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High oil temp 5000 rpm

in 912 / 914 Technical Questions 8 years ago
Hi , I have 220 F at 5000 rpm . This is in cruise 2000 ft a kind of std day , I mean 24 C and 1015 hpa. I think that is too hot for a long cruise .That temp reach in 10 min and stay there unless I reduce rpm.
I change my propeller angle to reach 5400 rpm WOT.
The engine is new and the propeller is a whirl wind.

  • Re: High oil temp 5000 rpm

    by » 8 years ago

    Hi Alejandro,

    Two things.
    First. 220F is not too high. Here in Arizona we can see that all the time. So long as you stay under 230F all the time no worries. 230F just starts the yellow watch me range.

    Second:
    5400 rpm WOT is too low and it contributes to your engine temps. Over pitching a prop has no redeeming qualities. Reduce the pitch about .5 degree so you can get around 5600-5650 rpm WOT in level flight at your average altitude. This can lower your engine temps. Plus you'll climb better, use less fuel and may go faster a less throttle setting.

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

      
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  • Re: High oil temp 5000 rpm

    by » 8 years ago

    Sometimes I see people getting scared because the CHT/Oil Temp suddenly get's higher than normal.
    You must take into consideration, that you're temperatures are directly linked to ambient temperature.
    If all other parameters are equal (Cruise speed,radiator, oil type, etc) you're temperature will be X degrees above ambient temperature.

    So if it's 60F outside, and your oil runs at 195F your delta is 135F. So if the next week it's 85F outside, you should expect the oil to run at 220F.

    Other thing I notice, is that if you are flying heavy, your engine will run hotter because you'll use more power and fly slower at a greater Angle of Attack, which can affect the airflow inside the cowl.
      
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  • Re: High oil temp 5000 rpm

    by » 6 years ago

    hi , is there anything else that will cause the high oil temp, i have a 914 that has run at 200-mid green for the first 450 hours of its life,now for some reason
    as i increase throttle, the temp abnormally climbs with it ?
    4800 rpm 200
    5000 rpm 230
    5200 rpm it climbs to 240
    on heavy climb with passenger iv had it climb to 255?
    all services are up to date , oil and filters all changed, had a extra service done to find problem to no avail fitted to Autogyro Cavalon, standard config no changes.
    the temp climbs with throttle, yes expected but its abnormally so and abnormally high, clean filters, new oils, oil cooler cleaned and checked, no leaks ,cht doesn't climb
    and is the same and consistant, oil pressure steady 50
    nothing was done or changed, no warning lights , no boost gauge fitted
    on a cross country trip east coast Australia to west coast and return the turbo boost decided to reduce giving 5100 wot on takeof one morning, a very interesting departure 2 up fully loaded on a bush track from a strip in the middle of the Nullabor Plains, through that day i had 5100 wot and the oil temp run between 235 and 260 . At the next LAME everything was checked ,all ok, left Broken Hill (outbackAUST) on the way the boost came back and gave 5450 wot but motor has run hotter ever since,with an increase in oil temp ,most worryingly is that it moves diectly with throttle,all that was done at broken hill was an oil and filter change ?so i have no explaination for the reducion of power , or its
    unexpected return but am left with a much hotter oil temp, anyone have any ideas?
      
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  • Re: High oil temp 5000 rpm

    by » 6 years ago

    Run a Cylinder compression test.
    You may have a leaking piston and are blowing extra hot gasses into the crankcase.
    This will give a power loss and heat the oil as the crankcase is vented through the Oil Tank.

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

      
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  • Re: High oil temp 5000 rpm

    by » 6 years ago

    Thanks Bill for that suggestion, the LAME did a leakdown test and its is exact as per rotax ,so he said the pistons/rings / valves were ok
    your comment is very thoughtful though and appreciated, so other than that ,if the leakdown test result is all even and within rotax guidelines
    any other thoughts?
    ill listen to anything at the moment because we haven't a clue,
      
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