Brake pedal to the floor

Tiny
TODD VILLANUEVA
  • 2007 HYUNDAI TUCSON
  • 1.8L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 190,000 MILES

Hello,
I replaced rotors and pads and calipers that were clearly faulty. I replaced the master cylinder, bench bled it, bled the brakes with the bleeder screw and a hose into a plastic bottle of clean brake fluid, but the brake pedal still goes to the floor when the car is running. The brake booster seems good because when I have the car running and the brake pedal pushed down, I will turn the car off and the pedal lifts back up against my foot with good pressure. There are also no leaks anywhere. Is it possible that another caliper is letting air in some how and I do not know it? How would I find that out? Should I just replace the remaining calipers that are old and original to the car and then see what happens?
Thanks for any help.
Todd Villanueva

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Wednesday, February 22nd, 2017 AT 3:31 PM

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Tiny
CARADIODOC
  • EXPERT
  • 28,550 POSTS

I suspect your car has anti-lock brakes. If it does, and you let the master cylinder run empty while the calipers were off, yo will likely need a scanner to command the computer to open the valves in the hydraulic controller so air can be expelled from some of the chambers. To prevent this next time, use a stick from the seat to hold the brake pedal down an inch or two. The lip seals on the master cylinder will stop the brake fluid from running out.

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Wednesday, February 22nd, 2017 AT 3:43 PM
Tiny
TODD VILLANUEVA
  • MEMBER

Do you mean if I had the master cylinder off the car and a caliper off the car at the same time?

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Wednesday, February 22nd, 2017 AT 3:52 PM
Tiny
TODD VILLANUEVA
  • MEMBER

I did not let the lines run dry when a caliper was off.

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Wednesday, February 22nd, 2017 AT 4:02 PM
Tiny
TODD VILLANUEVA
  • MEMBER

I did not let the lines run dry when a caliper was off

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Wednesday, February 22nd, 2017 AT 4:56 PM
Tiny
CARADIODOC
  • EXPERT
  • 28,550 POSTS

You do not have to have both off at the same time. With just one caliper disconnected, brake fluid will siphon out of the reservoir, especially if the cap is loose. It is also possible for the fluid to be held in the reservoir from vacuum when the cap is tight, but it can run out of the line all the way up to the hydraulic controller.

You still did not say if you have anti-lock brakes, but it sounds like the controller needs to be energized to bleed the air out.

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Wednesday, February 22nd, 2017 AT 5:42 PM

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