Q: Replaced master cylinder and brakes still going to the floor and not working. Bed both master cylinders and each wheel.

Hi, thanks for writing in. At first it sounds like you may still have air in the system. The other option is that you may have a leak somewhere. Try to bleed the master cylinder and the lines again. The new master cylinder must be bench bled off of the vehicle exactly as the instructions say. The other problem could be a leak on the system. You should check for drips, puddles forming, or other signs of leaking brake fluid. Worst case scenario, the replacement master cylinder may have come to you faulty in the first place. This is rare but can happen, especially when it comes to remanufactured master cylinders. New ones typically don’t have issues. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.