1957 w/s washer fluid disappearing

[Ward 57]

A couple of years ago I replaced my washer fluid bag. Finally getting my car road worthy last spring I refilled the reservoir. A couple of months later I discovered the bag empty. Refilled it and a couple of months later it was bone dry again.
I've got it sitting in my vanity sink with plain water in about the same position as when in the car and no leak to be found. Does that stuff evaporate in a loosely sealed container? I searched here and several with retro birds also experience the same thing.

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[zeroroadkill]

Ward, not sure about the 57, but on the 55 the washer bulb on the floor above the headlight bright switch might be leaking or one of the hoses to/from the washer pump bulb?

 

[Hernando Muñoz]

Check underneath your carpets, drivers side... wet??

 

[Ward 57]

Everything is dry. Replaced the washer pump last year and know it's good. I don't think there is any chance of the fluid siphoning out.

 

[zeroroadkill]

Interesting, I filled my older bag two years ago and it’s still full! (I don’t use it). Maybe pressurize the tube from the bag and check for leaks? Let us know what you find.

 

[Ward 57]

It's been sitting in the sink for hours and no leak. The only thing I can think of is that it is a winter mix with high alcohol content as an antifreeze and it evaporates. Goes back to the model 'A' days when alcohol was the only available anti-freeze for the cooling system.
But still weird. This spring I'll just fill it with plain water and see what happens.