>Applying an exterior coat does sound like an interesting idea. One concern I would have, is whether if and as it deteriorated, it might trap moisture and corrosives next to the tank, turning from protectant to trap and accelerant.
This is a real concern, and one of the big problems with conformal coatings. The short of it is that when coating ferrous materials, you need to make sure as much rust as possible is removed before coating. (As rust forms, it takes up a greater volume that the iron is forms from. This results in pressure that will lift coatings, and allow water to seep underneath, accelerating wear.)
Just to repeat, in your case, wire brush + the spray will probably net you another year or two, which is about what you could hope for with a tank that has already had seeping issues anyway. So I agree with your assessment of borrowing some rack time and giving it a shot. It is an inexpensive way to eek out a little more use of what you've got.
>As for the alcohol blend fuels, I was aware that they help significantly in keeping the tank "dry". It's been my understanding that they may also contribute to the lower instances of "vapor lock" that we see, these days. At least, at my mild altitude and (mostly) non-extreme environment.
Vapor lock used to be an issue when fuel pumps were located in the engine bay, powered off a rotating cam that ran a diaphragm pump from the gas tank to the carburetor. The pump would be pulling from the tank to the front of the car, then pushing from the pump a few feet up to the carb. Sometimes, in hot environments, the suction of the pump + heat of the engine bay would result in the fuel boiling inside the feed line before it reached the fuel pump itself, rendering it unable to pump any fuel at all until the system had cooled enough for the fuel to condense back to a liquid. Thus the term 'vapor lock'.
Nowadays, everything uses fuel injection and high pressure lines, with the pump located in the gas tank itself. There isn't any low-pressure part of the system that would allow vapor lock to happen any more, so it ceased to be an issue. :)
This is a real concern, and one of the big problems with conformal coatings. The short of it is that when coating ferrous materials, you need to make sure as much rust as possible is removed before coating. (As rust forms, it takes up a greater volume that the iron is forms from. This results in pressure that will lift coatings, and allow water to seep underneath, accelerating wear.)
Just to repeat, in your case, wire brush + the spray will probably net you another year or two, which is about what you could hope for with a tank that has already had seeping issues anyway. So I agree with your assessment of borrowing some rack time and giving it a shot. It is an inexpensive way to eek out a little more use of what you've got.
>As for the alcohol blend fuels, I was aware that they help significantly in keeping the tank "dry". It's been my understanding that they may also contribute to the lower instances of "vapor lock" that we see, these days. At least, at my mild altitude and (mostly) non-extreme environment.
Vapor lock used to be an issue when fuel pumps were located in the engine bay, powered off a rotating cam that ran a diaphragm pump from the gas tank to the carburetor. The pump would be pulling from the tank to the front of the car, then pushing from the pump a few feet up to the carb. Sometimes, in hot environments, the suction of the pump + heat of the engine bay would result in the fuel boiling inside the feed line before it reached the fuel pump itself, rendering it unable to pump any fuel at all until the system had cooled enough for the fuel to condense back to a liquid. Thus the term 'vapor lock'.
Nowadays, everything uses fuel injection and high pressure lines, with the pump located in the gas tank itself. There isn't any low-pressure part of the system that would allow vapor lock to happen any more, so it ceased to be an issue. :)