Brakes binding

[Fisherman72]

Hi, good morning. Just bought a 2005 rav4 diesel, and having brake problems. The pedal was going slowly to the floor at first. Replaced Master cyl seals, freed up the seized slide pins, things got better. Now I have binding front brakes. After a trip released the bleeders, let out a squirt of fluid and the brakes released. There must be  a stuck valve somewhere? Balance valve? ABS unit? Any ideas would be very welcome.

[Red_Corolla]

Check the condition of the flex hoses and replace them if they're starting to rot. Old ones can de-laminate on the inside and then the loose flap of rubber acts like a non-return valve. No personal experience of it but it's something I've heard of.

[Fisherman72]

Thanks, yes good point, heard of that myself. Have done the back ones, will try the fronts. Mind you, if it is it's both of them.

[TonyHSD]

Callipers, rebuild or replace. 
With age and mileage on all cars brake callipers needs service and at some point they need total rebuild. 

[Fisherman72]

Yes, thanks, had this happen to three calipers on other cars. Rebuilt one on the Rav, the other is free. This is fluid under pressure, when bleeders are released the calipers let go. Both binding, both let go. Unless things have changed in the last few hundred miles the calipers aren't sticking.

The other thing, when the brakes are binding, which gives a lot of steering shake at speed, the brake pedal comes up really hard. Fluid is new, old fluid was very bad.

[Fisherman72]

Update. Drove around a bit, parked on a slight slope, brakes binding, no handbrake, out of gear. Let go the front outlet from the ABS, fluid came out and the brakes released, car rolled forward. Seems unlikely that the master cylinder is maintaining pressure on that circuit. If I can replicate this once more I will have enough evidence to change the ABS unit, I suppose.

[Fisherman72]

....so the next question is, if I change the ABS unit will I need to code it for the car, or can I just change the valve body and keep my electric module?

[Fisherman72]

So, update #2, and a lesson learnt, even after 60 years of doing this stuff.  Brakes got worse while I was driving round trying to diagnose the trouble, until I was unable to bleed them at all. No pressure from the MC.  Removed the MC. The circlip holding the pushrod in was not properly engaged, and had twisted slightly, jamming the pushrod in so it didn't retract, and this would have been holding the pressure on the front calipers. Gave myself a good kicking. Just a note on bleeding, had to bleed the pipes between the MC and ABS unit, difficult, two tubes on the MC-ABS feeders, stick them in the reservoir top. Doing the wheels I use a long tube on the bleeder, keep it vertical and put it through the door handle, so the bubbles come to the top. Sadly the Rav reservoir has no threaded lid so can't use the pressure bleeder kit. Will have to invest in a reverse bleed kit or make one.Thanks for the replies, take care!