Diesel engines are significantly different from gasoline engines. But the problems with them are almost the same as with gasoline units. Having read automobile forums, you can see a lot of all sorts of topics where these or those problems are discussed. But especially often you can see topics where motorists complain about the fact that diesel engines periodically go black smoke from the exhaust. Let's see what the problem is, why this phenomenon occurs. We will also see how this problem can be solved.
Diagnose by exhaust colors
Diesel engines, as well as gasoline ones, can have exhausts of various colors. More often it is white, gray, gray and black smoke.
Let's start with white. Often white is called smoke of a bluish tint. This happens when the turbine is destroyed, and the lubricant goes straight into the intake tract. In such a situation smoke of a gray color comes down from the chimney. But an inexperienced motorist will completely take him for white smoke. And if you also smell it, then immediately it is 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. Still, such smoke can be confused with steam, which is more often observed in the winter months from the exhaust of not only diesel cars. All the fault is water, which appears as a result of combustion.
Later, after warming up the engine, steam will not be noticeable, although it will not go anywhere. This can be easily verified. You just need to put your palms to the exhaust. The palm will be slightly damp. This steam causes significant inconvenience when tuning the engine, and especially in winter. For a quality setting, you have to warm the unit for a long time. And in the cold, tuning may not work at all.
White smoke is a signal of a serious problem.
If the smoke from your diesel engine is not steam, then it’s for sure the coolant that enters the combustion chambers. Typically, a cylinder that has been filled with cooling mixtures does not have the ability to idle. Therefore, the motor can troit.
How does coolant penetrate cylinders?
The 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 crack of the cylinder head, the tank, often full of fluid, also completely goes into the pipe.
Repairs
If you find a cylinder head crack, then here you can only recommend replacing the head. However, the prices ... Therefore, many motorists do not disdain contract details. These are used spare parts from Europe.
Cracked cylinder head can be repaired, but we will not recommend this technology, because during this repair a hole is drilled that will fall onto the crack, and then a copper rod is pressed into the hole. There will be no breakthrough of gases, however one of the cooling valves will be blocked by half. Such a head will have a significantly reduced resource.
Blue smoke
For those with smoke coming from the exhaust pipe, the diesel engine made them worry when they saw blue smoke.
Blue, and on some engines it can be gray, on the working engine it is often caused by late injection. This problem has been said more than once, many motorists managed to discuss this topic far and wide.
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, naturally, if no one has touched the pump.
Causes of Blue Smoke
The high pressure fuel pump in our conditions works as follows. The set of parts in this assembly constantly rotates, works, rubs. And lubrication is provided by the 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 diesel fuel tanks. Everything in it is excellent, but there are no lubricating fractions at all. Well, or almost absent. All its fat content along with various paraffins was removed at the refinery.
So, when winter comes, most injection pumps on diesel engines operate without lubrication and are subject to severe wear. Due to this completely natural, but already too quick and increased wear, the advance of injection is reduced. Diesel fuel stops heating, and the cylinder stops working normally. The engine twitches, shakes. Fuel that does not have time to burn out, as a result, turns into blue smoke. On some engines there is black smoke from the exhaust. If the engine is warmed up, then it will stop smoking, or at least the amount of exhaust will decrease. In this case, the fuel manages 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 cylinder where the compression is less will not work.
Such a picture often happens in parking lots. Cars are trying to start, and the entire area is filled with blue smoke. But sometimes diesel releases black smoke from the exhaust pipe. After warming up, the fumes will disappear. After all, the temperature in the engine rises, and temperature increases, even in worn cylinders, will be enough to ignite.
Case of life
Mechanics on this subject tell one story. On the unit, the cylinder head gasket was replaced. After the motor was assembled, they found strong shaking at idle. After a couple of kilometers, these vibrations ceased, and after a couple of minutes of work, shaking again appeared at idle.
The mechanics analyzed this situation and found that the new gasket is a bit thicker. Until the diesel engine warmed up to operating temperature, it did not work exactly.
So, the main cause of blue smoke is late fuel injection and low compression characteristics. Many modern engines have a device that injects a little earlier. Cars work harder, but the fuel in the cylinders heats up and burns out without smoke, that is, completely. Further, the unit heats up, the coolant heats the actuators, and they return the injection advance piston to its rightful place. The motor works softer and more pleasant.
How to remove blue smoke
If the engine shakes and the diesel exhausts black smoke from the exhaust pipe, well, or blue, then you can safely turn up 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 shift the timer to late injection. This will cause shaking.
Black smoke
Such smoke can be observed if the fuel does not burn to the end. This happens if too much fuel is supplied or if the wrong fuel mixture is supplied. If too little air is supplied to the motor, the effect will be the same as if excess fuel were supplied.
Why is black smoke coming from the diesel exhaust pipe?
A larger volume of supplied fuel is usually a signal of either incorrect adjustment of the injection pump, or wear on the nozzles, or wear on the speed regulator in the pump.
