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Tips needed how to stop the working piston from poping out and leading.

Using GT85 on non working piston.
Have got new pads.

Trying push in n out non working one.

Put old pads in, use a flat head screw driver then wiggle the screw driver to push the piston back in.. Should always do this before putting new pads in...

As above piston moves out then not back in. Wiped crude from piston sprayed GT85 repeat 10+ times.

Piston doesn't retract!

Could be air in the system, may require a bleed, if the levers have adjustment on them make sure they're fully wound out so there at the loosest for bite and reach adjustment. It's always a good idea to push pistons back in using the opposite pad, place screwdriver between old pad and non stuck piston, this allows constant full pressure on the opposite piston.

Undo the bleed nipple on the caliper slightly with the bleed kit attached or open the reservoir by the break lever, then try the screwdriver method. Otherwise the caliper may need stripping down.

Thanks for the advice.
Probably will end up at shop then dick about can see brakes fluid getting every were

The bleed nipple shoule always be open when you push the pads back!!

Right I'll give that a go. Ta

In any step by step instructions or video on how to bleed brakes I have never seen this mentioned, where did you get this from?

I find it helps to open the resevoir to let a bit out if its the first set of pads for while

Opening the bleed nipple a little while pushing the pistons back is easier than opening the brake fluid reservoir (you usually have to move the brake lever to ensure the reservoir is level) plus you run less risk of pushing any dirt particles that may have got passed the piston seals back up the hose, which can then move down and foul everything up later. If you fluid level is low you risk sucking in air by opening the reservoir. A lot of people just bleed their brakes every pad change. I suppose it depends on what pads you run though.
How to bleed brakes depends slightly on what brakes you have. Bleeding Shimano ones general involves opening the bleed nipple and reservoir and refillig/draining the fluid via the reservoir, pumping the lever until no more bubbles appear in the bleed tube.

Avid's and others: http://www.bikeradar.com/road/gear/arti ... kes-21800/
Shimano and Hope: http://www.bikeradar.com/gear/article/w ... akes-21609