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Generator question: soaked windings

Discussion in 'Technical Discussion' started by Danvilletim, Feb 10, 2019.

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  1. Danvilletim

    Danvilletim Senior Member

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    Location:
    isleton, ca
    I got some news about one genset and I just wanted to bounce of the collective wisdom. We have a 50kw Kohler w John Deere power that has been shutting off randomly after an hour or two. We’ve been chasing this problem for months. Latest diagnosis is leaking main seal that is soaking the windings with oil. I’m not there but I think this part is true. Theory is that windings/ stator get overly hot and throw a fault.

    Question. What’s most reasonable means to fix? We have to unbolt the backend and change the seal. But does the windings need to come off the boat or can they be cleaned in place? If they are to get sent out, what should I look for? I think the backend weighs close to 600 pounds. So will have to move the boat to a yard and boom or crane it off.
  2. Capt J

    Capt J Senior Member

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    Does the generator have a lot of hours on it? Generally if it does, the rear main seal went bad, because the main bearings have a lot of wear and the crankshaft is bouncing around and eating up the rear main seal. You may get away with changing the rear main seal and having it last for a while. I would absolutely take the back end off of the generator and boat. You may be able to clean it thoroughly of oil with brake cleaner, but chances are the windings are sacrificed and they and the stator need to be replaced. You may consider, if it's a high hour generator, of just replacing the entire thing or at the very least rebuilding. I don't like rebuilding 20 year old + generators as technology has changed a lot, and all of your castings are 20 years old and generally even after rebuild, things still break on them, sometimes with catastrophic results and you're just pissing good money after bad.
  3. MBevins

    MBevins Senior Member

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    What J said, also you can take the stator to any industrial motor rewind shop, they can wash it and put it in the oven to dry it out. Worst case they could even rewind it, however that is becoming less and less cost effective.
  4. Danvilletim

    Danvilletim Senior Member

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    Good input guys. Plan is to take to Southern Armature. Anyone used them?
  5. Capt J

    Capt J Senior Member

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    No, but they've been around for a long time.
  6. Capt Ralph

    Capt Ralph Senior Member

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    We have used Broward Armature forever. I did not know about any another shop.
    Even if there is another shop, I will keep using these kids.
  7. Capt Fred

    Capt Fred Member

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    I would invest in more trouble shooting before I would remove and repair/replace. I'm not an expert but hard to believe the oil is causing the problem, could be a bad sensor or whole host of other issues. Generally there is a pass for the oil to get out between the motor and genset before it soaks the generator windings. If there is that much oil getting to the armature then I would think it is slung everywhere. Not trying to argue but provide an alternate train of thought.
  8. chesapeake46

    chesapeake46 Senior Member

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    If the windings are not damaged , you can get away with a " clean, dip and bake" . Relatively inexpensive.
    The motor shop would bench test this to see if the windings stand up to an insulation test.

    If the windings are really saturated with oil, that oil will degrade the winding insulation over time and cause more problems. If it's really saturated, you prolly need a clean dip and bake at least.

    I replaced my 30+ year old genny last year because it began to dollar me to death and the parts were scarce to non-existent. It was obsolete and it was time to go. It had about 3600 hrs on it at the time.

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