, the picture is reversed: the smoke on a warm engine will intensify, since it is easier for hot oil, which has a low viscosity, to enter the cylinder through worn parts.
It is always easier to identify a malfunction associated with more serious defects or even broken parts. So, detonation usually leads to breakage of the jumpers between the rings on the pistons, less often to the breakage of the rings themselves. Severe overheating of the engine causes deformation of the piston skirts, a large gap is formed between the piston and the cylinder. The deformed piston warps, disrupting the operation of the rings. The same result is possible when the connecting rod is deformed, for example, due to water hammer when water enters the cylinder or after a belt breaks and the piston strikes an unclosed valve.
The use of poor quality oil can cause the rings to stick and stick in the piston grooves. And due to prolonged glow ignition, the rings can simply be rolled in grooves with a complete loss of mobility.
The defects discussed above usually do not occur in all cylinders at once. It is not difficult to find a failed cylinder by comparing the condition of the spark plugs and the compression value in different cylinders. Moreover, such defects are often accompanied by all sorts of extraneous noises and knocks that change with engine speed, load and degree of engine warm-up, as well as unstable engine operation due to cylinder shutdown (especially during cold start).
A common group of malfunctions that cause oil smoke and oil consumption is associated with wear of valve stems and guide bushings, as well as wear, mechanical defects and aging (loss of elasticity) of valve stem seals. These defects tend to produce a noticeable increase in engine smoke as the engine warms up, as thinned hot oil passes through gaps between worn parts much more easily. In addition, the ingress of oil into the cylinders increases at idle and during engine braking. In these modes, a large vacuum occurs in the intake manifold, and oil flows through the valve stems under the action of a pressure drop, accumulating on the walls of parts and in the exhaust system. The subsequent opening of the throttle at the first moment sharply increases the density of blue oil smoke.
In turbocharged engines, oil consumption accompanied by blue smoke is possible due to a malfunction of the turbocharger, in particular, worn bearings and rotor seals. The wear of the compressor front bearing seal gives a picture similar to the failure of the valve stem seals (including oil soot on the candles), but at the same time a puddle of oil collects in the compressor inlet pipe. It is difficult to determine a turbine seal failure, since the oil enters directly into the exhaust system and burns out there.
In operation, blue smoke and oil consumption often appear when one of the cylinders is turned off due to an ignition malfunction or valve leaks. In the latter case, the smoke becomes white-blue, especially if the valve has a clear burnout. Such a defect is easily determined - the compression in this cylinder is insignificant or absent at all, and an abundant black deposit appears on the candle, often in the form of growths.
There are also quite exotic defects that cause blue oil smoke. So, in automatic transmissions with a vacuum load cell, the regulator diaphragm may break. Since its cavity is connected by a hose to the intake manifold, the engine simply begins to suck oil out of the gearbox. As a rule, oil enters only those cylinders near which a vacuum is taken in the manifold. In this case, spark plugs can be thrown and oil can splatter from the spark plug holes (recall that ATF oils usually have
Red color).Black smoke
Black smoke from the exhaust pipe indicates a re-enrichment of the fuel-air mixture, and, consequently, a malfunction of the fuel supply system. Such smoke is usually well visible on a light background behind the car and is a soot particles - products of incomplete combustion of fuel.
Black smoke is often accompanied by high fuel consumption, poor starting, unstable engine operation, high exhaust toxicity, and often loss of power due to a suboptimal air-fuel mixture.
In carbureted engines, black smoke is usually caused by an overflow in the float chamber due to a defective needle valve or due to coking of the air jets.
In gasoline engines with electronic fuel injection, over-enrichment of the mixture occurs, as a rule, in case of malfunction and failure of various sensors (oxygen, air flow, etc.), as well as in case of leakage of injectors. The latter case is dangerous due to water hammer in the cylinder at startup with all the consequences mentioned above. The bottom line is that a lot of fuel can flow into the cylinder through a faulty nozzle on an idle engine, and it will not allow the piston to approach top dead center. In diesel engines, black smoke sometimes appears not only when there is a malfunction in the high-pressure pump, but also with a large injection advance angle.
A common feature of the operation modes of gasoline engines on a re-enriched mixture is increased wear and even scuffing of parts of the cylinder-piston group, since excess fuel washes oil from the cylinder walls and worsens lubrication. In addition, fuel enters the oil and dilutes it, worsening lubrication conditions in other related engine parts. In some cases, this thinning is so great that the oil level in the crankcase (more precisely, the oil-fuel mixture) rises significantly. Diluted oil acquires a distinct smell of gasoline. It is obvious that the operation of an engine with such malfunctions is not only difficult, but also highly undesirable, since it quickly leads to new, much more serious troubles.
As I promised in the last article, I will analyze all types of smoke. Today, a series of "black smoke" has come, it can appear both on and on diesel engines. Why this happens and what it means, in detail in this article ...
You know, to my great relief, this does not indicate a serious breakdown of the engine or its auxiliary systems. But if this problem is not eliminated in time, then it is possible to bring the supply system, the fuel ignition system, as well as the engine itself to a deplorable state, because they are the causes of black smoke from the muffler.
Appears: - in the form of a thick black exhaust from the muffler, it goes especially strongly when you press the gas pedal. Moreover, the car does not work stably, often the motor “troits”, it does not start well in the morning (especially in the winter period). Fuel consumption increases.
