Can a hose clamp be over-tightened?

PeteBlu · 18-01-2019, 12:09 PM

I recently had a mechanic tell me that it is impossible to over-tighten a hose clamp so much that it could cause a flange to break. This was after they replaced the radiator hose in my car, and the flange on the thermostat housing broke off (see pic.)

Seems unlikely to me, what do you think?

Cheers.

roKWiz · 18-01-2019, 12:31 PM

I've broken a few new hose clamps over tightening. SS, mild steel.
Broken a alloy pipe flange under it over tighening one as well.
New stuff seems to be chinese junk.

**Mont5.0** · 18-01-2019, 12:33 PM

it would depend what you did it up with. A phillips head screwdriver will only let you go so far, but a 7-8mm socket can go a lot harder.

**Silver Ghia** · 18-01-2019, 12:53 PM

Quote:

Originally Posted by PeteBlu

I recently had a mechanic tell me that it is impossible to over-tighten a hose clamp so much that it could cause a flange to break. This was after they replaced the radiator hose in my car, and the flange on the thermostat housing broke off (see pic.)

Seems unlikely to me, what do you think?

Cheers.

Looks badly corroded, which would have caused it to break off.

But care should be taken not to overtighten hose clamps, otherwise they may fail too.

bangm001 · 18-01-2019, 01:01 PM

Do you use coolant? Is it the proper ford coolant?

**aussiblue** · 18-01-2019, 01:07 PM

Quote:

Looks badly corroded, which would have caused it to break off.

I think he has a Mondeo with a plastic thermostat housing. And they are more vulnerable to stress fractures like that. Pretty corrosion resistant thought :-)

PeteBlu · 18-01-2019, 01:46 PM

Quote:

Originally Posted by bangm001

Do you use coolant? Is it the proper ford coolant?

Yes, and yes. Can I ask why?

PeteBlu · 18-01-2019, 01:47 PM

Quote:

Originally Posted by aussiblue

I think he has a Mondeo with a plastic thermostat housing. And they are more vulnerable to stress fractures like that. Pretty corrosion resistant thought :-)

Correct. And the stress fracture could be caused by over-tightening the clamp do you think?

**aussiblue** · 18-01-2019, 01:49 PM

Yes; plastic deforms then breaks.

**Silver Ghia** · 18-01-2019, 01:57 PM

Ah, it looked like badly corroded aluminium. Sorry.

Yes, plastic would break.

xeeclipse · 18-01-2019, 02:18 PM

Always used TRIDON clamps. They don't cut into the hose like some other brands.

Should always be done up with an 8mm 1/4 drive until the worm drive binds. If reusing an old hose either switch the drive around 180 degees or trim if excessively swollen.

galaxy xr8 · 18-01-2019, 08:42 PM

Hose clamp's should never be done up tight, let alone super tight.
Just firm, if the correct hose is used and in new condition then the clamp should only be firmly done, if you over tight them then you run the risk of future leaks.

The clamp should be just positioned on the far side of the ridge on a housing and done firmly, people often over tighten clamp's thinking the tighter the better but in actual fact you squeeze/squash the hose and cause leaks.

**aussiblue** · 18-01-2019, 09:34 PM

It's also good practice to put a thin layer non hardening gasket goo around inside of the hose end far enough to go past that ridge. It helps the hose slip on and prevents leaks by filling any nicks, dents and casting imperfection in the fitting it's going on. It was normal procedure when I first started working on cars and was even prescribed in various factory workshop manuals but seems to fallen out of favour in recent decades. I usually use this: https://www.permatex.com/products/ga...ealant-liquid/

383hq · 19-01-2019, 07:57 AM

Quote:

Originally Posted by aussiblue

It's also good practice to put a thin layer non hardening gasket goo around inside of the hose end far enough to go past that ridge. It helps the hose slip on and prevents leaks by filling any nicks, dents and casting imperfection in the fitting it's going on. It was normal procedure when I first started working on cars and was even prescribed in various factory workshop manuals but seems to fallen out of favour in recent decades. I usually use this: https://www.permatex.com/products/ga...ealant-liquid/

This was common when manufacturing variation was much larger than it is today - back in the day when dad would pack a spare fan belt, tools, water for anything more than a 30 mile journey "just in case"

Modern manufacturing techniques have reduced the variation so it is no longer a problem (in modern countries). The tolerances they make stuff to nowadays is amazing in comparison to back then, unfortunately others things have also progressed - we also now know how to make something last *exactly* 3 weeks longer than the warranty...

falconhell74 · 19-01-2019, 08:58 AM

Plastic coolant flanges go brittle with heat and age so it is possible that over tightening the hose clamp could cause this.

