I have a 1997 Chevy Silverado Z71. My wheel cylinder went bad so I replaced it. After replacing my brake pedal kept falling to the floor. I then replaced my master cylinder, bench bled it and bled all the brakes twice, had steady fluid. I have no leaks and I am not losing brake fluid. Does anyone know what the problem could be?

Thank you in advance.

 

check to make sure the new wheel cylinder isn't leaking inside its bore.
if you have access to a pressure bleeder, try that, or try bleeding the brakes (with two people) while the engine is running; these things can be a pain to bleed out; seen a few proportioning valves go bad while bleeding as well, could be your not getting full pressure to the front or rear brakes. does the brake light come on when the pedal drops?

 

I have a 1997 chevy 1500 z71. Purchased it with 110,000 miles and now has 198,000. It has always had soft brakes. I've changed the booster, master cylinder twice, fully bled them several times. Had it to 3 different mechanics. Put through an auto bleader. New pads new rotors. Nothing has fixed them. They still feel the same. Mechanics have no idea. Any suggestions?