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Diesel Engine Raw Water Cooling System Flush Valve

Discussion in 'Engines' started by T.K., Jun 25, 2020.

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  1. T.K., Jun 25, 2020
    #1
    T.K.

    T.K. Senior Member

    Joined:
    Jan 31, 2007
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    Location:
    Cairo - Egypt
    Gentlemen, I hope you are all well.

    Has anyone ever fitted a fresh water flush valve to the sea water cooling system on a diesel engine? I have been reading some articles about flush valves being fitted on the suction line between the strainer and engine sea water pump or on the output side of the engine raw water pump and in this setup the cooling system can be flushed without running the engine.

    The idea sounds logical but is it feasible on the larger diesel engines?
  2. Capt Ralph, Jun 25, 2020
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    Little engines with Groco or Perko strainers can be fitted with a 3/4" garden hose attachment. Freash water with the engine at idle will almost suck the garden hose down but some rinsing action.
    I would reserve the thought of forcing water in the raw side with out the engine running.
    Study the height of your dump cans well. I just see to many small to mid sized boats with the dump just ( just) barely under the rise before water goes back to the engine. These poor installs rely on the expanding exhaust gasses to keep the riser water out.
    On big engines, a water hose would just offer a worthless trickle vs what a 5 inch impeller can move. There would be not much rinsing action there.

    Now, a 3 to 4" trash pump from your swimming pool to the crash side of your large mains thru hull could offer a good running rinse.
  3. bobhorn, Jun 26, 2020
    #3
    bobhorn

    bobhorn Member

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    Have one on our almost new to us boat. Found it the hard way. Yard relaunched after bottom job and opened not only the seacock, but also the flush valve for some reason. Got into the slip, connected to dock water and flooded the engine. I knew the valve was there, never really traced it back, assumed it was the feed for the watermaker or some such.
  4. ranger58sb, Jun 27, 2020
    #4
    ranger58sb

    ranger58sb Senior member

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    We installed Groco flush valves on raw water systems for ACs, genset, and both mains (latter three ahead of the engine's raw water pump) and they worked as advertised.

    Groco's crash valves would be an option for larger engines, and I would have preferred those for our mains but couldn't get through the installation obstacles in the time available for that project.

    -Chris
  5. NYCAP123, Jun 27, 2020
    #5
    NYCAP123

    NYCAP123 Senior Member

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    I've known a few boaters with flush valves on gas motors. Showed it off to everyone when they bought the boats. In theory a great idea, but none used them a month later. Human nature. Lazy.