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Thread: older 912 ul heating up

  1. #1

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    Default older 912 ul heating up

    ok guys need some help just got the old bird back in the air flew great hands free but as I made the 4th lap around patch EGT (1530F) CHT (251F) stared to get on the high side oil temp was good 185 F I do have a in line coolant temp sensor and it was at 230F oh sorry RPM at 5100, I back off RPM everything drops back down . So I know lean right I check the needle setting was good even drop them down still heating up ?? check the jet size 158 right to the book has any of you guys gone richer then 158 ?? oh by the way pulled the plugs they are white in color after wot shut down . I'm burning 100 LL this cause problem ?? just pulling my hair out trying to fix . thanks for any help

  2. #2
    Senior Member Norm's Avatar
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    Default Re: older 912 ul heating up

    Not sure because I just fly mine and have never had to adjust but "drop down the needle" wouldn't that make it leaner as less gas is being allowed in the carb. Not sure on the 912 but I know that is how the 582 would work.
    Norm
    Airdrie Ab, Can
    North of Calgary
    Flying SuperFox Model IV

  3. #3

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    Default Re: older 912 ul heating up

    Nope I drop the clip down that takes needle up and makes richer. I’m looking to see if I can maybe change the timing?

  4. #4
    Senior Member jiott's Avatar
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    Default Re: older 912 ul heating up

    Have you checked the entire coolant system including radiator for free flow?
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  5. #5
    Super Moderator Av8r3400's Avatar
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    Default Re: older 912 ul heating up

    How about the sender or gauge?
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
    YouTube Videos

  6. #6
    Senior Member kmach's Avatar
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    Default Re: older 912 ul heating up

    Are you using 50/50 antifreeze/water or Evans water less coolant? There is around 25F difference between them in coolant temps.



    Do you have all cylinder's exhausts monitored for egt ?



    Carbs out of sync can cause different egt readings on different cylinders .



    High egts can mean inefficient burn in the heads. Proper plugs? gapped at what?



    Prop pitch can affect heating, over pitched and you will generate heat. lugging the engine will do this also.



    Did you try increasing rpms ? to 5300- 5500, sometimes this will make the engine run cooler.
    Kevin,

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

  7. #7

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    Default Re: older 912 ul heating up

    Ok guys I have not flushed the coolant system good idea will do only have two egts one in the front and one in the back other side of motor. Carbs are synced right on the money and by the way brand new carbs not old ones also brand new spark plugs, have not try to run high RPM . I get if the coolant is a problem but would that send the EGTs through the roof again has anyone gone fatter on the main jet ?? I have 158 jet size and a 2nd through would be to much exhaust restriction could cause this also ?? Again hair pulling shi”” thanks for the help guys anything more you guys come up with let me know.

  8. #8
    Senior Member Dave S's Avatar
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    Default Re: older 912 ul heating up

    Oldfox,


    Just a thought. Many times when I have done engine diagnosis (not necessarily aircraft engines) especially when a symptom can have many causes such as this puzzling situation your are dealing with, I have found it useful to go back and check cylinder health first....meaning compression - reason being that no amount of work on the ignition or fuel systems will dispatch a problem if there is a mechanical problem such as an exhaust valve developing a leak.



    A cylinder problem can translate into high EGT or high CHT due to lack of cylinder efficiency. Ruling this out could help reduce the number of things you would want to consider.


    Again, just a thought.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  9. #9
    Russell320's Avatar
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    Default Re: older 912 ul heating up

    Before all this started, what were the original readings?
    Russ
    Model IV Speedster
    912UL IVO IFA
    RV6A
    Needle, Ball and Airspeed
    Maybe a little GPS

  10. #10

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    Aug 2013
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    Angola In
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    Default Re: older 912 ul heating up

    Quote Originally Posted by oldfox View Post
    ok guys need some help just got the old bird back in the air flew great hands free but as I made the 4th lap around patch EGT (1530F) CHT (251F) stared to get on the high side oil temp was good 185 F...
    A couple things to consider, Float level, carb vent line location. Check your
    Egt gauge and sender. Do you have an oil cooler? Do you have a heater installed?
    Make sure you not more than 50/50 on you antifreeze mix. Do you have a thermostat installed.
    Drain your cooling system and refill using a vacuum refill system. Very important if you have a heater and thermostat.

    I have a speedster with an early 912. I’m at 160 on the mains but I also have the zipper big bore kit.

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