DIY diesel injector repair

In detail: DIY repair of diesel injectors from a real master for the site my.housecope.com.

The injection mechanics is the main difference between a diesel engine and a gasoline engine. In a diesel internal combustion engine, fuel is supplied to the combustion chamber using a nozzle. The device injects fuel in a metered manner into a chamber with a high temperature and pressure, after which the diesel fuel ignites. The nozzle is subjected to the greatest load: the part is constantly in an aggressive environment and works at high intensity. Any negative factor can disable the part or significantly reduce its resource, after which the diesel engine nozzles will need to be repaired.

To understand the mechanics of the injector, we will describe the injection cycle schematically:

The injection pump takes fuel from the tank;
then the pump saturates the fuel rail with diesel fuel;
fuel enters the channels that lead to the nozzle;
inside the nozzle, fuel flows to the sprayer;
when the pressure on the atomizer reaches the set threshold, the nozzle opens and diesel fuel enters the combustion chamber.

Let us describe the design of the part using the example of a primitive mechanical nozzle with 1 spring. In the lateral part there is a channel that provides a continuous supply of diesel fuel. Inside the nozzle chamber there is a movable barrier with a spring and a needle, which drops when the pressure rises. The needle rises, clearing the path of fuel to the sprayer.

Additionally, more advanced types of nozzles can be noted:

Piezoelectric: The spring pusher is lowered by a piezoelectric element. This technology provides a high intensity of opening of the atomizer: fuel economy is achieved, while the internal combustion engine operates more smoothly.
Electro-hydraulic: The design includes an inlet and outlet choke and an electromechanical valve. The operating mode of the components is controlled by the engine control unit.
Unit injectors: used in engines that do not have a high-pressure fuel pump. The fuel is supplied directly to the nozzle. These spraying devices have their own plunger pair inside, which generates the pressure required for injection.

Video (click to play).

Due to excessive loads, the injector may fail due to a violation of the operating mode of the motor. Manufacturers declare the resource of parts to be up to 200,000 km, but due to negative operating factors, wear of parts appears much earlier.

Repair of diesel injectors may be required for the following reasons:

Low quality diesel fuel: the scourge of all "diesel operators". Due to impurities in the fuel, the sprayer becomes clogged; the dosage and the fuel supply mode are violated.
Poor assembly quality of the injection component or factory defect: the injector does not withstand the operating conditions, the part as a whole or individual components fail.
Mechanical damage caused by incorrect operation of adjacent ICE systems.

Usually, breakdowns are of the following nature: the spray angle and the amount of supplied fuel change, the integrity of the body is violated, and the needle travel deteriorates.

Let's briefly describe the "symptomatic series":

jerks and jerks are felt when moving;
The internal combustion engine is unstable at idle, stalls;
when the engine is running, an excessive amount of exhaust is emitted;
tangible loss of traction;
failure of individual cylinders;
gray or black smoke from the exhaust pipe.

It is preferable to entrust the routine maintenance or overhaul of diesel engine injectors to qualified specialists - they will be able to restore and adjust the part on high-precision automated stands. However, a certain set of repair procedures can be carried out in artisanal conditions without the use of complex equipment.

To carry out self-service of diesel engine sprayers, the car owner will need:

a set of open-end or spanner wrenches;
screwdrivers for straight and Phillips head;
clean dry rags;
maximeter;
flushing fluid for internal combustion engines.

It is recommended to carry out work in a dry and lighted, dust-free garage.

Diagnostics of diesel injectors and their maintenance involves removing the nozzles from the internal combustion engine. Before starting work, it is recommended to thoroughly wash the engine and engine compartment to avoid the ingress of debris and foreign particles. With particular fondness, you need to rinse the cylinder head. High pressure tubing should be marked with markings to avoid confusion during reassembly.

Before removing it is necessary to close the nozzle fittings (use plastic caps) to avoid contamination. It is not recommended to use ordinary open-end wrenches to dismantle the nozzles - an inexperienced repairman can strip the threads from the nozzles. If the required qualifications are not available, use spanners and a long-handled head tool.

