How to check the diesel engine when buying a car. How to choose a diesel car
IN last years on the car market There is a tendency to increase demand for diesel cars. Purchase of diesel has become almost fashion, on secondary market Cars with diesel engines are sold at higher prices than their gasoline equivalents. This phenomenon is not accidental. Over the past decade diesel engine passed through the revolution in the development of the "workhorse" to the tops there is no alternative in terms of its potential power plant. With the perfect balance between productivity and fuel, Gasoline Diesel slowly pushed his colleagues by the automotive market.
Modern diesel engine with direct injection Fuel has a very sophisticated system, more complex and multicomponent than gasoline. It is for this reason that it is not considered trouble-free and reliable, especially if the resource has 300 - 400 thousand kilometers, while the real age of most imported diesel cars from 8 to 10 years. The fact is that due to its economy compared to gasoline, cars on diesel fuel in the West mainly use people who travel a lot. Despite the fact that it is displayed on dashboard, There is a high risk to face a copy, "not knowing the run," and in fact it has a very "non-baking" resource. Hence the problems begin, eliminate which, in most cases, is quite expensive for the owner.
Diesel engine is much more sensitive than gasolineSo in the "Diesel from the second hand" equation, the most important unknown is the former owner. Untimely (or no no) replacement of oil and filters, as well as reckless driving and negligent attitude towards the car is commonplace, especially in Italy, from where a large number of used cars are driven. It is advisable to look for a car with a service history in a history of stories with evidence (although the service book falsification is not a problem for the seller). Generally worth being a bit suspicious to the fresh imported cars, no matter where they were made.
If you are oriented with a specific brand and model, read posts in online forums on the necessary subject. In Russian Internet space, there are forums where almost all car brands are discussed. You can learn from the first person, the service problems and the advantages of the model.
Any modern diesel engine is controlled by electronic block Control (EDC), following and controlling all functions. When problem with one of the parameters, the system issues an error and worsens the engine operation. It is necessary to check the selected car on computer diagnosticswhere special attention to the presence of errors and control the operation of the flow meter and the turbo pump (GNP).
Check the compression in the engine cylinders. Modern Common Rail Diesel engines in good conditionIt should be between 18 and 19 bar. In older diesel engines, compression should be above 22 bar (hence the characteristic "knock" and the roar of old diesel engines)
In connection with the tightening of environmental standards in modern diesel engines, many systems have implemented, which often create problems, especially for engines with big mileage. One of them is the ERG valve, which is also used in gasoline engines. In diesel engines, its role is to significantly reduce emissions. The secret is that diesel engines operate on a strongly depleted mixture (enriched with oxygen), which significantly increases it operating temperature. This leads to the appearance of nitrogen oxides, which is the main cause of the destruction of the ozone layer. ERG reduces this temperature, sends the exhaust gases to afterburning and thus suspend the influx of oxygen. When the sensor is output, there are cases it remains almost completely closed, and sometimes it remains open constantly. In any case, there is a problem with the power of the machine, the dynamics varies and the smoothness changes. Perhaps this entry into emergency mode. ERG is connected with another problem - due to high pressure In the engine, over time (mileage), there is a compression into the crankcase (pressure rises in the crankcase). This leads to the outlet of the oil through the hole for ventilation of the crankcase collector, where it is mixed with hot gases from ERG, forming black, sticky soot. This substance is deposited on the walls of the intake manifold, reducing its diameter and leads to a lack of air (power decreases). Part of the substance can get into the turbine, coke is deposited on the blades and they cease to be movable. This is the most common cause of the turbine breakdown. To make sure that in the car there is an overpressure in the crankcase, with a working cold engine, remove the probe to check the oil. From the tube should not go out smoke, steam or oil splashes. In addition, pay attention to the grinding of the suction manifold, the hose of crankcase gases and turbines. Avoid cars with a flawlessly washed with the engine.
There is an opinion that diesel car Better to buy in winterWhen the temperature is zero. First, make sure that he has not previously warmed up by the seller, then turn on the starter. A good diesel should start working at once like a gasoline engine, without long spinning and jerking. Faceless cold start is an important indicator The state of the diesel car, but the start is not less important when the engine is hot. If the warm engine starts with difficulty, with a long-lasting starter, this is a possible sign of a serious problem. Sometimes this is due to a weak battery or damage to the starter, but may be related to the problem of centering the GNP, the chain tension (for the engine with a chain drive), a low degree of compression, exhaustion of a nozzle or suction air in fuel system. These are prerequisites for expensive repairs.
