Dropping fuel tank to repair leak.

[Ken B]

> As much as I like the screw style "aviation" clamps, I've got to admit that
> spring clamps are more "durable" -- if tight enough when first installed,
> they'll remain tight as the underlying hose shrinks -- no retightening as
> may be needed with any screw clamp. It may even be that the much smaller
> cross section, where sealing force is applied, allows them to seal better.
>
> Ken H.

That is what I use on almost everything that I do not want to leak long term. I have a good collection of all of the smaller sizes here. I need more
larger sizes over 1" in stock. The special ratcheting pliers make them easy to install and remove.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Matt Colie]

> As much as I like the screw style "aviation" clamps, I've got to admit that spring clamps are more "durable" -- if tight enough when first
> installed, they'll remain tight as the underlying hose shrinks -- no retightening as may be needed with any screw clamp. It may even be that the
> much smaller cross section, where sealing force is applied, allows them to seal better.
>
> Ken H.

> That is what I use on almost everything that I do not want to leak long term. I have a good collection of all of the smaller sizes here. I need
> more larger sizes over 1" in stock. The special ratcheting pliers make them easy to install and remove.

I had a set of the ratchet pliers with big deep groves both end and side, but they got borrowed.....

Detroit uses constant tension clamps for one simple reason: Warranty

The creep with time and thermal cycle is is what I have also found and the same thinking went into the USCG requirement for constant tension clamps
for all applications that could allow flooding if the clamp loosens. The problem I have with the wire "Corbin" and others is that most are very
sensitive to the wall thickness of the hose in the system. The USCG approved clamps are a screw (like Ideal) clamp but with a spring under the screw.
They work, but they are expensive.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[Stu Rasmussen]

I'm not sure what style of clamps y'all are referring to. Are they like
https://www.mcmaster.com/hose-clamps/clamps-and-ferrules-for-hose-and-tubing/constant-tension-spring-clamps-for-firm-hose-and-tube/
or something else?

Can you post a link to a picture?

Thanks

Stu

>> As much as I like the screw style "aviation" clamps, I've got to admit that
>> spring clamps are more "durable" -- if tight enough when first installed,
>> they'll remain tight as the underlying hose shrinks -- no retightening as
>> may be needed with any screw clamp. It may even be that the much smaller
>> cross section, where sealing force is applied, allows them to seal better.
>>
>> Ken H.
>
> That is what I use on almost everything that I do not want to leak long term. I have a good collection of all of the smaller sizes here. I need more
> larger sizes over 1" in stock. The special ratcheting pliers make them easy to install and remove.
>

 

[bdub1]

Wow! Nice looking clamp.

https://www.westmarine.com/buy/trident-marine--stainless-steel-constant-torq
ue-hose-clamps--P07431893?recordNum=33

-----Original Message-----
From: Gmclist On Behalf Of Matt Colie via Gmclist
Sent: Monday, February 24, 2020 8:19 AM

Detroit uses constant tension clamps for one simple reason: Warranty

The creep with time and thermal cycle is is what I have also found and the
same thinking went into the USCG requirement for constant tension clamps for
all applications that could allow flooding if the clamp loosens. The
problem I have with the wire "Corbin" and others is that most are very
sensitive to the wall thickness of the hose in the system. The USCG
approved clamps are a screw (like Ideal) clamp but with a spring under the
screw.
They work, but they are expensive.

 

[jim kanomata1]

I use them on my Twin Turbo 540 Cad as there are places I cannot reach it
easily once the high pressure tubes are clamppef.
If done right is more important than going that route.
For the coach application, it is not worth going this route .
My personal comment.

On Mon, Feb 24, 2020 at 7:30 AM Billy Massey via Gmclist <

> Wow! Nice looking clamp.
>
>
> https://www.westmarine.com/buy/trident-marine--stainless-steel-constant-torq
> ue-hose-clamps--P07431893?recordNum=33
> https://www.westmarine.com/buy/trident-marine--stainless-steel-constant-torque-hose-clamps--P07431893?recordNum=33
>
>
> -----Original Message-----
> From: Gmclist On Behalf Of Matt Colie via Gmclist
> Sent: Monday, February 24, 2020 8:19 AM
>
> Detroit uses constant tension clamps for one simple reason: Warranty
>
> The creep with time and thermal cycle is is what I have also found and the
> same thinking went into the USCG requirement for constant tension clamps
> for
> all applications that could allow flooding if the clamp loosens. The
> problem I have with the wire "Corbin" and others is that most are very
> sensitive to the wall thickness of the hose in the system. The USCG
> approved clamps are a screw (like Ideal) clamp but with a spring under the
> screw.
> They work, but they are expensive.
>
>
> _______________________________________________
> 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
http://www.gmcrvparts.com
1-800-752-7502

 

[jesse farr]

That is the picture.

jofarr, soddy daisy tn '74 canyonlands 26"

----- Original Message -----
From: Stu Rasmussen via Gmclist
Reply-To:
To:
Cc: Stu Rasmussen
Sent: 2/24/2020 10:20:49 AM
Subject: Re: [GMCnet] Dropping fuel tank to repair leak.
________________________________________________________________________________

I'm not sure what style of clamps y'all are referring to. Are they like
https://www.mcmaster.com/hose-clamps/clamps-and-ferrules-for-hose-and-tubing/constant-tension-spring-clamps-for-firm-hose-and-tube/
or something else?

Can you post a link to a picture?

Thanks

Stu

>> As much as I like the screw style "aviation" clamps, I've got to admit that
>> spring clamps are more "durable" -- if tight enough when first installed,
>> they'll remain tight as the underlying hose shrinks -- no retightening as
>> may be needed with any screw clamp. It may even be that the much smaller
>> cross section, where sealing force is applied, allows them to seal better.
>>
>> Ken H.
>
> That is what I use on almost everything that I do not want to leak long term. I have a good collection of all of the smaller sizes here. I need more
> larger sizes over 1" in stock. The special ratcheting pliers make them easy to install and remove.
>

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Unsubscribe or Change List Options:
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[Ken B]

Get two of them. One for round type and one for flat type clamps. Mine came from Sears years ago so I have not looked at what Harbor Freight is
selling.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[johnny]

A shop kept my VW toad a week without completing the job, so I went by and reclaimed it and towed it broken into Texas where I had the time and place
to finish fixing it. Since I'd told them I had to leave on a given date when I dropped it off, I didn't feel bad about the 'mechanic' leaving his
spring band tool in the car. Since then I have the ability to do single and double wire and spring band as well as screw clamps. On all of them, I
take a small ball peen and tap all the way around the clamp if it's accessible, or around whatever part can be got to, to distribute the tension. I
find doing this precludes any seeping and they all seem to stay tight.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[Randy Van Winkle]

> Filled the coach last week and found fuel leaking at the front driver's side corner of Aux tank, from above the fill connection. Slow(ish) leak
> and eventually stopped after driving 5 mi and raising rear of coach. I'm home now, and planning to drop the tanks and figure out what's going on -
> once I find somewhere to pump the (50?) gallons of fuel.
>
> In any event, I plan on replacing the rubber supply and vent lines with metal and moving the Onan supply from the Coachman tee to the GM stock
> location. Also splitting off the Aux tank vent and running it forward closer to the fill vent line.
>
> So, one question is how to couple the new metal lines to the sender assembly. I have seen photos of 3/8" compression fittings and others showing
> short rubber nipples with hose clamps. I am leaning towards the rubber nipples - seems like good vibration isolation - and wondering if it's worth
> it to swage a bead on the ends of the new lines.
>
> Another thing I am wondering is whether in-tank pumps are a good idea. Any issues with fuel pump cooling at low fuel levels? Also wondering
> whether leaving the two existing external EFI pumps as a backup makes sense - would they pull through the in-tank pumps?

Bill,

I have had in-tanks pumps for about 7 or 8 years. I like the fact that I have no negative pressure in the fuel lines and no problems with vapor lock.
I followed Emery's excellent presentation of Bill Bramlett's method for in-tank pumps. This also includes an approach for hard lines. I installed hard
lines at the same time and did use compression fittings. For 8 years, no problems at all and did not have to try to make a bubble flare. I left the
vents lines rubber because, at least on my coach, the vent nipples came out at too much of an angle and I did not want to try to bend them down. If
you go with in-tank pumps, I have a couple of suggestions. 1) the pump part numbers references an Airtex pump that has now changed specs. While still
within specs the new specs, it may not provide the pressure needed for the EFI system. 2) the stand tube shown in the presentation is made from brake
line material. I had to drop my tanks after 3 or so years and I found that the stand tube broke where it had been threaded. I got some solid metal
stock of the same size and threaded the end of that. I then drilled down the center deep enough to intersect the cross drilled hole to provide the
needed venting. On another coach I have, I put two pumps as close to the tanks as possible and have had no problems with that installation. I always
recommend removing the selector valve and going with two pumps and two filters selectable with the same fuel selector switch on the dash. On-board
back-up with a flick of the switch allows you to get home before having to address a problem (either pump or filter).

Overall, happy with the performance. A bit of a pain when there is a problem as it requires dropping the tank(s). I picked up some really bad gas once
(I think the filter on the gas pump had come apart) that clogged up the socks restricting pressure/flow. I dropped the tanks and noticed the broken
stand tube. Since I had the tanks down and a few years on the pumps, I decided to replace the pumps with new. I was having problems with reduced
pressure on hard pulls so thought maybe one of the new pumps were bad. I had to drop the tanks again and was about to replace the pump with the same
part number again. This time, I looked up the specs and found that at minimum psi it would not maintain the psi needed for the efi system. I just
looked and it appears they have discontinued the E3902 pump. These pumps are from a mid 90s Chevy S10 pickup for the TBI applications. I looked and
the minimum psi in the specs is 13 to 15 psi depending on manufacturer. That would work on a Rochester with larger injectors but not on a Howell where
we are running higher psi (approx. 18 psi). I am now using pumps for the same application but with specs supporting an MFI system that was available
on the S10. The last pump I put in was a BOSCH 69225. It has been a couple of years. It is extremely quiet compared to the Airtex pumps.

Good luck with your project.
--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO