72 Imperial - ran great from 1993 to 2001 and then I put it in dry storage to travel for work.
Fast forward 11 years.
I trailer it to the house and up on jack stands it goes for new leaf springs, new tank, new sending unit, new fuel lines, new carb.
Test drive around the block and I notice it feels like its dragging when I stop accelerating. I pull it in to the garage and hear the front tires squealing and a screeching. Mostly the right.
Pull off tires and try to recess puck on right caliper. FROZEN. Going no where.
Peek in master cylinder and front chamber is clear - you can see to the bottom. Back chamber looks like coffee.
I remove the right caliper with hammer assist and unscrew rubber brake line. No gravity flow.
I replace master cylinder cover and pump pedal. No flow.
I start car and pump pedal twice; I get a marginal amount of fluid in my drip pan.
I remove the left side caliper and unscrew from rubber brake line. Gravity drip to the tune of about 3 drops per second, and still no flow from right line.

Master cylinder was replaced by me in 1995 and the brakes worked fine all the way til I parked it in 2001.

How do I check the no-flow condition on the right side? Break the line at the rubber-to-steel junction?

Could it have developed blockage in the proportioning valve?

Master cylinder?

The rubber brake line?

What say you?

I'd suspect the rubber line. With everything hooked up, do you have a firm pedal?

The rubber lines are notorious for swelling internally and restricting fluid flow, replace all 3 hoses and retest. Replace the rear hose too just for good measure.

AMEN to Kroil! I was patient and let it soak in for 5 mins of each application - for 3 squirts - and it broke loose. Right side rubber line / hard line junction broke loose. Two new calipers on the bench.

Back chamber of master cylinder drained out before I broke loose the right side line - so my rubber stopper on the left obviously failed.

With rear chamber drained - it looks nasty in the bottom. Rustish, muckish, nastyish.

Off to parts store in the AM for a new master cylinder and two new rubber lines.

Thanks to those stopping in and thanks to those commenting! Support is great when in these predicaments!

Yes - pedal was firm prior to investigation.

I replaced the master and the hoses on my 72 after it sat for 15 years. They worked okay but I didn't trust them.

The brakes are far more effective now.

Sounds like you're well on your way to getting it fixed. that said, rubber hoses breaking down and plugging are pretty much standard.

happens all the time on late model Dakota's after about 10 years! lots of guys have had the rubber lines break down and fill the caliper with crud. then the caliper siezes up and won't let go of the rotor.

replacing the hose and the caliper fixes it though.

Thanks Kaptain!

Just had an ordeal this spring...A vehicle had both front brakes dragging {as in no way to hand spin after a few miles}...And against all odds...Both rubber lines went bad !!! Usually one or the other but this was a first for me and had me for a while...TIP: For a quick check bleed the caliper...If it releases it's the hose or upstream from there...If it does'nt bleed/release pressure it's a caliper issue....