E92 brake job gone bad, Master Cylinder

[Rumz]

So i was swapping out my worn pads and rotors on the front and completely forgot to uncap the reservoir. finished everything and i get in to test them, mind you the front is still jacked up. Hard pedal, perfect. I go to throw on the wheels and drop it and I notice a fluid leak under the front driver side door, inline with the mirror. brake fluid... thats when i realized i forgot to uncap the reservoir.

Anyway i go check the reservoir and there's fluid alll around the cap. I cleaned it up, threw the wheels on and prayed for the best. Sure enough the pedal went almost all the way to the floor, after pumping it a few times it would hold but not for long. I bled it hoping that was what it was but no dice. Theres no fluid leaks anywhere so im assuming i blew the master cylinder.

Can anyone confirm this or help me diagnose it. Also if it is the master cylinder, is it just a seal (can it be rebuilt) or do i need a whole new one?Iin my search for a new master cylinder some sites and diagrams state the master cylinder is just that little metal piece under and including the reservoir while others say it includes that big drum behind it all. Any help is appreciated.

And yes i feel like a dumbass already, lets not go over that.:rolleyes

[cochise325]

Did you remove the brakelines at the calipers? Or perhaps damage a brake line at a caliper?

The overflow results from displacing fluid when you press the pistons in. That should not damage the master cylinder. I would look carefully at the brakelines at the calipers and carefully check to see if you damaged a bleed screw.

I would be very surprised if you need a new master cylinder or booster. But I would not be surprised at all if you have a fluid leak at one of the calipers.

[Critter7r]

+1

Fluid coming out of the master when pushing the caliper pistons back in is a sign only that the brake fluid was "topped off" at some point when the pads were worn down.

[Rumz]

i checked all the lines there doesn't seem to be a leak which is why i assumed it was the master cylinder, ill check again though.

[Vin328IX]

if you stepped on the brake while the caliper was not connected maybe some damage to caliper or master cylinder but if not then like others said you must have a damaged line.