After removing the nozzles from the holes, dry them and remove external dirt with a rag. O-rings are placed in the holes of the nozzles. When repairing injection parts, they are replaced with new ones without fail. Do not allow dirt from the rings to get into the injection system during removal.

There are several methods to check if the sprayer is working properly. The easiest way is to check the injector while the engine is running:

Start the "engine" at idle speed.
Begin to unscrew the nozzles one by one in turn.
If, after removal, the operation of the motor has deteriorated, then the remote nozzle is operational and must be returned to its place.
By the method of elimination, you will find an injector, the dismantling of which will not change the operating mode of the internal combustion engine. This will be the broken device.

You can use a multimeter for diagnostics. In advance, it is necessary to throw off the battery terminals and disconnect the wiring of the injectors, and then "check" every detail with the device. On high resistance injectors, the device values will be in the range of 11 - 17 ohms; at low impedance, the multimeter will show up to 5 ohms.

The defective injector must be inspected. First, we look for leaks in the body of the part. If there are none, proceed to disassembling the part. We fasten the part in a vise and knock out the sprayer with a gentle tap. Next, you need a thorough cleaning: we soak the parts of the nozzle in diesel fuel or solvent to remove carbon deposits. Remove fumes and deposits with a fine steel grater. After completing the cleaning, you need to check the nozzle at the maximum meter. If the optimal injection parameters have been achieved, the device is ready to be installed in the engine.

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To increase the life of your sprayer, it is recommended to follow a number of simple but important rules:

refuel only with high-quality fuel at proven gas stations;
change the fuel filter in a timely manner;
use fuel additives that clean the fuel system from water and impurities;
if there are any problems in the engine operation, immediately diagnose it at the service station.

These simple guidelines will help you avoid the costly costs of unscheduled nozzle changes.

The algorithm for replacing injectors on a diesel engine is quite simple. Even an inexperienced motorist can do this. Sprayer repair is more complicated and time consuming. However, if you have the desire and the necessary tools, you can also do it yourself.Refuel with quality fuel, change fuel filters in a timely manner, and problems with injectors will occur much less frequently. Good luck on the road!

Although modern diesel engines are becoming more and more complex, the Common Rail system appears to be technically even simpler than the previously used mechanical injection pump systems. Ultimately, the Common Rail system completely replaced competing solutions from the market, for example, with unit injectors.

Various concepts.

Several types of Common Rail systems are used in passenger cars. Simplistically, they can be divided into two types (electromagnetic and piezoelectric) and four manufacturers (Bosch, Continental, Delphi, Denso). Bosch, Delphi and Denso are renowned manufacturers of automotive electronics. Bosch has been developing injection systems at the very beginning of the last century. Delphi bought diesel injection technology from Lucas. The Japanese Denso has gained experience working with Bosch and Magnetti Mareli. Continental acquired Siemens and VDO, becoming the main competitor of German Bosch. The injectors of this company have been marked with the Continental emblem for about a year, previously they bore the Siemens logo.

The most versatile is the market leader Bosch, which produces both types of injectors: electromagnetic and piezoelectric. On a much smaller scale, both types of injectors are produced by Delphi and Denso. Continental (Siemens) is exclusively limited to piezoelectric technology.

Each sandpiper praises its swamp.

In advertising brochures, each manufacturer praises their product as the best solution. As you may have guessed, in practice, many of them often have a number of shortcomings. The simplest design is provided by Bosch electromagnetic injectors. Repair of German injectors is not difficult. Delphi wanted to go further and developed a much more sophisticated control system for its solenoid injectors. As a result, his product turned out to be the most sensitive to fuel quality and, unfortunately, not very durable. Among the electromagnetic injectors, Denso is considered the most reliable, but there are difficulties with the availability of spare parts for repair. The most balanced are the piezoelectric injectors designed by Bosch and Siemens (Continental), and also partly by Denso. The injectors are similar to each other, both technically and in terms of reliability. Only Delphi stands out from this group, whose piezo injectors were reputed to be less hardy throughout the entire time.

