The nozzle is used to inject and atomize fuel supplied to the diesel cylinders.
The MMZ 245.12 diesel engine uses a closed-type nozzle with hydraulically controlled needle lift
The injector is strictly fixed relative to the combustion chamber and is bolted to the cylinder head
The diesel engine is equipped with injectors (part no. 17.1112010-01).
The injectors are marked on the body.
The nozzles are installed with a spray nozzle mod. 145.1112110 or Motorpal (Czech Republic).
The use of other models of sprayers is not permitted.
The injector is a vulnerable unit of the fuel supply system.
Violation of the seal between the conical surfaces of the sprayer body and the needle, loss of needle mobility; a decrease in fuel injection start pressure, deterioration in atomization quality and an increase in atomizer throughput due to wear of the nozzle holes are the main defects of injectors
The functionality of the injectors must be checked during vehicle maintenance.
It is recommended to evaluate the performance of the injector on test benches at a frequency of full strokes of the lever of the manual test device of 60-80 per minute.
In Fig. Figure 2 shows a device for monitoring injector nozzles and adjusting injection pressure mod. "Motorpal" NS 50.
When using the KI-9917 device, you can check the start of fuel injection by the injectors without removing them from the diesel engine.
Regulation of the pressure at the start of fuel injection is carried out by rotating the adjusting screw 5, having first unscrewed the cap and loosened the lock nut 4 (Fig. 1).
The pressure recorded at the start of fuel injection should be 21.6-22.4 MPa;
After adjustment, tighten the locknut and cap. Tightening torque - 80-100 Nm.
The quality of fuel atomization should be checked using an adjusted nozzle.
It is considered satisfactory if the fuel is atomized to a mist-like state and distributed evenly across the cross section of the jet cone from all five nozzle holes.
Abundantly flying drops, continuous jets and condensations are not allowed. The beginning and end of the injection must be clear.
Fuel leakage from the nozzle after injection is not allowed.
The tightness of the locking cone of the spray needle must be checked by creating a pressure in the nozzle that is 1.0-1.5 MPa less than the injection start pressure.
The tightness is considered broken if, within 15 s, the fuel flows down in drops and forms an influx visible to the naked eye on the nozzle of the atomizer under the nozzle holes.
If fuel leaks or the needle gets stuck, the atomizer must be replaced or repaired.
If the nozzle holes become coked, disassemble the nozzle, rinse the sprayer and clean the holes.
It is recommended to clean the nozzle holes with steel wire with a diameter of 0.3 mm.
Before assembly, the atomizer and needle, which are a precision pair, must be thoroughly washed in clean gasoline and lubricated with filtered diesel fuel.
To check the smooth movement of the needle in the spray body, it should be pulled out of the body by one third of the length of the guide surface.
When the sprayer is tilted at an angle of 45°, the needle should smoothly, without stopping, completely lower under the influence of its own weight.
Disassembling the injector must be done in the following sequence:
- - unscrew the cap 3 (see Fig. 1) and loosen the lock nut 4;
- - turn out adjusting screw 5 2...3 turns, thereby weakening spring 6;
- - unscrew the sprayer nut 10;
- - remove sprayer 11.
Failure to follow the disassembly procedure may result in breakage of the pins centering the sprayer.
Before installing them in the nozzle, new nozzles must be re-preserved by washing them in gasoline or heated diesel fuel.
Assemble the nozzle in the reverse order of disassembly. The tightening torque of the sprayer nut is 50-70 Nm.
After assembly, you need to repeat the injector performance check in the sequence indicated above. During assembly, it is necessary to replace the sealing gasket 12.
When installing injectors on a diesel engine, their fastening bolts must be tightened evenly in 2 - 3 steps. The final tightening torque is 20...25 Nm.