brakes not disengaging

[notaprob]

I was driving around town for a few hours and I noticed the brakes started acting funny. When I was driving, the truck was veering to the left. When I engaged the brake, it would either dive hard to to the left and sometimes the right. When I let off the throttle, the truck would slow down quickly. Thankfully, I was a mile from my house when this happened so I was able to get back. when I was in the driveway, I pumped the brake pedal, got out and pushed the truck, and both the left and right front caliper was dragging hard.
Does this sound like a master cylinder? I replaced the passenger side caliper about 2 years ago due to it sticking. Today was about 92 degrees and it has been the longest I have driven it all summer. Could it be the brake fluid overheating? Either way, I`m going to flush out the old fluid since its starting to discolor. Any help is appreciated!
My truck is a 1994 ford ranger 4.0 4x4 5speed

 

[Dirtman]

Could be a stuck caliper, stuck slides, bad brake hose... need to jack it up and see if its one wheel or both and go from there.

A bad master cylinder usually gives a mushy pedal like having air in the lines.

 

[Ranger850]

What Dirtman said.
I would lean towards stuck slides.

 

[Denisefwd93]

When brake hoses are as old as they are on your truck even if they aren't collapsed inside you probably should replace them! No you can't tell by looking at them, you can only tell by trying to push fluid through them sometimes they work like a check valve! Good news calipers, brake hoses,pad etc aren't terribly expensive,

My 93 ranger the front brakes were dragging because I had a bad RABS valve, one of the most unusual problems I've ever seen in my life!

 

[notaprob]

Thanks for the replies! I greased the slides and bled the front brakes. The fluid was dark brown/black ? I drove it today with no problems.
However, I was not able to bleed the rear brakes. I opened the valve and the pedal got hard and would not go down. It was like the valves were not open at all. I had no problems bleeding the front brakes.

 

[Dirtman]

The bleeder valves and or wheel cylinders get rusted and sealed shut. Take the bleeders all the way off and physically clean or replace them. If you still get nothing, crack open the lines on the wheel cylinders themselves and try again, if still nothing then theres a blockage in the line from the master cylinder but thats unlikely.

Then do a full brake system flush. Youtube that if you've never done it. But, with fluid thats black you have a ton of corrosio in the system already. Maybe time to start saving up for all new lines, wheel cylinders etc.

 

[Denisefwd93]

RABS valve, they have they have very tiny passages and get clogged with rust, good chance it's shot, time to do your homework, if it is the rabs, options are: repair (not likely) Replace ($$$) or bypass what many do, but know the risks.

 

[Shran]

Had this issue in an '89, bypassing the RABS valve fixed it. But I also had done new calipers, hoses, wheel cylinders, master cylinder and rear hardware so it was simply the last item that could have failed. Hard to say exactly but if you're not getting fluid out of the rear wheel cylinders, I'd start at the front and work your way back. Bleeder valves may simply be clogged full of rust.

 

[Denisefwd93]

RABS in my 93 made me insane, cost nearly $1,000 going to the shop replacing rear drums three times ( or was it two times) finally he said he was perfectly comfortable by passing it, and was very knowledgeable and aware of the problems RABS has caused over the years

On my 94, didn't think twice, went right in bypassed it, then did front brake hoses, rotors, calipers, master cylinder, booster and rear brake shoes with a friend's help, I saved hundreds of dollars! I love my brakes!

 

[adsm08]

The bleeder valves and or wheel cylinders get rusted and sealed shut. Take the bleeders all the way off and physically clean or replace them. If you still get nothing, crack open the lines on the wheel cylinders themselves and try again, if still nothing then theres a blockage in the line from the master cylinder but thats unlikely.

I've had ones that had to be drilled out. On my B2 I just opened them, started the engine, and held the brakes. Popped the blockage right out.