Detection of Injector Nozzle Wear: Advanced Combustion Engine Measurement and Analysis

During a planned inspection on our customer’s Auxiliary Engine; MAKER: DAIHATSU, TYPE: 6DK20, OUTPUT: 900 kW, RPM: 900.

We identified several issues. One of these issues involved significant wear on the injector nozzle tip, which was discovered through vibration and combustion pressure measurements.

Our Service Engineer performer vibration and combustion pressure measurements on the Auxiliary Engine cylinder head (Fig.1) at approx 80% load.

Analysis and Inspection

After transferring all the measured data it was quickly recognized that there was an issue (Fig. 2).

It is clearly seen that the High-frequency vibration trace (Red line) near the TDC (0°) corresponds to the working of the fuel injector. In a normal working injector, these vibrations are much higher and have a specific pattern. Additionally, we observed that the pressure curve after TDC is tilted. Further data such as indicated power, and peak pressure angle, also pointed toward a problem with the fuel injector. It is worth to mentioning that Pmax and exhaust gas temperature from this unit were within limits and balanced.

A recommendation was made to check and clean the nozzle tip and to verify the fuel injector opening pressure.

Feedback and evidence of Fuel injector condition.

The crew sent us positive feedback and photos of the injector (Fig. 3).

n Fig. 3 we can see that the injector nozzle has some carbon deposits on it, which could explain the weak vibrations and low indicated power. Additionally, the crew reported that the injector opening pressure was below normal. After cleaning, overhauling and readjusting the injector was reinstalled.

Conclusion

ACE measurement and analysis of the Auxiliary Engine have demonstrated the importance of comprehensive vibration and combustion pressure analysis.

This example illustrates that determining Engine conditions solely based on Pmax and Exhaust gas temperature can be challenging. Advance Combustion Engine measurement helps to prevent such situations and provides the opurtunity to expend the life of Engine components.

Thanks to ACE, the crew saved time –  there was no need to extract and check all of the injectors.