You need to "bleed" the brakes at each wheel.
R
Did you bench bleed the master cylinder? Check the front flexible brake lines - they may be internally rutured and are blowing up (like a balloon) when you step on the brake
There is probably air in your brake lines. Or you might have a bad master cylinder.
There was no Caprice in 2004...
Yes, a brake master cylinder can leak internally. This occurs when the seals inside the master cylinder wear out or become damaged, allowing brake fluid to bypass the seals instead of moving the fluid through the brake lines. Symptoms of internal leakage may include a spongy brake pedal or a gradual loss of brake fluid without visible external leaks. In such cases, the master cylinder typically needs to be repaired or replaced.
At least the slave cylinder. The clutch master cylinder can be replaced at any time.
Master Brake cylinder replaced and lines bled-how long?
after the clutch master cylinder has been replaced.
The Slave Cylinder and the Master Cylinder control totally different systems. The Slave has to do with the clutch, and the Master has to do with the brakes. They have nothing in common.
leaking brake line or master cylinder..? It sounds like a bad master cylinder. Years ago these could be re-built, but with the newer ones, they must be replaced. By pumping the brakes, you build up pressure which prevents the piston in they master cylinder from leaking, cut after sitting, the seals leak again. A good mechanic will be able to tell if it is the master cylinder or not.
Master cylinder located at the driver's side firewall
get a new one then bleed your brakes A new Ford master cylinder must be bench bled before it is installed, or it will be impossible to bleed the system later.
If you did not bench bleed the master, you need to do that.