Paintzapper

I have a 1989 Toyota Pickup, V6 4wd over 200k miles (overhauled at 189k). I am having a problem with the front passenger brake building up pressure while driving and locking up completely. The brake peddle is stuck and does not budge and will not depress until I let loose the pressure in the caliper. I don't have to press the brake peddle down to let any pressure out. This will happen within 5 miles of driving or dependent on the amount of braking I do.

I have replaced both front calipers, front passenger flex line and the hard line that is connecting to the passenger caliper. I have also bled the lines with fresh brake fluid until I have clean fluid all the way down on all four brakes.

I've seen people saying that the master is at fault or the booster arm is at fault. My dad thinks the load sensing valve is at fault but the rear brakes work fine. I'm debating on overhauling my master to see if it is all gunked up. I do remember that I had some stuff floating around in the reservoir and I'm wondering if it is chunks of something inside the master falling apart.

I want to know any other possible things to look into before I start using up more time and money doing random repairs.

Any Ideas and help will be much appreciated!
Thanks!
Zappy

Night-rider123

Do you got to drive it or can you make it stick by sitting and pumping to brakes? As in when everything is cold.

Paintzapper

It doesnt seem to lock up while everything is cold.

Night-rider123

Sounds like a sticking caliper then. I would replace both calipers and hoses. I doubt it would be a problem in the master cylinder simply because a master doesn't direct fluid left to right only front to back.

Paintzapper

Both calipers and hoses have already been replaced. The caliper lets loose pressure even withought me pressing down on the brake peddle. The peddle wont even depress after it locks up.

Night-rider123

I understand you have replaced them but getting new parts that are bad isn't uncommon. If you let pressure of it without pressing pedal then thats a sign of a bad brake hose.

Paintzapper

I gotcha, ill look into it thanks!