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Old 02-10-2026, 10:37 AM   #2
glennpm
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Default Re: 1950 Ford Custom Brake Master Cylinder

Quote:
Originally Posted by DNLs1930 View Post
My question is: Is the master cylinder reservoir pressurized? Because while I was applying the brakes with the cap off fluid would "squirt up" an inch or so in the reservoir which makes me think the cap is holding pressure but probably not much but enough to make the cap leak if the seal is bad.
THANKS IN ADVANCE for any thoughts on this.
No, the master cylinder chamber is not pressurized. The "squirt" that you see is the pressurized fluid outboard of the master cylinder, the brake lines and wheel cylinders, squirting out the bypass port when the brake pedal is released. In addition, the master cylinder caps and gasket are vented to maintain atmospheric pressure. I just looked at a few links and I liked this one for graphic explanation.

https://www.youtube.com/watch?v=rcvhntRbTb4
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