Brakes go to the floor when engine is running
 

So I replaced the front pads a few months ago and everything was good. Then the brakes felt spongy so I replaced the rear pads rotors and calipers. I bled them well and with the engine off the pedal is hard but as soon as I start the car they go to the floor. Any ideas?

First question is have you regularly replaced the brake fluid? Did you open the bleed nipples when you pushed the caliper pistons back? It sounds like your master cylinder has failed. The hard pedal is an argumentive point. It's caused by the booster losing vacuum and manufactuters can't seem to agree how long they should hold vacuum for.

New member here. Just completed my wife's CX5 first brake job at 53300 miles of service and had this same issue. Put vehicle in maintenance mode replaced rear pads only and had to push piston in for clearance. Put vehicle maintenance mode back to normal. Replaced front pads only. All original pads were about 2-3mm thickness before replacing. No issues with rotors such as pulsing, shacking, glazing or grooves. I did a full flush of brake fluid and bleed brakes several times to get ride of mussy pedal. No good, still the same issue. All caliper pins were sliding easily no uneven wear of pads. So must be a failing master cylinder was my next thought. Well never seen one fail in 5yrs of service. I decided to put car in maintenance mode and back out. Now Traction Control and ABS lights on. Not Good. Decided to drive car down our dirt road and just for kicks apply E-brake at 10mph on and back off several times, well after 4-5 times at 20mph the brake pedal is back to normal and no Traction Control or ABS warning lights. Go figure, but I am very happy. Hope this will help others.

Welcome to the forum


You really need to start a thread in the correct area of the forum pertaing to your model mazda for service related questions.

See:

Mazda5 - Mazda Forum - Mazda Enthusiast Forums