Whose injectors can be repaired?

From the point of view of the possibility of repair, turbodiesels with classic Common Rail injection from Bosch are most preferable. Almost all specialized centers can handle the restoration of this type of injectors. But the end result depends on the diligence and honesty of the master. Delphi electromagnetic injectors are also repairable, but require replacement of the tip and injector coding after repair. This increases the cost of repairs, but without coding, the engine will run intermittently. Denso solenoid injectors are among the most durable, but repairs are only possible with spare parts available. But with this, just not all is well.

Delphi and Bosch piezo injectors are considered non-repairable. In the case of Siemens (Continental), injection tips have appeared, allowing you to change the size, which allows you to restore the injector to work. However, this only applies to some models with PSA 2.0 HDI 16V engines. Various modifications of this turbodiesel are used in Ford Mondeo IV, Focus, Galaxy, S-Max and Volvo S40, S60 cars.

What to look for?

The advantages and disadvantages of injectors should be known even at the stage of choosing a car. Considering the risk of injector failure, two models with the same engine should be avoided like fire: Ford Mondeo III 2.0 TDCi and Jaguar X-Type 2.0 d. The injectors of the Mercedes E250 CDI W212 of the beginning of production also had congenital defects. The rest of the cars with Delphi injectors raises no objections. Some motors allow the use of injectors from different manufacturers.For example, the 1.6 HDi / TDCi engine had four different types of injection systems, with Bosch being the cheapest to maintain. The situation is similar with 2.0 HDi. Siemens (Continental) injectors can be refurbished, but Bosch piezo injectors cannot.

What you need to know about injectors Common Rail.

Bosch electromagnetic injectors.

They are disassembled and relatively easy to repair. The cost of restoring one injector is about $ 100-150 per piece. They can withstand 200,000 km. In Opel's 1.9 CDTi and Fiat's 1.9 JTD, the injectors are capable of surviving up to 500,000 km. The price of a new nozzle is about $ 250-300 per piece.

Alfa Romeo 159 2.0 JTDM, Fiat Punto 1.3 JTD, Kia CEE'D 1.6 CRDi, Mercedes C 220 CDI W202, Opel Vectra C 1.9 CDTI, Renault Laguna II 1.9 DCI, Volvo V70 D5, BMW 320d E46.

Delphi electromagnetic injectors.

Compared to Bosch, Delphi injectors are much more sensitive to fuel quality. They are slightly more expensive to repair - around $ 150-200 apiece - due to the need to code with a new tip. Average service life is 150,000 km. The cost of a new nozzle is about $ 250.

Dacia Logan 1.5 DCI, Ford Focus 1.8 TDCi, Renault Megane II 1.5 DCI Nissan Almera 1.5 DCI, Hyundai Santa Fe 2.2 CRDi, Kia Carnival 2.9 CRDi, Ford Mondeo 2.0 TDCi III.

Denso electromagnetic injectors.

Denso electromagnetic injectors are considered to be of the highest quality. Until recently, there was a shortage of spare parts, but nowadays most of them can be restored. The cost of repairs is about $ 150-250 per unit. The price of a new nozzle is about $ 450.

Mazda 6 2.0 CD, Nissan Pathfinder 2.5 DCI, Opel Corsa 1.7 CDTI, Mitsubishi Pajero 3.2 DI-D II, Toyota Avensis 2.0 D-4D.

Continental piezoelectric injectors (Siemens).

Previously offered under the Siemens name, and now Continental. They are durable, but until recently were considered non-repairable. Spare parts appear today, and some workshops take on repairs. The resource of injectors is more than 200,000 km. The cost of a new nozzle is about $ 350.

Citroen C5 2.0 HDi II, Mercedes C220 CDI W204, Volvo V50 D4, Peugeot 207 1.4 HDi.

Bosch piezoelectric injectors.

