Rubber hose life? Silicone hoses?

Hi Michael,

I am in a similar situaton.

If you go "by the book" its 5 years, no argument/debate. From poor memory, Rotax allow 2 years (?) from date of purchase, before the calendar clock starts.

As all my hoses were still nice a flexible (stiffening being one of the signs of deterioration) had been stored (along with the engine in its original box/packing) away from UV,  in a dry and relativly cool environment, I have elected to go 5 years from the first start. This will make my hoses about 5 years + 12-18 months old at the first 5 year replacement.  This is not a recommendation, just my call.

As a 15 year user of Rotax 912ULS engines,  I would advocate for replacement with the standard "rubber" hose. Silicon sounds great, but the cost is high and it tends to be higher weight as well.

If your legislative environment allows, you can replace almost all hoses, with aftermarket ones, that meet/exceed Rotax standards, at a much lower cost than purchasing  from Rotax.

Further - Even with a few silicon hoses, you will still have "rubber" components to replace at 5 years. Why not use the 5 year interval to do a full rubber replacement AND a top top of the line service?😈

WhenI had my engine rebuilt, the mechanic replaced my hoses with silicone ones. They look nice but it is much more difficult to tighten the clamps sufficiently on the joints. The hoses are very slippery and I actually had one of the coolant hoses come off where it was secured using the original Rotax sprung clamp.

The silicone material also seems less robust than the rubber with regard to abrasion and cuts. Although it doesn't degrade like rubber it may not be a better solution in our application.

Thank you, Sean and Kevin.  I appreciate your suggestions.

Mike

You are right about silicone and hose clamps. I had a supplier of silicone and teflon hoses tell me that clamped connections are not recommended. They recommended JIC (flared) fittings be installed on the hose ends. Obviously this is not practical on large coolant hoses, but is preferred for smaller higher pressure hoses.

Sean, do you recall if the "two year" grace period before the five year clock starts appears in any of the Rotax documentation?  I searched through the Line Maintenance Manual but only saw the "five year" period mentioned.

Thanks!