Originally Posted by
DMCMW Dave
When you replaced the slave, what did you use for a seal where the adapter joins the slave? OEM is a plastic seal, and I've seen a couple that would not leak but would somehow let air in. That should be replaced with a copper washer.
Otherwise, I'd agree that you have something gone wrong in the master. The master can leak internally, but a bad slave will leak on to the ground. If the master is bad, a good test is to take the cap off and press the pedal. If fluid comes up out of the filler hole, it's bad internally.