Home » Public Forums » GMCnet » [GMCnet] Cracking of rubber vacuum lines and gas lines
| [GMCnet] Cracking of rubber vacuum lines and gas lines [message #335510] |
Mon, 23 July 2018 12:25  |
Anonymous
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Here is a posting from 12 years ago on the topic that was discussed yesterday about cracking hoses.
On May 29, 2006, at 7:15 AM, Steven Ferguson wrote:
> Since the coach has been "resting" since the GMCWS rally, yesterday
> was start and run day for it and the Onan . Fired everything up,
> turned on the AC and walked away to clean up the shop etc. Came back
> in about 10 minutes, looked underneath and there was a lake..of
> gasoline. Quickly shut everything off hoping for no errant sparks,
> and started looking for the leak. It was a pressure fed leak on the
> line coming from the electric fuel pump to the fwd steel line that goes to
> the mechanical fuel pump.
> I replaced every hose in the fuel system 6 years ago with top quality
> NAPA dedicated fuel line hose. I strongly urge anyone with a GMC that
> hasn't checked or replaced your fuel lines in the past 5 years to do a
> thorough inspection.
> The hose I replaced had many cracks along it's entire length.
>
> -- Steve Ferguson
Steve - that is exactly why all my fuel lines and my transmission cooler lines are all steel. I have used 3/8" steel brake tubing to form the lines. I have a short piece of stainless braided teflon "hose" to connect the steel line to the electric fuel pump which is alongside my outside frame rail but everything in the engine compartment is solid steel, from the fuel pump forward.
I find that even my rubber vacuum lines will crack from time to time. I also had a rubber cap over one of the unused inlets to the base of my TBI system. It would crack about every year or so. I finally crimped it off and brazed it shut.
I suspect that the rubber deterioration is accelerated by the higher temperature in the engine box and the stretching of the rubber, either by internal pressure as you have found with your fuel hose, or the stretching of the rubber cap over the TBI base nipple that I experienced. Vacuum lines last longer as they don't have any internal pressure and the rubber will stand up to compression better than tension. However, I examine them and replace them as necessary. They also usually fail where they are put over a fitting.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Cracking of rubber vacuum lines and gas lines [message #335520 is a reply to message #335510] |
Mon, 23 July 2018 14:37  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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We have had some luck using a soft plastic type plug caps to plug up open
ends.
They are available at Automotive Parts supply.
On Mon, Jul 23, 2018 at 10:25 AM, Emery Stora via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Here is a posting from 12 years ago on the topic that was discussed
> yesterday about cracking hoses.
>
>
> On May 29, 2006, at 7:15 AM, Steven Ferguson wrote:
>
>> Since the coach has been "resting" since the GMCWS rally, yesterday
>> was start and run day for it and the Onan . Fired everything up,
>> turned on the AC and walked away to clean up the shop etc. Came back
>> in about 10 minutes, looked underneath and there was a lake..of
>> gasoline. Quickly shut everything off hoping for no errant sparks,
>> and started looking for the leak. It was a pressure fed leak on the
>> line coming from the electric fuel pump to the fwd steel line that goes
> to
>> the mechanical fuel pump.
>> I replaced every hose in the fuel system 6 years ago with top quality
>> NAPA dedicated fuel line hose. I strongly urge anyone with a GMC that
>> hasn't checked or replaced your fuel lines in the past 5 years to do a
>> thorough inspection.
>> The hose I replaced had many cracks along it's entire length.
>>
>> -- Steve Ferguson
>
> Steve - that is exactly why all my fuel lines and my transmission cooler
> lines are all steel. I have used 3/8" steel brake tubing to form the
> lines. I have a short piece of stainless braided teflon "hose" to connect
> the steel line to the electric fuel pump which is alongside my outside
> frame rail but everything in the engine compartment is solid steel, from
> the fuel pump forward.
>
> I find that even my rubber vacuum lines will crack from time to time. I
> also had a rubber cap over one of the unused inlets to the base of my TBI
> system. It would crack about every year or so. I finally crimped it off
> and brazed it shut.
>
> I suspect that the rubber deterioration is accelerated by the higher
> temperature in the engine box and the stretching of the rubber, either by
> internal pressure as you have found with your fuel hose, or the stretching
> of the rubber cap over the TBI base nipple that I experienced. Vacuum
> lines last longer as they don't have any internal pressure and the rubber
> will stand up to compression better than tension. However, I examine them
> and replace them as necessary. They also usually fail where they are put
> over a fitting.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Cracking of rubber vacuum lines and gas lines [message #335526 is a reply to message #335520] |
Mon, 23 July 2018 15:24 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Senior Member |
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You can also get them on eBay:
or
http://tinyurl.com/yd2ojpu2
Just do a search for vacuum line caps and loads of them pop up.
JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan
> On Jul 23, 2018, at 3:37 PM, Jim Kanomata wrote:
>
> We have had some luck using a soft plastic type plug caps to plug up open
> ends.
> They are available at Automotive Parts supply.
>
> On Mon, Jul 23, 2018 at 10:25 AM, Emery Stora via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Here is a posting from 12 years ago on the topic that was discussed
>> yesterday about cracking hoses.
>>
>>
>> On May 29, 2006, at 7:15 AM, Steven Ferguson wrote:
>>
>>> Since the coach has been "resting" since the GMCWS rally, yesterday
>>> was start and run day for it and the Onan . Fired everything up,
>>> turned on the AC and walked away to clean up the shop etc. Came back
>>> in about 10 minutes, looked underneath and there was a lake..of
>>> gasoline. Quickly shut everything off hoping for no errant sparks,
>>> and started looking for the leak. It was a pressure fed leak on the
>>> line coming from the electric fuel pump to the fwd steel line that goes
>> to
>>> the mechanical fuel pump.
>>> I replaced every hose in the fuel system 6 years ago with top quality
>>> NAPA dedicated fuel line hose. I strongly urge anyone with a GMC that
>>> hasn't checked or replaced your fuel lines in the past 5 years to do a
>>> thorough inspection.
>>> The hose I replaced had many cracks along it's entire length.
>>>
>>> -- Steve Ferguson
>>
>> Steve - that is exactly why all my fuel lines and my transmission cooler
>> lines are all steel. I have used 3/8" steel brake tubing to form the
>> lines. I have a short piece of stainless braided teflon "hose" to connect
>> the steel line to the electric fuel pump which is alongside my outside
>> frame rail but everything in the engine compartment is solid steel, from
>> the fuel pump forward.
>>
>> I find that even my rubber vacuum lines will crack from time to time. I
>> also had a rubber cap over one of the unused inlets to the base of my TBI
>> system. It would crack about every year or so. I finally crimped it off
>> and brazed it shut.
>>
>> I suspect that the rubber deterioration is accelerated by the higher
>> temperature in the engine box and the stretching of the rubber, either by
>> internal pressure as you have found with your fuel hose, or the stretching
>> of the rubber cap over the TBI base nipple that I experienced. Vacuum
>> lines last longer as they don't have any internal pressure and the rubber
>> will stand up to compression better than tension. However, I examine them
>> and replace them as necessary. They also usually fail where they are put
>> over a fitting.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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