Today, it is equipped with about 80% of all commercial vehicles and special equipment coming off the assembly line of environmental standards Euro 4 and above. And if so, it's time to talk about the features of its repair and operation, taking into account Russian specifics and, in particular, the quality of domestic diesel fuel
engine
Russian carriers and service technicians have accumulated considerable experience in the operation, maintenance and repair of cars with the Common Rail (CR) system, which allows not only to structure the problems that arise with CR components during the warranty period and after its end, but also give recommendations on how to to avoid.
Pay particular attention to the electrical contacts of the injectors
Pay particular attention to the electrical contacts of the injectors. Pay particular attention to the electrical contacts of the injectors.
The fact that the main reason for the failure of pumps and injectors is poor quality fuel, today it is no secret. In Russia, two main types of fuel are currently produced and sold at gas stations, which comply with GOST R 52368–2005 (EN 590: 2004) and GOST 305–82. Moreover, in their physical and chemical characteristics, in particular, in the percentage of sulfur, lubricating abilities, they differ significantly. So, the lubricity of fuel in accordance with GOST R 52368–2005 is regulated as not more than 460 microns, and this parameter is not regulated in case of one released according to GOST 305–82. Even the employees of the gas station often don’t know what kind of fuel gets into the car’s tank - what the fuel truck brought in was then poured into the tanks.
At the same time, the fuel specialist will easily determine what fed the engine. True, for this he will have to disassemble the failed components and assemblies of the fuel system or, at least, diagnose them on special stands. The hardest hit by the carrier carrier is the failure of the fuel pump.
Common Rail power system controlled by electronic controller
Common Rail power system controlled by electronic controller Common Rail power system controlled by electronic controller
Promising diesel Yaroslavl plant YaMZ-534 with Common Rail
Promising diesel of the Yaroslavl YaMZ-534 plant with Common Rail Promising diesel of the Yaroslavl YaMZ-534 plant with Common Rail
The drive of the Common Rail pump is reliable and durable - no hassle
The drive of the Common Rail pump is reliable and durable - the hassle does not deliver The drive of the pump Common Rail is reliable and durable - the hassle does not deliver
Fuel pump malfunctions
One of the most common failures in the fuel pump is fuel leakage at the joint of the camshaft seal. The phenomenon is most often observed in cold weather in almost all pumps in which fuel acts as a lubricant. It is noticed that when the engine warms up to operating temperature, the leak usually stops. The cause of the leak is almost always the increased fuel pressure inside the pump. The maximum measured at the drain pipe should not exceed 1.2 bar.
Supply system. Scheme
Supply system. Scheme Power System. Scheme
For clarity, I will give a typical case from operating experience. Air temperature minus 15 degrees Celsius. After starting the engine, fuel immediately begins to dig in at the junction of the pump with the engine. After about two minutes of operation, the leak disappears. During this time, fuel leakage may be about 100 ml. However, when checking the pump at the bench, there are no problems in its operation. If this defect occurs, do not rush to disassemble the pump. Try to measure the pressure at the drain - most likely the fuel drain line is throttled.
A possible cause of the leak may be hidden in the increased viscosity of the fuel. In the bitter cold, even high-quality winter diesel fuel thickens, let alone summer grades of fuel that unscrupulous businessmen sell in winter. In the CR system, the amount of fuel passing through the drain (return fuel line) is incommensurably greater than in the classical system. So, for example, an injector gives about the same amount of fuel into the "return" as it injects into the cylinder. In a word, fuel leakage at the joint of the gasket is not a defect or malfunction.
Despite the fact that the high-pressure line is a very high-loaded zone, priority should be given to the low-pressure line, since it is precisely in these zones that high pressure (at the discharge) and increased vacuum (at the suction) can easily form
Despite the fact that the high-pressure line is a very high-loaded zone, priority should be given to the low-pressure line, since it is precisely in these zones that high pressure (at the discharge) and increased vacuum (at the suction) can easily form. Despite the fact that the high-pressure line is a very high-loaded zone, priority should be given to the low-pressure line, since it is precisely in these zones that high pressure (at the discharge) and increased vacuum (at the suction) can easily form.
