brake pedal goes to the floor??

[kmyles]

Filled and bled my brake lines today. Once I fired up the car my brake pedal went right to the floor?? Dosconnect my vacum from the booster and it obviously didn't, but still no brakes?? What could be the problem?

[wagesofsin]

Filled and bled my brake lines today. Once I fired up the car my brake pedal went right to the floor?? Dosconnect my vacum from the booster and it obviously didn't, but still no brakes?? What could be the problem?

so, it felt firm, with no obvious bleed down until you fired it?
and by this i mean even after a few minutes, then applying pressure.
sure you got no leaks, it doesnt take much to suck air back in and make a weak pedal.
if youve checked everything and are confident you have no air leaks, are pushing straight fluid...
then your booster is tanked.

[kmyles]

so, it felt firm, with no obvious bleed down until you fired it?
and by this i mean even after a few minutes, then applying pressure.
sure you got no leaks, it doesnt take much to suck air back in and make a weak pedal.
if youve checked everything and are confident you have no air leaks, are pushing straight fluid...
then your booster is tanked.

I t was quite firm before I started the engine. Once I did the pedal went right to the floor on it's own!! Turn engine off and then it came back up. I think I still have air in the system but would that cause the brake pedal to righ down to the floor once fired up? Could it be that something is hooked up backwards??if it's not one thing it's another

[Bullitt-]

New master cylinder or one that has been bone dry needs to be "bench bled"...
Is this the situation and did you do it?

[kmyles]

New master cylinder or one that has been bone dry needs to be "bench bled"...
Is this the situation and did you do it?

It is a new master cylinder and it wasn't bench bled. I found out about the bench bleeding a new cylinder after I had the fluid in the master. I talked to a friend of mine and he said to open all the bleed valves and let gravity do the rest. What should I do and is this why my pedal is going right to the floor???

[Bullitt-]

Enough air will do it....or if your rear drums have not been adjusted out

[kmyles]

Where should I go from here??

[72rtchallenger]

try bleeding it again,,when bleeding is it getting pressure or does it dribble out the bleeders slowly?new master cylinder could just be bad,,if its getting plenty of pressure it could be the booster,,when it goes to the floor can you pull it back up ?does it feel sloppy?

[BIGSHCLUNK]

Start in the begining. Make sure everything is tight. Second (and this will appear like a dumbazz comment=sorry) Bleed again w someone that knows how to bleed brakes. I've came accross people (including employees) that couldnt bleed brakes with a gun to thier head!  Start farthest away first Rt REAR then work your way closest to the master. This process may have to be repeated a few times if you got tons of ait from not benching the master. Let the guy at the bleeders run the show (give commands) Hell I've got it done with the wife and even the neighbors younger daughter! BTW if the boosters bad the pedal would be like a brick! Poviding you got the air out that is.

[kmyles]

So if I didn't get all the air out (which I am 99% sure I didn't) would that bring the pedal all the way to the floor when i start it?? I know how to bleed brakes but I was quite rush as I am having a party in my garage and my baby has to sit outside for a few hours . My pedal was not like a brick, so I guess, or at least I hope the booster is not bad.

[BIGSHCLUNK]

It is a (possibility) that the master is bad. Maybe remove it and try benching it, although I dont really think that would help. But I suppose that would confirm that it pumps. My only similar experience with that was on my big loader when we had the air pressure to high and that would take out the master on the first stroke. Anyway You dont HAVE TO have the car running when you are bleeding (hence no booster). This may help the process of elimination.  I'll bet you got a ton of air in those lines somehow (everything tight??). I'm sure someone here has another opinion on this (Chryco??)

[kmyles]

I would hate to have to take the m/c off!!! It has the paint eating brake fluid in there as well!!!!

[dodj]

I would hate to have to take the m/c off!!!

You can bleed the m/c without removing it. Remove the two brake lines, install plastic ones and loop them back into the reservoir and secure with a clip, then slowly pump the brakes.

[Aussie Challenger]

You can bleed the m/c without removing it. Remove the two brake lines, install plastic ones and loop them back into the reservoir and secure with a clip, then slowly pump the brakes.

  I don't like pumping the aerated fluid back into the master cylinder, if any fluid gets on your paint pour soapy water on until gone, only if left on will it damage the paint.
  Seems to be a couple of problems here, if you have a good pedal before starting up and it goes away when motor starts it could be the wrong booster, the booster could be for a low vac. motor.
  Re bleed as BIGSHCLUNK described, furtherest wheel from master cylinder first etc. When expelling fluid don't hold bleeder open until last drop has come out, shut it just before so air doesn't enter.
  Another problem, have you replaced the front calipers? if so are they on the correct sides, that is, is the bleeder at the top and not the bottom.
  After re reading your original post and you said that the pedal went down by itself when motor started and returned when engine shut off, possibly a booster problem.
  A few thoughts for you to check out.   

[Chryco Psycho]

Pump slowly , have 2 people obviously , make sure the drum brakes are adjusted with very little slack or the pedal will drop a long way before the shoes hit the drums