1976 Evinrude 9.9 conversion to long shaft

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  • PugetSoundBoater


    Replies: 900
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    #10899

    I did this last year and after the conversion it sprays way less water out the exhaust relief than it did as a short shaft. I noticed this today running in a barrel at the highest idle in neutral. It does spray a bit, my hand getting totally wet within less than 10 seconds or so.

    Is this because the water level doesn’t get high enough in the now longer midsection to get mixed with the exhaust and blown out like it did as a short shaft?

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    dan-in-tn

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 961
    Topics: 78
    #81453

    Jim; Did you add ref #57 part #319340 extension, impeller housing to exhaust housing. That seals the impeller housing from sucking exhaust gases. The top of the impeller housing would normally butt up against the exhaust housing without this piece. That might be one explaination? Of course the water pump needs to be in good shape to pump further, but that goes without saying. Mighty small pump, though. Don might have a better idea.

    Dan in TN


    PugetSoundBoater


    Replies: 900
    Topics: 105
    #81458

    Yes I installed the pn#319340, and the water tube extension with o rings. I did my usual thorough research on this conversion ,studied parts manuals as this was new to me.
    Thanks, Jim PSB

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    optsyeagle


    Replies: 29
    Topics: 1
    #81489

    How old is your impeller? I have a short shaft 1976 motor of the same model, and I find that when I fire up the motor, all I get is a light spray of water out the exhaust. I also have to put my hand back there to sometimes even see the water or in this case, feel the water. When I run it on the boat, that spray turns to more of a stream of water that moves away from and then towards the midsection of the motor, as my t-stat opens and closes and as my rpms increase and decrease.

    All that said, all of the various forms of water spray do seem to decrease over time, as my impeller ages. It is useful because it kind of tells me when my impeller is getting weaker before it totally fails. I have never taken an impeller past 5 or 6 years so I could not say what happens after that, but I definitely can tell the difference in water flow between a brand new impeller and one that is 5 years old. The older one pushes out a little less water.

    I have never noticed any big difference in the temperature of the powerhead in either of the older or newer impellers that I have used. I suspect a good working t-stat will compensate for this small reduction in pumping power from the impeller. The t-stat would just stay open longer when the impeller gets weaker.

    So if you see some form of spray out the exhaust relief hole you are probably OK to go.


    PugetSoundBoater


    Replies: 900
    Topics: 105
    #81490

    When i did the conversion,everything was new or in good shape. I think it is the longshaft that makes the difference. I will get out out on a boat and see how it acts.
    Jim PSB

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    optsyeagle


    Replies: 29
    Topics: 1
    #81494

    Well every inch of elevation reduces the pressure of the water, not to mention any additional restrictions that might be added upon the conversion, so I would not be surprised that you might notice a reduction in water out the back. I would bet that the t-stat will more then compensate for it and will most likely be nothing to worry about.

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