Why wont my silicone hoses seal?
Discussion
I've bought a set of silicone bends to make up my cooling system and I can't get it to pass a leakage test.
I'm using T-bolt clamps and swaged alloy straight connectors.
The fit is good. Not difficult to place the hose on the joiner, but not loose. You know, about right. Dia is 32mm.
The joints start to hiss at 5 psi. System is completely dry.
If I wiggle the joint at 10 psi it lets gulps of air out.
So I keep tightening the clamp.
The leakage does improve, but it's so tight now I feel like I could damage the pipe.
Although, I can confirm that there is no damage at all after pulling it apart.
How is everyone managing to use silicone?
Is it a case that it may leak with air, but not with water?
My system really should be holding 20 psi so this is a bit of a problem.
I'll keep the manufacturer quiet for now, as I may return them and go with rubber.
I'm using T-bolt clamps and swaged alloy straight connectors.
The fit is good. Not difficult to place the hose on the joiner, but not loose. You know, about right. Dia is 32mm.
The joints start to hiss at 5 psi. System is completely dry.
If I wiggle the joint at 10 psi it lets gulps of air out.
So I keep tightening the clamp.
The leakage does improve, but it's so tight now I feel like I could damage the pipe.
Although, I can confirm that there is no damage at all after pulling it apart.
How is everyone managing to use silicone?
Is it a case that it may leak with air, but not with water?
My system really should be holding 20 psi so this is a bit of a problem.
I'll keep the manufacturer quiet for now, as I may return them and go with rubber.
4 points of note from the pics you show.
Make sure you aren't clamping the hose directly over the "crimp" in the pipe, that is there to prevent the hose being pushed off, not to seal on.
The pipe is "seamless" and round isn't it? As a welded pipe isn't as easy to seal & a deformed one will never seal.
The clamps you are using are sh!t. If you look closely at the rounded parts that spread the torque to the clamping ring creating the tightening effect, they aren't fully cylindrical. When done up tight, these deform the ends of the clamping ring & can even snap the ends.
Pic below shows the type with fully cylindrical ends, which are Much better.
The clamps you are using are MUCH too long, which means the fixed radius saddle part of the clamp ring will have the wrong radius for the pipe creating gaps.
Make sure you aren't clamping the hose directly over the "crimp" in the pipe, that is there to prevent the hose being pushed off, not to seal on.
The pipe is "seamless" and round isn't it? As a welded pipe isn't as easy to seal & a deformed one will never seal.
The clamps you are using are sh!t. If you look closely at the rounded parts that spread the torque to the clamping ring creating the tightening effect, they aren't fully cylindrical. When done up tight, these deform the ends of the clamping ring & can even snap the ends.
Pic below shows the type with fully cylindrical ends, which are Much better.
The clamps you are using are MUCH too long, which means the fixed radius saddle part of the clamp ring will have the wrong radius for the pipe creating gaps.
Edited by E-bmw on Wednesday 10th November 09:31
Edited by E-bmw on Wednesday 10th November 09:33
Thanks for the input.
Let's start with the easy bits
Ally Joiner:
I'm not clamping on the crimp. The joiner is 100mm so plenty room for clamping.
The joiner is seemless and round.
Clamp Size:
It's as good as I can get.
Outside diameter is 41.1mm when fitted.
Or 40.7mm when not fitted.
The clamp sizes that are available are:
36mm to 39mm
or
40mm to 43mm
So I naturally went with the larger.
Looking at other suppliers, the only other size I can find is 37mm to 40mm. I will probably struggle with this size I think. Plus it's the same style clamp that I have now.
Pipe Fit:
I think the above image is clearer that shows the pipe hugging the joiner quite nicely.
Also note that the diameter of the hose is 0.4mm bigger when fitted so it's not rattling around on there.
Clamp Design
This one is unused and it's already wonky. The used ones look the same.
Here's one clamped up to a reasonable force. Roughly the force I would expect to have to use.
Note that with a reasonable clamping force, it's exactly half way through the travel on the thread.
It can't be the wrong size, yet:
Note the gaps next to the load spreading bit.
Urghhhh.
Are we certain the the other style of T-Bolt clamp is going to be that much better?
Do you know who supplies them, as all the big names that sell silicone hoses seem to sell the style I have.
Am I just better off using the skinny worm drive clips then? I've heard these aren't great with silicone.
If worm drive is the way to go, does that mean that rubber is also the way to go?
I hope I can get a refund on some of these items as this has turned out to be a bit of a waste.
Thanks all.