Diesel car turbine
One of the elements that often creates problems, especially in engines with high mileage is a turbine. The turbine develops more than 60,000 revolutions per minute and is subjected to extreme loads. Its overheating, overload, and also unreasonable replacement Oils and filters are factors that dramatically reduce the service life of the turbine. Sometimes you can go through the turbine yourself, but with a serious problem there may be necessary to buy a new one. Check the turbine lubrication, bringing paths and intercooler. Look no cracks through which air can suck. Listen to the sound of the turbine, it should not be heard (howl, whistling). Click on the pedal almost until you stop and release the pedal. If you hear the screech at a time when the turns fall, the turbine requires repair.
Look at the exhaust gases overlooking the pipe. They should be almost colorless. If because exhaust pipe It turns gray smoke, the car burns the oil and the engine is worn out. White smoke is a sign of water in cylinders (gaskets, cracks in the block, head). When pressed for gas, a normal diesel car briefly appears black smoke. If smoke did not disappear and continues to go black smoke, you may have a problem with a nozzle or centering.
Remove the dipstick and look at the color of the oil. Characteristic for diesel cars is that the oil is always black, even 20 kilometers after its shift. Any other color can mean the presence of additives in the engine.
On the idling Listen to the sound and vibration of the engine. A good, modern diesel engine should work smoothly and calmly, almost like gasoline - without excess noise and vibration, shaking, roar and jumping. If this is observed, then problems may be due to damage to the airbags of the engine and more serious, centering, dubs, etc.
Ask for the car before buyingBecause without this you will not be able to detect any problems with the engine or car as a whole. The owner has no reason to refuse you (if only does not hide something). Try to give acceleration a car - diesel engines work evenly with tangible burden, even with low speed. Put the machine to the slope and try to ride without pressing gas - a good diesel engine should smoothly move along the side on the first transmission without acceleration. If this trick did not work, it means that the engine is sucks.
You need to know what to pay attention to when testing it, so that the purchase does not disappoint you subsequently and did not require additional unforeseen investments for repairs.
Otherwise, instead of the expected use of all possible benefits of a diesel engine, you can get a complete set of "minuses" inherent in it, in the form of bad launch, increased smoke and great expense Fuel.
Even before the car market, it is necessary to clearly define for yourself which of the main characteristics of the engine are of the greatest value for you. In this issue, it will inevitably have to look for compromise solutions, since the universal engine does not happen and it cannot be, for example, at the same time powerful, "not voracious", that is, is economical, reliable, and cheap in repair.
As a rule, small diesel engines, in general, have good fuel efficiency, but on the other hand they are less reliable, have a smaller resource than more powerful motors. In most cases, a large working motor volume indicates a fairly high reliability damage, but to wait for a large economy from such a diesel engine, compared with small motors, it is not necessary.
Also, diesel engines are considered more reliable, compared with the turbocharged "fellow". In turn, the turbine engines have the best powerful characteristics, although less economical.
How to check diesel when buying
When deciding in advance with what kind of diesel, you need and pick up the car in the car market, carefully examine the engine.
1. Inspect force aggregate For the presence of oils of oil, coolant, indicating that the engine overheated. There are not so dangerous traces of fueling oil on the engine, but the glands are better to not be.
2. Remove the nozzle connecting the air filter with intake manifold Or in diesel engines with a turbine - air filter with turbine. If traces of oil are noticeable in the nozzle, then it can talk about severe pollution air filter or in the worst case, about the large wear of the cylindrophone engine.
3. Try running the engine. If a hot motor I did not start immediately, "from the floor turnover", then this may be a sign of a hidden defect. Trial launches are better to produce several times, with different intervals between them. At the same time, do not push the gas pedal and do not warm up the glow candles.
- If the motor starts normally, pay attention to the exhaust gases at startup. If the motor is hot, then on idling Smoke should not be. It is possible only a small emission of smoke directly at startup.
- Sounds resembling a quiet tapping, like rolling pebbles are normal for diesel. Through the sounds falling out of the general rhythm, especially if they continue even after increasing the revolutions.
By running the engine and giving it a little to work at idle, smoothly increase the revs to 3 - 4 thousand revolutions per minute, while the motor should not vibrate and twitch. At the same time evaluate the color exhaust gases. If simultaneously with increasing revolutions, the smoke of the SIZAL color appears, this may indicate a late ignition or other problems in the engine.
Sharply add motor turn by pressing the gas pedal. At the same time, follow the engine and exhaust. If on high revolutions The engine vibrates, and the smoke has a scary color, then in such modes of operation there will be a significant loss of power.
If the smoke is black and the stuffs in the engine become heard, then it is better to give up from buying such a car.
