Hello everyone. I will be doing a brake fluid exchange when I have the time. I will begin by sucking out all I can from the master cylinder. I was just wondering, is there chance of introducing air into the system if I suck too much fluid out? There are a lot of people saying that you should never run the master dry as you could get air in your system. Should I purposefully leave a little bit in there to prevent this from happening? Or should I not be worried. Thanks.
If you don't touch the brakes then it should be fine. But it also doesn't hurt to leave a teaspoon full down there.
Yep
As long as you don't press the brake pedal with all the fluid out of the master cylinder reservoir all is good...no air introduces into system.
Of course you realize that the brake fluid doesn't circulate like coolant does. So, you will still have old fluid in the calipers...it doesn't travel in the brake system.
The only way to change it all is to open the bleeders and have someone push the brake pedal partially down...not to the floor. (because then you would be getting into a problem internally with the master cylinder rod traveling farther than normal and risk ruining the internal seal in the master cylinder)
As the fluid level drops in the master cylinder, never letting it be empty, keep adding new brake fluid into you have that new fluid exiting all the bleeders. Then close all bleeders and start bleeding the brakes from the one farthest from the master cylinder.
There is a slick way of doing it involving some see through containers, small plastic tubing over the bleeders. As long as the tubing stays submerged in brake fluid...no air. Just pump and add new fluid until you see clean fluid traveling in the plastic tubing.
