Replacing GenSet Cylinder Head Part I

  In the previous installment of our maintenance series, we diagnosed lack of power output on a Northern Lights M843NW3.3 12KW generator with 6,700 hours of use over 10 years. We concluded the #3 cylinder exhaust valve seat had failed.

In this second part of the series covering the low power output issue with our generator, we first have a look at the parts ordered to complete this service operation and then remove all engine components above the engine block to confirm the diagnosis and replace the cylinder head.



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10 comments on “Replacing GenSet Cylinder Head Part I
  1. Roby Bedford says:

    I loved part 1 of the generator head replacement. I was moving on to part 2 and then found myself in a “Netflix” hole. Can’t wait to see how it turned out.

    • Thanks for the feedback. Part 2 got delayed by us being in the boat yard getting some work done but that work looks like it’s going to be complete today and we’ll probably be put back in the water tomorrow so should again have some time again soon.

  2. Chris Jones says:

    Hi James, Loved your latest video! I noticed your nice tool roll. Do you remember where you purchased that? I’m in the process of looking for something similar.

  3. Tim Connolly says:

    If it wasn’t for COVID I would be there! We’d have to fly my buddy Gary as well as he is the mechanical engineer and I am the Electrical. He had a fascinating career directing the test of new military aircraft for McDonnell Douglas. I never knew how much aircraft wings could flex until he showed me tests for the P-3. Yikes!

    So I trusted him when he said “We can lift that generator”.

    Funny, at first, I had the same overhead restriction of about 12″ but then I removed a ceiling panel and found another 5″ once I removed the insulation and another floor strut. Gave us just enough for the smallest chain lift I could find with sufficient capacity.

    I labeled the plug in the galley floor as “Generator Lift Access” so it looks like a feature, not a hole in the floor for future owners. :>)

  4. Tim Connolly says:

    Thoroughly enjoyed the video! Jennifer is an expert at reading my mind and asking just the right questions.

    This past winter I lifted my generator as the “pan” looked to be in bad shape. We considered making an “A-Frame” to lift but just did not have clearance. So got creative and came at it from above. Drilled a hole in the galley floor (much to my wife Dianne’s consternation…) and dropped the lift ring though a 4×4 directly above the genset lift ring. Then used a chain lift to pick-up the generator. Worked great and I found nice teak wood plugs to fill the hole. (Thankfully or I would still be in the doghouse.)

    Put this album together for a friend. Maybe some ideas for your upcoming oil seal adventure

    Also, saw that you are heading in the Milwaukee tool direction. I started same thing a couple of years ago. Favorite and one to put on your wish list is the power ratchet…super time saver and perfect for tight spaces.

    Looking forward to Part 2!

    • Thanks for the tips on the oil seal change. I’m not sure how I’m going to lift the generator but probably won’t go up through the salon floor as much as I like the expediency and safety of taking that route. The set of pictures you sent was useful. I like your approach of using tin foil as a paint mask. Nice approach. For us the biggest challenge is the height between the top of the generator at the ceiling is only 8 to 10″. Not much room for the lifting equipment and there still be room to do the lift.

      My thinking is to hold off in doing that job until later in the year. I’ll just put up with the flinging oil until later in the year when we less on the go.

      Thanks for the suggestions. By the look of what you accomplished on your job, I need to talk you into flying over to Scotland for a quick bit of work on a slightly smaller generator.

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