i own a 914 rotax ,i have new little problem
my pink coolant go in my overflow bottle but dont go back on they engine
i check all my hose and attach nothing goes wrong
how can i find it the problem
  • Re: cooling overflow bottle

    by » 12 years ago


    If this is a new problem and the overflow bottle has been acting correctly up until now, I would suspect the reservoir or radiator cap first. If it doesn't seal properly, air will leak into the coolant system instead of the coolant being sucked back in as the system cools off. The valve mechanism that is built into the radiator cap will keep the coolant in the system until the pressure rated on the cap is reached. As the radiator cools however, a one way valve in the cap opens very easily under vacuum and pulls the overflow back into the system. You could have a leak in the system somewhere else as well. If you are losing coolant through a leak the result can be the same as you are experiencing. If coolant can leak out when hot, air can leak in when cold.


  • Re: cooling overflow bottle

    by » 12 years ago

    Hi richanrd,

    I agree with Bill. Rule the radiator cap in or out as the problems first. If you have someone near you with a 912 try his cap for a quick check. My other question is why are you over flowing coolant in the first place? Are you having some hot temps or could it be a bad cap? Caps tend to hold up and last a long time.

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

  • Re: cooling overflow bottle

    by » 12 years ago

    I gone a change the cap first
    and see

  • Re: cooling overflow bottle

    by » 5 weeks ago

    Related but new thread.

    My 912ULS overflow hose is milky white hard plastic.  I want to replace it but can't really identify the part # from the IPC (no photo of a bottle like mine and no photo of a hose).  Auto parts stores don't seem to stock this hard, vacuum, high-temp hose.   Any help appreciated.

    Bottle is top spout, with the hose just shoved into the cap.


  • Re: cooling overflow bottle

    by » 5 weeks ago


    Any good quality coolant hose (sometimes called heater hose), of the correct ID, will do the job - it need not be translucent/clear.

    I preferer Gates hoses.

    To allow for engine movement/vibration, you should use a flexible hose (not hard plastic).

    See: https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-pac-009.pdf

    For the  expansion reservoir (bottle) to work correctly it must either have top fitting like this:

    Fits For Engine For Takeuchi Reserve Expansion Coolant Tank 50 60 65 80

    or a bottom spigot/barb similar to this Rotax style one:


    A transparent bottle, where you can check the fluid level is best.

    Make sure your bottle has sufficient capacity (see Rotax reference above)

    In all cases, the top of the bottle must have an open to atmosphere hole/spout.

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