I just noticed that the vent tube on my 56 doesn't go back into the filler neck. The tank was replaced by my father-in-law back about 10 - 15 years ago. The gas pump nozzle never clicks off when I fill and I've had issues with gas leaking out around the sender unit in spite of several different gaskets. Could this be the issue? Also, he put carpet tiles between the tank and the trunk floor. Does the tank need to be insulated from the trunk floor? Rich
Where is the vent tube ending if not in the oem position? '57 p***enger cars ran the vent tube outside, up over the license plate. I'm guessing the epa doesn't think much of that at all. I was surprised to see your illustration showing the vent tube returning to the filler neck. Actually seems like a better idea, wonder why they dropped it in '57.!? Something is not making sense here...maybe the '56 guys could chime in on the vent tube...but I'm thinking the gas filler neck, like '57 p***enger cars, is too low to use a vented gas cap, so if the vent is just going back into the tank, how is excess pressure releasing? The factory cars had a thin layer of something that rotted away after many years. If a tank is pulled for the first time, you'll usually see those remnants. Most of the '57 guys put a layer of something in between the tank and the floor. Some just use heavy roofing paper. I used a dynamat type stuff. If nothing else, I thought it would help dampen the noise from the internal fuel pump. Lots of guys don't put anything in between, but I don't see any reason not to, lots of reasons to do it. However, with that said, something as absorbent as carpet tiles combined with a leaky sending unit can't be good. Fix the leak before you're having to dial 911.
My experience with both a 54 Ford and a 56 Bird show only rubber pieces go between the tank and the trunk floor. It would seem that the 56 sedan would be the same. The 56 tank uses a vented cap as well as my 54. No separate vent tube. I think Ford started using the extra vent with 57 as they did with the TBirds. Speculation though. Using fabric, like carpet, holds water and would lead to rust out in both the trunk floor and gas tank and because it can get saturated with gas and cause a fire hazard. Get rid of it and use rubber pieces located at various points around the tank top. No need for insulation in my opinion.
The vent tube does end in the oem position except it doesn't connect to the filler neck (upper left of picture). Thanks for the idea of a dynamat like material for the top of the tank. I'll get that carpet tile stuff out of there right away.
Wild guess here..........It looks like your father in law maybe had an issue with gas sloshing out of the neck with the vented cap that would have been needed if the vent tube was not venting externally, so to cure that he rerouted the vent tube outside ala '57 setup and then was able to use a non vented cap and eliminate the sloshing out. Mine sometimes has a faint odor when inside the garage. Others with that setup have had odors as well, and one '57 forum member just rerouted/or is rerouting his vent tube thru a charcoal filled canister.
The '59 has some funky tube that runs up the driver-side rear fender and back down like the '57. Cap is non vented. For the mat between the tank and bottom of trunk, I used a non-skid mesh mat product, like used to keep cutting boards from sliding on counters. Found it at Ace in a 12" roll. This will never rot out.
Thanks for the help, I'll get those mats out as soon as I have time. The vent tube seems to be ok venting outside the filler neck. I still don't understand why the tank seems to overfill. In the mean time I'm going to work on that sender issue some more. I read somewhere that someone used teflon tape on the screws. I'm going to try that also.
Maybe our old vented tanks are easy to overfill because, well, they're vented. Modern vehicles have non-vented tanks so the back pressure at the gas pump nozzle shuts off the flow before the tank is full (I find this very annoying). Since our tanks aren't vented and the filler necks are huge in comparison to modern cars, there is less back pressure to tell the gas pump to shut off.
55 fords have a vent tube which does not connect to the filler neck. It vents into the filler neck aperture. The cap is also vented. New cars are vented but this is through the return line/overflow system. Most use a charcoal filter in line to vent to atmosphere. This is supposedly to stop global warming through hydrocarbons evaporating into the atmosphere. The tanks have to be vented by some means otherwise the vacuum would collapse the tank or fuel flow would stop as the pump would cease to function when it could **** no more.
RCalzada...Teflon tape on the screws is probably not a good idea...too easy for bits and pieces to end up in the gas/lines/filters/carburetor. I filled my car for the first time yesterday. Put the automatic on a slower fill speed and held the rubber seal tight against the neck. Clicked off automatically, but right at the top. I hadn't done this before because I had done a substantial amount of welding on the new tank to recess a plate for the pump. Happy to report no leaks. Rick55...Vented cap? where is your filler neck? in '57 wagons and rancheros used a vented cap because the filler neck is up high. They did not have a vent tube. All the others with the filler behind the license plate used a vent tube and non-vented caps to prevent spillage from gas sloshing around. Edit...also, on the teflon tape...gas will eventually dissolve the traditional plumbers white teflon tape. If your going to use it on fittings, you need to use the yellow made for natural gas. Available in Lowe's, Home Depot, etc.
The vented caps that the wagons had are not available. Thank the EPA for that. They vented out to release pressure. The new caps only in. I found this out the hard way after I bought one. I had to drill a small hole in the cap to allow the tank to vent properly.
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