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I have a 912ULS with a Rotax airbox and Rotax drip trays. I need to run a drain line from the barb nipples on the bottom of the drip trays down the firewall. The problem I have is that any hose I connect to that drain nipple comes pretty close to the exhaust pipe (maybe 3/4" away--see attached photo). I ordered some high-temperature (450°F) fluorosilicone rubber tubing (blue color) for fuel and lubricants, but the durometer on this hose is low and the tubing crimps too easily. What have others done? Thanks, Mike
11022_1_Carb Drip Tray.jpg (You do not have access to download this file.)
  • Re: Plumbing for Rotax Airbox Drip Tray Drains

    by » one week ago


    Speculation:

    Gates fuel injection hose (has slightly higher heat rating than the carb variant), with strategically placed aluminium wrap.

    My favourite aluminium, for this sort of job, is builders flashing (replaced lead many years ago).

    Obtained from hardware/builders supply in a role.

    Its mailable, can be cut with scissors (don't use the wife's dress making ones).

    Secure with safety wire.

    If you need added heat protection, silicon a piece of exhaust wrap to the inside of the aluminium.

    Note: The flashing, is very handy,  can be used for all sorts of other jobs eg making a temporary channel for draining oil, electrical "noise" shielding, etc😈


    Thank you said by: Michael Tucker

  • Re: Plumbing for Rotax Airbox Drip Tray Drains

    by » one week ago


    I was also thinking about fabricating a heat shield from a flat piece of 0.050 sheet and affixing it to the drip tray.  The shield would be designed to be between the exhaust and drain hose.


  • Re: Plumbing for Rotax Airbox Drip Tray Drains

    by » one week ago


    Yes that would work too. Sounds a bit more "involved" than the ductile aluminium.

    FYI: Just my opinion;

    The drip trays main function is as a heat shield, to shield the underside of the carburettor, especially float bowl

    The likelihood of your drain pipes ever "seeing action" is extremely low.

    When engine running, the drip tray will be quite hot, any fuel coming from the carb will likly be "flash" evaporated, long before it gets to drain away.

    😈


  • Re: Plumbing for Rotax Airbox Drip Tray Drains

    by » one week ago


    Are you saying to wrap the ductile aluminum around the drain hose?  I have some fiberglass tape with a thin aluminum reflective coating...you can see some around a coolant hose in my photo.


  • Re: Plumbing for Rotax Airbox Drip Tray Drains

    by » one week ago


    Yes.

    I also use "fiberglass tape with a thin aluminum reflective coating" but not where the adhesive will be "cooked"😈


    Thank you said by: Michael Tucker

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