Can't seem to get the brakes bled

[zoom240]

I'm frustrated. Just replaced the rotors & pads on my front brakes on the 260Z. Everything's back together & I can't seem to get the brakes bled. I read the other posts on the procedure & I made up the bleeder bottle discussed. I bled the rear brakes first, even though I didn't tear into them this time. I keep getting air - despite about 1/2 bottle of DOT3. I bled the master - lots of bubbles, took a long time to get them to stop & never completely stopped. I then rebled the whole system from furthest to closest.

The front brakes never seem to quit giving up air. Can't believe I've got this much air in the system - seems like I've got an air leak. But I don't see any brake fluid leaking - you'd think you'd see it. I don't know if my bleeders are leaking or what's going on. I've bled the brakes on 3-4 Z's, including this one & never had this much trouble.

Before I replaced the brakes, they were working ok (except I let the pads get too worn, had to replace the rotors). After weeks of idle time, the brakes would be spongy, but firm up with one or two strokes - so I know I had a slow leak somewhere before.

Any ideas?

[LanceM]

My guess is a bad master cylinder, it shouldn't take much to bleed the master, say 10 pedal pumps or so. Spongy brakes are another good indication that the master is going south. Considering the pressure in a closed system a pin hole leak in a line looks like a water fountain and will for sure leave a mark on the floor!

Not to sound like I'm trying to sell you a fix but I have a MC that is a store rebuilt that has had fluid in it but never driven that I'll let you have for $15 shipped if you want it. I put it on then decided to do a 4 wheel disk conversion and put on a large MC from an 81.

[2ManyZs]

I'd try it one more time, starting with the master, and if that doesn't help, it's almost assuredly a weak master cylinder that is causing the trouble.

[zoom240]

Lance, 2ManyZ's,

Thanks for the quick feedback. I think the MC might be it- I had to replace it on my 240Z, this one is original. Lance, it's a nice offer, but I'm trying to use new parts when things break - so I'll probably just order it in the morning.

Dave