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High oil temperature 912UL

in 912 / 914 Technical Questions 6 years ago

  • Re: High oil temperature 912UL

    by » 6 years ago

    do a differential compression test and if you have any leakage listen to the intake, exhaust and oil tank to hear what is leaking.
    You will always have some air going by the rings, and so you should hear the oil tank gurgle but if it is blowing a hurricane you have a cylinder issue.
      
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  • Re: High oil temperature 912UL

    by » 6 years ago

    I finally managed to get down to the plane yesterday and carry out a differential compression check. All cylinders were about the same at about 5% with the engine cold. There was no leakage past the valves but you could hear the oil gurgle and there was some air coming out. I don't have a point of reference to know whether you would define it as 'blowing a hurricane' or not.

    Is it possible that I have a problem with the nikasil linings that is stopping the rings from bedding in? Is there any way I can tell and what can I do about it? I see that there are companies that will re-plate nikasil cylinders.
      
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  • Re: High oil temperature 912UL

    by » 6 years ago

    Hi Kevin,
    Yours sounds perfectly normal.
    Depending on how accurate your gauge is the average residual psi is usually 76-79 with an 80 psi test pressure or 83-86 with an 87 psi test pressure. This is cold or hot engine. The air leaking past the rings should have pushed the oil out of the bottom of the crankcase and you should have heard a semi quiet gurgle in the oil tank as the air escapes. This is normal. You shouldn't hear out come out the exhaust or air intake. If you want to hear what air sounds like coming out the exhaust just turn a cylinder 180 degrees out and do the test. You won't have any questions about where the air is coming from.

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

      
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  • Re: High oil temperature 912UL

    by » 6 years ago

    I had about 80 psi from about 85 psi test pressure and sound similar to what you have described.

    Any thoughts on why my rings haven't bedded in twice now after 2 rebuilds? Either I'm doing something horribly wrong or there is a problem with the cylinders/rings.
      
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