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Westerbeke drops RPM's after an hour

Discussion in 'Sea Ray Yacht' started by 55 Sea Ray R, Jul 15, 2019.

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  1. 55 Sea Ray R

    55 Sea Ray R Member

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    Guys I looked for anything like this and could not find so if I am duplicating I am sorry. I have a 15 KW Westerbeke in my 55 Sedan. It will start fine and run fine for around an hour loaded up light load etc does exactly what it is suppose to do. The nall of a sudden it will drop some RPM's and instead of putting out 230 it drops to 180 or less depending on the load. Completely unload it and the RPM's go back up and volts to 230. Load it and they drop. I have had a Westerbeke guy out and he said the back end is 100% ok but that is all he works on is the back ends governor functions as it is suppose to it is just an RPM loss. By any miracle has some one had the same issue I understand there is a speed sensor that might be the culprit. ? Thanks for any help.
  2. Pascal

    Pascal Senior Member

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    First, how old and how many hours are the primary and secondary filters? I always change BOTH filters whenever a genset shows sign of an issue under load

    If that doesn’t help, I would suspect the governor is acting up but I m not familiar enough with the WBs to suggest anything beyond that
  3. 55 Sea Ray R

    55 Sea Ray R Member

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    Thanks filters all fresh. It did the same thing a while back the guy fixed it and I forgot to ask what it was I know it was a speed sensor of some type.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Some of the Mitsubishi engines did have a speed sensor. Kind of like a tach pick up.
    It helped the engine keep rite on 1800 (1500) RPM for a perfect 60 (50) htz.
    In a worst case scenario with some imagination, I can see this (your fault) happening.
    BTW, what color is the exhaust smoke when this happens.
  5. 55 Sea Ray R

    55 Sea Ray R Member

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    No change it is like someone flips a switch and drops a few hundred RPM's almost instantaneous.
  6. CSkipR

    CSkipR Member

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    Its possible its the fuel pump. They are known to have weak fuel pumps after a few years old. Have you also checked the temperature, oil and exhaust temp switches with an ohmmeter?
  7. 55 Sea Ray R

    55 Sea Ray R Member

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    Thanks, exhaust temp oil all good. It runs perfect loaded up with 5 AC's for an hour then like someone flips a switch drops RPM's and volts go to 180. Next day it will do the same thing like clock work. One time I waited an hour and it reset. One thing my guy has found is the speed controller\ magnetic sensor was spliced when it was replaced last year which apparently is a big no no apparently it drops the ohms out of spec. he said it is definitely out of spec. and cheap connectors were used. My hope is that it is breaking down after a period of time and no longer sending the correct signal.
  8. Capt J

    Capt J Senior Member

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    I've had the same issue on a 2007 Kohler 12 EFOZD for the past 7 years. We've replaced fuel lines, fuel pump, circuit board, and many other things and it still does it and nobody can find out why. Ours is intermittent, sometimes it will run all day and no issue, sometimes it will do it 5 times in 1 day. No rhyme or reason to it, but I don't believe it has a crank position sensor.
  9. Beau

    Beau Senior Member

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    Do generators of this vintage have rpm limiters for low oil, hot water etc??
  10. Capt Ralph

    Capt Ralph Senior Member

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    The EOZD & EFOZD have mechanical swinging weight governors. There is no fine electronic HTZ adjustment on these models.
    The Kohlor electronic module probably does the best in exciting and maintaining a very pretty and clean sine wave. HTZ is still up the the governor. There may be a tach pick up but does nothing to the governor.
    When your tired of your issues, pull the lil valves on top of the Yanmar injector pump. You will probably find a broken spring. Replace all springs and lil disk. Keep all clean and reassemble with all new. Here, you will not need to adjust pump height.

    For the OP, Replace the pick up first, ensure all wires are soldered or crimped correctly. If your issue returns, you have the same task as for #8.
  11. Capt Ralph

    Capt Ralph Senior Member

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    There are over speed cut off functions in some governors. Swing weights go to far, fuel is cut off.
    Old monsters had this.
    Some electronic speed pick up sensors will also shut it down and offer an error code.

    I have never notice a limiter like on later outboards, stern-drives or wet-bikes.
  12. 55 Sea Ray R

    55 Sea Ray R Member

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    Will let you know this definitely has a sensor. Man I have hit a few forums trying to fix and I have to tell you I have never seen so much Westerbeke hate. I always thought they were the top of the heap I guess Northern lights seems to be well liked.
  13. 55 Sea Ray R

    55 Sea Ray R Member

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    mine has cut offs
  14. Capt Ralph

    Capt Ralph Senior Member

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    When in doubt, KISS.
    That is what NL does and well.
  15. Capt J

    Capt J Senior Member

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    Westerbekes were very popular in the 90's. But several of their issues, caused them to be very disliked. Some models the heat exchanger is part of the expansion tank and when it goes bad, you have salt water running through the engine. Then they had exhaust risers that went bad every 5 years, etc. They also simply did not keep up with technology. I saw one in a new boat recently, the only one in a new boat in 10 years and it still ran like a briggs and straton lawn mower......noisy, vibration etc.

    All marine generators that I know of have automatic safety switches that shut off the generator for low oil pressure, high coolant temp, etc.
  16. cleanslate

    cleanslate Senior Member

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    On a whim, make sure the Racor filter turbine/housing is clean by disassembling it and cleaning every part inside, carefully putting it back together the way it came apart.
    Second , if you can ,take apart the fuel pump and clean that little filter/screen out, inside the pump if there is one on your unit, checking for dirt and such in the pump. Then blow the fuel lines out with some puffs of air till you hear it bubble up in the tank to clear out the pick up tube and the return line too.. then run the unit and see what happens, that may fix it.
  17. Lepke

    Lepke Member

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    Filters aren't the only concern. The injector pump can get buildups that can make it sticky. As the load goes down the injector pump reduces fuel and then sticks when more fuel is needed. Before I started buying a lot of parts, I'd add a fuel conditioner known to remove deposits. Probably a 3x dose. I use Archoil AR6200, available online. Also helps today's crappy fuel burn better. I get about a 6% mileage boost, too. https://cdn.shopify.com/s/files/1/1997/2921/files/AR6200614.pdf?72
  18. Beau

    Beau Senior Member

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    Just seems to me that this sounds like a sensor protecting the engine by dropping the rpms due to heat or some other condition that develops after an hours running on load. How's the impeller? I wonder if it does that with no load - genny breaker turned off, but jenny running. That test can be done while you're still on shore power.

    Also, don't operate at those lower rpm, the output is greatly reduced and you will start burning up 220v a/c motors, refrigeration motors, etc...
    Last edited: Jul 19, 2019
  19. Pascal

    Pascal Senior Member

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    Generator sensors do not drop RPM. That would make no sense whatsoever since RPM sets frequency. The last thing you want is you genset running at 45 or 60 hz

    Sensors like oil, water temp, water flow or exhaust temp will shut it down not reduce rpm
  20. Beau

    Beau Senior Member

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    Makes sense.