Brake boil over
I doubt there's any "boil over" involved unless you've experienced a ton of brake fade when driving. The gaskets that come on those master cylinders are kinda lousy. If you open and close them a bunch (like during the bleeding process) it seems like they start to leak.
You can buy replacement caps and gaskets for them, I did that with mine and haven't had any issues since. Dorman #42044 for caps, #42081 for gaskets
Also, on the cap that raised section of plastic on the cap is a vent, and it works best if that's at the highest point- ie, don't put that facing the front of the car, because when you stand on the brakes the fluid shift will put fluid out the vent.
Like in this particular picture, your vents are facing mostly forward...
I doubt there's any "boil over" involved unless you've experienced a ton of brake fade when driving. The gaskets that come on those master cylinders are kinda lousy. If you open and close them a bunch (like during the bleeding process) it seems like they start to leak.
You can buy replacement caps and gaskets for them, I did that with mine and haven't had any issues since. Dorman #42044 for caps, #42081 for gaskets
Also, on the cap that raised section of plastic on the cap is a vent, and it works best if that's at the highest point- ie, don't put that facing the front of the car, because when you stand on the brakes the fluid shift will put fluid out the vent.
Like in this particular picture, your vents are facing mostly forward...