NL Generator/ governor issue

[doc g]

I have a 20 kw NL 1984 , M854 that has a four cylinder Alaska engine. It overspeeds as the load is reduced. I have tried to adjust the gov and it can't be adj'd to keep it from overspeeding. It will also lag and drop rpm as the load increases. I have cracked the injector lines and all cyl's are firing equally. It has a Bosch type injector pump /gov ass'y on it. What say the experts?? Any help greatly appreciated!!! ............Pat

 

[Avenger]

Did this problem develop suddenly? How many hours on the unit? How much does the RPM (Hz) change?

 

[doc g]

Not suddenly. The unit has 3300h on it . I don't know how much it goes up but sounds like its turning over 2200-2500 rpm,it will lag also if loaded. I set the rpm to 64 hz and it will lag to 54 hz if I load it more than 50%......Pat

 

[Avenger]

I looked at NLs website to see exactly what type of pump/governor you have and I can't find info for a M854. They have an 844 and an 864 each has a very different governor.

First thing I would check is to make sure the throttle is solidly locked. Then make sure you have no fuel supply issues. Clean filters, good pump etc. If you can tap a pressure gauge into the injection pump inlet that would be the best way to validate fuel supply under load.

 

[doc g]

the throttle is definately locked. I would assume that if the lagging was due to a lack of fuel it would not be able to overspeed either or is that incorrect? I looked at the NL website and rechecked model is M854a . looked at 844 also on NL . The pump I have does not look like that . I could not open the 864 files for some reason......Pat

 

[Avenger]

You stated that you set the RPM to 64 Hz... Will it stay where you set it if you don't load it or does it try to take off? Also, is there any exhaust smoke at any point?

 

[doc g]

I dont know if it will just stay where it's at no load . No smoke at any point . I am starting it now to see if it's going to stay at 64 hz....Pat

 

[Timm]

I've received great tech support in the past from the folks at Alaska Diesel in Seattle. Give them a ring.

Corporate Headquarters, Seattle, WA
4420 14th Avenue N.W. | Seattle, WA 98107
Tel: 206-789-3880 | Fax: 206-782-5455
Toll Free: 1-800-762-0165

 

[doc g]

I can start it cold sometimes it will overspeed sometimes not....

 

[Avenger]

So if it starts and controls it runs fine, carries load etc.?

 

[doc g]

I ' ve been mesing with it . If I unload it quickly it will overspeed every time.

 

[Avenger]

Honestly, most of what you're describing sounds like the governor is coming apart, but since I can't see it from here I'm hesitant to condemn it. However, unless there's an outside fuel source or linkage problem I would be hard pressed to think of any other reason for the overspeeding you're seeing.

 

[doc g]

Thanks for all your help. I will check fuel and linkage issues , but I think the gov is messing up too. I was just watching the hz meter anywhere from 58-64 and the speed of the enhgine is all over the place too.I will follow up later. Thx again. ......Pat

 

[Avenger]

Check your PMs

 

[Pascal]

"I was just watching the hz meter anywhere from 58-64 and the speed of the enhgine is all over the place too."

that's normal since Freq is directly linked to RPM. If the governor acts up and RPM varies, Freq will follow.

3300 hrs isn't that much, but at this point you may be better off getting the injector pump rebuilt. right, now I'm have injector pumps checked on a pair of 2002 NL20s (M844) with 3500hrs as one was starting to leak diesel into the crankcase and the other was developing a small leak outside the pump

 

[Canuck Dennis]

A possible tip when replacing re built injector pumps, smear the casing and internals of the crankcase housing adjacent to the pump body with regular grease, apparently it helps to prevent moisture getting into moving parts of the pump, that's the recommendation after my bosch pump broke a spring in the piston bore.

 

[REBrueckner]

I like SCROD's suggestions....Be sure to play with the governor/speed linkage by hand.....easier with the generator off...a worn linkage bushing and resulting loose linkage might cause such a problem....

Very often if you look cloosly, especially with an auxiliary light aid, you can find some simple mechanical weakness/worn part/loose part....if not, maybe time for some professional help.