Hyundai Man DG 820 KW

Hello folks,

I have a question for you. I work on a ship which has 3 DG Hyundai Man 820 Kw each. The problem is that, when the DG is started but not conected into MSDB, after a few minutes, its showing the alarm temperature deviation on random cylinders, but this problem its appearing only when the DG is running on iddle. When its been connected on MSDB this problem dissapears. Anyone know why this problem appears ? Thank you so much!

The chief engineer asked me this and i could not aswer correctly.

Perhaps a low temperature limit alarm setpoint is very close to idling EGT?

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I’ve seen this on DGs running on heavy fuel. Only one DG or all of the units? New problem or has this been the case since delivery? Did you recently switch onto a new batch of bunker fuel? Low load=low fuel flowrate so is the fuel temperature AT THE ENGINE INLET the proper temperature (aka viscosity) for the fuel in use? How many hours since the affected unit(s) had their injectors serviced?

Do the local thermometers correlate to the digital readouts from the thermocouples? Has anyone recently attempted to zero and span the thermocouples (and maybe did it incorrectly)? What is the deviation setpoint in your AMS? Does that setpoint correspond to what the manual says it’s supposed to be?

Lastly, I’ve been on ships where the EGT deviation alarms are offscanned at low engine loads so if you do all this troubleshooting and find no problem, maybe the CE and company technical superintendent might look into making that change in the AMS.


Running smoothly on idle and very low loads is difficult for medium speed engines. Most of the turbocharging/inlet air flow dynamics are targeted towards efficient operation at full or near full load. Likewise with the fuel injection system. At idle the amount of fuel being injected into cylinders is extremely small and thus very difficult to precisely meter. Tiny differences in these volumes can cause significant difference in cylinder load and thus cylinder temperature. Barring issues with temperature sensing devices themselves, I’d guess either the fuel injection pumps may need overhaul or the injection nozzles themselves should be checked/replaced.

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hawspiper and allgonquin i think nailed it. That looks like a deck suit you’re wearing in your avator? (so is the cme testing you?) … I see a huge potential for humor here, You don’t have a prob with the plant … yet!!