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Kevin, Auto Mechanic
Category: Mazda
Satisfied Customers: 2158
Experience:  Diagnostic technician
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Just replaced the power brake booster on 2011 CX-9, went

Customer Question

just replaced the power brake booster on 2011 CX-9, went thru one round of bleeding, getting good "spurt" out of fronts, no air seen, rears seem to have almost no pressure to them, pedal is very soft when engine running, no brakes at all. when bleeding wn eng off, feels like only the spring in booster is resisting, no hydraulic pressure. any ideas?
no leaks.
Submitted: 1 year ago.
Category: Mazda
Customer: replied 1 year ago.
I have bled the system, 4 more times, getting good pressure at rear, no air yet. Got quite a bit of air from fronts. took car for drive, brakes seek a bit soft, but car stops fine. since I was driving it with the bad booster, pedal was very hard, now pretty soft!
maybe its good...
Expert:  Kevin replied 1 year ago.

This is quite normal if you have had fluid at all four now if pedal is hard without car running and doesnt pump up then all air is out pedal will feel soft when running because of booster

Customer: replied 1 year ago.
what about the stability control unit? I read that Mazda has a computer program that will purge/bleed the air from the system, (The distribution block where the brake lines run from master Cylinder) in order to remove the booster unit, these 2 lines had to be removed, possibly introducing air into the system??
If so, would air in that system affect the stiffness of the brake pedal?
Just curious....My Wife and 2 young daughters drive the Mazda......I could not live with myself if I gave them an "F-d" up car to drive.
Expert:  Kevin replied 1 year ago.

This is true it would only need to be electronically bled if run dry . If pedal is hard and doesn't pump up or creep without engine running then your all good

Expert:  Kevin replied 1 year ago.

Please remember to rate my service and let me know if you need anything else at all

Customer: replied 1 year ago.
ok, we've been driving it for a few days now. the pedal is still REALLY REALLY WEAK! Mind you, the brakes DO work after you depress the pedal to the max, they work great. Note: there is no gradual build up of resistance, like if there were air in the brake lines, the ledal just goes to within 1-2 inches of the floorboard. I am at a loss. unless this is "normal" for a Mazda, with a new Booster, we are worried there may be something wrong.
can you tell me what the travel distance is/distance from pedal to floorboard when applied?
can the brake pedal be adjusted? "Back out" the booster shaft connector end? ANY information would be helpfiull
Expert:  Kevin replied 1 year ago.

No adjustment that I'm aware of . What is pedal like without car running ?