If I understand correctly, you already identified the cause of the problem. Spitting brake fluid means that part is leaking and all the brake fluid has been lost. All cars have a dual hydraulic system. When a leak occurs in one part, the red "Brake" warning light should turn on telling you of the problem. You'll still have brakes to two wheels at that point, until all the fluid is gone. That gives you plenty of time to stop safely.
Something else to be aware of is you will likely need a rebuilt master cylinder as part of the repair. There's two things that could have caused damage to it. The first is when you replaced brake pads. To do that, you have to press the pistons into the caliper housings to make room for the new, thicker pads. The last step of the procedure is to press the brake pedal repeatedly to run the pistons back out to adjust them. In doing so, many people push the brake pedal all the way to the floor.
The second possible cause is now that you have no brakes, you pushed the brake pedal to the floor again. In either case, crud and corrosion build up in the lower halves of the bores in the master cylinder where those pistons don't normally travel. Later, when the pedal gets pushed too far, the rubber lip seals run over that crud and can be ripped. That, by itself, typically leads to a slowly-sinking brake pedal, and that commonly takes two or three days to show up. The brake pedal will feel like there's a slow leak, but you won't lose any brake fluid. The leak is an internal leak inside the master cylinder.
That corrosion that forms is a product of age, not mileage. It typically doesn't develop yet for about the first year. With any master cylinder older than that, it is standard practice to never push the brake pedal over halfway to the floor, to avoid causing those ripped seals. This includes when pedal-bleeding with a helper.
If you aren't sure what's leaking, try to post a photo of the suspect part(s). When you said, "it's all dry", do you mean the brake fluid reservoir is empty, or there's no wetness to indicate something is leaking?
Here's links to some related articles you may find of interest:
https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system
https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor
https://www.2carpros.com/articles/how-a-brake-system-works
https://www.2carpros.com/articles/symptoms-of-a-bad-brake-master-cylinder
https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder
You likely don't need all of these, but they might benefit others researching this topic. I'll be back tomorrow evening to see how you're doing.
Monday, July 28th, 2025 AT 9:04 PM
