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I've got a 97 Honda Civic, no ABS, front disks, and rear drums.

A few days ago I had to slam on my brakes and I locked up the tires, and after that my brake pedal went to the floor. I got home, and immediately noticed brake fluid pouring out of my rear passenger side drum and front drivers side caliper. The brake cylinder in the drum had basically exploded under the pressure, and some seal in the front caliper failed and was leaking.

So I replaced both wheel cylinders on both sides in the back, put brand new shoes in, and I put two brand new calipers on the front, and reused the old brake pads since they were only about a month old. I did adjust the wheel so the shoes are just barely rubbing on the drum. Now when I tried to bleed everything, I noticed that when my helper pushed on the pedal, fluid was leaking out of the master cylinder too. Now this master cylinder was replaced about three years ago, so I was a bit mad about it already leaking, but whatever, I bought a brand new one from NAPA.

After I bench bled the new master cylinder and put it in, I bled all four corners of the car, starting from the passenger rear and working closer to the new master cylinder, and I put about two quarts of brand new fluid through the system, and no air was coming out of the lines.

My brake pedal still goes to the floor though. When the engine is off, it's firm like it should be, so I think the booster should be fine, but when the engine turns on it just drops to the floor with very little resistance. What's going on here? This has frustrated me for four days now.

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    Just a hint, but is this one of those car / models where you have to jack the front high up into the air to get the master cylinder to bleed properly? Or use a pressure bleeder? – Solar Mike Jul 31 '17 at 6:40
  • when the engine turns on ? Does the pedal go to the floor immediately when parked, or does the pedal go to the floor after you try to drive the vehicle ten feet or more? Are you sure you have all the right springs inside the master cylinder? Possible the master cylinder you bought is missing a spring or two? – zipzit Jul 31 '17 at 9:00
  • With the engine on and you press the pedal does the engine run normally, or stall? – GdD Jul 31 '17 at 9:24
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    you can't under estimate trapped air. after doing some major repair work like you I had this problem for months, finally replacing everything, calipers pads, master/slave cylinders, down to the hard lines and fittings... everything but the booster as that was the only thing it couldn't be... then just kept bleeding running 4 quarts of new fluid until they were useable... still not what they were new but... – axa Aug 1 '17 at 6:50
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    Did you check for vacuum leaks? If none, I might double check that master cylinder application part number and return it for a new, proper fitting one. – Ted Pants Aug 1 '17 at 16:41

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