**aussiblue** · 19-01-2019, 11:47 AM

Quote:

This was common when manufacturing variation was much larger than it is today

I'm not convinced when it comes to cooling system parts; some of the Chinese castings, even for OEM parts, for thermostat housing and water pumps I've seen are fairly rough. Yes the plastic radiator tank pipes and thermostat housings are much more perfect. I think the quality of the castings from the Japanese and Australian factories from the 60's, 70's and 80's was better. The other problems using sealant overcomes is the modern phenomena where pinholes have been punched in hoses where price or number tags have been attached to them with plastic ties.

**aussiblue** · 19-01-2019, 12:11 PM

What Gates says at https://www.gatesaustralia.com.au/~/...april-2015.pdf :

Quote:

Hose suggestions: Replace with the recommended Gates hose. Gates uses
compounds that offer better resistance to the negative effects of compression set.
Clamp torque suggestions: To avoid cold water leaks, adjustable tension clamps must
be retightened after a brief run-in period. Another solution is to use constant-tension
clamps, which automatically adjust with the heating and cooling of the system.
Connector suggestions: A beaded connector offers better sealing and retention
characteristics. The smoother the finish of the connector, the less tendency to leak under
the clamp. Brass and cast iron fittings adhere to common rubber compounds after time,
which reduces possibility of leaks, as does the use of sealants and viscous gels.

And Supercheap https://www.supercheapauto.com.au/bl...ator-hose.html :

Ok I know SC are not always the best place for tech advice.

Quote:

Apply some sealing compound to the inside of the new hose fittings and place the loosened clamp over the hose ends before sliding the new hose into position on the engine block and radiator fittings.

**aussiblue** · 19-01-2019, 12:28 PM

Typically cast parts also have a joint ridge where the two parts of the mold join running the length of the pipe fitting on both sides like on this apparently OEM BA Falcon thermostat upper housing

from ebay https://www.ebay.com.au/p/BA-BF-Falc...Ltd/1171348148

Sealant will help seal the hose there. Even plastic parts often have these mold join lines e.g.: https://www.ebay.com/p/Coolant-Coole...18/23014214355

Ditto with this Ford OEM FG one albeit the the ridge looks smaller and smoother except on the underside outer lip and look at the lump there https://www.ebay.com.au/itm/GENUINE-...H0-:rk:43:pf:0 So more precision hmmm? Perhaps we've gone full circle and the focus on cost of parts rather than quality means the use of sealants on coolant hose will be back in fashion again.

383hq · 19-01-2019, 08:22 PM

No one has said sealant is a bad idea, combined with tightening firm, it is a rock solid combination

The old gasket goo / aviation cement #3/4 use to be top shelf of every tool box, that's not the case any more.

regarding quality, (as with many things - including hose clamps) you usually get what you pay for, I wouldn't use no name brand hose clamps or thermostat housings - cooling and oil systems are too important.

snap0964 · 19-01-2019, 08:50 PM

Well you won't overtighten a spring/constant tension clamp.

IMO they are better than the screw drive clamps.

Anyone have any negatives/bad experiences with them? - apart from getting them off, which is usually because of not using the correct tool.

**aussiblue** · 19-01-2019, 11:13 PM

I prefer this type of stainless T bolt hose clamp but there is probably even more chance of over-tightening and breaking something.:

I find the spring/constant tension clamps lose tension with age.

snap0964 · 19-01-2019, 11:37 PM

Quote:

Originally Posted by aussiblue

I find the spring/constant tension clamps lose tension with age.

Yes they do, and replacing them is easy enough - can't say though I could ever find any the size for the upper and lower rad hoses.

