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Kohler 70kw generators - after service issue

Discussion in 'Generators' started by Jw-marine, Jul 13, 2014.

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  1. Jw-marine

    Jw-marine New Member

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    Our kohler/John deere 70kw generators just had their 500 hour service by contractors to keep their warranty valid. I oversaw the operation.

    After changing fuel filters etc they bled the fuel system on the filter bleed screws and using the fuel lift pump priming handle.

    They didn't bleed all the way upto the injectors. However both generators started and ran without any fault on completion of the service.

    We then returned to using shore power once the generators had ran for a while, the next day both generators stalled on start up and we've had the problem intermittently for the last two weeks. After stalling they always start second time without fail. The control of the generators is remote from an MPA screen which we use for most systems onboard.

    The skipper has emailed them to come back but in the meantime I've been trying to find the cause. I've bled the system at the filters again to get any air out, checked all fittings to make sure they are air tight, we know the fuel is good because it's been spun in the centrifuge several times now.

    I'm starting to think there could still be some air in the lines between the filters and injectors? Is this possible that air can stay in there for that long and cause the engine to stall even after we have ran the generators for a good 10-20 hours each since the service?

    I can understand why they didn't initially bleed at the injectors because it's pretty tight to get in there, but I'm starting to think this could be the problem. I don't want to get to involved to the point where we invalidate our warranty. Also the contractors may refuse to do anymore work because we've fiddled with them since they serviced them a week or so ago!

    Has anyone got any ideas on what the cause might be aside from the obvious?

    Thankyou.
  2. K1W1

    K1W1 Senior Member

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    Hi,

    If they stalled due to air they wouldn't re start immediately which I am assuming they do from your description.

    Do you get any alarm when they stop? If so what is it?

    It could well be some engine protection that's stopping them.
  3. Capt Ralph

    Capt Ralph Senior Member

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    Like fresh thick oil. No pressure on first start up.
  4. Capt J

    Capt J Senior Member

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    If they do eventually prime and run and stay running for hours with a load. It's not air in the lines to the injectors from the initial bleeding. You have small air leaks. Either they didn't tighten the bleed screws enough, the filters aren't tight enough or they might even be the wrong filters or some other fuel connection isn't tight. Is the priming hand pump on the motors in all of the way and screwed tight? Have you checked the tightness on the racor or primary fuel filter lids or a bleed screw on them? If the lid is loose, they'll usually run, but when you shut them off they'll eventually gravity feed the fuel in them to the tank, then when you go to start them air and no fuel.
  5. Capt Ralph

    Capt Ralph Senior Member

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    If the injector lines were not opened; no need to bleed them. If it runs under load, there is no air in them. It's not an injector line issue unless their leaking, but this sounds not.. Your bleeding the system but no air?

    Did they change the oil? Oil has a second to flow & hit that oil pressure switch. Thick or low oil will not hit that pressure switch before bypass has timed out or released.
    Vacuum gauge works?
    Run the set, close the tank valve, draw a vacuum and shut down, watch the gauge.
    I have wrapped small oil'sorb strips around joints to find small leaks also.
  6. Capt Bill11

    Capt Bill11 Senior Member

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    The common denominator seems to be the fact that they changed the fuel filters. I'd start there. Perhaps they messed up the gaskets on the filters and they are letting air into the fuel system.
  7. Jw-marine

    Jw-marine New Member

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    Hello, thanks for your replies. Lots of useful information thats appreciated will work on it the generators again today.

    I have got the fault codes off the Generator remote monitoring/operating panel, however these are historical - although the boat is only 4 months old.


    Port:
    - 1380 BB F<
    - 1300 BB U<
    - 3460 Generator not ready
    - 1510 G unbalance
    - 1500 G unbalance
    - 4570 Start failure
    STBD:
    - 1380 BB F<
    - 1300 BB U<
    - 3460 Generator not ready
    - 1500 G unbalance 1
    - 2630 De-load error
    - 4570 Start failure
    - 1510 G unbalance

    There is no description for these alarms in the Kohler/John deere manuals, so I don't know if they are relevant to the problem we are having.

    I am still waiting for an email back from Kohler about the fault codes.

    Thanks.
  8. Jw-marine

    Jw-marine New Member

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    The oil is marginally lower than before they were serviced so will top up the oil and see if this corrects the fault.
  9. Capt Ralph

    Capt Ralph Senior Member

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    Is this the same oil as before service? If so this may be nothing.

    Another Q; JD stuff is now programmable, did the tech update any software?