Let's start with the easy bits
Ally Joiner:
I'm not clamping on the crimp. The joiner is 100mm so plenty room for clamping.
The joiner is seemless and round.
Clamp Size:
It's as good as I can get.
Outside diameter is 41.1mm when fitted.
Or 40.7mm when not fitted.
The clamp sizes that are available are:
36mm to 39mm
or
40mm to 43mm
So I naturally went with the larger.
Looking at other suppliers, the only other size I can find is 37mm to 40mm. I will probably struggle with this size I think. Plus it's the same style clamp that I have now.
Pipe Fit:
I think the above image is clearer that shows the pipe hugging the joiner quite nicely.
Also note that the diameter of the hose is 0.4mm bigger when fitted so it's not rattling around on there.
Clamp Design
This one is unused and it's already wonky. The used ones look the same.
Here's one clamped up to a reasonable force. Roughly the force I would expect to have to use.
Note that with a reasonable clamping force, it's exactly half way through the travel on the thread.
It can't be the wrong size, yet:
Note the gaps next to the load spreading bit.
Urghhhh.
Are we certain the the other style of T-Bolt clamp is going to be that much better?
Do you know who supplies them, as all the big names that sell silicone hoses seem to sell the style I have.
Am I just better off using the skinny worm drive clips then? I've heard these aren't great with silicone.
If worm drive is the way to go, does that mean that rubber is also the way to go?
I hope I can get a refund on some of these items as this has turned out to be a bit of a waste.
Thanks all.
montyjohn said:
The clamp sizes that are available are:
36mm to 39mm
or
40mm to 43mm
So I naturally went with the larger.
Here's one clamped up to a reasonable force. Roughly the force I would expect to have to use.
Note that with a reasonable clamping force, it's exactly half way through the travel on the thread.
It can't be the wrong size, yet:
Note the gaps next to the load spreading bit.
Urghhhh.
Am I just better off using the skinny worm drive clips then? I've heard these aren't great with silicone.
If worm drive is the way to go, does that mean that rubber is also the way to go?
You can see the gaps in those clamps, the clamps are too big, the smaller ones may be a better fit, but they are still cheap/nasty for my liking.36mm to 39mm
or
40mm to 43mm
So I naturally went with the larger.
Here's one clamped up to a reasonable force. Roughly the force I would expect to have to use.
Note that with a reasonable clamping force, it's exactly half way through the travel on the thread.
It can't be the wrong size, yet:
Note the gaps next to the load spreading bit.
Urghhhh.
Am I just better off using the skinny worm drive clips then? I've heard these aren't great with silicone.
If worm drive is the way to go, does that mean that rubber is also the way to go?
The ones with the full cylindrical load spreaders on the adjusters are definitely the way forward for me.
If not then as was stated above normal jubilee hose clips will work better than the ones you are using, and whoever said they aren't great with silicone was wrong, they are 100% fine when used/sized correctly.
The good quality type similar to yours are available literally all over, just look at the pics closely before ordering.
RS online are one of many, many suppliers.
E-bmw said:
You can see the gaps in those clamps, the clamps are too big, the smaller ones may be a better fit, but they are still cheap/nasty for my liking.
Ye I know there are gaps, I pointed them out in my last post. Horrible looking things.But it's not that it's too big, it's just the wrong shape.
If I go a size smaller it wont fit.
So the size is fine, it just isn't round for any of the range it's specified for. I'm fully within the size range specified, and the ranges are all pretty consistent regardless of where you get them from.
E-bmw said:
The good quality type similar to yours are available literally all over, just look at the pics closely before ordering.
RS online are one of many, many suppliers.
Maybe I don't know what I'm looking for, but they all seem to be the exact same design to the ones I have.RS online are one of many, many suppliers.
Here's RS Onlines offering
https://uk.rs-online.com/web/p/hose-clips-jubilee-...
Here's RS Onlines versions compared to mine side by side.
Yes mine is wonkier, but the stock photos always look perfect so it doesn't appear easy to pick a good one?
Deamon Tweeks offer the same thing also.
https://www.demon-tweeks.com/uk/mikalor-stainless-...
Basically they are all made by Mikalor.
I'm also struggling to understand what the difference is with the one you posted a pic of earlier. Is it all down to the "D" shaped ears vs round ears?
To me, the big issue seems to be the radius of the plate in yellow not matching the stated radius of the clip. Since mine are Mikalor just like all the rest of them, I wouldn't have any confidence that it's not a problem with all of them.
montyjohn said:
I'm also struggling to understand what the difference is with the one you posted a pic of earlier. Is it all down to the "D" shaped ears vs round ears?
