Mine's leaking on my 71 Charger. Slight bubbling when you push the pedal and of course its sucking in air when you release the pedal. What's its purpose and how do I fix it?

Are they repairable?

The purpose of the metering valve is to hold off the front disc brakes until a certain system pressure is achieved, I don't know if they can be rebuilt but Inline Tube has new ones for around $70.

http://www.inlinetube.com/Prop%20Valves/BLK252.htm

Thanks, John.