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Discussion Starter #1
Normally they say that Mazda 3's have a cross connected braking system, so that the brake flush / bleed procedure for the car is the following order ( at least per the Mazda3 forums / flatlander937 Feb2012 post on how to bleed a Mazda3 brakes etc)

RR ( right rear) -> LF (left front) -> LR (left rear) -> RF ( right front)

Mistakenly I started with the opposite order. I did the LF & RF section first. I had no problem bleeding till I got clean fluid out.. nor bubbles etc.Brake pedal felt great.

I then started the opposite section. What I noticed when I cracked the bleeder screw that hardly any fluid came out at all... maybe an oz. or so of old fluid.

With my son working the pedal and myself cracking open and closing the bleeder we worked almost 50 cycles... no more fluid was coming out the bleeder screw. At not time during this procedure did the brake fluid reservoir ever go much lower than the "MAX" setting... we were very careful about it.

This morning I started work again, but went to the Advanced Auto and rented a Vacuum Brake Bleeder tool. Still.. even using it there is no brake fluid coming through. I tried for almost 1/2 an hour.. nothing.

The Vacuum brake bleeder setup itself works... I have verified that it holds vacuum for a long time so I no there is no leak in applying the vacuum.

I tried with
- parking brake engaged as well as parking brake disengaged
- I used a C clamp to press the disc cylinder/calipers back into the bore
Still absolutely no difference. I cannot seem to get any fluid through the line whatsoever to the RR ( right -rear) brake bleeder Screw.
As an FYI, the bleeder screw is a new one.. I decided to just replace them when I started the job. So it is brand spankin' new.

When I first started with the RR bleed I got maybe 1 1/2 oz of fluid out.. and then it all stopped! I assume the 1 1/2oz was in the caliper.
I took the bleeder out completely..... dry.. dry.. nothing but a few drops if the pedal is pumped.

I then decided to check the LF ( left front or driver side) to see if it's caliper behaved the same. I got the wheel off; cracked open the bleeder screw on the front left and here also hardly any fluid, could not suck anything through with the Vacuum bleeder tool.

In my mind, what is the probability that that both LF and RR calipers are bad or that both flexible hoses to these two calipers have an issue/blockage. Comments? Do multiple flexible hoses just suddenly go bad. The car had decent braking before I started this process. Ok, so the reason I started this was that I wanted to flush the brake fluid. I had done my Toyota Corolla and the Mazda3 was purchased 2nd hand... the brake fluid was old and discolored badly...so that was my driving force (main reason) to do this.

I also find it hard to believe that my process /method that I started with somehow caused so much air into the system. It makes no sense.
I now have to figure out how to debug the Master Cylinder?

So no fluid in front driver side caliper or the rear right passenger side caliper. Could there be a trip circuit in the master cylinder have got set due to the brake bleeding of the initial first hydraulic system ( Left Rear & Front Right) ? ( i.e. if Mazda's work like this). There is a link on the web at 2carpros that seems to reference something like this, but I am unsure if it is applicable to a Mazda3.

That same link recommends driving a burst of compressed air up through he bleeder valve. I am worried though about sending compressed air up the brake system through the bleeder valve of the bad (dry) calipers. And if I do, should I have the Brake fluid reservoir cap on or should it be removed?

Comments? Suggestions? I really would like to be able to resolve this within the next couple of days.
 

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Discussion Starter #3
Yes, it does have ABS.
And I did read elsewhere of where air gets in the ABS module and needs special tools ( i.e. scan s/w to pulse the ABS) to clear the air.
But the ABS light is not on indicating any problem with the ABS modules.


I inspected
- The outsides of the flexible brake hoses of the RR and LF calipers.... look ok... no leaks
- Checked operation of of the power booster... operates as expected when the car is off and pedal is pumped and when the pedal is depressed and the car is started
- Looked for brake fluid leaks under the dash where the pedal piston enters the booster.... no leaks
- No brake fluid leaks

So there was never any unexplained loss of brake fluid.
Not before I started the brake fluid flush.... not even now.

Fluid level in brake fluid reservoir does not drop even if the bleeders are left open on these two calipers.

I used a few short bursts of compressed air through the bleeder aperture ( bleeder screw removed) of the RR caliper. Then again tried both the vacuum pump and the normal brake pump two helper manual mode method of bleeding the brake caliper. No go.... absolutely no fluid coming out and the fluid level in the reservoir does not drop when I did this...
 

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Yes, it does have ABS.
And I did read elsewhere of where air gets in the ABS module and needs special tools ( i.e. scan s/w to pulse the ABS) to clear the air.
But the ABS light is not on indicating any problem with the ABS modules.


I inspected
- The outsides of the flexible brake hoses of the RR and LF calipers.... look ok... no leaks
- Checked operation of of the power booster... operates as expected when the car is off and pedal is pumped and when the pedal is depressed and the car is started
- Looked for brake fluid leaks under the dash where the pedal piston enters the booster.... no leaks
- No brake fluid leaks

So there was never any unexplained loss of brake fluid.
Not before I started the brake fluid flush.... not even now.

Fluid level in brake fluid reservoir does not drop even if the bleeders are left open on these two calipers.

I used a few short bursts of compressed air through the bleeder aperture ( bleeder screw removed) of the RR caliper. Then again tried both the vacuum pump and the normal brake pump two helper manual mode method of bleeding the brake caliper. No go.... absolutely no fluid coming out and the fluid level in the reservoir does not drop when I did this...
Service manual doesn't specify a order. It gives directions to do the pump hold procedure on one and then says to repeat on remaining calipers.

I had this same issue recently on a 2008 Honda Ridgline. No fluid out of the RF and LR on that one. Bad master cylinder. The master cylinder does feed the system diagonally through the ABS unit I suspect. Did on the Honda. It's possible that the master cylinder defected while bleeding the first two calipers.

I diagnosed the Honda by cracking both lines at the M/C and having an assistant slowly push the pedal to the floor. Very little came out the bad side. Normally there will be a steady flow out of both. Had assistant hold it to the floor while lines were tightened back up before releasing the pedal so air would not get pulled in during the pedal release. Did it again, same issue.
 

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that would be my next test
crack fittings at flexible hose to wheel cylinder
press pedal and see if fluid comes out
then other end of hose then keep working closer to master until you identify where you do and dont have fluid
 

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Discussion Starter #8
Just saw the replies that have come in over the past day or so.


Meanwhile here is what I have been doing.

Borrowed a Motive Pressure Bleeder from a colleague at work who also works on cars and spent around a day trying to get the setup going. Several trips to Menards/AdvancedAuto/HarborFreight to get the fittings, gasket etc. Most of my time was spent trying to get an air-tight seal to the brake fluid reservoir cap/top.


I then put 64oz of fluid in the tank and pressurized it to 20psi. Then I cracked open the RR bleeder.. some fluid came out, but not a continuous steady flow. Some air and then it slowed to a trickle. The pressure at the Motive bleeder dropped to around 18.5psi and then nothing more.



For grins, I decided to check if the LF ( which is on the same hydraulic system as the RR) would bleed. So I jacked up that side of the car and cracked the bleeder. Lots of pressure... fluid and air came out and was continuous till after a while when no more air came out. I just closed off the bleeder. Note I am aware that I will have to bleed this again once the rear is done.... my main reason for doing this was to check if the MC was faulty.


Question1: Doesn't the fact that I was able to bleed the LF indicate that there is no problem with the MC? Or at least no problem that appears to cause the RR no-fluid issue?


After noticing this... I decided to check if the LR ( left-rear) that I was able to bleed correctly a couple of days ago would work. Jacked up the wheel, got it off, cracked the bleeder..... a little fluid and then nothing.


Question2: So now, I have an issue where it appears that the LR side is showing the same issue as the RR side. ( Interestingly the LR side did not have this issue a few days ago)


I am going to check the RF ( right-front) to see if it bleeds correctly.

I am quite baffled/mystified... but will next attempt to take off the rear flex hose connections. But the hoses with visual inspection look to be in good condition. Of course I have heard that they can swell or break apart internally.



I do have flare wrenches and will use those, so that I do not mess up the nuts.
However I find it odd that the problem seems to be moving around like this.


Question3: ( I think I am doing this right, but I'll ask the following anyway.. just in case I am doing something stupid!

- I do not believe I need to put the car on 4 jack-stands... i.e jack up all 4 wheels, right? I have seen folks on youtube bleeding Mazda3 brakes, one wheel at a time.
- Do not need to turn the car key "ON", right?
- Nor do I need to have the car running to bleed brakes in general?



Lastly there is no Brake fluid leak.... the fluid in the reservoir remain steady.
Right now I am bemoaning the fact that I touched the brake system, to replace dirty fluid; the brakes were working well per my son who drives the car.
 

