Thought I would try this as a source of help. I have a 92 civic VX with power brakes. Having a problem where the brake pedal goes to the floor once I start the car. The car still stops but the pedal travel is alittle troubling. I have replaced the master cylinder, bleed the brakes and checked the pads for wear. They look fine. The rear brakes appear to be adjusted out fine as there is a slight drag on the drums when I rotate them.

Would anyone have a suggestion on what else might be the problem?

Thanks in advance

 

could be proportioning valve. all 4 brake lines run to it out of the master cyl.

 

did you bench-bleed the master cylinder? Were the brakes fine before you replaced the master cylinder?

 

have you tryed adjusting the clutch pedal play?