1997 F-150 brake problem

1997 F-150, 2 wheel drive, disc-drum set-up. Replaced front brake pads, and found left front caliper seized. Replaced caliper, now can't get the air out of the system. I've gone through over 3 quarts of brake fluid and get foamy fluid coming out of the caliper. I double checked all the connections and lines - front and rear lines including the rear wheel cylinders. No problems found. I have braking power at the bottom of the stroke and get fair pedal after pumping the pedal about 5 times. I know that is air in the system, but where is it coming from? Could the master cylinder be bad with the seized caliper? 3 quarts of brake fluid is enough to do several brake systems. Any help would be great.

While you were changing the caliper, did the reservoir run dry from the line dripping? That may be where your air came from. You asked if the master cyl could be bad, well it could, but as long as it stayed full of fluid no air could get in it. How are you bleeding it? If youre using a helper to pump, be sure they know how to do it. I learned that lesson the hard way years ago, and still have the t shirt. Thats when i started doing it by myself . You can buy a kit to do it with, but its easy to improvise with some clear neoprene tubing(that fits the end of the bleeder good and tight), and a fruit jar. You can also use a large syringe. If one ran out of fluid, i like to reverse bleed it, so you dont have to fight with it to get that last little bit from the master cyl, down to the wheel. Air bubbles actually would rather go uphill than down. The syringe(60cc works good) works great for this. I have a stand made , where i can hang the jar, or syringe high enuff to see it, and tell when the air is out. If you do have to put a master cyl on it, make sure you bench bleed it before you put it on. Good luck.
Later
Ed

While you were changing the caliper, did the reservoir run dry from the line dripping? That may be where your air came from. You asked if the master cyl could be bad, well it could, but as long as it stayed full of fluid no air could get in it. How are you bleeding it? If youre using a helper to pump, be sure they know how to do it. I learned that lesson the hard way years ago, and still have the t shirt. Thats when i started doing it by myself . You can buy a kit to do it with, but its easy to improvise with some clear neoprene tubing(that fits the end of the bleeder good and tight), and a fruit jar. You can also use a large syringe. If one ran out of fluid, i like to reverse bleed it, so you dont have to fight with it to get that last little bit from the master cyl, down to the wheel. Air bubbles actually would rather go uphill than down. The syringe(60cc works good) works great for this. I have a stand made , where i can hang the jar, or syringe high enuff to see it, and tell when the air is out. If you do have to put a master cyl on it, make sure you bench bleed it before you put it on. Good luck.
Later
Ed
Its also a good idea to prefill the caliper/wheel cyl before you put em on, saves alot of time. They syringe works great for this too, You can get them at your local co-op/feed store. Good luck.
Later
Ed

I got the problem figured out. I feel like a boob. the bleeder was below the line feeding the caliper which caused the caliper to trap air above the bleeder. I did replace the master cylinder, I don't think I needed to, but at least I know the master cylinder is in excellant condition with no contamination. Thanks for your help.