Honda 40 cooling mystery

Discussion in 'Outboards' started by Carlazzomark, Apr 28, 2022.

  1. Carlazzomark
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    Carlazzomark Senior Member

    Raining today, but can do tomorrow. What would like pictures of?
     
  2. baeckmo
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    baeckmo Hydrodynamics

    The pump side of the gear housing with pump in place and then the separate pieces you have at hand when pump is dismantled.
     
  3. Carlazzomark
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    Carlazzomark Senior Member

    I will take pictures in a few hours.

    could there also be a problem with a vacuum line, and, if so, which tests could I perform?
     
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  4. Carlazzomark
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    Carlazzomark Senior Member

    I have the photos, which I will include here, and videos showing lower unit problem and upper unit flow, which I will try to upload.

    5BED49D3-FE58-40EE-939A-6B2E64E3611A.jpeg 33AA6E08-220B-411E-A836-4A4C13358B48.jpeg 7015BF03-7DCA-4535-A949-B5E54DB3CA30.jpeg 4E9EC401-6C93-4063-88DD-AC990FA09DC7.jpeg 0D5D8837-E849-44C8-9610-6863700D6729.jpeg 4953C3D9-605C-46D7-B58C-0D67DF6AA1C5.jpeg 6DA16C7A-FB4E-4E68-A09C-C8FA90E46F0B.jpeg DAB3212D-E66C-4115-8A9C-13B56C892576.jpeg B099B38A-3CDE-49A2-8D98-7C22339631D2.jpeg 202CC695-1036-4FE5-B107-9DBAF5DBA88F.jpeg 100B94CD-A313-4837-A003-CC5A1E9160B3.jpeg
     

    Attached Files:

  5. Carlazzomark
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    Carlazzomark Senior Member

    Uploads, continued
     

    Attached Files:

  6. Carlazzomark
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    Carlazzomark Senior Member

    So, to update:

    I installed a new impeller at the end of last season as I always do.
    A week ago I started the motor and there was no telltale flow.

    I have since taken the lower unit off at least six times. I have inspected all parts and gaskets, tested again and failed, and replaced most parts again.

    I have tested the thermostat and the water flow in the upper unit via hose in the intake tube, and the water flow is perfect.

    I have had the lower unit in a tub and tested the pump with a drill on the shaft, and water does not exit the output hole. I have checked for obstructions in the feeder tube and intake vents five times, and there are none.

    super frustrated
     
  7. baeckmo
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    baeckmo Hydrodynamics

    Ok, two observations:
    A/ The shaft key is nowhere to be seen, where is it? If it is in situ, the lower part (the sealing housing) can not be lifted together with the pump housing. I think you have lost the key, it is a small, cylindrical pin (not a conventional rectangular or Woodruf key!).
    B/ There seems to be a crack in the suction pipe (on the horizontal part). It may just be a "flake", but if it is real, there is a gas leak preventing pump priming. Now, if you dip the unit deep enough to submerge the crack, the pump is operational. But it won't work with engine running.
     
    Last edited: May 1, 2022
  8. Rumars
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    Rumars Senior Member

    In your pictures I dont see the woodruf key, that's the little triangular thing that sits between the flat of the shaft and the groove of the impeller. Without it the shaft turns, but the impeller does not.
     
  9. Carlazzomark
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    Carlazzomark Senior Member

    It’s there, just not pictured.
     
  10. Carlazzomark
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    Carlazzomark Senior Member

    A/ It sounds like you are not talking about the impeller key. I am not sure what the shaft key looks like, and this very likely is the problem if you cannot see it. I am not sure where it goes.

    B/ I have looked at this fairly closely. What appears to be a long crack is in fact the border of some rubber insulation. I do not know why the rubber is not consistent. I will bring a magnifying glass to look at it better tomorrow.

    Thanks for your continued help.
     
  11. Carlazzomark
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    Carlazzomark Senior Member


    Here is the parts schematic. Can you please identify the shaft pin? Thanks.

    Honda Marine - Parts Look Up - Official Site https://peparts.honda.com/marine#/browse/me/bf/bf40/BF40D-LRTA
     
  12. baeckmo
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    baeckmo Hydrodynamics

    Your impeller key is my shaft key..... Ok, so it is there after all, and there is no crack. Wise words of an old tugboat chief engineer: if the water can come into the pump, you can be darn shure it comes out somehow-somewhere. In that context, I would lift the suction (lower) pipe and check the flow path all the way from the inlets to the pump. When re-installing check that the rubber components have a slight pressure fit, and use some special grease as sealant. "Special" as in grease suitable for rubber!

    Edit: saw that you have inspected the suction pipe already, consider the tightness of all connections between rubber lips and metal! No air leaks anywhere?
     
  13. BlueBell
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    BlueBell . . . _ _ _ . . . _ _ _

    So, diagnostic questions:
    Was the telltale working before you replaced the impeller last fall?
    And what about after, did you test it or simply store it for the winter only to find it unserviceable this spring?
     
  14. Carlazzomark
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    Carlazzomark Senior Member

    yes it was working prior to new install last fall, and no, I did not test it then.

    seems like I have a telltale problem every spring, but not from clogged passages.
     

  15. Carlazzomark
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    Carlazzomark Senior Member

    I decided to take the lower end to a boat shop today. I just could not figure out the problem, even with all the kind you you all have offered. I will let you know how it turns out.

    thank you
     
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