Mikalor clamps used to be really nicely made with cross-drilled rods connecting the screw to the strap. Nowadays they have these flimsy cast things. I guess they figured they can save money. The design should still work, but perhaps they compromised other details like the exact fit of the clamp.In your case I think the problem is that the connecting plate shown in yellow doesn't match the curvature of the hose well enough so you are not getting an even clamping pressure. This may be combined with the hose not being a tight enough fit on the connector. I think you mentioned a fraction of a mm stretch, which is effectively nothing. There should be a significant stretch over the connector and not just over the barb. Also make sure that the outside of the connector and the inside of the hose are undamaged - it's easy to nick / chip them with repeated refitting and clamping and that will prevent a seal.
GreenV8S said:
There should be a significant stretch over the connector
You see I went with 32mm unions and 32mm hose.The radiator fittings are all 32mm, so to get a bigger stretch I would need to take the hose down to 30mm which I'm guessing is a feasible stretch.
I might keep that in my back pocket for now.
I've found a bunch of random sized worm gear clamps and they appear to be working fine.
I can't confirm it's holding pressure long term, as it's now apparent my blanking radiator cap isn't sealing all that well. As I have an expansion tank, the radiator has a blanking cap on it, and a quick google suggests finding a decent blanking cap is a minefield where current offerings just don't seal. Let the trial and error begin.
Pumped up to 12 psi and I'm losing about 3psi per 10 minutes with the only noise coming from the cap.
But it's looking good for the hoses so thanks all.
Edited by montyjohn on Wednesday 10th November 15:43
montyjohn,
You might try a self-fusing silicone tape, around the connecting tube, under the hose. I use silicone hose but onto an old cast iron water pump housing. The connector just doesn't match any silicone hose size, and is pitted - I don't think it was ever smooth. A single turn of tape around it, hose pushed over and then secured with a Mikalor produces a perfect seal. So much so, I use it where it's not so much needed!
Google for 'self-fusing tape'.
John
You might try a self-fusing silicone tape, around the connecting tube, under the hose. I use silicone hose but onto an old cast iron water pump housing. The connector just doesn't match any silicone hose size, and is pitted - I don't think it was ever smooth. A single turn of tape around it, hose pushed over and then secured with a Mikalor produces a perfect seal. So much so, I use it where it's not so much needed!
Google for 'self-fusing tape'.
John
OK, one thing at a time.
If I go a size smaller it wont fit.
So the size is fine, it just isn't round for any of the range it's specified for. I'm fully within the size range specified.The shape is correct (as in round) the radius of the bend on the saddle is too big which is why there are gaps at each end of the saddle & also why you have used up so much thread on the screw to do them up.
The one you show on the hose in the pic is too big.
Either use the smaller size or use a good quality jubilee clip.
montyjohn said:
E-bmw said:
You can see the gaps in those clamps, the clamps are too big, the smaller ones may be a better fit.
But it's not that it's too big, it's just the wrong shape.If I go a size smaller it wont fit.
So the size is fine, it just isn't round for any of the range it's specified for. I'm fully within the size range specified.
The one you show on the hose in the pic is too big.
Either use the smaller size or use a good quality jubilee clip.
montyjohn said:
E-bmw said:
The good quality type similar to yours are available literally all over, just look at the pics closely before ordering.
RS online are one of many, many suppliers.
Maybe I don't know what I'm looking for, but they all seem to be the exact same design to the ones I have.RS online are one of many, many suppliers.
Here's RS Onlines offering
https://uk.rs-online.com/web/p/hose-clips-jubilee-...
Here's RS Onlines versions compared to mine side by side.
Yes mine is wonkier, but the stock photos always look perfect so it doesn't appear easy to pick a good one?
Deamon Tweeks offer the same thing also.
https://www.demon-tweeks.com/uk/mikalor-stainless-...
Basically they are all made by Mikalor.
I'm also struggling to understand what the difference is with the one you posted a pic of earlier. Is it all down to the "D" shaped ears vs round ears?
To me, the big issue seems to be the radius of the plate in yellow not matching the stated radius of the clip. Since mine are Mikalor just like all the rest of them, I wouldn't have any confidence that it's not a problem with all of them.
Here are just a few found by googling "silicone hose clamps" taken at random from the results, all of which use fully cylindrical ends, which clamp more evenly without deforming the ends.
