my brakes are jacked up :(

amy

Ok, for a long time I had a problem where my brake pedal would sink down when I was sitting at a stoplight or wherever. It went away for a while but has come back recently with warmer weather, and my friend said it was the master cylinder. So I replaced it with a junkyard unit (first possible mistake) today. Then we bled the brakes, but i didn't have a tube to bleed with so I'm not sure how good a job I did (2nd possible mistake).
Now my pedal goes almost all the way to the floor instantly any time I try to brake. I seem to be able to stop somewhat well but it's obviously not operating right at all. I don't know if there's massive air in the lines or what? Should I try rebleeding properly, a new MC or could it be something else? My friend messed with it and got it to firm up for a while but when I turned the car off then back on a couple minutes later the problem had returned.
Need help ASAP.

If it is your cylinder, you should have some brake fluid leakage near the master cylinder itself. What I would do is trace all the brake lines going from the master cylinder out, and make sure none are dipping or anything.
I would also make sure that your reservior is full, and I would keep an eye on it pretty frequently.
Lastly, if you aren't sure you did a good job bleeding, then do them again. It really isn't that hard, you just need 2 people to do it right. You really don't need a tube to bleed with, just make sure that the valve is completely closed before the person lets off the brake pedal. I would do each wheel at least 7-8 times if not more, depending if bubbles appear in the brake fluid when it's coming out. Make sure that after you close the valve, have the person pump the pedal to make pressure again, before opening it. Also every couple iterations of opening/closing the valve, check your fluid reservoir to make sure there is fluid still in it. When it gets low, just keep adding more.
[Modified by Ramocheese, 1:21 AM 3/26/2003]

Here's what I would've done..  First I'd look to see if there were any leaks and inspect all of the Rubber Brake hoses..  Then I would take apart the Master Cylinder and inspect it.  It's most likely that the Cup Seals are leaking..
But hey, when you installed the used MC, didn't happen to bleed it?..  And when you bled the Brakes did you bleed them in the correct order??..