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Folks,
I'm looking to replace my 912ULS radiator hose clamps from the worm drive type to constant tension spring type. These are the 25mm ID hoses that run from the radiator to the water pump and to the coolant expansion tank at the top of the engine. I get a slight "weep" from these joints and I'm wanting to stop this. The cylinder head hose clamps ARE the spring type as supplied by Rotax and are water tight all the time.
Are there any recommended brand and/or part numbers I should look at?
BTW... the hoses I'm using at @ 33-34mm in OD.
Thank you!
  • Re: Radiator hose constant tension clamp OK to use?

    by » 10 years ago


    You can use the spring clamps on the 17mm coolant hose, but the large 25mm (1") hose will be too large.

    I would use something like the Zebra Hose clamp. This is a good solid clamp that won't strip out and provides good all around circumference pressure.

    http://www.wurth.co.uk/automotive-small-components-spares/pipe-tube-and-mounting-clamps/pipe-clamps-and-hose-clamps/zebra-hose-clamp-50-70mm

    If you are going to use a screw clamp on your engine then a fuel injection clamp is good (best) or the Zebra clamp for the larger hose. Do not use those worm drive clamps that have the serrations on them. Those might be okay for your garden hose, but not good enough to put your life or an $18K engine on the line. They can over cam and provide poor 360 degree circumference pressure. Oetiker clamps on fuel lines, but fuel injection will work.

    Her is a good article for you in our blog section.

    http://www.rotax-owner.com/rotax-blog/item/21-rotax-5-year-rubber-replacement-the-installation-considerations

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


  • Re: Radiator hose constant tension clamp OK to use?

    by » 10 years ago


    It may not be a perfect solution but Rotax now does have a spring clamp for the 1" hose: part number 951350. It is used on the 912iS coolant expansion tank. Item #12 in he attached photo.
    Caution: It may not fit every 1" hose you find at the auto parts store as some have a thicker wall than the hose used on the 912iS

    912iScoolingIPC.jpg (You do not have access to download this file.)

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