I just did a clutch, radiator, driveshaft, and steal break line install. Everything went perfect. Except the breaks. I bleed them as much as I could. But the breaks won't hold pressure when the car is on. Off, it holds fine. As soon as I turn the car on. The peddle will just sink to the floor. My friend said I need to buy a couple bottles and keep bleeding them over and over until it stops doing it (when every last bit of air is gone. I checked for leaks. No leaks any where. The rear breaks calipers are a BITCH to bleed. Before I start going through a bunch of bottles, anyone know if it could be anything else wrong? Insight needed, thanks.

 

Use a vacuum bleader, the system can be a bitch to bleed. You will get there, however it takes time. Otherwise see if someone else posted the same problem.

Cheers
Rogier

 

Have your friend help bleed the brakes by pumping the air out of them while you turn the screw to adjust. Your friends advice sounds illogical to me

 

About your symptoms:

If you have some air in the lines, the pedal will feel spongy/soft, but will still build resistance as the pedal goes down.

If the pedal sinks without increasing resistance, the master cylinder has an internal leak.

 

If you push on the pedal, with the engine off, and the pedal does not go down, but will go down, and hold, with the engine on, you have either a vacuum leak in the brake booster line, or a bad booster.