Recently, I replaced the rear brake lines after noticing tonnes of rust and some leakage. I performed the bleeding process and all seemed okay - no leakage, brakes worked but still a little spongey/soft. Bled the brakes again after a few days. Trying to figure out why the brakes are still soft/spongey.
Replaced the master cylinder; bench bled the unit until all air bubbles were eliminated; noticed that the passenger side rear brake cylinder was seized, so I replaced that and bled the brakes again.
Removed the driver side brake cylinder and both ends seem to function better than the other side, but once I dismantled the cylinder I discovered there was no fluid inside the cylinder. I am guessing that there is supposed to be fluid inside the cylinder. When I bled the brakes, there is fluid in the brake line leading up to the cylinder. Figured I had dirty cylinder, so I removed the cylinder, cleaned it up and re-installed the piece. Still have little to no pressure on the brake pedal.
Is this brake cylinder bad as well? Appreciate any and all replies! Thanks

 

I'd suggest replacing the wheel cylinder. They are wear items(consumables), if the seals are allowing air into the system then you will never get a solid pedal. They may not leak fluid but the seal may allow air in when the brake pedal is released.

 

Replace the old wheel cylinder, then get a good brake bleeder to help you bleed the brakes. Also, make sure all bleeder valves are on the top of the wheel cylinders...not on the bottom(Like if you swapped a left and right wheel cylinder).