How to check compression on diesel and other nuances
1. Check the compression in the engine. This is most accurately done by a special device - compressometer in accordance with the instructions. An acceptable value for a diesel engine is considered to be 36 atmospheres, and permissible at least 31, while the variation of the pressure of the cylinders should not be more than two atmospheres.
2. In the absence of the device, you can estimate the compression on the "eye". Run the motor and carefully remove the lid oilty neck. After that, place the lid without winding it on the neck. If at the same time the cover discards the outgoing gases, it means that the engine is not all in order with the engine compression. However, this is not the most reliable way to check and high-quality diagnostics can be made to a hundred, using special equipment.
3. Give the motor a little cool and open the radiator cover. Different in the radiator coolant to the edge. After that, close the lid, start the motor, wait until the thermostat opens and see if the air bubbles do not leave the engine with the engine. Such bubbles may indicate the leaks of the cylinder block or damage to the block itself.
It is advisable to check how the diesel "on the cold" starts, that is, in winter
If the engine started without problems, just as good as high temperaturesYou can say that with compression everything is in order, as with the work of the cold start system.
On the "idle" diesel should work without interruptions. It can be somewhat "tougher" to work in "cold" mode - this is allowed, as it may be due to a special cold start system, which specially shifts the injection advance angle at low temperatures to improve the engine starting conditions in such conditions.
Of course, tested diesel, and the whole car, without his testing in real road conditions It is impossible. Try the power unit by giving it to work for a few seconds in the limit modes and it will be enough to identify possible problems.
It is no secret that the operational qualities of the car directly depend on the state of its engine. First of all, therefore, when buying a used car, you must make sure of the adequate state of this unit.
Special attention should be paid to diesel engines, since their repair is usually expensive than in the case of gasoline engines, and the cost of diesel engines above.
Check the state of the motor, we advise you to start with an external inspection. Note that on the engine housing and in motor compartment there were no traces of leaking oil or other operational liquids. If the motor is clean, then it should alert, because thus the seller could try to hide traces of leaks.
A great appearance The engine does not mean its excellent technical condition.
Of course, leaks are not always very dangerous, perhaps, to eliminate them, you just need to pull out any sealing connection. But, if leaks are caused by, for example, the wear of the crankshaft salinity, then work on the replacement of such a gland can cost considerable money.
In general, in any case, be careful, and pay attention to everything, even seemingly minor shortcomings.
Remove the oil dipstick engine and determine the oil level and its condition
If a the maple is very clean and transparent, then, it was definitely recently changed. It is worthwhile to ask the question, why did it do if the car was going to sell? It is probably not in order to protect you from the excess spending on the replacement of oil. If the oil is a little darkened, it does not speak at all about the poor state of the motor - it is quite normal, if, of course, the oil is not entirely black.
If a oil has foaming traces and its color has milk, a somewhat whitish shade, then, most likely, a coolant coolant was hit, for example, due to damage to the gasket of the cylinder head, and, in which case, it is better to refuse to buy such a car.
Check the cooling fluid level, and also pay attention to whether expansion tank Cooling systems of rust traces.
If such traces found, and even more so if the coolant itself has a rusty color, then, most likely, the motor overheated, which is a very dangerous sign.
If the external inspection of the engine did not reveal any problems, then ask the seller of the machine, run the motor, and at this time, watch and listen, how it starts, and what color have exhaust gases at the time of start-up.
The worst sign is a blue smile.
If you saw such smoke, then the further inspection of the car can not continue - look for another car for purchase. A bluish shade of smoke gives oilThat burns in combustion chambers together with fuel, and in all in a good motor, the oil should not get there.
Even black smoke, in principle, not so "terrible", and not rare, it is quite corrected if the black smoke is associated with the wrong adjustment of the fuel supply system, etc. (True, not always).
If smoke is white, then perhaps it is at all and not smoke, but the condensation of moisture in the air, then, after warming up the motor, smoke should disappear if it is not too cold on the street.
In general, if you are not sure that the reasons for the smoke of exhaust are insignificant, and easily eliminated, then better car not buy, because in good diesel engine The exhaust is almost blunder, perhaps only easy smoking at the time of start.
As a last resort, refer to the service station for a more detailed diagnosis of the "suspicious" motor, if you are not sure about its technical service.
Listen to how the motor works on various revs
The sound must be smooth, without shooting and interruptions. Ask the seller several times sharply press the gas pedal. At the same time there should be no interruptions in the engine operation, and the exhaust gases should not be painted in black.
There is one more method for determining motor health - Just break the muffler's output. At the same time, a certain pressure of exhaust gases should be felt, and the more the outlet is overlap, the larger the pressure of gases should be. If this is not the case, then you can suspect the squeak in the graduation system.
