Re: 1934 gasoline tank - how do it breath?

Posted by Odd Moen On 2013/5/7 14:22:13

I will look for a picture of my tank. The tank is original and the tank has as well the original pick-up /sender unit.
If it is a vent in the pick-up/sender unit, could gas come out through the vent when the gas is filled up to the top of the filling neck, because the top of the filling neck is 4" higher than top of the tank? Or is the vent so small that only air can go through?
I`m sure that I have sealing compound on the gasket for the pick-up / sender, and then I`m also sure that this vent is closed!
For sure it has to be a vent in the tank, because the filling neck is not mounted on the top of the tank, as it is for my 1929. The air pressure inside and outside has to be aligned on the 1934.
But what is the function of the small 1" high neck/cap on on top and at the left side of the pick-up / sender?
I thought this is a oneway vent. That mean: it is closed when filling up the tank, as the air pressure inside is higher than outside. And the vent is letting air into the tank when the engine is running, because the pressure on the inside of the tank is lower. Maybe I`m wrong.