ot, 98 villager

now i got 1 for ya, working on a 98 mercury villager, now for history, this van? was bought new by a friends mother, now deceased, around 20,000 miles she brought it to one of those swindle shops that prey on people who dont know about cars for an oil change, they told her it needed a full brake job, [ yeah right] cost 500 bucks, thats where the problems started, when driving in city traffic [ stop and go every block the brakes will get hot,and lock one of the front wheels, she had it towed to 3 different shops none could fix the problem, now today, it still does that, but not the same front wheel its usually the left but sometimes it does the right one, the brakes will not release until it cools off, then its fine again,the rotors will easily turn and the pads are retracted, we took the thing apart, took the brake pads and rotors in and the pads are correct, the rotors are good , true, and withing spec, the vehicle does not have antilock brakes, the caliper pistons look good and slide in and our like they should, so its not sticking calipers, id blame the mastercylinder, but to my mind if that was bad it would lock both front brakes, not just 1 and alternate wheels, any ideas??

possibly a collapsed brake line at one of the front calipers, or a bad proportioning valve.

I'm leaning towards the proportioning valve.

Sounds like maybe something is blocking the flow of fluid back out of the caliper. Maybe a rubber line is disintegrating inside and causing a blockage when the fluid is returning to the master cylinder.Are you sure it doesn't have an anti-lock brake system? Weren't all vehicles of that time supposed to have an anti-lock(ABS)system?
Friend had a 99 Windstar,( Ford version) and it had the ABS system. She had many problems with the ABS and wound up replacing it before it was right. Hers was a problem from the day she got it. She finally got it fixed by a reputable shop and then gave it to her son. It was a nightmare of problems with so many different electrical modules.

we thought so too and have carefully followed the brake lines, found out it was an option in that year but not standard, this one doesnt have it

thanks guys we will check the lines and porporsioning valve out and go from there, ive never seen anything do what this thing is doing

Next time it does it, be prepared to quickly start cracking lines, see what releases it.

Start at the master cylinder, crack each line, see if it releases. If so, it is the mc. I say to crack both lines, not sure on the Ford, but some Chrysler products did an X on the dual mc instead of front/rear.

If not, go to the next fitting, keep doing so until you find the one holding pressure.

If no lines release it, open the bleeder on the binding brake. If that releases it, it is the rubber line.

You may have to drive it again if it begins to cool off.

Chances are now the rotors are warped and the pads glazed from being overheated, but be sure the binding is corrected before going back into the brakes.

sounds like this thing sat around a lot , I would be looking at the places the caliper is supposed to slide in and out. If it has pins or slides , make sure they are clean and lubed . Make sure where the pads move in the bracket that they can slide freely . Sounds like a mechanical binding situation from clearance issue more than a hydraulic issue. A hydraulic problem usually doesn't travel , it is always the same wheel. Rust buildup somewhere is what usually causes that issue.