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Kohler 9EFOZD generator

Discussion in 'Generators' started by charlesmurless, Apr 14, 2014.

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  1. charlesmurless

    charlesmurless New Member

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    kariba
    The unit is mixing oil and water in the sump and we suspect this is coming from water getting into the cylinders due to an incorrect raw water pump being used.
    I suspect this has caused a hydraulic lock at some stage and suspect a slightly bent conrod as the unit runs rough and is difficult to start.
    There are two options
    1 Replace the unit
    2 Strip and rebuild the existing unit
    We can fit a new raw water pump for now and change oil and filters and see how she runs

    The raw water pump circulates fresh water through the closed cooling system on the genset and then is fed into the exhaust which is then fed overboard.
    A electric pump was fitted in place of this pump which also is used for deck washing etc.
    This is where the problem is .

    Hopefully a conrod is not bent - any suggestions to see our way forward?
  2. dennismc

    dennismc Senior Member

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    So, you are in a f/w lake ?

    If in salt water then the salt water does not go thro the closed cooling system

    I doubt the pump caused the issue of water in the.oil.




    Regardless you need to lift the head first and check if you have a bent rod, if so, then the choice is yours, rebuild or replace.
  3. Marmot

    Marmot Senior Member

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    If it's a wet exhaust and the electric raw water pump was operated for a period without the engine running it is very likely water backed up in the exhaust and flooded a cylinder or two and damaged some rings, a piston, or maybe bent a rod. That is why there are warnings for every wet exhaust system to NOT overcrank an engine that does not start.
  4. Beau

    Beau Senior Member

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  5. dennismc

    dennismc Senior Member

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    also, that electric pump is not designed for raw water cooling application, usually they do not have enough capacity, even so, the pump should be interlocked so as not to run unless the fuel solenoid is in the run position, continuous cracking without flash up would potentially allow water back into the cyl head thro exhaust valves.
  6. Capt Ralph

    Capt Ralph Senior Member

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    I think Marmot got it. To much water from the electric pump, filled the exhaust and into the cylinders.
    Start the engine first and then turn the pump on.
    That electric pump may also give to much water and over fill the muffler when running.
    I think it's a current model 50htz gen set. Why the water modification for a late model gen-set?
  7. dennismc

    dennismc Senior Member

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    I was told by the Jabsco rep that they do not make a 12 v pump sufficient to do Gen set cooling..however, I'm sure he is mistaken by the answers on here..so some other mfr must have that issue resolved..worth checking for future ref.
  8. Marmot

    Marmot Senior Member

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    As several others have noted, there seems to be a problem with your terminology.

    In a conventional heat exchanger cooled marine engine with wet exhaust, a raw water pump delivers seawater (or whatever floats the boat) to a jacket water (or fresh water coolant as some call it) heat exchanger. This heat exchanger uses raw water to remove heat from the coolant. The raw water pump can be driven by belts or an auxiliary gear drive but in the case of small engines is commonly belt driven.

    After leaving the heat exchanger the raw water may pass through an exhaust manifold cooling jacket, before leaving the system through a spray ring located on an elbow usually connected directly to the outlet of the exhaust manifold. Here it is sprayed into the exhaust flow to cool and reduce the volume of hot exhaust gas.

    Jacket water, fresh water, or coolant is a separate closed loop that is circulated by its own pump, usually driven by a belt on smaller engines just as on a car engine.

    It is virtually unheard of for small diesels to use a separate pump for jacket water cooling.

    It is not unheard of to install an electric raw water pump, but, in that case there is a great risk of the problem you have described unless operator proof interlocks are provided to prevent the pump operating before the engine is running or after it has stopped.
  9. Capt Bill11

    Capt Bill11 Senior Member

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    You use an AC powered pump powered off the Genset AC output. That way the pump only runs if the Genset is running.