Another crucial point is the discharge in front of the fuel priming pump. If its value is below 0.2 bar, this will lead to unstable operation of the fuel priming pump and its accelerated wear. The vacuum again depends on the viscosity of the fuel, the state of the pre-filter, the cleanliness of the grid of the fuel receiver in the tank and the condition of the fuel line on the suction line. The latter may have dents that reduce its cross section.
The cycle feed depends on the amperage on the dispenser. The higher the current, the greater the supply. The smallest particles can lead to a loss of stem mobility and, consequently, a disruption in fuel
The cycle feed depends on the amperage on the dispenser. The higher the current, the greater the supply. The smallest particles can lead to a loss of stem mobility and, consequently, a violation of the fuel supply. The cycle feed depends on the amperage on the dispenser. The higher the current, the greater the supply. The smallest particles can lead to a loss of stem mobility and, consequently, a violation of the fuel supply.
Often, problems in the power system provoke a dosing unit (in Bosch - ZME). If in Rail there is insufficient or increased pressure, then the reason most likely lies in the inadequate operation of the dosing unit, which, being a precision product, is extremely sensitive to the ingress of foreign particles into it. The impact of the abrasive on the precision pair of the block causes its rod to freeze, which is expressed in unregulated fuel supply to the Rail and fuel supply to the cylinder. In this case, washing the dosing unit is ineffective. The problem is solved only by replacing it with a new one.
But even in some cases, alas, it brings only a temporary effect. So, after replacing the ZME or injector, for the first time the engine works like a Swiss watch, and after a short time the car loses traction, fuel consumption increases, and start-up worsens. Diagnostics will give an unambiguous conclusion: the cause of the malfunction is similar to that which was recorded before the repair - wear of the precision filling of the dosing unit due to the ingress of abrasive particles or water into it. Conclusion: to avoid losses, require service workers to clean the fuel system as thoroughly as possible (up to flushing the fuel tank and Rail) and changing all fuel filters without fail.
The most “moody” size in the injector is the anchor stroke. It is measured in microns, but the accuracy of the fuel supply depends on it
The most “moody” size in the injector is the anchor stroke. It is measured in microns, but the accuracy of the fuel supply depends on it. The most “moody” size in the injector is the anchor stroke. It is measured in microns, but the accuracy of the fuel supply depends on it.
No less terrible is the corrosion formed inside the pump. If she hit his parts, then, as a rule, the pump can no longer be restored. Damaged precision plunger couples cannot be repaired or repaired! The sad thing is that if corrosion was detected in any one CR component, be sure that other components are affected by the same ailment, which means that in order to restore the power supply system, all (!) Of its components will have to be replaced. It is very expensive. It’s easier to prevent a disease than to cure it.
Important
In practice, there are often cases when there are no signs of corrosion at all on the parts of the fuel system. However, the ball valve may be leaky. As a result, the fuel goes to the drain line, and therefore the fuel supply does not meet the norm. The reason for the destruction of the valve seat is cavitation of the fuel, which begins to destroy the seat. Due to high pressures and, as a result, huge fuel speeds, the saddle begins to rapidly collapse.
This is fuel drained from the filter of a new car whose engine suddenly stalled. Most likely, not a single CR component after operation on such diesel fuel will be subject to recovery
This is fuel drained from the filter of a new car whose engine suddenly stalled. Most likely, not a single CR component after working on such diesel fuel will be subject to recovery. This is fuel drained from the filter of a new car, whose engine suddenly stalled. Most likely, not a single CR component after operation on such diesel fuel will be subject to recovery
Fuel filtration
The Common Rail power system imposes strict requirements on fuel cleanliness, therefore special filters with a high degree and fineness of purification are used to filter diesel fuel. When replacing, only filters recommended by the manufacturer of the vehicle should be used, since they have passed comprehensive tests, both in terms of screening pollution and resource. As a rule, in the power supply system there are at least two filters: a preliminary one with a water separator (filtration fineness - 100 microns) and a main filter (filtration fineness - 3-5 microns). For 4-cylinder engines with a cylinder volume of one liter, the filter capacity is about 380 liters per hour. Now imagine how even the most advanced filter can fulfill this standard if dirty diesel fuel is poured into the tank ?!