Listen to the motor, paying attention to extraneous knocks and noises. Look, whether there is no excess vibration during operation.
Not bad if there is ability to measure compression In motor cylinders. Such a procedure will not take much time, and the compressometer itself is not so much, but, the compression measurement can say a lot about the state of the engine.
So, with compression below 18 atmospheres, diesel will be badEven "hot." With compression from 18 to 23 atmospheres, diesel will start, only if it is hot or warm, if the compression is 28 or more atmospheres, the motor will start even in the cold. In addition to the size of the compression, pay attention to its uniformity of cylinders.
Behind this part of the diagnosis of the engine, it can be said that a serviceable diesel should be smoothly, without failures to gain momentum, its exhaust must be practically colorless, no suspicious knocks and noise should be brought, it should be easily run, even if it is cold.
Next you need to check the motor, what is called "on the go"
You should spend a trial trip by car. Check how "pulls" the motor, pass a few kilometers at high speed, it is on high speed, when driving at high speed from the motor, all its forces will be required.
Materials on the topic
Fuel costs - a characteristic, which at current times when choosing a car often stands at the head of the corner. Dysfolly today is cheaper than the 92nd gasoline, and despite this very soon after buying a car with a diesel engine to many car owners comes frustrated. The reason is that most drivers are not accustomed to diesel engines, they prefer gasoline cars. At the same time, in some European countries, for example, France, Spain, cars with diesel engines are very popular, which is confirmed by sales - sometimes diesel modifications buy more than gasoline. We also have a number of factors explaining the "cool" attitude towards this type of motors. Nevertheless, those who decided to buy a diesel engine should be aware of some intricacies of its purchase, operation and maintenance.
Efficiency is a well-known dignity of diesel engines, which is the main "bait" for buyers. But they have both "minuses", which many, especially admirers of the comfort and sports style driving, soon turn out to be taste.
The first thing is very quickly bored - a characteristic elevated "tractor" sound of a working engine. Although the insulation of the cabin is not bad in the salon, completely protect the sitting in the cabin from diesel "music" to automakers has not yet succeeded. Then, although not in all machines, the increased vibrations begin to annoy. And fans are "rewarded" clearly do not like the weak dynamics of overclocking, especially if necessary to accelerate at high speeds.
Interestingly, with all these shortcomings, buyers have time to get acquainted in the inspection of the car offered to buy. But "programmed" on cost-effectiveness, many of these "nuances" do not pay attention. Only after some time, new car owners begin to replenish the ranks of dissatisfied with diesel cars.
Complements the picture that diesel is a specific type of motor with an individual character, which causes the features of its work and requiring compliance with certain rules of operation and management. Usually they do not know, and if they know, they do not observe. As a result, the diesel engine instead of the 500-600 thousand miles of the run before overhaul Looks into two, and even three times less. So before buying diesel, make sure that it matches your temperament and driving style and that you can "satisfy" its needs for operation and maintenance.
Although the car market offers a lot less than gasoline, with a great desire to find the desired option is still possible. The control inspection of diesel cars on many points does not differ from gasoline - check body, chassis, transmission, health care, etc. The difference is to test the engine. Two points are important here - check when the "cold start" and the nature of the work "on the hot". True, it should be noted that summer is not the best time to purchase a diesel engine. Therefore, if after this article, someone will have a desire to become the owner of a diesel engine, it is better to wait for the onset of a cooler season. The perfect period for the dyel dough is winter, when the degrees on the street is 10-20. Under such conditions of "disease" of this type of engine, it is much easier to reveal. The main indicator characterizing the service of diesel is the "cold start". It is carried out in such a sequence: to increase the fuel supply, the manual "gas" key is drawn (if there is no thermal pumps); The rotation of the "ignition" key turns on the incandescent candles, which informs the instrument lighting on the instrument on the panel - the yellow lamp with the spiral symbol; When the candles warmed up (it takes about 20-30 seconds), the lamp goes out - this is a signal that allows the start of the engine. If, after doing these operations, the engine starts from the first attempt and without a long-lasting starter, it means everything is normal.
Diesel on the frost does not start mainly for several reasons: "sat down" battery, faulty incandescent candles, in the fuel system uses summer fuel, low compression in the cylinders. The accumulation replacement procedure, incandescent candles does not require particularly large costs (2000 - 3000 rubles). But as for small compression in the cylinders, then there is a need for expensive engine overhaul (30,000 - 50,000 rubles). The fuel frozen to the gel-like state is not able to pass through the filter, and it means that it is possible to remove it from the power system only during heating in a warm garage, followed by a replacement for the winter diesel fuel or additive antigel additive.
