no pedal when i crank the car

[sj28henry]

I have a 89 honda civic and i just replaced the front brakes. I bleed them and no air in the system. When I get in the car before I crank it, I have a good pedal. I can pump them and feel the compression. But as soon as the car is started, my pedal goes to the floor. The brakes are working properly. I have all the tires off and I can see the calipers grab the brakes and feel the shoes go out to the drums. No leaks in the line that I can tell. Please help me. This has been an on-going problem for a week now and it's about to drive me and my friend crazy. Thanks for the help.

[FuLL BLown STD]

well what i would do first is remove the resevoir cap pump all the brakes while the car is running..see if the level goes down..hopefully it will and u can top it off again..also make sure u dont have any leaks..when the car is running u have more pressure so juss inspect it neways. also dont get all crazy with the pumping of ur brakes or u will wear out the master cylinder pushrod and or the m/c seals. and if all else fails I WOULD remove the calipers and inspect my install..make sure theres no frozen calipers and make sure the install was done right.also if u did drain all the brake fluid..the bleeding process can take awhile..i would juss make sure again theres no air pockets..and there is a seqeunce u follow while bleeding the brakes..u start with the farthest wheel which is like ur left rear bleed that first..yeah i use to take my brakes pretty damn serious after racing down a highway with a bunch of friends b4 my brake upgrade doing 130 and they all stopped on the dime and my brakes faded and i ended up swirving into on-coming traffic lol from there brakes were priority!

[sj28henry]

I never drainded the reservior and I did take the cap off and pumped the brakes and never lost fluid and never seen air bubbles. None of the calipers are frozen because I can actually see them working. Could it be the master cylinder? I'm puzzled as to why I have a pedal before I crank it but it hits the floor when cranked.

[Christ]

Re-bleed them, starting with the furthest one, then working your way to the shortest one... except, this time, use a hose that fits tightly onto the bleeder valve, and run it into a full, clean bottle of brake fluid.

What you're going to do here, is after you've done that, you're going to get in, and pump the brakes, without the car running, 10-15 times.. keep making sure the hose is fully submerged in the fluid.

After that, start the engine, and pump them 10-15 more times.

Do this for each brake... 10-15 pumps with engine off, 10-15 more with engine on.

What happens here, is that when you pump the brakes with the line in fluid, it allows the air to push out, and replaces the air with fluid from the bottle, instead of drawing it in from the reservoir... since the bottle is closer, it requires less vacuum to suck fluid from the bottle... this will manually bleed all the air out of your brakes... if it still does what you're saying after doing this, it's the brake booster, and it's bad/needs replaced.

[2002corolla]

you do realize that it does that beacaue of the brake booster right? as long as it brakes like it should when it is started. does it slowly go to the floor when you are at a stop (internal leak at the master cylinder)?

[Christ]

It still should not go to the floor when you start it, unless the brakes need bled or the booster isn't working properly.