I changed my front pads and now have spongy brakes. No, I did not leave the cap on when pushing the caliper pistons back in for either side. Simple pad change is something I have done on many cars over the last 30 years and have done this at least 4 times on this 2006 T5 V50.
I bought a brand new master cylinder, bench bled it then we bled all of the wheels in order of Rear passenger, rear drivers, then Front passenger and finally front driver's. It seemed nice and firm but went soft as soon as the car was started. I noticed I failed to
put the MC o-ring gasket on, so had to remove the new MC and reinstall with the O-ring on it this time. We re-bled the system as before and now Same result, soft pedal when car is running. This has never happened to me before.
I noticed the vacuum pump for the booster was not working so replaced it ( used one ), rebled system this time but this time with ignition on and in the run position, still soft brakes but better. I could now drive vehicle around the block but pedal goes to the floor, pumping helps. Before I had zero stopping power! I ordered a new pump, since the used one I bought runs hot and is very loud. I believe its going to die soon.
This still does not address the original problem of a soft spongy pedal with after simple pad change. I never touched anything that involved letting air in the system. Is there anyone who can tell me why this is happening? I am almost ready to rool this car in front of a MACK truck or train or down a cliff side. Is there a solution?