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Discussion Starter #9
I also noticed a reply from someone on EricTheCarGuy's forums who references problems bleeding rear brakes to be due to a "proportioning valve" that needs to get "RESET".


1. Is there such a "proportioning valve" on the 2008 Mazda3?
2. And if yes, how do I reset it, other than the way described in Eric's website below?


https: //ericthecarguy. com/kunena/8-Service-and-Repair-Questions-Answered-Here/48133-brake-bleeding-no-fluid-when-bleeding-rear


Comment? Suggestions?
 

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Discussion Starter #11
To VWandDodge


"ABS systems can be gravity bled"
But doesn't this require that the system at least be fairly full of fluid first?


To Iout


Per the Haynes Mazda 2004 - 2011 Repair Manual.


Section 9-4;

=> Symptom: Brakes Slow to Release Cause: Malfunctioning proportioning valve, replace valve
=> Symptom: Brakes Drag Cause: Malfunctioning proportioning valve, replace valve
=> Symptom: Rear brakes lockup under light braking conditions Cause: Malfunctioning proportioning valve, replace valve


=> Symptom: Brake warning light comes on instrument panel ( or stays on)
Cause: Failure in one half of hydraulic system
Defective pressure differential valve or waning switch
Piston in pressure differential wanting valve no centered


That being said.....there is absolutely no indication in the manual where the proportioning valve or the pressure differential valve is at all.
There are also several websites that talk about ABS and indicate that ABS cars may also have a proportioning valve.


And update on what I have been upto.


- Got tires of jacking up wheels one by one and rotating through the different bleeders. Car is now on 4 jack stands and the wheels are off.
- With the Motive pressure bleeder set to around 20-22psi ( it does hold this pressure until bleeding is started)
=> Tried RR caliper.... cracked bleeder open... quite a bit of fluid starts to come out then it peters out..... runs dry....
=> Tried LR caliper.... cracked bleeder open... quite a bit of fluid starts to come out then it peters out..... runs dry....
Unable to bleed these two wheels completely.. but fresher fluid is coming out... just not continuously
=> FR caliper..... cracked bleeder open..... fluid comes out till all bubbles gone..... then closed bleeder
=> FL caliper.... cracked bleeder open..... fluid comes out till all bubbles gone..... then closed bleeder

During the bleed of the FR and FL the Motive Pressure bleeder pressure indicator drops 4 - 5 psi, for the RR and LR it drops maybe 1 psi.


All of the above was done with the battery disconnected.
Tried RR and LR with battery connected and car turned ON and then OFF after 5- 10 seconds.... no difference in observations of bleeding the rear wheels.


Not sure what to try tomorrow. Will disconnect the flex hose but do not think that the hoses are blocked since fluid comes out for the first 4 to 5 seconds at decent pressure and then nothing.


Questions:

If there is a lot of air in the longer brake lines to the rear wheels, would 20 psi necessarily be able to actually push the fluid out the top, or would it just compress the air?
Does it just make sense to try and open the rear lines out of the ABS modulator and see if fluid is coming out continuously?












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Yes, gravity bleeding requires the reservoir be filled to capacity and monitored so it doesn't run dry.
 

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.... Not sure what to try tomorrow. Will disconnect the flex hose but do not think that the hoses are blocked since fluid comes out for the first 4 to 5 seconds at decent pressure and then nothing....
IMO you might be better off starting at the MC connections, as Rickkari described in a prior post. You've forced fluid through, but I don't think that proves the MC is good. If you start diagnosing at the MC, then you can continue to go top-down, until the problem has been flushed out :wink2:

And just as a side note, I gravity bled my Daughter's 2011 3i a couple months ago, and had no issues. Fluid came out of the 4 bleeders at roughly the same flow rate - always slow, but steady. Gravity bleeding can work well for anyone who's not in a big hurry to get the job done, and multi-tasking with other things is how it works best for me.
 

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ok, i dug out my genuine mazda workshop manual
conventional brake system proportioning valve is located mounted to brake booster, below master cylinder
ABS brakes do not have a proportioning valve
 

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Discussion Starter #15
Got busy over the New Year holiday and did not get much work done on this problem.


Did the following which were relatively easy to do in the little time that I had to work on the car..


