Exhaust water show up slowly

Discussion in 'Diesel Engines' started by Henrik Voldsgaard, Jun 26, 2019.

  1. Henrik Voldsgaard
    Joined: Jun 2019
    Posts: 3
    Likes: 0, Points: 1
    Location: Denmark

    Henrik Voldsgaard New Member

    My Yanmar 3GM30, which is the freshwater cooled, when started, has begun to take some time to get the cooling water through to the exhaust exit when running at low speeds. When I give more gas, the water will show up. The engine seems to work OK, but earlier on, the exhaust water would show up immediately.
    Is there any advice as to what I may have to do?

    Thank's in advance
  2. gonzo
    Joined: Aug 2002
    Posts: 16,565
    Likes: 1,555, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    That sounds like the impeller needs replacing. When was the last time you changed it?
  3. missinginaction
    Joined: Aug 2007
    Posts: 1,102
    Likes: 254, Points: 83, Legacy Rep: 512
    Location: New York

    missinginaction Senior Member

    Since you're running a closed cooling system this would probably be related to wear in your raw water pump. I'd start with the raw water impeller. Depending on the type of pump you may be able to inspect the impeller without actually opening the pump's case. Can you take off one or both of the water hoses and look inside? Often you can see the impeller vanes with a flash light. If the pump checks out OK there could be scale in the raw water portion of the system that's interfering with the water flow. Do you have a raw water strainer? If not you could have some debris plugging up your heat exchanger or oil cooler that is slowing the flow. There are typically small passages in the heat exchanger that can become restrictive. I'm not familiar with your specific application nevertheless these are general observations that I hope might help you out.
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