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.:)

[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.

[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.

[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.

[jiott]

What about fuel injection hose clamps? They are screw type but I believe considered 360 degree const. pressure clamps?

[jrevens]

I'm using some of those using the belleville washers also, Dave - made by Breeze, all S.S. I found a really good deal on them on the internet in boxes of 10, but I've misplaced the info on that - it was a big truck supply place. I think they're a little large & bulky for the small coolant hoses on the engine, but I like them for the oil hoses that go to my oil thermostat especially. I decided not to use them on my silicone hoses... I think the surface of that hose is so soft & "conformable" that they won't be needed for a reliable leak-proof joint. I did use "silicone" type clamps with an all-smooth surface against the hose though. I got sizes for both the smaller & the larger 1" hose,but ended up not using the larger ones. I'd sell the constant pressure ones I have left over for $3 each. As I said, I've got some for the big & small hose sizes.

[jrevens]

What about fuel injection hose clamps? They are screw type but I believe considered 360 degree const. pressure clamps?

Those have a more uniform, 360 deg. smooth contact with the hose alright, but they are not "constant pressure". I do like those fuel injection type clamps over a standard worm screw type... my favorites are made by ABA in Sweden.

[Dave S]

I learned that lesson along the way too John....the fuel injection clamps work great on...well....fuel hose!

Drips do not seem to be a problem on fuel lines even if there is no "constant pressure" feature...I would speculate that has to do with two things...the materials used for fuel line connections being less succeptable to cold shrink; and, the fact that cold shrink is a % of scale thing with a small diameter application ending up with far less total shrink than a larger diameter application - i.e. 5% of 1" is more than 5% of 5/16".

[Guy Buchanan]

Yeah, here they are:

Fastenal (https://www.fastenal.com/products/hydraulics-pneumatics/clamps-and-collars/constant-tension-clamps/_/Navigation?r=~%7Ccategoryl1:%22603388%20Hydraulics %209and%20Pneumatics%22%7C~%20~%7Ccategoryl2:%2260 3508%20Clamps%20and%20Collars%22%7C~%20~%7Ccategor yl3:%22612491%20Constant%20Tension%20Clamps%22%7C~ )

Breeze (http://www.breezehoseclamps.com/breeze/constant-torque/)

The Breeze are available on Amazon (https://www.amazon.com/Breeze-Constant-Torque-Stainless-Worm-Drive-Diameter/dp/B009SD05NC/ref=pd_sim_328_1?_encoding=UTF8&pd_rd_i=B009SD05NC&pd_rd_r=6J8JYEG47N6TZPMVGVMV&pd_rd_w=B6Uwy&pd_rd_wg=M47Zw&psc=1&refRID=6J8JYEG47N6TZPMVGVMV). Only $43 for a box of 10! Yowza!

[jrevens]

I learned that lesson along the way too John....the fuel injection clamps work great on...well....fuel hose!

Drips do not seem to be a problem on fuel lines even if there is no "constant pressure" feature...I would speculate that has to do with two things...the materials used for fuel line connections being less succeptable to cold shrink; and, the fact that cold shrink is a % of scale thing with a small diameter application ending up with far less total shrink than a larger diameter application - i.e. 5% of 1" is more than 5% of 5/16".

I think you're exactly right, Dave. The neat thing about the high quality silicone hoses, for coolant applications, is that the cold shrink is very minimal, if any, and it remains soft & pliable at low temperatures, as well as having a very high upper temperature limit. It also has a very long life... it doesn't "age" for all practical purposes. That's the main reason I didn't use the larger, heavier constant pressure clamps on those lines. I used the Rotax supplied spring clamps for the 8 hoses on the engine itself, but on all of the 1" hoses I used the smooth lined worm screw clamps, with "relieved" edges that can't dig into the hose as easily, made by ABA. There are other similar clamps made by others... the race car guys have a good handle on this stuff.

[ken nougaret]

How about ClampTite wire clamping?

[efwd]

That ClampTite tool is an awesome field expedient way to cary clamps. Kinda pricey.
Eddie

[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?

[Dave S]

Fastfred,


I don't think this is a common problem. The tubing has not been an issue by itself. I don't think this is a cold shrink deal like can happen on the larger coolant hoses.



A few things to consider:


1) Do you have the plastic header tank or aluminum one? The plastic one is more succepible to issues - such as sealing the threaded nipple that goes in the center for for the vent line.



2) Fit between the hose and the nipple - if the fit is not as close as it should be it might be hard to clamp up. Hose should fit snug on the straight part of the nipple and tightly over the barb.



3) Any cut, scratch etc on either the nipple or the inside of the hose could be a source of problems. How old is the hose?



4) The clamp should be 100% round - if there is a bend or kink in the clamp material that's a potential source.


Not sure if this helps any, but, sounds like something that might take some detail work figuring out.


Good luck.


PS - the transparent line is historical on Kitfoxes and there is some thought seeing the fuel might allow a person to realize they are running on the fuel in the header tank only if a bubble shows up coming down the vent line, although I'd like to think everyone would keep a better reserve of fuel, or at least a legal reserve .

[fastfred]

It is a new aluminum tank and fittings.

The hose fit seems good and I have to cut it off to remove it every time.

All new hose.

I put a new perfect fit clamp on and a normal hose clamp. Double clamped!

I have a low fuel light installed so the clear hose is not an issue.


All these steps improved the problem but after leaving it over night it still seeped out a little.

I finally epoxied the hose and flew a couple hours yesterday . I pulled the seat and checked the paper towel I wrapped around the fitting. No seepage but on most descents I still got a fuel smell. Why is that?

Now a new problem the Tach is no longer reading correctly? My research says they do go bad and I assume it is the original 2004. I ordered a new from Spruce. So I can go to Loch Haven next week.

I saw on here where changing all the lines to fuel injection lines stops the odor in descent?

Thanks for looking at my issue .It has been frustrating and I have gotten good at pulling the seat and about $20 in zip ties.

[Esser]

If you just did fuel Injection hose and AN fittings in the cockpit it wouldn’t be too expensive.

[fastfred]

Is that fuel smell in descent normal? Have you seen that the fuel injection line helps?

I have a Fly in safety seminar Saturday and Trip to Loch Haven next week to really give it a test . Then the fuel injection lines are next. That is if I get the Tach installed.

[GMKman]

This is what I used when I changed my fuel lines. I have no more fuel smell at all now.”PARKER SUPER-FLEX 397 SERIES FUEL LINE HOSE” you can get it at aircraft spruce. It’s designed to not let hydrocarbons vent out like other fuel hoses do.