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Compression

in 912 / 914 Technical Questions 7 years ago
Hi all, I have noticed when pulling through the prop to gurgle the engine that the compression on one cylinder is lower (pulls through top ded centre with less resistance) , after the engine has warmed up it’s fine, is this normal ? The engine is a 912ul with 350 hrs on the clock.
Thanks Andy.

  • Re: Compression

    by » 7 years ago

    Normal. If you feel like you want to check it do a differential compression test.

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

    Thank you said by: andrew owen
      
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  • Re: Compression

    by » 7 years ago

    Thanks Roger, I take it this is done with the engine at running temperature,
    Andy
      
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  • Re: Compression

    by » 7 years ago

    I did a research project with a 12 912 engines. I did a compression test cold and hot on each engine. Really no difference. A couple may have had 1 psi difference, but that isn't enough to worry about. This just goes to show the tight tolerances of this engine vs a Continental or Lycoming. I do most of them cold anymore. I use 87 test pressure and usually get 84-86 psi on a cold engine.

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

      
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