My wife's 2006, auto sport is currently having brake issues as well.
I took her to get brake bleed but is still going on.

The person said may be master cylinder being bad.
There are no brake fluid leaks since the fluid hasn't dropped or shown any.

The hose does make sense but its a constant thing as well.
The brake works but you have to press it all the way down.
I do notice air or sound when pressing on the brake.

I am looking at master cylinder change.
If you changed yours, did you change the brake line/hoses too?
Just wondering because yours maybe is hose? but then again, you had no leaks...

I would still be weary about the MC.

I also took it to a shop to have the brakes flushed and changed to get any contaminants and air bubbles out. Still same... The guy saw what I was talking about prior to flushing and new brake fluid. Since it is the same, he said to check the master cylinder.

I also know he did bleed the brakes using the BG brake flush kit since I was watching him do it and in the shop.

Its either a bad MC or vacuum booster, IMHO.
However, I wanted to be sure and ask if there are any checks I can do to pin point if its MC. In addition, it is Mazda 3, Auto, HB Sport edition.

I also wanted to ask for help or confirmation.

I am planning to get a new MC if need be and have been looking at this site.

06 2006 Mazda 3 Brake Master Cylinder - Brake - A1 Cardone, Beck Arnley, Centric, Dorman, PBR - PartsGeek

However, there are many versions.
I know it has ABS, but notice there are different bore sizes and model #.
Which would fit without having to pay the highest price?

Any suggestions, insight to get the correct one?
I plan to replace myself then have it bleed or flushed at a shop.

Thanks!

 

Just because you have no leaks doesnt mean your MC is good, I had a '90 F250 that the MC failed (made a nice POP sound) while I was going down a hill too a red light, needless to say I failed to stop at that light......and the next.......and next, they were timed for 40mph and I just floored it when the 1st went red to get through the verrrrrrrrry late yellows of the next ones. Mine had failed internally to the point the piston was just shuttling fluid from front to back till it was all the way forward.

Your best choice of parts would be to get one that has the exact part number, different bore sizes will give you more or less braking, one might be setup for a 2 piston caliper and the other for a single. Some MCs even have the bore size stamped/cast/etched onto the MC itself.

 

Yes, I realize that no leak doesn't necessarily mean the MC is good.
I was referring to leaks in hoses or in the caliper/brake areas, too.

Also, I concur on replacing the MC with same part #. However, found that link and wondered if anyone know or has experience to find the closest or exact one. Do you know the OE part # so I can try finding for a replacement? I do not wish to go to the shop to have them do it since they charge an arm and a leg and changing the MC isn't that hard.

Thanks!

 

I went here to find but it doesn't s how part #

Mazda Parts - Mazda Parts Online

 

It appears the car may have a MC issue.
Had the car at the shop to get new struts installed and told the guy about the issue.
He checked the bleed valves to make sure they were tight, and for leaks.
No leaks anywhere so he is guessing it is probably the MC. Inside there may be a leak in the seal causing the decreased pressure. It explains why you have to push the pedal all the way down in order to get brake.

I was looking at this site, anyone have any recommendations or it is pretty much all the same except price? It will be an ABS version of course...

http://www.autopartswarehouse.com/search/?N=0&Nr=AND%28wpn_tl_name:Brakes\%2C+Suspension+%2 6+Steering,wpn_cat_name:Brake+Master+Cylinders\%2C +Boosters+%26+Components,wpn_scat_name:Brake+Maste r+Cylinders+%26+Components%29