Main reasons
Black smoke indicates a too saturated (re-enriched) fuel-air mixture. A lot of fuel enters the cylinders, which does not have time to burn efficiently, so the exhaust is repainted black. It is much more toxic and harmful than normal exhaust, because it cannot even contribute to the combustion of excess fuel in the exhaust.
The main reason for this is a malfunction of the fuel supply system, found in all types of internal combustion engines ().
The second reason may be a malfunction in the ignition system, the fuel is not ignited in the chamber and therefore the raw mixture goes directly to the muffler, and the engine will be.
For carburetor ignition
Everything is quite simple with the carburetor - if the exhaust is painted in gray-black tones, there is not stability in the first place you need to look. Most likely, there is an overflow in the float chamber.
This happens for two reasons:
1) The “needle” (needle valve) is faulty, it can stick or, on the contrary, let excess fuel through.
2) Clogged, coked (from our fuel) jets. Small "nozzles" with exact size.
You need to disassemble the carburetor to clean it, if it doesn’t help, then you need to buy a repair kit and replace the “needle” and jets and correctly set the gasoline level in the chamber.
injection option
Everything is a little more complicated on the one hand, and easier on the other. The injector does not have chambers with float needles, etc., it is a completely different system that supplies the fuel-air mixture electronically. Injection into the cylinders occurs with the help of special devices - "injectors", hence the name.
The main causes of black exhaust:
1) Often the cause is the injector itself, it simply clogs and cannot supply fuel normally. There is an accumulation of pressure, and then a “strong” injection, often with excess. The operation of the engine will not be stable, then low revs, then high - in simple words they will “float”. In such a situation, you need to clean the injectors, there are many different ways, from removing the fuel rail to special products that are added to gasoline - it's up to you, but after such manipulation you can often get rid of black smoke from the exhaust pipe. Functionality is restored. Cleaning should be done at least once every 60 - 70,000 kilometers.
2) Since the system is automated, it monitors the various cycles using sensors. So if the sensor is not working, it will either not let the car start at all, or it will supply too much fuel. Here you yourself are unlikely to be able to diagnose a breakdown, you need to go to the service station.
3) Fuel pump. Usually injectors have it in the tank, there have been cases when it applied increased pressure. Which also led to overflow in the injection chambers. Again, it needs to be replaced.
diesel engine
In general, a diesel engine is the record holder for black exhaust. The thing is that it has a slightly different fuel ignition system (from pressure), and it works on diesel (diesel fuel), and even in normal condition it gives a slightly blackish-blue exhaust. Recall at least our "KAMAZ". However, recently they have been struggling with such exhaust, because it is very toxic and poisonous, it contains a lot of lead. Therefore, now almost all diesel engines are equipped with "", for the sake of EURO 5 standards, it cleans the exhaust and prevents harmful substances from entering the air.
Causes of black smoke:
1) This is a commonplace failure of the particulate filter, it just needs to be replaced. However, the intensity of the smoke will not be as high.
2) The high pressure pump is broken. There is an overflow. You just need to change.
3) Incorrect ignition timing. Need to be adjusted.
What can cause such smoke from the exhaust pipe
If measures are not taken in time, then you can run into decent malfunctions. For example, in injection cars, the catalyst dies quickly, but replacing it is not very cheap (many even just remove it).
Also, if there is a large overflow through the "injector", this can almost lead to, because sometimes the fuel is supplied in liquid form, and not in the air mixture. This is very dangerous, complex breakdown.
On a diesel engine from a large volume of fuel, it can break the block, because there is even more pressure there than in gasoline engines.
As you can see, black smoke itself does not cause complex malfunctions, but if you do not react to it in time, this can result in big problems.
When accelerating or starting a diesel engine, black smoke comes out of the exhaust pipe. It indicates problems with the engine or fuel system. Let's deal with the source of the black exhaust + video how to fix it.
When examining a smoking engine, first check that the smoke does not stop after the engine reaches operating temperature.
Main reasons
- Clogged air filter or air inlet ()
- Low compression ()
- Faulty boost pressure control system
- Clogged exhaust system
- Valve timing or start of injection incorrectly set
- Glow plug leaking (if equipped)
- Fuel injection pressure too low due to injector firing or wrong type of injector fitted
- Faulty injection pump (high pressure fuel pump) or injection pump of the wrong type
- Motor overload (during acceleration)
Some of the points listed in the description of the causes of malfunctions can be discarded if you carefully examine the very soot from the exhaust (soot particles, drops, oil films, smell).
Black smoke from the exhaust pipe of a diesel engine is produced by incomplete combustion of fuel, when unburned hydrocarbons are converted to soot. Incomplete combustion means that there is either not enough oxygen (i.e. air) in the combustion chamber or too much fuel. An obvious cause of lack of air is a clogged engine filter..
Read about the causes of white and black smoke at.
The cause of poor filling of cylinders with air can also be incorrectly adjusted valve clearances or worn camshaft cams. The fuel may not burn completely if the start of injection is set incorrectly (late injection) or if the injector malfunctions, which does not provide good atomization of the fuel.
Causes of soot may be leaking injectors (opening pressure too low), low fuel cetane number, or excessive coolant entering the combustion chamber.
Video - how to fix it?
To more accurately determine the cause, check the air intake or exhaust system. Also check the boost pressure (on turbocharged diesel engines), valve adjustment, compression in the cylinders, the condition of the cooling system and oil level, and for signs of gas breakthrough into the crankcase.