What is your history with this car?
What direct knowledge do you have about when the calipers were last rebuilt, hoses replaced, fluid changed?

When I approach an unknown (to me) chassis, I assume that nothing has been done and go from there.
I do most of my own wrenching and IMO, the worst part of hydraulic work is the bleeding process, so I try to minimize that step by going through the entire system at once.

You already suspect a bad master cylinder and the potential exists that the booster has been compromised if that's so.
Now is the perfect time to rebuild/replace with reman the calipers and install new hoses.
If you want to upgrade the booster/MC, now is the time (the FC "soft pedal" is to a large extent a Mazda design decision...the four piston calipers respond well to larger boosters and cylinders).

There is absolutely nothing exotic about our brakes, all the work involved is Automotive 101 level stuff and except for a good 10mm flare wrench, no special tools are involved.

About 70% of the labor is the same whether you rebuild the calipers or not, so it's not like you're taking on a whole bunch of extra work.

The point is, replacing the whole system at once will give you years of problem free operation (assuming normal maintenance) whereas it's very likely that working on one area at a time will mean constant attention as the domino failure chain progresses.
It's the labor- yours or a paid techs- that will get you, far in excess of just the parts cost.

 

I can't afford to replace everything at once. I have to replace the clutch hydraulics as well and if that doesn't fix my clutch issues then I'll need a new clutch/pressure plate and that will run me hundreds. I don't have a job right now and having difficulty finding one. So one part at a time is how I could approach the situation. My girlfriends mom's boyfriend is a supervisor for the mines heavy duty mechanics and hes willing to help with almost anything on my car. He's replacing the brake master cylinder, clutch master and slave and we're fixing an exhaust leak/gasket. All for free too.

 

I understand and sympathize but you know what, your car doesn't care.
It wants what it wants and your situation does not enter into the equation.

In that way, cars are much like cats.

 

sounds like you are in good hands, keep us updated broseph

 

I can't tell if that was sarcasm or not, aha. Classic I know a guy who knows a guy. Either way he rebuilds small engines on the side and has all the tools I could need.

When changing from 1 to 4 piston front brakes I would need a different brake booster and master cyl?

 

Need, no want, yes.

 

amended.

 

So I use the brake booster and master from a car that came with the 4-piston fronts right? How would the master be any different considering I don't have ABS or anything.

 

Other boosters can be larger and have twin diaphragms, other master cylinders can have larger bores.
The most common swap would probably be from a Mazda 929, I've had success with that as well as combos from Honda (on my car currently), Subaru (on the FD) and Nissan (interesting because the master cylinder incorporates the proportioning valve).

 

what i meant was check for leaks from inside the cabin. just above the pedal assy. you'll spot a little bit of fluid running down the firewall if it's leaking there. a lot of times, if you can't find the leak anywhere else, that's where it is. a lot of people don't check there

 

That was one of the first places I looked and no leaks.

 

ok. i hate to ask you this, but you're absolutely positive you are dealing with an external leak, yes? i mean, normally if you have an external leak, the brake pedal will sink right to the floor when depressed.

 

not positive, if I was I wouldn't be stumped and asking the question, aha. The pedal is stiff, feels the same as when it wasn't leaking. But I know there's a leak because I have to keep refilling the reservoir every week.

 

Well.... Went out for a drive today and all was well. Came home watched a few movies, went to drive the car again and the brake pedal goes right to the floor without any resistance and doesn't stop anything... This sucks. The reservoir is down to nearly empty and before I left it had more than the min line. I'm screwed for a while since Mazda wants 380$ for a new master cyl and getting one off eBay will cost 110 shipped but take a week.

 

Cant you just hop the border and go to a parts store? They're carried all over the place here in Florida! I paid like 25 bucks for mine from O'reilly!

 

Have you any junkyards not buried in snow available?
All my brake upgrade adventures used junkyard parts.

 

..and you have had this problem for FIVE weeks..so what is the problem?.
You want to drive the car,Safely,then pay for its repairs.
You can't wait a Week?(it's been 5)
Really.That "mechanic" you brought it to should have been able to fix it.It is not a "rotary thing", its Basic Mechanics 101...Brakes.

 

Yes I am aware they should have found an issue. They couldn't find any leaks and I'm assuming didn't check the booster. Needless to say I won't be bringing my car there anymore, I figured I'd help out a local mechanic(I live in a small town) and it was a waste of time.

I don't have any money, my credit card is maxed out after buying my clutch hydraulics. I moved back here in December after college (hated program, dropped 1st semester) and haven't been able to find work since. It's been incredibly stressful. I only had a few hundred from christmas and paid some debt off and then this **** happened.

 

this Brake thing has really got you by the short and curlys...Dude if I had a spare I would send it.
Your dilemma could be a New movie: Saving Ryan's Privates...starring Tom Hanky!

 

Alright I took a look at it with her moms boyfriend and we seem to have found two places where it could be the leak. We will bring the car to my dads heated shop over night, ill wash the car and then drive it back to his place and we should see wetness. The pedal went to the floor because I got air in the system by not keeping the fluid topped up. We bled the brakes and fixed that so now the car is driveable. No leaks between the master and booster.

 

probably one of the rear hard lines rusted through...

 

I love the saying:Most car problems are caused by a "loose nut" located behind the steering wheel!

 

so you are still driving the car?
what did you wash ? the undercarraige? A leak that is substantial enough to let all the fluid out should be pretty easy to spot

 

It's winter... The undercarriage and wheel wells and everything inbetween is ice and slush and snow. So we couldn't fully identify the issue. So I will be hosing down the entire underbody/wheel wells and let it dry over night as if it was a nice dry summers day and we should see the leak more clearly. It didn't let all the fluid out. It goes from MAX to MIN in about a week or so and it doesn't leak when I'm stationary only when the brakes are being used.

 

max-min in a week means you would lose the whole thing in under a month, even through the salt this should be visible