brake problem
 

Yesterday my husband decided to change the front brakes. Replaced them, now the brake pedal goes to the floor. Bought a master cylinder today, all lines have been bled. Pedal still goes to the floor. What else?

new husband
do you have life insurance

ha ha, the car is my 17 year old daughter's by the way.

still sounds like air in system start bleeding from rear to front

We have.....twice. Now, the pedal only hits the floor when we turn the car on. When its not on, the pedal feels great.

maybe someone else will chime in an try to help you

If you don't have a leak in the system, then only 5 things I can think of remain:
(Choices 2 and 3 are the most likely)

1. Your master cylinder is faulty. (Not very likely)
2. Your brake pads are installed incorrectly. (allowing inappropriate caliper/pad movement)
3. There is air hiding in the system somewhere, most likely the Master Cylinder. (They can be hard to bleed.)
4. Proportioning valve failure. (Very unlikely)
5. A flexible line/hose has a bubble. (They usually burst, not bubble, therefore very unlikely.)

The change between motor running and not running is not a surprise. The vacuum assist only works with the motor running (and it has enough vacuum storage to operate at least one time after the motor stops.) When the assist operates it applies far greater pressure to the system, squeezing the air into a much smaller volume, hence more pedal travel.

Question? Does the pedal "Fade" to the floor, or simply go there when you first push it?
If it "Fades", the master cylinder or a leak are the suspects.
If it just goes there, or is "Spongy" then air or inappropriate installation of the pads is more likely.

Check all 4 wheels for leaks. You never know when you'll pop a seal.

Be sure to bleed all 4 wheels until the fluid runs clear. It should look brand new, not old and dirty.

Also, if you have Front Disk/Rear Drum brakes, you have a proportioning valve. They don't go out often though.

If that doesn't solve the problem, take it to a professional. Brakes are too important to be a questionable system on a vehicle.

Did you bleed the new master cylinder before connecting it up to the system? The way to bleed the master cylinder is to get some short pieces of brake tubing with flared ends and connectors. Screw them into the M/C outlets with the tubing bent up and around so as to submerge the ends in the reservoir. Stroke the M/C a few times. The air will push through the tubes and form bubbles in the reservoir. When it stops bubbling, the M/C is free of air. Then hook it up to the system and bleed the system again, starting with the wheel farthest from the M/C.
I agree with irdaneel. If you can't get it right, bite the bullet and pay a pro. You gotta have brakes.

All good info above, but just want to throw in another idea in case it helps-- if you have ABS (if not then ignore this), you probably got air into the ABS solenoids when changing the master cylinder. If that's the case, it must be bled using a special scan tool and procedure and you'll have to take it to a shop to get it done.

Not mentioned above, though it may be common sense, you should not try to drive the car to the shop-- if it comes to that, it should be towed.

Another night last night being unsuccessful, which could only mean two things.
1) either the Master Cylinder is faulty or
2)as Rick99 says, air in the ABS module.

My husband redid the pads Monday night, and re-bled the MC, yesterday we re-bled the brakes, this time with the key turned on, and he said NO AIR was coming out.

The pedal does not go straight down to the floor like the post of "irdaneel" says, it almost feels like like it gradually goes down, like there's air, and it stops approx. 1 1/2" from the floor.