Bad brake booster??

[ragtopfury]

73 Dart Sport, "Fred" , normal Mopar power disc brakes for the year. When we installed everything and bled the brakes, the pedal is typical super hard and high as a non running power brake should be. Fired Fred up for the first time on Saturday and the pedal goes nearly to the floor with very little effort. Brakes work, but damn is the pedal low. adjusted the rear brakes up to barely a drag and bled all 4 wheels to verify no air bubbles remained. No leaks.
Bad booster? Thoughts?

 

[4mulas]

I believe the pushrod is adjustable, and it sounds like yours needs lengthening?

 

[dano]

Bench bleed the master cylinder prior to installing the lines?

 

[Murray]

Adjust the push rod from the booster to the M/C.

 

[Bewy]

If the pedal goes low, engine running....................... but is high, engine off, then you still have air in the line

 

[RedFish]

Driving it? Does it stop just fine? If you're just testing sitting still there may not be a problem. While sitting we can push right on through a booster after making more than enough line pressure to stop. Been there done that.
Grand daughter kept my 96 Camry about 4 months. When I drive it again I stopped at a light. Pedal went right on to nearly the floor. I thought, "dang master cylinder is bypassing. She didn't tell me." By the time I reached home I had realized there's nothing wrong with the car. To be sure I tested the master for bypass with engine off. Pedal wouldn't fall a little bit. Light pressure, start engine , pedal falls a little. Again I could push it on down. Into reverse, idle rpm, had to let the pedal waaay up before it moved. No fault found.

 

[RustyRatRod]

Does the master cylinder sit level in the car? If not, you may need to jack the car up until the master cylinder is level and then bleed the brakes. Sometimes air can get caught in the front of the master cylinder if it's high in the front.

 

[ragtopfury]

Seems to stop fine. Haven't driven it anywhere except up and down our 200ft driveway.
The master isn't level, it's super dang close to it.
Car is at the exhaust shop for a day or 3 now, so it'll be later this week before we get back into it.

 

[RedFish]

So if they drove it in and out, ask if they noticed a brake issue at retrieval. Good luck

 

[ragtopfury]

Bled and rebled. Same. Adjusted the pushrod about 3/16 longer. Feels real good.