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Thread: Rotax 912iS overheating

  1. #1

    Join Date
    Jun 2010
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    Mahanayim Israel
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    Default Rotax 912iS overheating

    As previously posted here, we installed a Rotax 912iS on a KF-IV.
    Now, during our phase 1 test flights we are having overheating problems, especially on the ground.
    We installed the coolant radiator under the belly of the plane, with and without the scoop. With no significant differance.
    we get 220°F coolant and 200°F oil temperatures.
    What is your experience with overheating of 912 engines.
    Does anyone baffle a 912 engine?

  2. #2
    Senior Member Esser's Avatar
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    Default Re: Rotax 912iS overheating

    You can make a fiber glass plenum to direct air over the fins. Are you running an oil cooler? What size is your rad?
    ------------------
    Josh Esser
    Flying SS7
    Rotax 914iS
    AirMaster Prop

    Edmonton, AB, CWL3

  3. #3
    Senior Member Dave S's Avatar
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    Default Re: Rotax 912iS overheating

    Ofergd,

    Which coolant are you using? Rotax approves either evans waterless or ethylene glycol mix.

    Although we did not have an overheating issue - the glycol mix (Dexcool mixed 60%) resulted in 20 degrees F lower running temp than the Evans under similar conditions. This also resulted in a lower oil temp.

    Have you verified the accuracy of your temp indicator? They have been known to lie a little on occasion. Reading the instrument while boiling the probe in plain water should show 212 F or a little lower if you live at a higher elevation.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  4. #4
    Senior Member kmach's Avatar
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    Cupar, SK, Canada CLC4 Loon Creek Airfield
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    Default Re: Rotax 912iS overheating

    200 F is okay for oil temp. you want to hit 212 F oil temp at some point in your flight.
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  5. #5

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    Default Re: Rotax 912iS overheating

    I'm using a Rotax approved coolant, but I don't remember which type. I have the Rotax 912iS engine which has an ECU and I get all reading by computer communication to my display, so I have to believe it is pretty accurate.
    I was thinking of making a plenum, but it seems a lot of work. Did anyone make one for the 912? If so, pictures please. . .
    The engine is mostly running LoP therefore it is running hotter.

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Rotax 912iS overheating

    What is your ambient temp during the test flight? In a fairly warm ambient, the 200F oil temp is not a problem at all.

    Don't use Evans waterless coolant. It has fallen out of favor with Rotax, and I believe it is no longer on the approved list.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7

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    Default Re: Rotax 912iS overheating

    The ambient temps here at this season is around 70 deg F. i'm worried about the temperatures we expect in summer at around 110 deg F.
    I know oil temps are relatively OK. The problem is with the water temps especially on the ground during taxiing.

    OferGd

  8. #8
    Senior Member
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    Default Re: Rotax 912iS overheating

    HI Ofer

    I to have a 912is sport - Yes, the oil temps are fine - very similar to what I get - in fact it is hard to get the oil temp up to the recommended 100"c during the cooler months. As for the coolant - I don't have any issues on the ground but on hot days it can get up to 110'c on climb - it settles in cruise - Mine is a SS7 so is different - I would be looking at airflow if you are already using the recommended coolant (which mostly have a boiling point of 130'c) sounds like you have a different airflow as others have suggested.

    r
    Ross
    Mt Beauty, Vic
    OZ
    Sold to Richard and Scott Taubman in OZ, 2019. Kitfox SS7,Rotax 912is Sport, Airmaster CSP 75" blades.
    Landcruiser and Cub off road camper (doesn't get any kudos on this forum!)

  9. #9

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    Default Re: Rotax 912iS overheating

    Sounds great.
    Can you send some pictures of your installation. Where the radiator is installed and how? and what is the air intake look like?
    I need some ideas for improvement. I have the round bumpy cowl and it is hard to make the intake at the point where the rear and front cowls attach.

  10. #10
    Senior Member
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    Default Re: Rotax 912iS overheating

    Have a look here offer -

    http://www.teamkitfox.com/Forums/sho...t=5029&page=15

    and there are many more to give you the idea of how the airflow happens in the SS7. I think it could also be worth chatting with John at the factory about his thoughts of how to best modify your KF4 for the 912is sport.

    good luck

    ross
    Ross
    Mt Beauty, Vic
    OZ
    Sold to Richard and Scott Taubman in OZ, 2019. Kitfox SS7,Rotax 912is Sport, Airmaster CSP 75" blades.
    Landcruiser and Cub off road camper (doesn't get any kudos on this forum!)

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