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912ULS EGT Differences

in 912 / 914 Technical Questions 14 years ago
My right EGT sits around 60 degrees Celcius above the left. Both sit within operating range (cruise left/right = 760/820). Carbs have been synced and air filters are new.

Any reason for concern?

  • Re: 912ULS EGT Differences

    by » 14 years ago

    Hi Len,

    That temp deference is 140F (60F)and the max should be no more than 115F-120F. Even then the normal is anywhere from almost equal to 80F difference. So 140F is too much. How are the CHT's and oil temp? Have the carbs been rebuilt? You may need to check the needle clip position on the right carb. What is cruise rpm and what is your wide open throttle setting rpm? Depending on those answers it is easier to figure which carb may need to help. That said the left EGT is running at 1400F which is closer to normal and the right EGT is running 1508F. The 1400F is closer to normal so you may want to see why the right side is running leaner. Depending on your aircraft, cowl setup and and few other factors the normal EGT temps should usually run around 1400F-1480F. They can run into the high 1300F's depending on a few factors, but the 1400F range is better.

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

      
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  • Re: 912ULS EGT Differences

    by » 14 years ago

    Hi Roger

    Thanks for the heads up. I took the plane for a test run yesterday and recorded the engine readings as per below. Readings were pretty reasonable in the cruise (5000rpm) but the right EGTs at max revs were around 838C/1540F, 53C/127F to 62C/144F above the left.

    I will check the needle clip position on the right carb this weekend and see if it makes a difference. I will also try and swap the EGT leads over and see if the situation reverses itself

    ZU-CJD
    Engine Readings 01/06/2011 11:00
    OAT: 19°C (Durban North Coast)
    Oil EGTs
    Revs Press Temp CHT Left Right Diff
    Bar °C °F °C °F °C °C °C °F

    5000 3.5 87 189 89 192 752 800 48 118
    5000 3.5 88 190 91 196 755 795 40 104

    5150 3.7 89 192 88 190 724 755 31 88

    5500 3.9 99 210 93 199 783 836 53 127
    5500 3.7 87 189 91 196 776 838 62 144
      
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  • Re: 912ULS EGT Differences

    by » 14 years ago

    I have Rans S7-S which means that I have swapped sides with the manifolds. All has been well until about 2 weeks ago at about 135 hours on the engine. On full power take-off, ONLY, on full power take off I get a EIS warning light that I have over 200 degrees difference in my EGT's. This is due to the left front (#1) being well above the others. After I throttle back to cruise rpm (5200) the difference drops to normal with all cylinders being about 1390 - 1489.

    What do you think may be the cause of this?
      
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  • Re: 912ULS EGT Differences

    by » 14 years ago

    Hi Stan,

    I have had a number of these. It is a poor connection on the wiring from the sender to the gauge set you have. Make sure all the connections are good. These EGT probes are very sensitive to slight changes in resistance and if the wiring connection or ground isn't solid from the sender to the gauge things like this will show up. I would bet yours is just that one wire.

    Another tip with the EGT probes is to not let header wrap cloth touch it. If you wrap over it or under the probe the EGT temps will bounce all over. Only wrap up to one side and leave 1/4" space the start on the other side.

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

      
    Report

  • Re: 912ULS EGT Differences

    by » 14 years ago

    Problem found :cheer:

    Just got the aircraft back from its annual and was informed that 3 of the 4 exhaust manifolds had to be replaced due to cracks (some very minor, one major). On the test flight I immediately noticed that the left/right EGT difference is now down from 60 to around 10 deg C in the cruise (L780/R790 at sea level)

    The EGTs were thus pointing to a genuine problem with the engine!
      
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