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debbiej
Samba Member
Joined: December 14, 2008
Posts: 1591
Location: las cruces, nm
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 Posted: Fri Feb 10, 2012 5:53 pm Post subject: why do fuel line clamps get loose? |
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fuel lines replaced last year, then I replaced worm style clamps when they started leaking. no leaks for long time, then yesterday I smelled gas. leaking on rail and couple other places. what causes these clamps to loosen? cold weather? warm weather? vibration?
gonna plan daily checks before driving, I guess.. |
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syncrodoka
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Joined: December 27, 2005
Posts: 12295
Location: Santa Cruz, CA
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| Posted: Fri Feb 10, 2012 6:33 pm Post subject: |
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Heat cycling, hot, cold, hot, cold, hot, cold etc.
The hose shrinks as well |
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scottjk
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Joined: May 31, 2006
Posts: 485
Location: Salt Lake City, UT
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kamzcab86
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Joined: July 26, 2008
Posts: 8438
Location: Arizona
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| Posted: Fri Feb 10, 2012 7:22 pm Post subject: |
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| syncrodoka wrote: |
Heat cycling, hot, cold, hot, cold, hot, cold etc.
The hose shrinks as well |
One reason I prefer spring clamps; they, usually, expand and contract with the hose.
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1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
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"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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thummmper
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Joined: November 25, 2009
Posts: 2015
Location: Meadow Valley, California Republic
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| Posted: Fri Feb 10, 2012 7:29 pm Post subject: |
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| are they chinese stamped wannabe stainless? only german forged ss clamps will hold--like bmw or mercedes clamps. auto parts store clamps are junk. |
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r.e.wing_fc3s
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Joined: April 16, 2010
Posts: 599
Location: Vanagon Capitol USA: Bellingham, WA
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| Posted: Fri Feb 10, 2012 7:42 pm Post subject: |
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your questions answer is why the factory used crimp clamps on the fuel lines. the new generation- "clic-r" reusable crimp clamps are the best imho. they maintain uniform tension throughout temp range and are difficult to over or undertighten. special pliers required.
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jackbombay
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Joined: October 19, 2007
Posts: 2725
Location: Portland Oregon
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| Posted: Fri Feb 10, 2012 7:43 pm Post subject: |
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Those will not maintain constant clamping force on the hose as the hose shrinks over time.
| kamzcab86 wrote: |
One reason I prefer spring clamps; they, usually, expand and contract with the hose. |
THIS!!! "Corbin clamps" are the "real name" for them and as you mention they work very well because as the hose shrinks over time the clamp maintains constant pressure.
Given the propensity for vanagons to leak fuel and catch on fire I would not consider using anything but corbin clamps for fuel lines.
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debbiej
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Joined: December 14, 2008
Posts: 1591
Location: las cruces, nm
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| Posted: Fri Feb 10, 2012 7:48 pm Post subject: |
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| they probably are. I'll get some good ones, thanks for the answers! |
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90Doka_Guy
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Joined: April 08, 2007
Posts: 550
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SCM
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Joined: January 26, 2011
Posts: 3365
Location: Bozeman MT
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| Posted: Fri Feb 10, 2012 9:11 pm Post subject: |
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no one ever commented on that thread about the cracking issue mentioned on the site where the photo of a corwin clamp came from
http://www.simplexco.com/auto/corbin/corbin.html
anyone care to now? I'm curious because I'm just about to order a bunch of Oetiker clamps for my own hose swap. Seems like any springy steel type of clamp would expand and contract to a suitable degree to match a bit of hose shrinkage while the worm-screw type of clamp could back out over time.
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Captain Pike
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Joined: December 30, 2003
Posts: 3437
Location: Talos IV, Piedmont Arizona
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| Posted: Fri Feb 10, 2012 9:32 pm Post subject: Re: why do fuel line clamps get loose? |
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| debbiej wrote: |
fuel lines replaced last year, then I replaced worm style clamps when they started leaking. no leaks for long time, then yesterday I smelled gas. leaking on rail and couple other places. what causes these clamps to loosen? cold weather? warm weather? vibration?
gonna plan daily checks before driving, I guess.. |
entropy
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kamzcab86
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Joined: July 26, 2008
Posts: 8438
Location: Arizona
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| Posted: Fri Feb 10, 2012 10:24 pm Post subject: |
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These are the type of spring clamps that my Cabriolet came with from the factory (on the coolant lines; its fuel lines use banjo bolts):
I've never had a single problem with them; all of them are original and not one has ever broke, nor have any hoses leaked. My van has a few of those clamps on the coolant hoses; I need to still go through replace all of the screw-on clamps. All of its fuel lines have a slightly different style but resemble ^those. I've no idea what they're called, but they appear to be doing a dandy job.
I didn't read much of ^that link, but in the other thread this is the only mention of cracking:
| MaritimeMultivan wrote: |
| Putting good clamp - bad clamp theories aside for a moment; I have noticed that new rubber fuel lines from the chain store parts places tend to really suck – as far as longevity goes. My current vanagon is fine, but I replaced the fuel lines in my 76 bus several times over the 10 years that I owned it. The seem to crack from the outside far sooner than I would expect. When it’s time to replace them on the Vanagon, I’ll be looking for the super duper supreme quality type |
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1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
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"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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jackbombay
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Joined: October 19, 2007
Posts: 2725
Location: Portland Oregon
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| Posted: Fri Feb 10, 2012 11:27 pm Post subject: |
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| SCM wrote: |
| I'm curious because I'm just about to order a bunch of Oetiker clamps for my own hose swap. Seems like any springy steel type of clamp would expand and contract to a suitable degree to match a bit of hose shrinkage while the worm-screw type of clamp could back out over time. |
I don't think that hose clamps back out, I think "loose clamps" are solely due to hose shrinkage.
The oetiker website states their clamps are springy to maintain constant clamping pressure, but, to me, the non-reuseable aspect of them makes the less appealing than corbin clamps which have always worked flawlessly for me.
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jackbombay
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Joined: October 19, 2007
Posts: 2725
Location: Portland Oregon
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| Posted: Fri Feb 10, 2012 11:34 pm Post subject: |
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He's writing off all corbin clamps because he had problems with ones that were, 47 years old? As if they are still made from wire like the ones pictured? I bet that guy still hates fuel injection.
They're typically flat spring steel nowdays, just like kamzcab86 posted, at least all the ones on VWs are. With the right pliers to handle the corbin clamps they are the best thing going IMO.
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SCM
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Joined: January 26, 2011
Posts: 3365
Location: Bozeman MT
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| Posted: Sat Feb 11, 2012 8:24 am Post subject: |
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| jackbombay wrote: |
| They're typically flat spring steel nowdays, just like kamzcab86 posted, at least all the ones on VWs are. . |
That's what surpised me. The photo on this thread shows one of the wire-style clamps that looks pretty iffy. Kams' photo looks more like something I would trust.
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Wildthings
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Joined: March 13, 2005
Posts: 52301
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| Posted: Sat Feb 11, 2012 9:07 am Post subject: |
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For what it is worth my '72 Dodge has all of its original wire style clamps. They work very well in a non corrosive environment. As in no road salts or acid rain, hey to Oregon. The flat clamps work very well and are my preferred clamp if I can get them in exactly the right size. Unfortunately there are variations in hose outside diameter that means that a clamp that will work with one 7mm FI hose may not work with another.
Screw style FI clamps can back off, a bit of silicon on the screw once the clamp is properly tightened often is enough to prevent this. |
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