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Kohler 7.5 generator shuts down in 15 minutes?

Discussion in 'Carver Yacht' started by Folly414, Jul 23, 2012.

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  1. Folly414, Jul 23, 2012
    #1
    Folly414

    Folly414 Guest

    Hi,

    I hope the people on here that are more experienced at boating can help us out. We have a Kohler 7.5 generator on our 1986 Carver 44 Aft Cabin that runs well if the AC is not on, but after we do turn it on, it will run 15 mins then shut down.

    A mechanic said he cleaned the heat exchanger and charged us $1100, but it does the exact same thing. We had another man come out and used heat gun...runs at 180 without AC load. Heats up to 200 with AC units running then shuts down after 15 min. again. He suggested that we may need a new water pump. It is probably the original genset that came with the boat.

    We are docked in an area with a limited number of marine services, so we've even called around for commercial help with this, but they won't work on a private boat.

    Any help or suggestions would be greatly appreciated. We aren't running her on the river as we've been enjoying triple digit temperatures for about 3 weeks now. And it's nice and cool when we have all 3 AC units running at the dock. :)
  2. K1W1, Jul 23, 2012
    #2
    K1W1

    K1W1 Senior Member

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    Hi,

    I assume this 200 degs is measured around the Fresh Water side of things.

    Which Pump has it been suggested you change ? The Raw Water one or the Jacket Water one?

    Has anyone measured the raw water side of things, it should be very close to the same temp as what your sitting in where it enters the pump and warmer where it exits the Heat Exchanger.

    Is the Raw Water inlet strainer and all pipework free and clear?

    I was once sailing on a boat that developed an overheating problem and found a mangrove bean about the size of a glass marble was in the inlet of the pump resting on the cam nearly blocking the inlet , took it out and away it went like new

    Do you have a deck wash system or dock water hose you could hook up to bypass the Raw Water pump temporarily?

    When doing any type of temporary jury rigging you will need to really pay attention to how much water flows till you make sure it isn't too much and fills your exhaust up too much, if it is too little you will probably have the same problem you have now.
  3. Pascal, Jul 23, 2012
    #3
    Pascal

    Pascal Senior Member

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    $1100 to clean the HE??

    Start with the impeller!!! No need to replace the whole pump. Kohlers are known plugs and impeller eaters...

    How is the raw water flow out the exhaust?

    Did you check the strainer and did you make sure there isn't anything stuck in thru hull?

    OPen the strainer, then open the sea cock to make sure water is flowing thru.

    Also when changing impellers ALWAYS make sure you find all the rubber pieces from the impeller vanes. You may have to check the heat exchanger inlet. Many "mechanics" don't bother and over time it will restrict flow

    And check the thermostat too...
  4. dennismc, Jul 23, 2012
    #4
    dennismc

    dennismc Senior Member

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    Yep, Kohler w p's are a pain, I turfed mine and went to a bottom pulley bolt on one, way better.
  5. tommyfmu, Jul 27, 2012
    #5
    tommyfmu

    tommyfmu Member

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    Oil?

    Since I didn't see it posted earlier, you did check the oil level, didn't you? That's the main reason ours shuts down; low oil pressure. We add a quart or two (whatever's needed to the fill line) and problem solved. Other than that, we've heard the same that the raw water impeller is a frequent culprit. It's a snap to change; simply 4 screws, remove old, put in new, and done.
  6. Capt Ralph, Jul 27, 2012
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Read before?

    Kohler 7.5 generator shuts down in 15 minutes?

    Have we been here all ready on another thread?