Can you bleed the Brake Master cylinder while it is mounted to the firewall? If not, why? I just want to know if people generally don't because they don't have enough room (in other cars), or that it just doesn't work correctly. Please let me know. I need to replace brake lines this weekend. Thanks.

 

Anyone??? please?

 

Wirelessly posted

You can I just dont. I usually bench bleed then bleed all four corners

 

If you are going to swap the master out then i would bench bleed it. Typically you have a temporary line that feeds from the pressure side and dumps into the reservoir. You can get some short brake lines from auto parts store and bend them to make this work.

As long as the master isn't bone dry you should be ok to bleed the brakes with w/e method you prefer. I just swapped my master out and found out my bleeders were almost rusted in place. I was able to use a Craftsman Bolt Out to loosen them, I have swapped them now with speeder bleeders. I still need to change the rear hose and bleed that back half again.

 

Replacing brake lines shouldn't require bleeding the MC. Just plug the end of the line so it doesn't drain the MC dry. Then bleed to the wheels using your prefered method.

I prefer someone on the brake that pushes while I on the bleed screw loosen and let some out. The other person lets their foot drop (not all the way to the floor) and hold that position while you tighten the bleed screw. Then they let the pedal up drawing more fluid into the line. Watch the reservoir so it doesn't go dry. My grandchldren (ages 9 and 12) are pros on the pedal! In fact I think that was my first job helping my father when I was about 5.

 

A line broke before and drained a bit of fluid. There is a huge air pocket somewhere in the lines.

 

Put a vacuum or pressure bleeder on the brake system to get the air out, doing it manually will take you awhile if there is a LOT of air in the lines. I prefer the BG PF7 pressure bleeder system, but it isn't affordable for anyone but a repair shop. Most reputable tool manufacturers sell a good hand-held pressure bleeder system as well.