DLLA152PN269 Common Rail Diesel /Fuel Injector BOSCH Injector Nozzle

Inspection and Replacement of Injector nozzle

The needle valve coupling is also called the injector nozzle coupling. It is composed of a needle valve and a needle valve body to form a high-precision coupling. After being ground in pairs, it is not interchangeable. The main fault of the needle valve assembly is that the nozzle hole is clogged and the seal is not tight.

1 Technical appraisal method

(1) External observation method. The technical status of the fuel injector assembly can also be judged from the quality of the fuel atomization. After adjusting the injection pressure, when there are fog spots or oil lines with uneven thickness in the spray, it is generally the fuel injector. The coupler is severely worn; when the oil mist is unevenly distributed or the center line of the oil line is skewed, it indicates that the nozzle hole is not clean; when there is oil dripping after spraying, it means that the sealing cone of the needle valve is not tightly sealed.

(2) Sealing test. Adjust the fuel injection pressure of the fuel injector to be 3-5MPa higher than the normal pressure, and check the time elapsed when the fuel pressure drops from 20Pa to 18Pa, which should not be less than 9-12s.

2 Precautions for replacement

The replacement of the injector assembly should be carried out in the following order and method: (1) Remove the injector cap and lock nut, and loosen the adjusting screw. (2) Take out the spring, spring seat and ejector pin in sequence. (3) Clamp the fuel injector housing on the vise, unscrew the tight cap of the fuel injector, and remove the fuel injector. (4) Clean the disassembled parts in clean diesel oil, and check whether the parts are intact or not. It is required that the ejector rod is not bent, the steel ball of the ejector rod is not round or peeled off, and the contact surfaces of the shell are smooth and free of rust marks. (5) Flush the new fuel injector assembly in diesel oil to remove anti-rust oil and make the oil passage, nozzle and oil chamber unblocked. (6) The assembly steps are opposite to those of disassembly. When installing the injector assembly, it is absolutely not allowed to carry out under the pressure of the spring. (7) Tighten the cap according to the specified torque, then put the ejector rod, spring seat, and pressure regulating spring into the shell in turn, and screw on the adjusting screw. Adjust the pressure on the nozzle tester, and then lock the tight cap after passing the test.