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Oil temps high, are Oil Coolers required?

in 912 / 914 Technical Questions 6 years ago

  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    Yes, By all means, Go Fly it.
    It will probably be cooler in the air.

    From 912UL Operation Manual...

    Oil Temp.
    Normal 90-110°C (190-230°F)
    Maximum 140°C (285°F)
    It is recommended to reach >100°C (>212°F) Once per Day to boil off any Combustion Water Condensation in the OIL.

    Coolant Temp.
    Maximum 120°C (248°F)

    Cylinder Head.
    Maximum 150°C (300°F)

    You are nowhere even close to getting it Hot!

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

    Thank you said by: Andrew Dunning
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    So I went and flew it today after the coolant change.
    It is definitely cooler after the change but still not quite there. Still seems to want to run up past 250 pretty easily.

    Another thing I found was that my back cylinder is running about 40 degrees hotter than my front cylinder. (I have one sensor on the front left and a second on the back right)

    Running it around 4500 rpm helped keep temps bellow 250F
    Cruise at 5100 rpm showed the same higher temp rise issue.
    Front left cylinder is 205F (Water)
    Back right cylinder is 250F (Water)
    Oil 255F (And rising slightly under hard power)
    EGT is a little over 1400F

    The oil cooler will get installed next week but will that drop the temps by 20-30 degrees?
    I know that my grandfather had always stated that the right side senor ran hotter than the left.
    Do the back cylinders run hotter than the front?

    Whats your guys thoughts...
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    How are you measuring Coolant temp in the cylinders?
    If you are using the original 20-Year-Old cylinders, The stock Rotax senders are Not in the Coolant.
    You would be measuring Head temperatures.

    The Rear cylinders typically run hotter because they are getting warm second-hand air from the front cylinders unless you have baffles that separate the airflow.
    The #4 Cylinder, Left Rear, is typically the hottest and should have the rear sensor on it.

    Without an Oil Cooler, the water coolant has to do double duty and may be getting overwhelmed.
    Most people barely make it to 200°F if the temperatures are below 75 or so.
    And in the Winter, have to put Aluminum tape over part of the radiators to get the temps over 180.
    The Oil cooler might lower your Temps by 50°.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    In my 40 something years of being around aircraft I don't think I have ever seen a 4 cycle aircraft engine without an oil cooler, just saying.
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    Hmm well the cooler I have is slightly smaller than the other ones I have seen but hopefully it does the trick. The outside temp yesterday was around 70's and definitely saw climbing oil temps. I just wonder if there is a blockage with such large temperature differences between heads.

    Also IDK how my grandfather was able to fly it for almost 70 hours like it was. Maybe he just had it pulled back real far and was putting around 4500 RPM.

    Cooler was ordered Thursday but won't ship till Tuesday (Shakes fist at Kitfox!).
      
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