6 kinds of common faults and 8 maintenance points detailed explanation for diesel engine injectors

With its own advantages, the diesel engine is gradually becoming an increasingly popular choice for more and more car owners in the car market. With the natural wear and tear and other reasons during the use of diesel engines, injectors can have different types of faults. Today we take a detailed look at the common failures of injectors and maintenance points.

Common injector failure and impact

(1) Poor fuel injection atomization

When the injection pressure is too low, the spring end wear or spring elasticity is reduced, the injector will open early, delayed closure, and poor spray atomization phenomenon, resulting in diesel engine power down, insufficient combustion and exhaust smoke.

(2) Seal failure, exhaust white smoke and accompanied by gunfire sound

When the injector is working, the sealing cone surface of the needle valve body will gradually appear scratched or pitting due to the frequent strong impact of the needle valve and abrasive wear, with the cone surface contact width increases, thus causing the sealing failure and making the injector drip. When the temperature of the diesel engine is low, the exhaust pipe has the phenomenon of white smoke; when the temperature of the diesel engine is high, the exhaust pipe in addition to black smoke, but also from time to time to issue a discharge sound. At this time, if you stop supplying oil to the cylinder, the exhaust smoke and the sound of firing will disappear quickly.

(3) Needle valve jammed, can’t inject oil.

Diesel fuel in excess of water or acid will make the needle valve is stuck due to corrosion; when the needle valve sealing cone surface is damaged, the combustible mixture in the cylinder will also scurry with the surface and form a coke, so that the needle valve is stuck, the injector cannot inject oil, resulting in the cylinder to stop working.

(4) Internal leakage, injection time, start difficulty

When the needle valve in the needle valve hole for frequent reciprocating motion, if the diameter of diesel impurity particles is too large, it will make the needle valve hole guide surface gradually wear, resulting in an increase in injector leakage, pressure drop and injection time to extend, resulting in diesel engine start difficulty, increased vibration at work.

(5) Injector and cylinder head with the combination of the hole leak, oil scurrying

If the injector in the cylinder head mounting holes in the coke, copper gaskets are incomplete, uneven, asbestos sheet or other materials instead of copper material, or gasket thickness cannot ensure that the injector out of the plane of the cylinder head, will cause poor heat dissipation or cannot play a sealing role, resulting in a combination of injectors and cylinder head at the hole in the leak, scurrying oil.

(6) Black smoke

As a result of high pressure diesel continued to jet erosion, injection nozzle hole will be due to gradual wear and increase, resulting in a drop in injection pressure, shortening the injection distance and uneven mixing of combustible mixture, which makes the diesel engine smoke phenomenon, cylinder carbon will also increase.

The use of fuel injector maintenance points

(1) Improve the installation location of injector pads

Due to the metal working at high temperature conditions are most likely to wear, and shaft needle injector and hole injector nozzle into the combustion chamber, most of the surface directly with the gas contact, suffer high temperature, high pressure gas baking, which is caused by injector needle valve cone surface and needle valve guide surface wear of the main reason. For the shaft needle injector, in order to avoid the injector as a whole by gas baking, can be installed in the head of the injector with an appropriate thickness of copper gasket; for hole injector, can be installed v-shaped cushion, v-shaped cushion should be designed to make the outer diameter as large as possible, so that the inner hole as large as possible under the small, in order to replace the injector when the disassembly and prevent gas intrusion.

(2) Periodic inspection, adjustment of injectors

The injector should be checked and adjusted once every 700h or so. If the opening pressure is lower than the specified value, the needle valve should be removed, put into clean diesel fuel with wood or copper scraped off the coke, with a thin wire to unblock the spray hole, after installation and then debugging. Require the same diesel engine on the injection pressure difference between the cylinders must be less than 1 MPa.

(3) Regularly check and adjust the advance angle of fuel supply to the injection pump.

In order to make the injector into the cylinder of diesel fuel can be mixed evenly and completely combusted, must be regularly checked, adjust the size of the injection pump fuel supply advance angle. If the fuel supply time is too early, will make it difficult to start the diesel engine, appear knocking cylinder, vibration increase failure; If the fuel supply time is too late, will lead to exhaust pipe smoke, machine temperature is too high and fuel consumption rise and other adverse consequences.

(4) According to the season oil change, regular maintenance diesel filter

Because of the needle valve even parts of the precision is very high, and injector hole diameter is very small, which must be in strict accordance with the seasonal changes in the selection of the provisions of clean diesel fuel, and to regularly maintain the diesel fuel filter, often discharge the filter and fuel tank in the precipitation oil, in order to prevent dust, impurities and accelerate the intrusion of the needle valve even parts of the wear and tear.

(5) Carefully clean and replace the needle valve even parts

Replace the needle valve even parts, the needle valve even parts should be first put into 70-80 ℃ hot diesel soaked in 10min, – and then in the ‘clean diesel in the needle valve in the valve body back and forth pumping, in order to thoroughly cleaned. This is the good way to effectively avoid the failure of the needle valve sticking due to the melting of anti-corrosion oil when the injector is working. In addition, when cleaning the needle valve even parts, do not touch with other hard objects to prevent the needle valve guide surface from being scratched.

(6) Avoid needle valve jammed

When loosening the high-pressure pipe joint, if you see a lot of bubbles or oil froth out, then the needle valve has been stuck in the open state, so that the cylinder compression of the compressed gas produced by the injector back into the high-pressure oil. At this time, if you touch the high pressure oil pipe, you can’t feel the diesel pulsation or pulsation is weak. If the needle valve is stuck, due to the existence of particles in the oil and injectors have residual iron end, will lead to the cylinder injector work bad or not work. At this time, the needle valve should be re-cleaned and assembled even parts.

(7) Ensure that the diameter and size of the injector hole meet the technical requirements.

If it is determined that the injector injection pressure is not enough for the expansion of the hole caused by, for single-hole injector shaft needle, can be put in the hole end of a 4 – 5mm diameter steel ball, with a small hammer gently knocked, so that local plastic deformation of the hole and reduce the aperture; for multi-hole direct injection injector, because of its many holes, small diameter, only with a proprietary punch in the Tap lightly on the end of the hole. If the installation still cannot reach the technical requirements, the needle valve should be replaced even parts.

(8) Avoid long time overload operation of diesel engine.

Diesel engines should be avoided for a long time overload operation, to prevent overheating of the body and the injector needle valve even parts jammed. For long-term storage of diesel engines, the injector should be removed and immersed in clean diesel fuel to prevent the needle valve corrosion and cannot be flexible to open and close.

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6 kinds of common faults and 8 maintenance points detailed explanation for diesel engine injectors

Common injector failure and impact