My brakes are stuck on. I can not get any wheel to spin freely when i lift the car into the air. The brake pedal is stuck all the way up. I have also noticed that the brake fluid level has dropped significantly. What i think happen is that all the brake fluid missing from the resevoir is now in the hydrolic system.... thus it is completely full causing hte brakes to be activated and the pedal to be completely up. My question is what is the solution to this? Bleeding the system might help the problem, but what should i do to fix the problem?
I have a few options:
1. just bleeed the brakes when it gets screwy (not very attractive option)
2. rebuild the master cylinder
3. buy a new one

has anyone done a rebuild on a master cylinder? I searched briefly but didnt see much turn up. The haynes has a section on it. I would like to have your opinions on what i should do/if ihave diagnosed the problem correctly.

it looks like a non oem replacement master cylinder is 75-125$ and a oem one is 136 from mazdatrix. the rebuild kit is $85 from mazda trix.


thanks in advance

 

The system is always "completely" full, so you have something else going on.
Probably the master cylinder but if you've lost a lot of fluid (reservoir empty) and don't have puddles under a wheel, then that fluid had to go somewhere...probably into the vacuum booster.

I think you should remove and inspect both- master and booster- and replace as necessary.
Personally, I prefer to replace rather than repair.

 

I finally got around to checking things out. I rebleeded the rear brakes and everything was back to normal. The one thing i did notice is that the fluid level in my resevoir barely dropped during the process. Before bleeding i could not depress the brake pedal at all. As soon as i opened the bleeder i could shove the pedal in. I have a hunch that something went wrong in the master cylinder causing an over filling of the system (pedal all the way out and the pistons pressed out on the brake) but i will have to take it apart to see if that is actually the case. I think i am going to check and see if this was a freak occurance, if not i am going to replace the master cylinder.

 

How can u overfill a hydraulic system? it just dont work that way

 

did u try just starting ur car???
if you pump the brake pedal whilst ur car is off, pressure builds up in the lines and will give the same effect as u describe. The booster works on vaccumm...

Carlos

 

tried it when the car is started and the pedal was still hard/barely moved.