Had a squeak from my back wheel that sounded like it was coming from the brake disk rubbing, so took the pads out to see what state they were in.

Gave the lever a couple of pulls as well to see if the pistons were moving OK and one popped out with fluid going everywhere.

Wasn’t sure if I could replace it but went ahead anyway then gave them a full bleed.

Got hardly any stopping power at all now and there’s loads of play in the lever despite bleeding twice.

I’m assuming the pads are contaminated so need to change those anyway but are my calipers now also ruined or should I be able to just push a piston back in like I have?

I did that on an old Shimano brake. It was fine

APF

What brakes is it? It’s possible to damage it while returning the piston, but in all honesty I’d suspect the bleed- bleeding from a dry system is way easier to screw up than bleeding a fairly full system.

Yup, got away with that a couple of times too (slow learner apparently). Pads probably got a soaking so I’d just bin them, give the caliper a good clean, then see how they are.

You’ll be fine, does the piston still move when you pull the lever?

It sounds like you’ve done a poor bleed and you need to do it again/properly – sorry 🙄

make sure you clean the rotor thoroughly with hot soapy water too, not just a quick wipe off with a rag/tissue

Meths/IPA to clean all the old fluid off the rotor and caliper. As has been said it sounds like a re bleed is needed. Do not mix fluids, Dot vs mineral as the seals will suffer etc if you put the wrong stuff in. Old pads are shot but I guess you know that.

Thanks guys – will strip, clean and re-bleed tomorrow.

Breaks are Magura Louise.

Does white spirit clean good enough?

White spirit leaves an oily residue, so not good. Meths, IPA,or brake/clutch cleaner are best, a good scrub in washing up liquid will also do the job. Would probably have been a good idea to thoroughly clean the piston and seal area before re-fitting, to prevent dirt ingress.