Ok. Something really funny is going on here. And i’ve worked as a bicycle mechanic for a good couple of years in the past…

…My brake pads on my maggy martas wanted checking.
…i removed the retaining pin, removed the pads, pushed the pistons back into the caliper housing using a tyre lever.
…i replaced the pads with the old pads (as they had a ride or two left back in em!).
…i pumped the lever…
…i did it some more

And nothing happened. The brakes seem to have lost some fluid…the lever pulls to the bar?!?!?! What the **** is going on? It doesnt make any sense. I don’t understand what could possibly be the problem. The pistons are both moving…they just seem to have lost some fluid.

How!?

sticky pistons?

did you bleed em with new pads & a thick spacer shoved in ?

or, err, something 😳

did you happen to pull the lever with the bike upside down? If so, any air in the reservoir will be drawn into the system, giving the symptoms you describe.

don’t know what martas are like, if they are an open system like hope then all is fine, just squeeze the lever a few times to pump the pistons out. As you pushed the pistons back the fluid went out of the piston and hose into the reservoir, pump the lever to push the fluid back into the hose and pistons (open systems are ‘open’ to the reservoir when the lever is in the return position)

In my case this resulted in air getting into the lever as the seal was on the way out. I left them on the bike tied back to the bars overnight and they were usable but never the same again. Magura wanted big money for a new lever though they would have replaced it f.o.c. (if I had kept the receipt)and they used to do so for levers up to five years old suggesting it was a known problem. I now use XTR.

I bet the pistons are sticking, so when you release the lever, instead of holding their position they are retracting fully.

When my Hopes did this I held one piston in, pulled lever (so opposite piston came out twice as much as normal) then used a cotton bud to wipe a little brake fluid around the piston. Pushed it back in and then did the other side, after a couple of goes they started holding their position as the lever was released and adjusted themselves within a few lever strokes.

pushed the pistons back into the caliper housing using a tyre lever.

As the pistons are further back into the calipers than before, the old pads won’t touch the disk. Stick some new pads in there and be done with it. ;¬) The chances are I’m wrong, but good luck with it anyway. Rob