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I have a 1992 Cadillac DeVille sedan. I put all new brake lines on the car and bled them all. No wheel cylinders are leaking. Someone I spoke to said I might have to cross bleed them and I did that but the condition is the same. When the car is off, the pedal feels hard. As soon as I start the car and pump the pedal, it goes right to floor with very little braking. Any advice on next steps are appreciated.

  • Welcome to the site. Assuming you ended up with the master cylinder drained, did you start by bleeding it first? Also, if the car has ABS, there may be specific steps needed to bleed the pump and valves. Look in the service manual for this car for specific instructions. – CharlieRB Apr 21 '17 at 19:26
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It can either be:

  • Leaks, should be visible for such severity.
  • Empty brake fluid reservoir, that should be under control since you've bled all wheels.
  • Damaged piston washer (I got that few times due to rough and damaged cylinder and low quality rubber on the washer).

Do the brake loose effect? or is it just super light?

If it doesn't loose effect, just very sensitive, you might have problem with the servo, in your case it should be an air vacuum thingy that looks like a drum right behind the fluid reservoir, I would leave that part for a professional.

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Brakes need:

  • Good sealing at master cylinder.
  • Good sealing at wheel cylinder.
  • Good job removing ALL air within the system via a robust bleeding process.

Any of those could cause you issues. And by sealing I mean that all of the piston seals are working correctly. They could look good and still not function correctly.

With that said, generally things shouldn't have changed that much by simply replacing brake lines, except the bleeding process.

What color is the brake fluid? If its black, that is a subtle hint that perhaps a rebuild (replacement of ALL seals in the system and the fluid) is appropriate.

Note: there is one other cause for "pedal to floor" that I've seen. If your rotors are not "straight" when the wheels spin, the brake pads are pushed far apart by the rotor. When you go to push on the brakes, the pedal goes right to the floor, because the pads have a long distance to travel.

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