20kw Northern Lights Generator Maintenance

We recently posted about attending the Northern Lights training class taught by Lugger Bob.  Of course, after the class, the first thing we do is come home to Red Rover and look at our Luggers and our NLs equipment…  And see that our 20kw genset is in need of some maintenance!  We’ve put 490 hours on the generator over the 2.5+ years of ownership.  Our survey at purchase only found a weeping raw water pump, which was replaced in the fall of 2016.  What parts we did not have on hand were ordered and readied to be installed.

Here is the list of items that were replaced or completed:

  • Raw water pump
  • Coolant pump
  • Coolant hose (removed hose appears ok, kept as spare)
  • Exhaust elbow
  • adjusted valve clearances
  • Belt (removed belt appears ok, kept as spare
  • Coolant temperature sensor
  • Replaced secondary fuel filter
  • Replaced the old clear coolant overflow hoses to black rubber hoses
  • Replaced coolant
  • Added a Start/Stop switch to the generator sound shield

Most of the images below show the telltale signs that caught our eye.  After learning what to look for, the issues were quite obvious!

Shot of the genset from the side
Front angle shot of the genset.
Raw water pump.  Water was leaking from the shaft seal down to the intake hose
Coolant pump.  The weep hole shows the leakage of coolant.  Appears to have been leaking a while.
Coolant pump after removal
Raw water pump removed.  I used a pulley puller to extract the gear off of the shaft.  I also had enough extra intake hose to cut an inch off of the end.
Genset with the coolant pump removed.  I also replaced the coolant hose shown in the photo.
Looking through the heat exchanger.
I cleaned this up a bit before reinstalling.


I first felt behind the exhaust elbow with a finger and it came back rusty.  The mirror shot shows the rust spot and the pinhole leak.
Elbow after removal.
You can see the buildup of the carbon where the pinhole leak was.
Inside of the brand new elbow.  Nice and clean!
Backside of the genset with elbow and air cleaner box removed.
Valve cover off and ready to make some adjustments.
Shot of head straight down.
An item that we wanted to add was a start/stop switch at the genset.  Currently we need to start the generator at the panel in the pilothouse.  Now, during maintenance, I don’t need to leave the engine room to wrap thing up.  I sourced the Y harness and switchplate direct from Northern Lights.  It was a plug and play operation.  The “difficult” part of this project was cutting the hole in the sound shield.


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