Are you sure all the line fittings are tight? Fluid doesn't necessarily have to leak out for air to get in. And did you install the reservoir or was it already installed? Something else to look at is the push rod length. Make sure that it has the correct amount of freeplay. Andrei ----- Original Message ----- From: "Walter Coe" <Whalt@xxxxxxx> To: "DMCForum" <DMCForum@xxxxxxxxxxxxxxx> Sent: Wednesday, December 31, 2003 2:41 AM Subject: [DMCForum] Urgent brake problem > I just replaced the master cylinder on Jim Sleeth's car, and > it don't work. Jim bought a rebuilt master cylinder from > NAPA. We bench bled it, connected the lines, bled the > calipers in the proper order, etc. Everything looks normal, > no fluid leaking anywhere. If we let the system sit for > more than 15 seconds and then step on the pedal, it almost > goes to the floor. With about 3 more pumps, it firms up > properly and stays firm for as long as we continue to pump > it. But if we let it sit for more than 15 seconds then the > pedal goes soft again. Apparently we just got a bad > cylinder from NAPA. The original cylinder was leaking, so > that was the reason for getting into it. > > Can anyone say what could possibly be wrong in a master > cylinder to cause this? Or could we be overlooking > something else? I don't see how trapped air could cause > this symptom. We bled the system by the good old-fashioned > two person way. Jim pumped the pedal while I turned the > bleed screws. We used up two pints of Castrol GTLMA dot 4 > because we wanted to thoroughly flush out some Dot 3 he > dumped in there to make the car temporarily drivable (after > the reservoir went dry due to the old leaky master). The > Dot 3 never touched the new master. If it caused a problem > in the calipers, I suppose they would hang up or leak. But > it isn't doing this. > > Walt > Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/SIG=12cqqogri/M=266841.4316200.5507732.1261774/D=egro upweb/S=1705126215:HM/EXP=1072963857/A=1911856/R=0/*http://www.lifescapein c.com/picasa/landing.php?capid=222&caId=1985> click here <http://us.adserver.yahoo.com/l?M=266841.4316200.5507732.1261774/D=egroupm ail/S=:HM/A=1911856/rand=439732963> _____ Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/DMCForum/ * To unsubscribe from this group, send an email to: DMCForum-unsubscribe@xxxxxxxxxxxxxxx <mailto:DMCForum-unsubscribe@xxxxxxxxxxxxxxx?subject=Unsubscribe> * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .