Jump to content

'63 Avanti fuel tank vent tube issue


Recommended Posts

Hello all. I recently had to replace my Avanti's fuel tank vent tube because I could smell gas coming out of the pores of the rubber. I believe it was original to the car. Certainly the sending unit was, which I replaced, and its gasket was nearly dust. However after all this I was still getting a strong gas odor from the car. I crawled around sniffing everything I could find and discovered that the smell was most notably coming from the end of the vent tube under the car!

I thought that since gas fumes are heavier than air that the figure 8 arrangement would have kept gas fumes from exiting the hose. I would have liked to have run the hose up in the c-pillar like the factory one, but there is no practical way to access that area. As a test I used a piece of a Home Depot bag and a rubber band to cap off the bottom of the hose, and the next day the gas smell in my shop was almost gone! But obviously that isn't a solution...so what is?

p.s. I am using a new Avanti fuel cap, I think I had bought it from Studebaker Intl but it's been 6-7 years. If memory serves it is a vented cap.


 

21,04-28, new fuel tank vent tube (2)_72.jpg

Link to post
Share on other sites

The vent originally connected to a hard line, then the rubber line went up into the 1/4 panel, and was secured by a riveted on clip. then it went back down to the hole in the floor. That way it's up high enough that no amount of fuel sloshing would cause the vent line to fill up with fuel. 

Also, check the fill tube large hose, they can hide cracks behind that are not visible unless you take it out. If you do, pay attention to the clocking of the fuel cap, so when tight the ear doesn't hit the filler door when it's closed. Also check the solder joints on both the return line and the vent line on the top of the tank. A poor trunk gasket, and also exhaust deflectors that have slots in the clamp end can all contribute to fumes.

Link to post
Share on other sites

I agree with Bez and add the following; The idea of a vent tube is to let the fumes escape and to let air in as you use fuel. It doesn't matter what bends you put in it. It should exit outside of the car.

Link to post
Share on other sites

 

4 hours ago, brad said:

The vent originally connected to a hard line, then the rubber line went up into the 1/4 panel, and was secured by a riveted on clip. then it went back down to the hole in the floor. That way it's up high enough that no amount of fuel sloshing would cause the vent line to fill up with fuel. 

Also, check the fill tube large hose, they can hide cracks behind that are not visible unless you take it out. If you do, pay attention to the clocking of the fuel cap, so when tight the ear doesn't hit the filler door when it's closed. Also check the solder joints on both the return line and the vent line on the top of the tank. A poor trunk gasket, and also exhaust deflectors that have slots in the clamp end can all contribute to fumes.

I doubt I have fuel inside the hose, the engine has not been turned over since I started to fix the gas smell issue. The figure 8 arrangement was partly because I didn't know if it would be a permanent solution so I didn't want to cut the line shorter than might be needed, and also because the figure 8 would keep the hose longitudinally stable during driving - relevant since it wouldn't be stabilized by going into the c pillar area like the stock one.

Sending unit was replaced and is sealing well. The filler neck doesn't smell at all and is not sweating. The tank's solder joints are solid.

There is no large hole for the original vent tube to go up into the c pillar area, there are two small holes each barely large enough to accommodate the Studebaker hose. As I mentioned in my OP, I would have replaced the hose exactly if it were possible, but currently I don't see a way to do that. Open to ideas...pictures would be even better.

The gas smell is definitely coming out of the vent tube. And I confirmed this by temporarily plugging it. What I would like to know is: WHY? The vapor, which is heavier than air, would have to travel up the new hose twice before falling down and exiting outside the car. And I cannot have fuel vapor leaking out making my warehouse stink. It's chemically bad for all plastics, and a potential fire hazard.

As for letting fumes escape, since I have a vented gas cap would that not also allow equalization of air pressure? So why have a second vent (tube) if the gas cap is already vented?
 

Link to post
Share on other sites

You might want to consider making a charcoal canister for the vent hose. I have had the same issue over the years with a variety of cars that vented into the open air and it resolved the issue.

Bob Caser

Link to post
Share on other sites
Posted (edited)
On 5/8/2021 at 5:21 PM, bob caser said:

You might want to consider making a charcoal canister for the vent hose. I have had the same issue over the years with a variety of cars that vented into the open air and it resolved the issue.

Bob Caser

Got a link to one I could buy that would fit the hose?

 

Or...what about using a check ball valve like this one?

https://www.amazon.com/gp/product/B08PSYF3GZ/ref=ox_sc_saved_title_1?smid=A1THAZDOWP300U&psc=1

Edited by Palantirion
Link to post
Share on other sites
Posted (edited)

*SOLVED*  😣

21,05-12, vent tube on coat hook_72.jpg

 

Using a Dremel I was able to cut out the panel between the two holes for the OEM vent tube, and eventually (rotating locking pliers against the panel for torque) I removed the hidden length of the original tube. It was nearly 2' long! Unfortunately I can't simply push the new tube up the gap because there is a second plate behind the panel I just cut, between the two holes. I can't see it, because of the tiny space, but I think it's fiberglass. I also am not sure if I should cut it - but it will be much more difficult because of the size of my cutoff wheel and the tight space. I was thinking of maybe trying to use thick armature wire as a guide to maybe force the new hose into turning inside the panel so I can run it like the stock hose. Does anyone know a good trick to make a rubber hose turn 180 degrees in a blind inaccessible cavity?

 

p.s. My gas cap is not vented, I checked: Blew into the vent tube with the cap on - blew gas vapor back at me. With the cap off it did not.

Edited by Palantirion
Link to post
Share on other sites

If you remove the right rear window, you can peel back the unpholstery, reach into the C pillar and deal with the 2' loop. It's tight, but doable and with all 2' of new hose up in there, no gas smell.  Add rollover vents, etc. under the car as you wish!

 

Link to post
Share on other sites
  • 2 weeks later...

For those (like me most of the time) that think kids these days don't care about working on cars...well, most of the time they'd be right. But there are exceptions: A front desk kid at a local BMW shop (where I was having some other work done) suggested that I drill a hole through the tube and use string to guide it around the internals. He was on to something. I ended up having to use a long twist tie to curve around whatever is inside that panel and then used that to pull the string which then pulled the tube successfully through both holes! It took a bit of futzing to get the right degree of tension on the tube to make it line up and pass through the 2nd hole, but overall it was not a nightmare. Kudos to those of the new car guy generation.

 

21,05-26, vent tube threaded_72.jpg

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...