I looked around and didn't find any topics that seemed to answer my particular problem adequately so here goes...
My neighbor and I replaced the innards to my master cylinder after I started noticing my brake pedal would slowly push to the floor while I was sitting at stoplights (particularly annoying on hills). Ever since then I have had some issues with the brakes. I've had to refill the master cylinder a couple of times because suddenly the fluid level would seem to drop. And then it would rise again for a while, then drop further. It's been a month or so since I last topped it off and that problem seems to have gone away, but now I have what seems to be a brake fluid expansion issue.
When I start the truck up after letting it sit, the brakes work with what I would call the proper amount of pedal travel before kicking in. But after driving for a few minutes (maybe 5?) the fluid seems to either expand dramatically or redistribute itself and I barely have to touch the pedal before the brakes kick in. I'm not even sure if I have enough pedal travel to activate the brake lights. The other day it felt as though the brakes were on while I was driving. Granted it's been unusually hot here in LA and that could be a factor, but I lived in Phoenix before this and never had this kind of problem.
I would drain a little of the fluid out, but as I said, when the engine is cold the brakes are perfect and I am worried that they will be too soft once I remove fluid. I'm not having problems braking... the truck stops fine. But I find the fluctuation rather unsettling and I'd like to even it out. I've had the truck since '97 and this is a first for me.
Has anyone else encountered this kind of problem? Known causes? Remedies?
Thanks folks!
