Mushy brake pedal (2006 Mazda5)

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2013 Mazda CX-5, 2.0 Manual Transmission, 1989 Mazda MX-6
A friend has a 2006 mazda 5. He was driving and hit a dip in the road. Now the brake pedal is very mushy. The pedal sinks almost like a bad master cylinder. But still stops just over halfway down. He says he now hears a hissing sound when pressing the brakes. I think that is just the vacuum for the power brakes. And he now hears its because the pedal moves so far.
My plan is to flush out the brake fluid.
If that does not help and I dont see anything else wrong, I can change out the master cylinder.

Anybody else have this issue, or suggestions on this? If it comes down to a new master cylinder I can get OEM for about $205. Or Reybestos much cheaper.
 
Master cylinders are one of the weaker parts on these. I have read about a few all-at-once failures.
 
I just posted on a previous clutch bleeding thread. The Motive pressure bleeder that I have for my BMWs is a perfect fit on our '08 MZ5 brake/clutch fluid reservoir. If you can get your hands on one of these, bleeding is an easy one-person job.
 
I had the exact problem on the 5 that I just traded for. Spent countless time bleeding brakes, checking for leaks, and even replaced the master cylinder. All to no avail. Then yesterday I picked up a used ABS pump from the local salvage yard for $75. Fixed! I guess if you were looking to properly diagnose you could get plugs for the master cylinder and then move down the line and get plugs for the ABS in order to isolate the problem. I had a hard time finding the plugs at any hardware store because the thread size is rare (M12x1.0).
 
Thanks for all the replies. I will try the bleeding, but maybe hold off on the master cylinder, and look into the abs pump. Just seems if it was the master cylinder, the pedal would keep going to the floor.

edit.
after some research, looks like the ABS will cause this with a stuck valve. Some have suggested a few panic stops might unstick it.
Bsedgal, did your abs light come on? because it is off on this vehicle?
 
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My ABS light did not ever come on and ABS would activate normally when skidding on slick roads. I did try a few panic stops but didn't help. The ABS pump was really only supplying good pressure to one wheel. You can test pressure by having someone pump and hold the pedal down while you crack the bleeders. See how far fluid squirts out.


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So if I am testing for pressure from the ABS pump to each wheel. Is that done with the car running?
 
In my case I had a soft pedal even with the key off so that's how I tested it.


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Scratch that. Yes you should have the engine running. Sorry after so many hours of troubleshooting that stupid problem some of it blurs together.


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Have you ruled out the master cylinder? $150 seems more accurate. I'm by Dallas and must have got a pretty good deal.


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I have not ruled it out. By what it is doing it seems unlikely. The guy that owns the car works a lot and its hard to get the car to my place to start on it. After telling him what I found out. He said when he hit the dip, he did apply the brakes and the ABS kicked in. Then immediately had the mushy brake. Apparently it was a good sized dip, and he scrapped the bottom somewhere. So when he came out of the dip I think he may have flown a little up and with the brakes applied with no traction at all, I dont know what happened.
So I first plan is to flush out all the brake fluid, and see if any wheel is not getting pressure.
Then try a few panic stops and see if that unsticks anything.
By the comments here and the research i have done the list in order looks like this.
1. ABS unit
2. Maybe he introduced air into the system when he went flying ( never heard of it, but who knows )
3. Master cylinder.
I will keep this thread updated when I get to see the car again.
 
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Having same issue - update?

Sounds good let us know what happens

Just had a similar thing happen on our 2012 Mazda 5 Sport. Heading to stealership on Monday. Suspect the master cylinder but would like as much info as possible going into it.

JMJ
 
Any resolution to this issue? My mazda5 2009 gt just crossed the 100k miles mark. Lately I have noticed the brake pedal to be mushy. Just had brake fluid replaced and brakes inspected but tech did not find anything wrong but mentioned that maybe master cylinder needs to be replaced.
 
So I went ahead with a master cylinder replacement today. There was a little improvment but brakes still dont feel solid. A post on another mazda site said that stuck cylinder pins were the culprit to this issue and using pematex caliper grease to clean them would resolve it. Anyone have other ideas to reolve this?


Any resolution to this issue? My mazda5 2009 gt just crossed the 100k miles mark. Lately I have noticed the brake pedal to be mushy. Just had brake fluid replaced and brakes inspected but tech did not find anything wrong but mentioned that maybe master cylinder needs to be replaced.
 
So I went ahead with a master cylinder replacement today. There was a little improvment but brakes still dont feel solid. A post on another mazda site said that stuck cylinder pins were the culprit to this issue and using pematex caliper grease to clean them would resolve it. Anyone have other ideas to reolve this?

I assume you mean lube up the caliber brake pins. I would suggest using https://www.amazon.com/dp/ (commissions earned) instead of permatex. Some people have experience issues with permatex grease causing the rubber parts to swell. There are several types of permatex grease, the silicon based one may be better.

Are your hoses ok? Do they flex a lot if you press on the brakes?
 
I assume you mean lube up the caliber brake pins. I would suggest using https://www.amazon.com/dp/ (commissions earned) instead of permatex. Some people have experience issues with permatex grease causing the rubber parts to swell. There are several types of permatex grease, the silicon based one may be better.

Are your hoses ok? Do they flex a lot if you press on the brakes?

Yes i meant lube the brake pins. Ive been bringing my 5 to a local shop aand I assume that they checked on the hoses. I will remind them to do this when I return tom. I will also ask them to look into lubing the caliber pins. I am hoping it is not the ABS. I dont have any CEL on but from what Ive read here CEL dont always turn on when damaged. Thanks
 
It can't be slider pins. Greasy pins are necessary for floating calipers to release and not constantly rub (causes uneven pad wear/warp rotors, builds up heat which creates air and leads to frozen calipers).
It's also unlike power brake booster or vacuum leak as that should lead to harder pedal feel (you loose power 'assisted' vacuum). You can test this by turning car off, step on brake pedal a few times so it sinks and stay down. Start car and norm vacuum should raise it back up.


Assuming you are not loosing brake fluid, mushy brakes is usually fluid related (mostly likely air in system -or worm fluid but this is more soft pedal). Sounds like you've bleed the system and replace the MC, which are the first things to check. I suspect there's air in the ABS module or the module is failing (but you 'should' get a code if failing). The ABS module is harder (or easier!) to bleed. Have the shop bleed the ABS module (computer controlled cycle) or you can buy a handheld device for ~$150 and DIY (!not sure if the cheap ones work for Ford!). You plug it in and click through options to have it perform automated bleeding procedure for all ABS solenoids. Look up youtube videos to get an idea.

Google 'Ford ABS Bleeding Tool'

http://www.aa1car.com/library/abs_bleeding.htm
 
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