I changed the master cylinder and front calipers. I also bled all the lines but when I start the car the brakes still goto the floor. Should I bleed them with engine running?

When I did this the car sometimes dies on me.

  • 3
    Did you bench bleed the master before you put it on the vehicle? Mar 9, 2017 at 2:42
  • I am just going to throw out this tidbit that you might want to make sure that all the vacuum lines are present and not rotted etc.
    – NitrusInc
    May 3, 2018 at 13:12
  • 1
    You have a vacuum leak. Not having bled the brakes correctly (bench bleeding the master, etc.) will cause braking problems, but should not cause the engine to die. It's likely that the vacuum connection to the new master is not sealing correctly.
    – 3Dave
    Aug 31, 2018 at 19:35

1 Answer 1


bleed the four tires when the engine is running,If the problem continues them you know that you master cylinder has problem.

  • 2
    while a bad part is a possibility it's more likely OP didn't follow service info and either didn't bleed the master, doesn't have a scantool to pulse the bypass modulator valve or didn't completely bleed the system.
    – Ben
    Mar 9, 2017 at 19:46

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