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Discussion Starter · #1 ·
Hello,
2012 Mazda 3i Touring M/T Skyactiv, 103k.
In recent months I noticed the brake pedal resistance was getting a little inconsistent. Suspected the master cylinder. Actually ordered the part online from Rockauto. Cardone brand, complete with reservoir.
Last week (hours before leaving on vacation) the brake pedal sank to the floor as I was entering my neighborhood. Very little pedal resistance or braking force, but pumping the pedal would give me a little.
Back from vacation now, changed the master cylinder. Bench bled, install went well, used my Motive power bleeder to do a four-corner bleed by myself. Pedal still very soft and inconsistent.
Bought another quart of fluid, put the car on jackstands with all wheels off, and had my girlfriend do the pedal routine while I super-bled all four corners again. Order was Right-Rear, Left-Front, Right-Front, Left-rear, in case that matters. Got a little bit more air out of the lines. Pedal firmed up partially, but toward the end we heard some hissing/groaning noises when the pedal was pressed. (Was it air moving around, or the cylinder seal leaking?)

Today I took the battery/tray out again to double-check things. I couldn't find anything. Pulled the MC from the booster enough to see if fluid was leaking between them, but I didn't see any. Brakes work at about 10% force - I could drive it around the block but even pumping the pedal, I'd get minimal braking. The pedal resistance varies quite a bit.

So I'm thinking one of two things happened:
1) Replacement master cylinder was junk or developed a seal leak in the process of bench bleeding, etc. I could buy a Mazda OEM reman MC for $225 and try again.
2) Something else is wrong - major air in the ABS pump, failed brake booster, ??. Let the dealer take over and rape my wallet mercilessly.

On a related note, my car has a button on the left dash that looks like the slippery-when-wet road sign (icon of a car with wiggly tracks). Does that mean I have DSC?

Thanks,

David
 

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I can't definitely say this for mazda, but you may have to activate the ABS pump to get all of the air out of the system. Sure sounds like air is in the system.
 

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Discussion Starter · #3 ·
Yeah I replaced the master cylinder again last night, and pushed through a pretty big bubble on one circuit. This time there is a soft pedal but some resistance and some braking force.

I'm going to cross my fingers I don't get screwed and take it to the dealer and have them finish bleeding it.
 

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a lot of hate for the dealer
your car could well have been fixed by now
instead you will waste days. how many m/cyl and brake fluid
and still may need professional help
 

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Lout, everyone has to learn somehow, not all have 30 years of experience wrenching cars.

Dgeesaman, I'd find an independent mechanic, explain what was done and see if they agree that a proper bleed is needed. My guess is it most likely needs to be bled properly. The dealer will want to replace everything again at crazy cost.
 
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