Contents: Visual inspection 🠛 Needle movement analysis 🠛 Checking injection pressure 🠛 Checking for leaks 🠛
Fig. 3.14. Location of the injector and glow plug in the pre-combustion chamber 1 - nozzle; 2 - nozzle assembly with sprayer; 3 - injector sealing ring in the cylinder head; 4 - flameproof washer; 5 - spray nozzle protective cap
- Remove the injector housing.
- Secure the injector body in a vice with the jaws covered with soft material.
- Disassemble the injector body and remove all parts, placing them in the order of removal.
Attention. The needle and the injector body are matched in pairs with high precision. This precision of processing requires careful handling. i.e. it is not recommended to touch them with hands that have traces of oil, fuel or caustic substances, as this will lead to microscopic corrosion of their surfaces.
- Check the condition of the injector parts.
- Assemble the injector in the reverse order of disassembly.
- Install the injector onto the cylinder head.
Visual inspection
Visually inspect the injector for the following defects:
- deformation of the needle locking socket or presence of roughness on its surface;
- wear or damage to the fuel injection channel;
- parallel marks or indentations on the needle;
- traces of cavitation on the needle;
- fuel injection channel ovality;
- excessive heating of the injector body;
- injector wear.
If there are any defects or damage to the parts, replace the injector.
Needle movement analysis
- Clean the injector parts in diesel fuel.
- Dip the needle into clean oil and insert it into the injector body.
- Remove the needle from the injector body by 2/3 of its length.
- Release the needle, it should move back into place, otherwise replace the nozzle.
Checking injection pressure
Caution: When checking the operation of the fuel injectors, never place your hands or any part of your body in the jet of fuel coming out of the injector. Fuel comes out of the injector under high pressure and can penetrate the skin and cause serious injury.
- Install the nozzle on the test pump.
- Create pressure with the pump and determine the opening pressure of the injector.
- If the injector opening pressure does not correspond to the required one, correct it by replacing the adjusting washers in the injector body.
Checking for leaks
- Install the nozzle on the test pump
- Create a pressure of 120 bar and maintain it for 30 seconds, while no fuel should leak from under the needle.
Note: On vehicles with G8T 714 engines, the opening pressure of the injector with the needle displacement sensor is not adjustable. If the pressure differs by more than 8 bar, replace the injector.