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How common are 912 water pump failures.& cause?

in 912 / 914 Technical Questions 10 years ago

  • Re: How common are 912 water pump failures.& cause?

    by » 10 years ago

    Thanks to all who replied.
    For once there is a clear consensus :) on what COULD have been one of those fuzzy "that depends" issues.
    The reliability of the water pump, and lack of anyone saying anything about corrosion problems in the cooling system sort of unticks a couple of the boxes in favor of the expensive waterless coolant.

    By the way (since we're talking about coolants):
    For what it's worth, although Rotax recommends 50/50, there is a case to be made IMHO in some installations for going with 40% coolant or 60% coolant:

    The lower 40% mixture has more heat transport ability (though a lower pointing point) and COULD paradoxically be a solution for someone whose installation tend to run hot. 40% still protects down to about -30 degrees F.
    On the other hand, 60% (or even more so 70%) coolant is slightly less efficient at transporting heat from engine to radiator and if you have (as some of us do) an installation where the engine has trouble getting hot enough to reach optimal operating temperatures or excessively long time getting warm enough for takeoff that could be a solution.

    Of course if you deviate from Rotax recommendations you do so at your own risk, but hard to see any risk in running 60 or 70% coolant unless your installation is already running too hot.

    Al
      
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  • Re: How common are 912 water pump failures.& cause?

    by » 10 years ago

    "According to them the color makes no difference any more. "
    Thanks for that update.

    I've seen claims (which I don't consider particularly reliable sources) that mixing the two colors is a no-no. Like "if you have pink coolant don't top up with green."

    Know if there's any truth to that or is it a myth?

    Al
      
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  • Re: How common are 912 water pump failures.& cause?

    by » 10 years ago

    In the older days (whatever that is) your right that mixing things like Dexcool would cause some issues. Dexcool has changed and many coolants are now compatible with Dexcool. According to Prestone if you mix or have to add let's say green colored coolant with the orange it wouldn't be an issue, Coolants have changed over the many years and become more friendly with one another.

    I'm not a chemist just stating what they told me and I know many that have mixed or topped of with something different with no ill effects. I still try to stick with like coolant and try not to mix and if I have to top off I use distilled water. Other countries may be different.

    If you use Evans then it is only Evans.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: How common are 912 water pump failures.& cause?

    by » 10 years ago

    912 water pump seals tend to leak after ~600 hrs. I replaced mine when coolant began to show from weep hole below/forward of pump. Seal surfaces are ceramic and very sensitive to any impact on installation. You must use the Rotax seal insertion tool for correct depth of insertion.

    The weep hole also shows when oil seal is going as that is about 1/4" away from the water seal on same shaft. I changed both at same time.

    Primary cause of water seal wear is not using the orange coolant with distilled water. After 1000 hrs, my coolant system is spotless with no corrosion indications whatsoever.
      
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  • Re: How common are 912 water pump failures.& cause?

    by » 10 years ago

    Water pump ceramic seals shouldn't leak after 600 hrs. Many run just fine until TBO. What you may be referring to is that sometimes through heating and cooling cycles or when it is really cold outside the seal may ooze. If you see a tablespoon or so on the ground of coolant that isn't a sign the seal is bad. It may be the temp change or even a piece of small debris which may go away shortly. If you see a fairly large amount of coolant on the ground then that's a different story. I see most 912's with a little time come in with a drop or two at the weep hole. That isn't in itself a cause for concern.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

    Thank you said by: Al C
      
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