Washer fluid boilover?

[Maybe Magpie]

Hi all,

Dumb, simple problem: I noticed that after drives out and about my washer reservoir is leaking lots of blue foam bubbles out of the cap. I had an exhaust leak about a year ago that was resolved, so I don't think it's that again (though I plan to do the paper test when it's not so nasty out and I have some time). Just so I know what to look for while I'm at it, does anyone know what other potential causes there could be, or ways to test or address it? Is it likely to just a tired reservoir/cap seal or some weird non-obvious culprit? I don't wanna throw the parts cannon at it or start taking the exhaust apart at it without a game plan. It's non-critical obviously, but it annoys me. I wouldn't be surprised if some exhaust studs just need another round of torquing or something, but a quick sanity check is always nice.

Thanks.

[82eye]

washer res shouldn't be pressurized at all. there is literally nothing that runs to it, it's a simple pump in a non pressure res. something is not adding up.

[Maybe Magpie]

washer res shouldn't be pressurized at all. there is literally nothing that runs to it, it's a simple pump in a non pressure res. something is not adding up.

Yep, that's why I'm so ????????? about it. I'm just not sure if the cap is just not sealing properly and normal thermal expansion is doing weird stuff, or if something is heating it somehow (pump motor electrical issue, exhaust leak, something else?) or whatever. Just trying to think through how to diag it and if I might have missed any other potential causes to investigate. I'll take a pic next time I pop my hood after a drive and I'll do the paper test to look for an exhaust leak when I get a chance.

[TobyB]

It's just a leaky cap.
They did that from new, if you filled them over about 2/3
and then went out and drove the car hard.

t

[Maybe Magpie]

It's just a leaky cap.
They did that from new, if you filled them over about 2/3
and then went out and drove the car hard.

t

I thought as much, I did the paper test and no exhaust leak I could detect and it didn't happen after a little spirited drive yesterday now that it's cooler. I wasn't super concerned about it in the first place, but good to know it's typical, I won't sweat it. Thank you!