Junkyard-Dog · 19-01-2019, 11:37 PM

You can definitely over-tighten a hose clamp on a car which has plastic inlet/outlet pipes on the radiator. With heat cycles and age the plastic gets brittle and it's not uncommon to see them collapse. I don't reckon it would even be that hard to crush a brand new plastic hose if you got a bit over-excited and kept tightening it.

smoo · 20-01-2019, 07:37 AM

Quote:

Originally Posted by snap0964

Well you won't overtighten a spring/constant tension clamp.
image
IMO they are better than the screw drive clamps.

Anyone have any negatives/bad experiences with them? - apart from getting them off, which is usually because of not using the correct tool.

Haha, I think the question should be, has any had any good experiences with them? Bloody dogs of things, especially if it’s in a tight spot or they need to come off/on with the engine hot.

I think if someone doesn’t have the ‘feel’ for tighten a conventional clamp with a ratchet, then they should probably leave the job for someone else.

When I was an apprentice at a truck shop we were Iveco service agents. Probably the worse built trucks with more PD issues than anything else. Around ten years ago the NZ fire service ordered some 80 Euro cargos, which ****ed coolant out of nearly every hose. I was sent to where they were kitted out for a week to seal up all the hoses with that aviation sealer... I can still remember what it smells like and it took about one week for it to run off my skin but it did the job.

roKWiz · 20-01-2019, 12:33 PM

Quote:

Originally Posted by snap0964

Well you won't overtighten a spring/constant tension clamp.
image
IMO they are better than the screw drive clamps.

Anyone have any negatives/bad experiences with them? - apart from getting them off, which is usually because of not using the correct tool.

Must say I've had a couple loose their tension. Many the smaller ones around a heat source.

**aussiblue** · 20-01-2019, 12:44 PM

The heat shrink (e.g. Gates Powergrip) ones never seen to have caught on here like they did in the US. https://www.youtube.com/watch?v=4O91YqHbp8c

Anyone ever used them or found them in a production car here?

arronm · 20-01-2019, 12:46 PM

Quote:

Originally Posted by PeteBlu

I recently had a mechanic tell me that it is impossible to over-tighten a hose clamp so much that it could cause a flange to break. This was after they replaced the radiator hose in my car, and the flange on the thermostat housing broke off (see pic.)

Seems unlikely to me, what do you think?

Cheers.

Plastic = hard and brittle. Cast metal = corrosion.

Over tightening will be a contributing factor but not the main cause

roKWiz · 20-01-2019, 12:58 PM

Quote:

Originally Posted by aussiblue

The heat shrink (e.g. Gates Powergrip) ones never seen to have caught on here like they did in the US. https://www.youtube.com/watch?v=4O91YqHbp8c

Anyone ever used them or found them in a production car here?

Looks nice but wouldn't fancy carrying extra removal tools and having to replace one out on the side of the road.

"Honey did you bring your 12v hair dryer."

**aussiblue** · 20-01-2019, 01:18 PM

The other issue with cast aluminium is that the cooling and/or quench cycles ( see http://www.themetalcasting.com/alloy-cooling-rate.html etc) can have an impact on both the strength of the product and the susceptibility to fracturing so the skills, experience, quality controls and cooling technology employed in the casting factory/foundry will be a factor. Where castings are left to air cool on racks, or cooled with blown ambient air even very variable ambient temperature or climatic location of the factory site may also be a factor (perhaps sometimes the sub zero sometimes in some Chinese factories V generally much warmer Kilkenny Castings in South Australia).

**aussiblue** · 20-01-2019, 01:41 PM

Quote:

Looks nice but wouldn't fancy carrying extra removal tools and having to replace one out on the side of the road.

"Honey did you bring your 12v hair dryer."

Yes definitely an issue. They've been using them for about 20 years in North America including on some production cars and they are also called shrink band clamps (see https://books.google.com.au/books?id...0bands&f=false etc.) and Boa Clamps (as in boa constrictor and with a wide variety of brand names. I can see why manufacturers would like them on assembly lines; probably much quicker to fit and a quaranteed seal but I wonder what their in use life is like.