Sticky pistons in MTB disc brakes - any advice?

[ceejay]

Seeking help from the more technically minded Agreeables...

I have Avid Juicy Three hyrdaulic disc brakes on my MTB and the pistons on the front one are not retracting, such that the pads are permanently pressing on the rotor. I have tried the procedure in the service manual of removing the wheel and pads, then getting each piston moving freely by holding the other one still, pulling brake lever to move the piston out, and then pushing the piston back - repeating a few times on each side so it seems both pistons are moving freely. In the past this has fixed it. This time, although when I put the pads and wheel back on the wheel spins fine, as soon as I apply the brake it doesn't release and the problem is back.

Do I need to bleed the brake? Clean the pistons? Overhaul the calliper? Replace the Juicy with something else?

Very grateful for any advice,

Colin

[Dan_K]

I'm not sure if this is a similar thing but on my Giant hardtail, the brakes kept seizing on for no apparent reason.
After some research, I found that the MPH brakes are affected by heat and in warm weather or when used heavily the fluid overheats and expands seizing the brakes on.
All I did to solve the problem was bleed a little fluid out from the bleed nipple using a syringe and a 10-15cm length of hose (bought from the aquarium section of the pet shop). You Tube have vids explaining how if you've never done it before.
Solved the problem for me. Might be worth a try before you start spending loads on new brakes etc.

[Dombo]

I had a similar problem with my Hope Mono Minis. Depending on how old they are it could just be they need bleeding and the fluid replaced. Unfortunately i cannot advise further as for brakes/forks i just leave the bike at Nirvana and pick it up next time i'm at Westcott. Last time it was 20 quid or so including rear pad replacement and fluid.

[ceejay]

Dan/Dom,

Forgot to say thanks for your advice. It seems I've fixed it (for now) by doing more of what I'd tried before, but time will tell.

Colin