Just changed rear brake pads on 05 mazda 6. now

There may be air in brake lines. While changing pads probably it got air from oil cap to inside. I assume that i was opened while putting new pads. You should flush brake fluid first. It should fix the problem

Air in lines or bad master cylinder

-Fix the leaking.
-Top brake fluid to " Full" level.
-Break again. (Recommend all 4 sides)
-Refill the reservoir to full level. You should be good to go.

Good luck

Mai

WHEN FINISH REPLACING BRAKE PADS.MAKE SURE MASTER CYLINDER COVER ON FLUID LEVEL OKAY.YOU PUMP BRAKE PEDAL UNTIL BRAKE PEDAL GET FIRM HARD.IF BRAKE PEDAL KEEP GOING TO THE FLOOR YOU HAVE AIR IN THE HYDRALIC BRAKE SYSTEM.BRAKE SYSTEM NEED BLEEDING.DONT DRIVE VECHICLE IF BRAKE PEDAL FEEL SPONGY OR GO TO FLOOR.

If the car has drum rear brakes, you may need to service the shoes as well. If the rear shoes are not manually adjusted properly, most of the brake fluid goes to the rear brake cylinders, leaving little for the disk brakes up front. You may need to service the master cylinder as well, if it doesn't provide the full amount of fluid per stroke. Hope some of this helps!

Start with brake in the rear that is the farthest away from the master cylinder ( if your master cylinder is on drivers side start with passenger rear,pump up brake pedal until hard have someone else open bleeder valve until air or fluid squirts out,while holding brake pressure even if goes to the floor dont release pedal until bleeder valve is tightened or you will **** air back into the line,do this several times making sure you get a full stream of brake fluid and no air,continue to other rear wheel and then proceed to front wheel furthest from master cylinderand then final wheel. if you still don't have brakes change master cylinder and bleed all brakes again.

It take a few full brake application for the brakes pads to adjust there self and check the brake fluid level. Top off as needed with DOT 3 and be safe.

Check the pads/rotors to see if they need to be replaced.
Check the brake fluid level. If low it could mean the pads/rotors need to be replaced. If replacing also replace the brake fluid.
Two years probably means you need a brake job.

Otherwise you may have air in the brake lines which you can bleed off.

pump the pedal until it goes hard this is common when you push it back all the way just needs a few pumps to get it to extend back to the pads making contact with the rotor, is there any fluid leaking anywhere? is there brake fluid in reservoir?

are your rear drums set up? why did you bleed the brakes. when only when you installed new pads?