Hey Ari,


Whats dangerous for the master cylinder is having the brake pedal go to the floor while pumping the brakes. It pushes the piston past its usual travel, where there may be corrosion in the bore. If its pushed too far into the rough area, it will tear up the o-rings. Damaged o-rings will cause the master cylinder to fail. Its best to flush before changing pads to avoid pushing dirty fluid into the master cylinder and lines, etc. This is especially the case if you have a ABS equipped car. A quick trip to the hardware store and an auto parts store should get what you need to make a power bleeder in a jif. You can also open the bleeder connected to a hose in a bottle with its end immersed in brake fluid. This will keep air out but is kind of unwieldy if you don't have five hands, lol.

Regards, Jon