Aaron65 Posted April 21, 2007 Share Posted April 21, 2007 Hey all, The gas tank on my '53 Special will actually spill out of the filler tube if the back end sits in the sun for a period of time. It's happened even when I had used 2 or 3 gallons of gas driving. It has a vented cap on it...what's going on??? Oh yeah, the cap works too... Link to comment Share on other sites More sharing options...
NTX5467 Posted April 21, 2007 Share Posted April 21, 2007 Simple, heat expands liquids.In the older systems, there is no specific expansion chamber in the tank's shape (no "expansion dome" on the top of the tank as the top of the tank usually conformed to the bottom of the trunk floor, which was flat) for this to happen, so the only place it can "expand" is out the vented fuel filler cap. On many tanks, there is also a "vent" that goes up over the rear axle area, sometimes, but others chose to use the "anti-surge" vented fuel cap instead. If it didn't go out the vented filler cap, it would push the fuel into the carb or somewhere else!Also, when fuel is dipensed from the pump, it's not "ambient" temperature, but somewhat cooler. Therefore, some expansion will take place anyway, just that it can become more noticeable if the vehicle is filled and parked rather than driven. One reason to not fill it past the second automatic turn-off of the nozzle.On a reality issue, though, if you fill the car and then drive it about 20 miles, it should not be a problem . . . unless there's something else at work here, which can include the delayed change to summer gas (which would have a little higher vaporization point than winter gas?) in your area. But if you fill it from a gas can and fill it "to the brim", what you describe CAN happen as ambient temperatures rise.Just some thoughts,NTX5467 Link to comment Share on other sites More sharing options...
Aaron65 Posted April 22, 2007 Author Share Posted April 22, 2007 Thanks NTX--I was hoping it was just another quirk of the vehicle...my 60s cars don't do that, but I've found that my '53 is a completely different animal...also, I never fill it up past the first click! Link to comment Share on other sites More sharing options...
bhclark Posted April 25, 2007 Share Posted April 25, 2007 I can't even fill my '65 Wildcat up to the first click. It overflows EVERY time I fill her up. Any clues as to why,or is it just that the filler neck is so short by the time the pump detects the gas backing up it's too late? Link to comment Share on other sites More sharing options...
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