I looked under the car and the fuel tank is partially crushed.
The tank must be repaired or replaced.
Does it appear to have been crushed by an outside force, or perhaps an internal/vent pressure problem?
I have no idea what crushed it. I think it was a gas cap that wasn’t equalizing pressure, but there could’ve also been some other minor denting prior to collapse.
Anyway, I finally realized how to fix it. Once I realized that the needle and seat of my carb would easily hold 5 or more pounds and the cap in fact was TOO airtight, there was only one thing left to do.
[YouTube]https://youtu.be/0c6ixMaGeEY[/YouTube]
Yes, that I did finhttps://youtu.be/0c6ixMaGeEYd it in Walmart right next to the basketball rack!! Once the pressure was equal, the gauge dropped slightly and I got another 6 gallons of gas into her!!
& yes, I did in fact remove the gas cap from the vehicle before using my smallest Dremel bit to make a vent hole. That’ll be the path of least resistance for air pressure shifts, not crushing the tank. The fact that it was so flimsy to fix is bizarre. You’d think that a fuel tank would be stronger.
Pinto beans anyone?
Please understand that if the gas cap is working properly it will not equalize pressure. Gas caps on 1967 - 1973 Cougars are vented to allow air to enter the tank. They do not allow fuel, liquid, or air to escape the tank.
Because of this if you were to fill the tank with fuel, then put the Cougar in the garage for the night, it is expected that if you were to remove the cap the next day you would get a face full of fuel. Don’t do that.
It’s not squirting out a face full of fuel, it was collapsing and crushing the tank. While some gas caps DO allow for pressure to differ inside or outside of the tank from the outside world, i decided that this “feature” was more of a liability then an asset. Therefore, I modified it so that the pressure inside of the tank is always equal to the barometric pressure in the ambient environment.
Besides, the gas cap in question is probably 50 years old and most likely came with the vehicle. I very much doubt that it continues to function according to its original specifications. The cap obviously didn’t allow air to enter OR leave the fuel tank at all!! If it allowed air in, the tank wouldn’t have collapsed. If it allowed air to leave, pressurizing the tank would not have even been possible.
Drilling a very tiny practically invisible hole in the fuel cap for air to pass seems like a very safe solution. Of course, a 1/4 inch hole in the cap is to much. A path of least resistance is a good idea, a 6 lane expressway not so much. I think the bit I used was 1/32nd of an inch in diameter. The top of the tank in the trunk did bow out slightly. When I noticed this, I shut off the air pressure. The top of the tank became level again once the pressure equalized. It’s at least possible in theory to over inflate the tank and possibly rupture it in my opinion.
A situation where fuel is squirting one’s self in the face at the filler pump probably isn’t such a great thing either. In fact, that sounds downright dangerous!! I’m an armed guard and I have to wear a uniform to work together with a gun belt. Imagine the look on my supervisor’s face if I were to show up reeking of gasoline!!
Working properly the gas cap prevents explosions and fires from escaping fuel and vapors. It would not cause a gas tank to get crushed. With your modifications explosions and fires are now much more likely.
A crushed tank can also probably rupture, which could explode as well. Unless someone is pointing a blow torch at the filler cap, I doubt that a fire can result.
Of course, the possibility of fuel shooting out of the tank could also cause an accident.
I discussed this with the shop that I was trying to get an inspection from. They told me that repairing the tank was ok. I also talked to them about the gas cap vent. They said that as long as fuel didn’t leak out during the test drive, it’s all good. They advised that any vent hole he as small as possible.
The only way one could possibly cause an accident would be to over fill the tank, nose facing down and then park it on a steep slope causing it to leak out. Even in that event, it would be an extremely slow leak.
If one was to put out a cigar on the fuel cap drilled like that, it could get interesting but I vape so…
Heck, this is the same way you store gas in a can over the winter.
With your home modified cap there are several scenarios that would result in bad consequences. For example if you were to fill the tank and then drive the car home and put it in the garage. The fuel expands and squirts out the newly drilled cap. Fumes / liquid gasoline ignites. House burns to the ground. Insurance denies payment because owner caused the fire.
Here’s the drill bit next to a normal tooth pick. I have it angled slightly under the sheet metal where you grab the cap to fill it.
The second layer of metal that holds the gas cap to the filler hole isn’t penetrated.
Nevertheless, air can leave with a faint audible hiss and will move piece of tissue paper.
The hole in the rubber hose joining the nozzle to the tank has been glued shut and taped, preventing venting into the trunk.
Since I’m trying to get it through inspection, I can’t have anything all that visible, or a distorted tank, not sure they’ll even remove the filler cap but hosing the mechanic won’t win any popularity contests.
Gasoline can’t really splash out because there is no direct path but obviously air pressure isn’t constrained by that.