The degree of corrosion of the elements of this injector is so strong that it cannot be repaired, like all other components of the CR system. Although the car is under warranty, no manufacturer of fuel equipment does not recognize this malfunction as a warranty case
The degree of corrosion of the elements of this injector is so strong that it cannot be repaired, like all other components of the CR system. Although the car is under warranty, no manufacturer of fuel equipment does not recognize this malfunction as a warranty case. The degree of corrosion of the elements of this injector is so strong that it cannot be repaired, like all other components of the CR system. Although the car is under warranty, no manufacturer of fuel equipment does not recognize this malfunction as a warranty case.
CR injector
Each generation of injectors differed from each other, first of all, with a high fuel injection pressure. If the first injectors were designed for an injection pressure of 1200, today 2000 bar is the norm. The trend of increasing pressure continues to be maintained, since the efficiency and environmental friendliness of diesel engines depends on it. This complex, precision fuel system assembly is required to provide the most accurate fuel dosage. And in one working stroke, the injector of a modern motor can carry out from two to seven injections. Moreover, the volumes of additional portions of injected fuel can be 1-3 cubic millimeters (!). Such miserable in terms of injection volumes (taking into account that the injection pressure, as mentioned above, reaches 2000 bar) can only be provided by fuel equipment with an accuracy of precision pairs of 1 micron (for comparison, the thickness of a human hair is 100 microns). If we consider the injector element by element, the statistics of the failure of its elements looks something like this: a ball valve - 35%, a spray gun - 30%, a high pressure o-ring - 25%, etc. (solenoid, anchor group, etc.) - 10%.
Channels similar to the sun's rays violated the valve tightness. The cause of this defect is the ingress of abrasive particles into the fuel. Due to the enormous pressures and speeds of the fuel, abrasive particles literally eat metal, violating the geometry of the outlet openings on the atomizer. This phenomenon is also characteristic of classical nebulizers, however, since the injection pressure in CR is approximately two times higher, destruction also occurs much faster
Channels similar to the sun's rays violated the valve tightness. The cause of this defect is the ingress of abrasive particles into the fuel. Due to the enormous pressures and speeds of the fuel, abrasive particles literally eat metal, violating the geometry of the outlet openings on the atomizer. This phenomenon is also characteristic of classical nebulizers, however, since the injection pressure in CR is approximately two times higher, destruction also occurs much faster. Similar to the sun rays, channels formed a leakage in the valve. The cause of this defect is the ingress of abrasive particles into the fuel. Due to the enormous pressures and speeds of the fuel, abrasive particles literally eat metal, violating the geometry of the outlet openings on the atomizer. This phenomenon is also characteristic of classical nebulizers, however, since the injection pressure in CR is approximately two times higher, destruction also occurs much faster
The design of the injector is so thin that even if during the repair work the assembly was carried out using only new parts, it is impossible to obtain an assembly that matches the factory parameters without using special equipment. The fact is that in the injector there are elements that require fine adjustment, the settings of which depend on the unit's performance. I note that during the assembly of the injector several dozen intermediate measurements of the characteristics are made.
The measuring equipment used in the assembly of the injector is special, designed exclusively for narrow application. The use of conventional micrometers is unacceptable, since when assembling the injector, before installing each subsequent component, they pre-calibrate the next part using special adapters.
Why such difficulties? Judge for yourself: if the average anchor lift is 50 microns, then the tolerance for deviation of this value is only one micron. To ensure such tolerances, strict observance of the tightening torques, which are provided with a special torque wrench, is also required. It is connected to a computer using a USB connector, and all data on the tightening torques is recorded in the memory and reflected in the assembly card of a particular node. The tolerance of the tightening torque is one Newton per meter - also a very small value. The keys that can work with such accuracy on the market once or twice and miscalculated. Needless to say, the assembly work should be carried out in a clean room, the parameters of which are strictly regulated by dust content.
An injector is a technically complex component that has gone through several stages of development over a period of 10 years. Only at the end of 2010, Bosch Diesel Centers developed an official technology for repairing injectors
An injector is a technically complex component that has gone through several stages of development over a period of 10 years. Only at the end of 2010, Bosch Diesel Centers developed an official technology for repairing injectors. An injector is a technically complex component that has gone through several stages of development over a period of 10 years. Only at the end of 2010, Bosch Diesel Centers developed an official technology for repairing injectors.
findings
1. It is unrealistic to repair the pump or injector yourself.
2. If any component fails, be sure to check all the others.
