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Thread: Expansion bottle and hex nut issues

  1. #1

    Expansion bottle and hex nut issues

    Hi all, my radiator is spitting out almost the entire contents of the expansion bottle (via the relief hole on the lid) after an hours flight. I have tried lots of options, any advice? Air lock perhaps, it used to stay around 1/3 full.

    Also the tall hex nut (mounted on the head) that supports the exhaust on my 582 keeps working itself loose. Should I use locktight?



  2. #2
    Senior Member 100 Club
    Join Date
    Dec 2012

    Expansion bottle and hex nut issues

    Hi Alan,

    You could well achieve a higher response to this question if you also post it in the section of this forum pertaining to your engine (see forum headings). Is it a Rotax 582?.

    I'm not an expert on the various types of Loctite - which may well do the job - but could an alternative be a locking washer?


  3. #3
    not real name 500 Club
    Join Date
    Dec 2006
    Thornhill (Easter Poldar) Farm Strip West of Stirling, near Kippen in Scotland

    Expansion bottle and hex nut issues

    Hi Alan,

    What anti freeze mix is in the radiator ? The ratio matters if you're flying in higher ambient temperatures (Not an issue here in Scotland, awful wx :-) )

    The Exhaust bracket on mine is secured with a bolt into the threaded extension piece (through the av mount on the exhaust bracket) which is torqued onto the cylinder head stud, and the top bolt and washer secures the exhaust bracket firmly. I recall that the cyl head stud is Loctited so the extension piece should not work loose if torqued up properly.


  4. #4

    Expansion bottle and hex nut issues

    Thanks for both replies, I will also add to the engine section Phill.

    Graham, the antifreeze mix is 50/50 currently. I've replaced the hose and also the rad cap, it's not easy to find a new version of the little chemist style bottle though. An Rotax expert recommended a large expansion bottle, but it's where to fit the darn thing.

    Thanks for the locktight advice also..

    Thanks Alan

  5. #5

    Expansion bottle and hex nut issues

    Answered elsewhere Alan. But I've run 462s without expansion bottles and never had an issue. So I don't think size is important ;-)

  6. #6
    Junior Member
    Join Date
    Sep 2011

    Expansion bottle and hex nut issues

    Re expansion bottle issue, sounds fairly typical of a head gasket leak into the water jacket. It will be a tiny thing so don't expect confirmation by compression test. You can get sniffers to look for combustion gases but I wouldn't bother if its as simple as you have described.

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