A few weeks ago I bled the brakes because the peddle was getting low and I wanted to switch to silicon fluid. The only snag I ran into was that I broke off one of the (too small) rear bleeders. After the break it didn't leak at that spot and the peddle was firm so I left it, although I did purchase a new bleeder screw since then and plan to install it soon.
Anyway the other day I found out that the peddle goes down to the floor! I had driven it at least a few hundred miles after the bleed without any braking problems, so it would seem that the bleed was lost while the car sat for a week or so.
Upon inspection I found all was dry and there is no fluid missing. My attention turns to the brake master cylinder. Other than the occasional replacing of pads and bleeding the system I haven't had to pay too much attention to the brakes for the past seven years, so I'm not sure how old the master cylinder is. It looks OK, although I know that means nothing.
I guess my question has to do with the master cylinder. Can they just poop out without even leaking?
I'm tempted just to replace it since, after all, we are talkin about brakes. But is there a way to trouble shoot it as it sits in the car?
Thanks.