How to choose a diesel used nozzle for auto disassembly?
The fuel injection system in diesel cars is the first node that feels all the disadvantages of low-quality fuel. In modern cars, the structure of this system is extremely complex. The most vulnerable point is considered to be fuel injectors, which can work incorrectly even on relatively new cars. Often, owners, due to the impossibility or high cost of repairs, have to look for a used nozzle on the market. The most common of them are Common Rail system components.
We understand the terminology
All injectors that can be found on the market related to the Common Rail system can be divided into two groups: piezoelectric and electromagnetic. They are manufactured by several brands, the main ones are Bosch, Delphi, Denso, Continental (Siemens). The reliability of brands is a relative thing, because, for example, among the electromagnetic type injectors, the top three are located in the following form: Denso, Bosch, Delphi. (from more reliable to less reliable), and among piezoelectric — Bosch, Continental (Siemens), Denso (from more reliable to less reliable)

The importance of high-quality fuel
Before buying, check with the seller in which country and under what conditions the engine from which the injectors were removed was operated. About what questions you still need to ask the seller — read our article "Six questions to the seller of auto parts". In order for the purchase to last a relatively long time, the operation of injectors with fuel of normal quality is very important. Ideally, if the nozzle is brought from countries where strict fuel quality control is in place, because the purity and quality of diesel fuel in these countries allow the injectors to work for the entire prescribed period (up to 200,000 km without complaints about the quality of injection).
But injectors from countries where there is no control or not very thorough should be abandoned — fuel in these countries is not clean, impurities are often found in it, with the help of which production is either cheaper or the volume of liquid increases. In addition, it was noted that fuel from some countries is characterized by the presence of small foreign metal particles. Prolonged operation of the injectors in such conditions leads to the formation of wear on the valves, sprayers and multipliers of the injectors: under high pressure, the metal begins to deform and become covered with microscopic foci of oxidation. All this leads to equipment failure and a large volume of diesel fuel sent to the reverse system.
Check the appearance of the nozzle
Inspect the nozzle from all sides. Pay special attention to the nodes that can be unwound or removed during the repair process. For example, in the design of Denso injectors, to remove the cap and the sprayer, it is required to unscrew the mounting nut. In its native state, it is twisted very tightly, so in any case, traces of impacts from wrenches in the form of bullies will be found on it. 

 You can read more about the "bullies" themselves in our article "How to choose a used engine for auto disassembly?". At the same time, the fact of removing the solenoid valve on the top of the same Denso nozzle can hardly be detected visually: the thread there does not imply strong tightening, because there is a rubber gasket in the design. As a general rule, there should be no traces of the repair carried out on the nozzle itself. 

 How to choose the right nozzle?
Before entering the market of used spare parts, the buyer needs to inspect the engine of his own vehicle. The ideal solution would be to analyze all working and non-working injectors with sequential recording of numbers from each of them. Often there is a situation when several different injectors work in the same system, which allows you to enter the market with already available data on suitable parts.

  
On Bosch brand injectors, the number is indicated as a digital code on the housing. Despite the fact that it is important to know all the numbers of the marking, the main meaning is given to a 10-digit designation of the type "0 445 110 110", where 0445 is the designation of injectors controlled by an electric unit, 110 is the coding of electromagnetic injectors, 115 (116) is the code of injectors installed on passenger cars (120 is installed on trucks
cars), 110 - the brand of the nozzle in the general range of modifications. The Delphi brand labels its injectors with a digital or mixed code of the form "EJBR04501D", "A6640170121". To select the nozzle, the code of the first sample is used (with the letters "EJ" at the beginning of the code). The Denso brand carries out the designation of its injectors using a 10-digit code of the type "23670-27030". It is he who is used in the course of further selection of components.
Repaired, restored or new. Which one is better to choose?
Is it possible to check the operation of the nozzle? Unfortunately, the buyer cannot check in his hands, only a visual inspection. However, the availability of access to a high-level service center does not guarantee that there will be an opportunity to check the nozzle. To carry out this procedure, a special expensive stand is needed, which any service center cannot purchase. The only way to ensure the operation of the nozzle is the selection of a non-disassembled part that will be as close as possible (or identical) to the equipment that has already worked on a particular engine.
The Council. If you hear from the seller claims that a specific piezoelectric nozzle has been repaired and now shows excellent results in fuel injection— it is better to refuse such a purchase. For the Bosch, Denso and Delphi brands, it is almost impossible to imagine a situation for the complete restoration of a piezoelectric type nozzle. The only solution that can be issued for "repair" is dismantling the tip and washing it in an ultrasonic bath. However, this procedure is not a full-fledged repair event, representing a cosmetic cleaning of one of the parts of the nozzle.
Of course, the ideal situation would be the presence of a test stand, where the configuration of the nozzle will be determined in the form of a code that will be written into the fuel supply control unit, so that the car system then correctly perceives the new part. Often, entering the second-hand market is associated with certain financial difficulties that will definitely not cover the work of the masters on the test stand. Therefore, the advice on smooth adjustment of the engine operation, indicated below, will in some cases be able to give almost identical results, protecting the buyer from additional expenses.
The Council. If you need to purchase two or more injectors for your engine, we advise you to install them separately. After installing one nozzle, you need to start the engine and let it idle for about 30 minutes so that the internal injection system tries to recognize the new equipment and adjust its operation. Then it is desirable to take the car to a public road in order to "load" the system in real conditions within 20 minutes. And only after that you can return to the garage again to install the next nozzle.
Let's summarize the results
Despite the complexity of the injectors, the Common Rail system itself is designed to quickly and efficiently replace components, excluding options with repair or restoration of parts. The breakdown of the nozzle is in the absolute majority of cases an event that indicates the need to purchase a new part. If this is not possible at the moment, then it is necessary to enter the used spare parts market. And to buy a link nozzle, contact the trusted sellers who are collected on the portal name.