While the diesel is cold, its work is usually accompanied by increased noise and black exhaust. For this type of engine, this is a common phenomenon, since the fuel in cold cylinders evaporates poorly, respectively, does not completely burn. As a good diesel engine is heated, noise decreases, and the black exhaust disappears. If the nature of the work does not change and the smoke continues from the pipe, it means that something is faulty. SIZY smoke is a sign of wear of the details of the cylinder-piston group (piston rings, sleeves, pistons), which requires capital overhaul. When the exhaust is black, then fuel in the cylinders burns not completely. This occurs in cases: poor-quality spraying of fuel faulty nozzles or their sprayers; supply of excess fuel by a rated fuel pump; Lack of air cylinders with a clogged air filter.
As practice shows, the resource of passenger diesel engines in our operating conditions is from 200 to 600 thousand km. Such a significant variation is due to the large dependence of the diesel resource on the operating conditions, systematic and quality of maintenance.
The ability to operate diesel is, perhaps, the main factor that is most influenced by its resource. This type of engines does not forget the driver's errors, which, for example, is used to spinning up to a maximum, the engagement gasoline engines and in the same mode makes it work and diesel. Owners of such machines should remember one an important rule - Diesel does not like large revolutions, since it significantly increases the loads on the details of the cylinder-piston group, fuel equipment, and the process of mixing and combustion itself is not at the desired "scenario". Therefore, it is necessary to ride with medium turnover or below average, and you should switch to increased transmissions much earlier than in the case of gasoline engine. It has long been verified in practice. No wonder on many motor transport enterprises, before "planting" the driver on diesel, he passes internship. If this is not done, the resource of the engines, which found themselves in the hands of untrained drivers, is reduced by 3-5 times, and sometimes more.
To reduce the effects of mechanical impurities and water contained in our diesel engine, on very sensitive diesel fuel equipment, it is desirable to equip the dietary system with a separator filter, better heated. This will extend the service life of expensive fuel pumps and nozzles and protect themselves from winter problems caused by increased viscosity of fuel. If you install additional filters, there is no possibility, the fuel is better to first give to some tank-sump. Pour it into the tank, by the way, without stirring in a sump, you can only after two or three days.
It should also be known that it is undesirable to launch diesel from the pusher or in a tug, since because of the large compression in the cylinders, the timing probability of the timing belt (if the belt drive) is high. About what consequences it can lead, we already wrote
An important aspect that affects the resource of a diesel engine is the timeliness of the maintenance and quality of the materials used and spare parts used. In no case cannot be poured into imported diesel engines the first oil, including popular in the Soviet times "KAMAZ" M10 / G2K. You only need to pour what the manufacturer recommends that the manufacturer or the best quality, for example, instead of the oil quality category, and even the CD oil API, which is intended for high-mounted high-pressure dseivation diesel engines working in difficult conditions on high-fired fuel.
Especially demanding on the quality of turbo diesel oil. Under conditions of high temperatures and speed of rotation of the turbocharger shaft, it is possible only high-quality lubricant properties. special oils For turbodiesel engines. Ignoring this requirement leads to the fact that in such harsh conditions, the oil film on rubbing surfaces obtained by using low-grade oil is very quickly destroyed. It causes dry friction and, accordingly, increased wear of the shaft, turbine bearings and an ambulance breakage of the turbine as a whole.
For the same reasons, the service of a diesel engine should be carried out in the time limit. Although when using ours diesel fuel With an increased sulfur content, which contributes to the accelerated oxidation of engine oil, the interval of its replacement is better to decrease by 20-30%. For example, if according to the instruction management manual, the replacement frequency is 10 thousand km, it is necessary to do it in 7-8 thousand km.
An important factor for "health" diesel is oil filters. The filter element of diesel filters has very small cells, delaying particles that filter gasoline engine I miss the lubricant without any problems. Therefore, oil filters for diesel engines need to buy only high-quality - original or well-known firms (Bosch, Champion, Delphi etc.). In fakes and products of unknown origin, filter paper from a gasoline filter can be used.
If "mineral water" or "semi-synthetic" is poured into the engine, it is preferably flushing a lubrication system every 20 to 40 thousand km (depending on the quality of the oil - domestic or foreign). In the case of "synthetics" with its excellent detergent properties, rinse the lubrication system can be less likely.
Expenditures on maintenance Diesel machines are less than gasoline. Savings are achieved by the absence of spark plugs that change more often than incandescent candles, in addition, there are no complex electronics that controls the operation of the power supply system (we are talking about diesel engines released until the mid-90s). So think, you need it.