They are found in many modern cars and are structurally very similar to Continental injectors. They also have a similar resource - more than 200,000 km. Unfortunately, they are not repairable. New ones cost about $ 300.

Audi A6 3.0 TDI, BMW 320d E90, Nissan Qashqai 2.0 DCI, Skoda Octavia III 2.0 TDI.

Denso piezoelectric injectors.

They are quite reliable, but not collapsible and therefore cannot be repaired. They are used in a small number of cars. Most often they can be found in Lexus and new Toyota models. The cost of a new nozzle is about $ 500.

Lexus IS 2.2D, Toyota RAV-4 IV 2.2 D-4D.

Piezoelectric injectors - Delphi.

The market is limited. Debuted with the Mercedes E250 CDI BlueEFFICIENCY in 2009 and started causing problems immediately. Later the design of the nozzles was changed.

Mercedes E 250 CDI Bluefficiency.

Injection system malfunctions Common Rail.

As a rule, the Common Rail injection system is able to hold out more than 200,000 km without any problems. But it all depends not only on the design, but also on the operating conditions. The least reliable and most sensitive to fuel quality are Delphi injectors. The first problems sometimes appear already at 140,000 km. The most hardy is Denso's products. Piezoelectric injectors from Bosch and Continental (Siemens), as a rule, can withstand more than 200,000 km. Bosch electromagnetic injectors serve the same amount of time.

Typical Symptoms of Injection System Malfunctions Common Rail:

- uneven engine operation;

- increased fuel consumption;

However, common rail malfunctions are not always the result of damaged injectors. The defect could overtake the high pressure pump, fuel pressure regulator and other sensors. In any case, the parameters of the injection system give an almost accurate answer to the question of the condition of the injectors.

What not to do in the garage.

It is possible to "examine" the system using a special diagnostic computer using the pressure parameters and the so-called "injector correction". Another easy way is to determine the amount of overflow. It is also possible to remove the nozzles for inspection or testing at the stand. Unfortunately, in some cases it is impossible to remove the nozzle - it sticks.

How to renovate.

Technical capabilities allow restoring all electromagnetic injectors (Bosch, Delphi, Denso). Limitations may be imposed by the availability of spare parts: valves, tips, coils, housings, etc.). In the case of Bosch, there are no problems. Slightly worse with Delphi components. And for Denso, the original components simply do not exist. There are only a small percentage of unofficial substitutes.The cost of refurbishment depends on the number of replaced elements and the manufacturer of the injectors. For Bosch, the approximate amount will be from $ 50 to $ 150 per piece, and for Delphi and Denso - up to $ 200-250.

Complete restoration of Bosch, Delphi and Denso piezoelectric injectors is not possible. All that is permissible is to remove the nozzle tip, rinse it in an ultrasonic apparatus and check the operation of the nozzle on the bench.

The situation is slightly better with some Continental (Siemens) injectors. Spare parts are available for individual injectors. The restoration cost is about $ 150.

Disassembly and repair of injectors should be carried out only by specialists of specialized services. Dismantling the nozzle itself requires a special tool. In addition, before and after parsing, it is necessary to check the operation of the injector on a special stand.

- checking the nozzle at the stand;

- dismantling and flushing of elements;

- troubleshooting and replacement of necessary parts;

- adjustment and assembly of the nozzle;

- measurement of parameters after assembly;

- assignment of an individual code, taking into account the characteristics of a particular instance (for some injectors).

Only after the regeneration process and the elimination of related malfunctions (for example, sediment in the tank or chips from the pump in the system), the nozzles can be installed back into place. Along the way, the fuel filter and copper washers under the injectors must be replaced.

Undoubtedly, the best tool for this is an injector test stand, which can be the most complicated electronic one for thousands of dollars and very simple, even primitive in the spirit of the fifties (Fig. 7) or even home-made (Fig. 8).

