Spring tension hose clamps

[phintz]

Hello everyone! It's been cold here in Nebraska and I've noticed small antifreeze leaks. I pulled the cowling off and noticed drips coming off the spring tension hose clamps. Does everyone use these or do you use regular hose clamps?? Thanks

Patrick hintz
Kitfox series 6
Rotax 100 hp

[jiott]

I used regular hose clamps for the cooling system hoses I installed, but kept the spring clamps that came with the Rotax 912 installed hoses. I have never had a leak with the Rotax spring clamps, but have had a few small leaks with my screw clamps. Whenever I change a hose I will use the better Oeticker or fuel injection clamps next time around. Will keep the Rotax supplied spring clamps on those hoses.

[Dave S]

Hi Patrick,

Can't say that we have ever had any observation of drips at the small hoses with the Rotax spring clamps...I did swap out the hoses at the 5 year schedule and found that the newer Rotax brand small hoses were more pliable and a little larger on the OD than the originals - The spring clamps are one version of a constant pressure clamp which adjusts for material shrinkage in extremely cold conditions. The only thing I can think of is either the spring clamps are a little weak, or the hose is not as pliable as it should be - but they should work in normal conditions.

I do not like the basic screw clamps at all....they are not smooth on the inside so the hose rubber tends to squeeze up through the slots; and, they are definitely not a constant pressure design. We replaced the 1" screw clamps for the radiator hoses with constant pressure clamps and found that solved the cold shrink/drip problem - the new clamps were smooth on the inside and wider than the screw clamps - this particular design utilizes a stack of small belville washers to accomplish the constant pressure.

[kmach]

I had screw type hose clamps on most hoses before my five year hose replacement. Our climate has a big tempature swing from summer to winter, in the winter I had drips from the coolant hoses.

At my 5 yr hose replacement I switched all coolant hose clamps to the spring type that apply constant pressure and have never had a drip ever since.

[kmach]

I just thought of this, make sure your spring clamps are on the hose just aft of the bulge on the aluminum fitting, not on it but just beside the flare.

The rotax hose is very flexible and soft, I could see a leak potential if you use a hard composition hose.

[fastfred]

This conversation sounds like it covers several of our hoses. I am having a seepage problem at the base of the vent line at the header tank. I have 2 threaded clamps and after decent I and smell gas. It sets over night and I get some leakage. Any solution? Why do they use the clear soft line?

[phintz]

Hi Patrick,

Can't say that we have ever had any observation of drips at the small hoses with the Rotax spring clamps...I did swap out the hoses at the 5 year schedule and found that the newer Rotax brand small hoses were more pliable and a little larger on the OD than the originals - The spring clamps are one version of a constant pressure clamp which adjusts for material shrinkage in extremely cold conditions. The only thing I can think of is either the spring clamps are a little weak, or the hose is not as pliable as it should be - but they should work in normal conditions.

I do not like the basic screw clamps at all....they are not smooth on the inside so the hose rubber tends to squeeze up through the slots; and, they are definitely not a constant pressure design. We replaced the 1" screw clamps for the radiator hoses with constant pressure clamps and found that solved the cold shrink/drip problem - the new clamps were smooth on the inside and wider than the screw clamps - this particular design utilizes a stack of small belville washers to accomplish the constant pressure.

Hey Dave , Not sure what to tell ya, I will keep an eye on it for now but may change the hoses alittle early maybe and try again. I agree that the spring tension should be the best.

[Guy Buchanan]

I really hate dealing with spring clamps during service. I know their worth, but hate them so much I replaced them all with screw clamps; much easier to install. So this begs the question, does anyone know of a constant pressure screw clamp?

[Dave S]

Guy,

I agree the spring clamps are a PITA....ended up buying a pliers for them from the auto parts store - the pliers has a pair of anvils that rotate to get at the ugly angles a person deals with. I kept the spring clamps on the small hoses.

I believe one of the other list members from Canada uses spring clamps for the 1" hoses - I couldn't find any the right size so went to an alternative style (which is a bit more costly @$7 each)

There are several versions of constant pressure clamps - the ones I got from Fastenall are represented in the attached photo and I used them on the 1" hoses

Others designs use small coil springs rather than bellville washers.