losing brake fluid

i recently replaced brakes all the way around, new rotors and pads up front, and new shoes and resurfaced drums, as well as both wheel cylinders, both were blown and what i suspected was the cause of my weak pedal and loss of brake fluid which motivated me to do all this in the first place. i thought the leak was fixed, until about a week later when my master cylinder lost about 1/4 of its fluid. the pedal is good sometimes, but about 80% of the time it has to be pumped twice or so to get a good pedal. there is no leaks from the front rubber lines, and no obvious leaks from the master cylinder. what could be causing me to leak fluid and have a weak pedal? brakes have been bled several times and the rear has been adjusted twice.

i would take the two bolts off the master and pull it away from the booster and see what that seal on the back looks like.

Ill do that in a few hours when i can get some daylight. if thats it would it be worth buying a rebuild kit for the master cylinder or should i just buy a new one?

Nevermind, the rebuild kits are more than a new master cylinder, for whatever sense that makes.

its one of those supply and demand things im sure.

took forever to reply, but you were right. it was the master cylinder. kinda stumps me though bc there were no visual signs of it leaking fluid fromm anywhere in that area. but the fluid was definitely going somewhere.

mine leaks and its been eating the paint off the top of my fender under the master cylinder. i have weak a pedal too. i havent bothered although i need to. i also have a bad shaking issue if i have to slam on my brakes. but i go weeks, somtimes months without ever feeling it cause i barely touch my brakes when i use them. i like to ease to a stop.