Any of them, with a greater or lesser degree of convenience, can be used for work. There are many diesel garages and stands in the country, although they have the simplest ones. And we know how to negotiate. But what if your diesel is the only one in the area? Not very scary efforts need to be made to make a homemade stand from a decommissioned tractor-KAMAZ or marine pump or to adapt the injection pump of your engine to check the injectors. Certainly not the most beautiful way, but without fish.

To do this, you need to make a tube - a tee, which at one end will be connected to one of the high-pressure fittings of your high-pressure fuel pump, on the other end we will attach the nozzle, and on the third - a 200-300 atmosphere pressure gauge (maybe more). First, we turn the engine with a starter until the nozzle starts firing, and then, remembering to leave the ignition on, manually. It is agonizing of course, but if there is no other way out, it is quite possible.

About injector opening pressure

During the compression stroke, the air charge from the cylinder flows into the combustion chamber at a very high speed. At the same time, due to its shape, a directed vortex appears in the combustion chamber, into which fuel is injected. Depending on the design of the combustion chamber and the degree of compression, the speed and shape of the vortex is different, therefore, there are different types of atomizers and different values of the fuel injection pressure. Designers set recommended as well as allowable injection pressures for each engine. As a rule, these values must be observed with an accuracy of 5-10 kg.cm2 within a set of nozzles. When the nozzle is overhauled, it makes sense to set the injection pressure by 10-15 kg.cm2 more than the required one, in the expectation that in the very first minutes of the nozzle operation there will be some shrinkage of the moving parts and, accordingly, a decrease in the set pressure.

It is especially necessary to note the specific property of the rotary-type distribution fuel pumps of the LUCAS company - very strict requirements for the accuracy of the injection pressure regulation within the set of injectors.For reference, in engines with such fuel pumps, it is often impossible to find a faulty injector using the shutdown method. The engine will immediately stall due to the cessation of fuel supply to the remaining injectors.

How to adjust the opening pressure of the nozzle at home

In the overwhelming majority of modern injectors, the opening pressure is regulated by adjusting the thickness of the spacer washer between the spring and the body. Decent workshops have sets of these washers to solve any adjustment problem. For amateurs, it should be borne in mind that washers exist of various diameters (for different nozzle bodies), and are available with or without a hole. Washers with a hole can always be used instead of washers without a hole, but replacement is not allowed. It is also unacceptable to use washers of "non-native" diameter.

As a rule, injectors are designed in such a way that an increase in the washer thickness by 0.1 mm leads to an increase in the injection pressure by 10 kg.cm2. It is very common to see when repairing injectors that, during previous interventions, the injection pressure was regulated using pieces of razor blades placed under a spring. This method of adjustment is completely unacceptable. First, with an uncontrolled backing, you create uncertainty in the spring support and thus non-uniform spring production and provoke lateral force. And secondly, there is a risk of chipping a piece of the blade and no one knows what he will do inside the nozzle. Therefore, the only qualitative solution to the problem is the manufacture of new shims of the calculated thickness. And only in those cases when the lathe, heat treatment and grinding are absolutely inaccessible, it is permissible to regulate the pressure with steel foil washers, placing them only between the body and the standard washer. If your spring rests on an unhardened lining, then after a short time, little will remain of it.

A typical problem with Japanese injectors

A distinctive feature of the injectors of Japanese engines is the return flow through the end face of the injector into a special ramp. Careless disassembly often results in deformation of the nozzle sealing end, which is why it is not possible to achieve a hermetic “return” seal. "Experiments" begin with tightening the ramp nuts, with the setting of sealing washers under the nuts, etc. However, the only way to solve this problem is only to undercut the sealing end of the nozzle on a lathe. However, it should be borne in mind that only one surface of the nozzle is corrected by facing, and the shape of the groove at the end may be deformed so much that the sealing washer can no longer overlap it. This nozzle must be replaced.

Indefatigable attempts to tighten sweating or flowing return lines often lead to deformation of the return manifold flanges. Seals cannot be achieved with such flanges and must be refurbished. It is not difficult to do this by hand on a small sanded tile with sandpaper on top.

Video (click to play).

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