Any fuel pump is equipped with a special adjusting screw. Using it, the amount of fuel supplied is adjusted. With this screw you 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 speed can be significantly reduced. Then you can increase the power. But to drive diesel black smoke from the exhaust pipe will continue. If the adjusting screw on the high-pressure fuel pump is screwed even more than it should be, the unit will practically stop reducing speed.
Nozzle wear
Here it can be assumed that the needle of the plunger pair does not fit tightly 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 its supply is carried out not in a sprayed form, but in drops. To warm and ignite, these drops need a lot of time. Hence the black smoke from the exhaust pipe, and the increased consumption (diesel) of fuel.
The saddest thing
One of the saddest failures that lie in wait for diesel owners is the inevitable wear of the fuel pump. As already mentioned, offal inside the pump works without lubrication. If in the summer the diesel engine still lubricates something, then in the winter - no. And domestic fuel is generally of low quality. So the inside of the pump wears out.
When the gas pedal is pressed very sharply, for example, in order to move off quickly, the fuel injection pump lever is translated to increase the fuel supply volume. This lever will rest on the support. And the position of this support is already adjusted by the regulator. Therefore, too sharply increase the volume will not work. So, pressing the pedal, the driver only wants to give a larger amount of fuel. And it’s not at all a fact that this will lead to an increase in turnover. It depends directly on how worn the speed control is. If it is in good condition, then the car will start with gray smoke. If the wear is large, then diesel black smoke from the exhaust pipe will spit a big 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. Moreover, a decrease in power is observed.
A clogged air filter may cause this. This is by no means a rare case, and this happens periodically with everyone. It has already been tested 10 or 100 times through bitter experience that only 15 minutes will be enough in a traffic jam in front of KamAZ, which has black smoke from the exhaust pipe. The diesel burns, and the new filter of the one standing behind can now be thrown into the landfill. But this happens if KamAZ has an incorrectly adjusted fuel system, although who has it adjusted.
Also, a lack of air can be observed due to improper operation of the EGR and throttle, incorrect gaps in the timing valves. Also among the reasons may be incorrectly set gas distribution marks, turbine malfunctions.
When the car is equipped with a turbine, and you observe black smoke from the exhaust pipe of a diesel turbo, it is worth checking the boost. Most likely, the point is in it. It is also worth looking for cracks in the nozzles 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 while driving uphill, the car puffed with black smoke. But a little puffing, the smoke disappeared and has not appeared since then. Moreover, he checked all the above reasons. He believes that the additive helped. The car did not smoke anymore. So, perhaps the cause of the smoke in this case may simply be soot from the fuel system, especially if the diesel engine 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 was 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 to be a solenoid valve for the ignition angle.
When the ignition is turned on, the serviceable sensor pops. What to do if black smoke appears from the exhaust pipe (diesel)? No matter what kind of ignition it appears, the sensor should be removed. If the motor has stopped smoking, and the machine is running smoothly, then this time to change this element.
Black smoke and cold start
A study of the forums has shown that many complain of smoke during the cold start of a diesel engine. Some say it’s a high-pressure fuel pump, but more experienced motorists say it’s not.
It is believed that this phenomenon is quite normal. Usually it is short-lived. This can be explained by the fact that during cold start a re-enriched mixture is fed into the cylinders. Hence the black smoke from the exhaust pipe. A cold diesel often does this. Therefore, do not panic about this.
The situation with the Kia Sorento
We give a concrete example. One of the owners of this car has a thick, black smoke when you press the accelerator pedal. In motion, the car is very reluctant to gain momentum.
A scan was conducted for possible errors in the electronic system, but there were no errors. Analysis of the operating parameters also did not give the desired result. There is simply no defect at first glance. The nozzle balance is in normal condition, no serious deviations have been noticed, the turbine gives out a normal pressure level, but at the same time, the Kia Sorento diesel still emitted black smoke from the exhaust pipe. When measuring readings, we thought of the USR. This is a valve that regulates exhaust gases.
After examining it, they found serious soot deposits behind the throttle. After removing the exhaust pipe, soot and oil were also found in the intake tract. As a result, everything was removed and cleaned. But a closer inspection of the valve itself revealed damage to its seat. As a result, the valve was replaced.
As a result, there is no smoke, and the car goes much better.
Coommon Rail System
There are also noticeable problems of the same plan. Many complain of black smoke from the exhaust pipe - the Komon Rail diesel engine during cold start successfully provides such a result. Car enthusiasts say that this may be due to low-quality fuel or problem nozzles. So, fuel is not sprayed, but poured. Therefore, black soot. And when the engine warms up, injectors pump fuel in normal mode.
In conclusion
We found out the frequent and popular causes of smoke. Also, when starting “on a cold” a little black smoke for a diesel engine is the norm. Most problems can be easily fixed on their own. However, the problem is that all the symptoms are suitable for black smoke, and it is not clear what to treat. Therefore, if you have black smoke coming from the exhaust pipe, the diesel engine trips and twitches, it is better not to tempt fate. In this case, you should give the car for diagnosis to experienced professionals.
So, we found out why black smoke is coming from the exhaust pipe. Diesel is a difficult thing, so these cars need constant care.