brake pressure

[LI Disco]

I replaced my brake lines this weekend, bled the brakes after.

when the engine is off I have full brake pressure, as soon as the engine turns over the pressure goes away and the peddle goes all the way down to the floor.. I'm looking for suggestions to this issue

 

[osiristheclown]

Did you have a pedal before you changed the lines? If you did you still have air in the system.

 

[LI Disco]

Did you have a pedal before you changed the lines? If you did you still have air in the system.

Prior to changing the lines there was NO pedal pressure at all

 

[osiristheclown]

Okay, lets take this from the top. You changed the lines why? Were they rotted out? I'm guessing yes? So, prior to the lines going did you have pedal pressure? If you had no pedal before and the lines were not leaking you most likely needed a master cylinder.

Care to give us some history on what occurred prior to changing the lines?
With the engine off you don't have pressure, you have a lack of assist because there is no engine vac.

 

[Jagfixer]

Whenever you change out brake lines, always find something to apply a small amount of pressure to the brake pedal. It keeps the fluid from draining and holds the system null until capped and rebled. ( Found this thru a series of different makes. ). If you had no pressure before the last post would be a ringer. Do not install new M/C without bench bleeding first. Install and carefully bleed and watch levels, to keep air out of ABS case.

 

[DiscoGirl4x4]

Re-bleed the brake system and make sure you are doing all four calipers and rotate around the vehical bleeding all four in sequence.

 

[ptschram]

to keep air out of ABS case.

Good luck!

 

[LI Disco]

Okay, lets take this from the top. You changed the lines why? Were they rotted out? I'm guessing yes? So, prior to the lines going did you have pedal pressure? If you had no pedal before and the lines were not leaking you most likely needed a master cylinder.

Care to give us some history on what occurred prior to changing the lines?
With the engine off you don't have pressure, you have a lack of assist because there is no engine vac.

From the top!
I changed the brake lines because I discovered 2 pin hole leaks in the brake line, prior to discovering these leaks the truck stopped fine, once the brake lines were changed the brakes were bled in the correct rotation.

to follow up, I took the truck out on the side streets today to see what is happening, it seems that if I pump the brakes there is pressure and I can stop the truck, but if I just put my foot down the pedal goes to the floor and it is difficult to come to a stop.

I think there is still air in the ABS line