Hydraulic brake not working

[technodup]

My mountain bike has been in the cellar for several years while I've been unable to get on it due to arthritis. Now I'm just about able to get my leg over it, and do a full pedal stroke so I pulled it out today.

Needs a clean, lube and air. BB sounds a bit crunchy. But the main issue is the rear Magura isn't working. Lever won't pull, and the pads were kind of jammed on the disc. I've had a poke about, and taken a pad out so at least the wheel turns, but I've never really set them up before.

Any obvious stuff to try before I drag my embarrassed arse to the repair man?

[Laurel Green]

Have you tried levering the brake piston back (with something softish) ?

This has happened with my Boardman and seems to do the trick.

[technodup]

I had a half hearted attempt with a screwdriver but I might try again.

Am I right in thinking if the lever won't pull it's because there's no more distance for the piston to travel? Or am I talking pish?

[Laurel Green]

Not absolutely sure, but think the piston would pop out if the disc were not in situ. I know there is a plastic wedge thing that can be purchased to stop the piston from popping out when in transport with wheel out.
It might be worth spraying some penetrating oil on the piston to see if that will help with freeing it.

[Fundoreen]

Careful trying to push the pistons back.Was doing very well on my magura back brake and then the piston cracked.
Compete replacement brake set with disc is cheap enough on ebay if you want to avoid stress. Not as good as the original though.

[sugerbear]

Do the brakes need bleeding? Air in the fluid will expand in the warm weather and jam the brakes on.

[BOR]

It's possible that the brake fluid has absorbed water in the intervening period, and this increase in fluid has caused the pads to push against the pads.

Try slackening the bleed nipples slightly to release the excess fluid and see if that relieves the pressure on the rest of the system.

Don't allow any fluid to drip onto the brake discs or pads (or paintwork for that matter)

[technodup]

BOR said:

Don't allow any fluid to drip onto the brake discs or pads (or paintwork for that matter)

That's exactly what I did on day one of owning the thing in 2003 because it was my first hydraulic brakes, which is also why I've been hesitant to touch them ever since.

I took it to an LBS on Saturday but they were shut. WTF? Who shuts a bike shop on a Saturday?

I'll probably go back to my usual guy even though he's a bit expensive. He's very well regarded and at least open when you need it.