Just got a 91 camaro z28 vert and the guy I got it from said he put a new master cylinder on it about a week ago ....I drove for a few hours then parked it in my driveway ...then when I went to put it away for the night I only had brakes if I put it all the way to the floor and didn't have much...so I pop the hood and I don't see any leaks anywhere ..not even under the car ...so I sit in the seat and pump the brakes and I see bubbles in the master cylinder....would my prob be that the seals in the master cylinder got pushed out or could it be something else? Please help

 

I don't have an answer, but I'm also having the same problem on my 91 z with drum rears. Brakes were almost non existent at first. I've installed a new booster, a1 reman master cylinder, russel stainless hoses, Wagner calipers/pads/hardware, wheel cylinders and hardware and adjusted drums. I had the combination valve rebuilt/modded by flynbye. System has been bleed a million times. No leaks. Brakes feel like they're about 80%. Not satisfied. I'm on my second master cyl. And both have been bench bled. I have a jet of fluid shoot up out of the reservoir while bench bleeding, and bubbles when I apply the brakes. It just seems like pressure is going up instead of to the calipers. Planning on switching to a new master soon. I hope this does the trick because these brakes are driving me crazy! If this works for me it, it might mean you just need a good quality new master cyl. I'll post my results when I get it done. Good luck.

 

Bubbles in new master cylinder -> master cylinder and/or brake system has not been bled or bled incorrectly.
Just do it all over or let someone do it and see how it goes.

 

sometimes the reman master cylinders have bad seals right out of the box- what do you expect for $29.00? they won't always leak fluid out the back, but they will let air in around the piston..

 

Fenco I just went of business as of Monday so don't buy any master Cylinders from autozone..just ordered a brand new master from advanced auto

 

If your buying something as important as a master cylinder spend the extra money and get an ls1 or an oem replacement.