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I filled my 69 up with fuel and drove it about 25 miles. When I shut it off I could hear a bubbling sound coming from the rear of the car. It was blowing bubbles out of the gas tank vent. There was quite a bit of pressure because it hissed when I took the gas cap off. It was a hot day in Tucson probably 102 or so. Do you think there is something wrong with the vent or is this normal if it is really hot out. I have had problems getting the car to start when the engine is warm in this type of really hot weather. Is it maybe vapor locking? Let me know what you think. One other thing is that it is spitting out coolant after that car is shut off. This only happens when it is 100 plus out. I have replaced the cap but it is still doing it. I have never gotten a hot engine light?? Is the 69 supposed to have a overflow tank?

Well... I'm definitely not an expert, but I know on hot days the plastic gas can I keep in my shed for my lawn tractor swells up like a balloon, and when I go to open it it's like opening a bottle of pop... So I'd say it's not unreasonable to expect the gasoline to boil off a bit in your tank...

As far as the radiator... maybe it's too full? Have you burped the system to make sure there's no air in the lines? I know I had an air-pocket in my lines, and my car wouldn't start right... Seemed to be boiling the gas right out of the lines. After burping it, it went away. Never had coolant leak from the cap though.