RS online.
https://uk.rs-online.com/web/p/hose-clips-jubilee-...
la-299938738460&gclid=EAIaIQobChMIx5WKxcGO9AIVnoxoCR0S0wkUEAQYCCABEgI56fD_BwE&gclsrc=aw.dsExoracing.
https://exoracing.co.uk/exoracing-t-bolt-silicone-...
Turbosmart.
https://www.turbosmart.com/product/barrel-hose-cla...
The Mikalor style clamps you are using are completely incorrect for the application - they were originally designed for semi-gas tight thin wall pipe to pipe joints...... i.e. they are exhaust clamps.
Use a good quality "Jubilee" style hose clip. The narrower width will create a greater clamping pressure across the area the clip acts on than pretty much anything else (which is what you want for sealing). Don't use the high torque version as these are not designed for soft hose joining.
Back in the days of 3.5bar coolant pressure and V10s in F1 the water rads on anything Cosworth were still retained with Samco and Jubilees - for the system pressures you're worried about they are way over spec'd
Use a good quality "Jubilee" style hose clip. The narrower width will create a greater clamping pressure across the area the clip acts on than pretty much anything else (which is what you want for sealing). Don't use the high torque version as these are not designed for soft hose joining.
Back in the days of 3.5bar coolant pressure and V10s in F1 the water rads on anything Cosworth were still retained with Samco and Jubilees - for the system pressures you're worried about they are way over spec'd
So I got in touch with the supplier and they said if your only using half the thread, then they are not tight enough.
Apparently they should be so tight that the two loops are touching one another.
I was skeptical on the basis that if I tighten it up that much it's surely going to either crush the aluminium tube or cut the hose.
I was also spectral as there isn't a single voice in many forums saying that these things actually seal well.
This one is a great example. Everyone says they don't work and just use a normal jubilee.
https://passionford.com/forum/general-car-related-...
I humored the supplier and tried using Hi-man scale forces on them on some offcuts at first. Had to use a vice to get them this tight as my piece was small. It's a ridiculous amount of force.
Anyway after removal, there was no damage at all. Just a slight in-print in the silicone. No different to what a jubilee would leave behind suggesting I'm getting similar clamping forces from the two approaches.
Also, the non-round shape issues noted when they were 1/2 to 2/3rd threaded went away.
Notice how it now contours around the hose. I'm not sure if the pressure plate is flexing, or it's just pushed it into the silicone so the exact radius no longer matters but it looks fine from the outside.
Yes the clamping force is deforming the silicone such that it peels up which isn't ideal. This is where the 30mm hose instead of 32mm would have been better.
So I tried this approach on the car and it's holding pressure just fine. No leakage at all from the joint.
Going down a clamp size is not the answer.
I'm not going to be able to get a 39mm or 40mm max diameter clamp onto a 41.4mm diameter hose. Nevermind getting it over the swage on the aluminium joiner (although there are ways around this).
Another approach is to use a longer bolt, but it seems to not be required.
I'm some point I will try a round pin style and see if it behaves any differently and report back, might be a while though.
Apparently they should be so tight that the two loops are touching one another.
I was skeptical on the basis that if I tighten it up that much it's surely going to either crush the aluminium tube or cut the hose.
I was also spectral as there isn't a single voice in many forums saying that these things actually seal well.
This one is a great example. Everyone says they don't work and just use a normal jubilee.
https://passionford.com/forum/general-car-related-...
I humored the supplier and tried using Hi-man scale forces on them on some offcuts at first. Had to use a vice to get them this tight as my piece was small. It's a ridiculous amount of force.
Anyway after removal, there was no damage at all. Just a slight in-print in the silicone. No different to what a jubilee would leave behind suggesting I'm getting similar clamping forces from the two approaches.
Also, the non-round shape issues noted when they were 1/2 to 2/3rd threaded went away.
Notice how it now contours around the hose. I'm not sure if the pressure plate is flexing, or it's just pushed it into the silicone so the exact radius no longer matters but it looks fine from the outside.
Yes the clamping force is deforming the silicone such that it peels up which isn't ideal. This is where the 30mm hose instead of 32mm would have been better.
So I tried this approach on the car and it's holding pressure just fine. No leakage at all from the joint.
Going down a clamp size is not the answer.
I'm not going to be able to get a 39mm or 40mm max diameter clamp onto a 41.4mm diameter hose. Nevermind getting it over the swage on the aluminium joiner (although there are ways around this).
Another approach is to use a longer bolt, but it seems to not be required.
I'm some point I will try a round pin style and see if it behaves any differently and report back, might be a while though.
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