1. Removed fuse box cover and checked ABS fuses.
The 10A, 20A and 30A fuses all good.


2. Removed the battery and the battery compartment cover to get a better view of the Master cylinder and ABS modulator
No appearance of external leaks at any of the fittings of the Master Cylinder
No appearance of external leaks at any of the fittings of the ABS Modulator
No appearance of external leaks at the connection between the Master Cylinder and the Power Booster
No leaks on the other side of the power booster... i.e. within the car.... under the dashboard near the break pedal... it is dry down there.


3. Attempted to take off the 10mm flare nut using a 10mm flare wrench at the rear wheels on both the LR and RR side ( the nut that connects the metal brake line to the flex hose). Darn it.. it's appears to be on really tight.... More PBlaster applied... and waiting overnight.
Got a MAP gas torch, but am dead afraid to use it to heat the line for fear of damaging the flexible rubber hose.


4. Read-up on MC cylinder tests
Pressing the brake pedal.. it does not slowly sink... does not appear to be any symptom of a leak

In fact brake fluid level held steady over the past two years of owning the car.


To Iout:

Yes, the 2008 Mazda3 does not have a proportioning valve. The ABS modulator it appears controls the proportioning and pressure of the fluid to the RR wheels. So I now know there is no way to change or reset a proportioning valve as there is none on this car.


To Rikkari / m3iguy:
The reason I do not think that the solution to the problem is the same as Rikkari's is the fact that he had a problem on one of the ports out of the MC. It was affecting the RF and LR brakes in his 2008 Honda Ridgeline. My problem started out with the LF and the RR having the issue. The LF and RR are on one of the ports of the MC ( since it is a diagonal or cross-connected hydraulic system). However on a subsequent brake bleeding attempt a day or so later using the Motive Pressure Bleeder, I was able to bleed both the LF and the RF ( i.e. the front brakes), but I could no longer do the RR and LR ( rear) brakes.


The latter indicates that both ports out of the MC are able to get pressurized and thrust fluid into the ABS modulator. The ABS modulator has two incoming brake lines from the MC, but 4 outgoing lines.... one to each of the wheels. It seems odd to me now that the symptom switched brake wheels.


BTW, in between all these attempts the car was switched ON several times to check if the ABS lights would light up indicating some sort of issue. So am not sure how the ABS modulator behaves in response to what we were doing while bleeding the brakes. I am now taking copious notes/observations of any steps I take with the car as it seems in most of the searching that I have done on-line, very few people have had issues similar to mine on ABS enabled cars.


I may just have to crack open the four outbound ports of the ABS modulator, but is it safe to do this, or are these ports under fairly higher pressure than the MC side? Either way, I have sprayed them with PBLASTER to get them ready in case I need to open them to see which one does not generate brake fluid pressure.
 

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i use a locking plier on seized brake pipes as i find even flare wrenches round the nut
outputs from abs are under same pressure as master cylinder
abs should not activate assuming working with ignition off
even with engine running if wheels are not rotating abs should not pulse
 

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Discussion Starter #17
Finally got back to this again.......so yeah, still not fixed.

After further examination of the hoses... the rear flex brake hoses has considerable rust and swelling near the joint of the coupling with the metal brake line.
Ordered both the rear and front flex brake hoses from RockAuto.

Replaced the rear flex hoses on 01/08/2019. The first hose took me 1 1/2 hour to remove / crack the nuts and replace. The second rear hose removal and install took 30 minutes. I had to cut off the flexible rear hose near the caliper to get a long/deep socket on the 14mm nut of the hose. The location and space prevented the use of a flare wrench or a flare crow-foot wrench.

The front flex hoses were replaced yesterday 01/09/2019. One hour for the first one, 35 minutes for the second.

I took a lot of pictures of both removal installs as well as the condition of the old hoses... but I am not sure yet whether I have permissions / rights to post images, links etc since I am a new user.

I do have several comments and feedback in general on the removal / install process... to others who may be interested.
I had never done this before.. past brake bleeds on a Honda Accord and a Toyota Corolla just worked, so I ( and my college going son) did learn a lot from this experience so far.

General suggestions:
1. If possible try doing a job like this in anything but the winter.....it ain't fun working in the cold. Or else get/use a space heater.
2. Have a lot of patience. If things get frustrating walk away for some time; do not make the job worse by messing something up in haste or frustration.
3. If exhausted or tired, stop and reconvene when rested.

Job focused suggestions:
1. Better tools / technique make the job easier.
2. Flare wrenches from places like Menards / Harbor freight are ok, but not great for nuts that are seized or rusted. The tolerances / slop can still cause rounding.
3. Flare wrenches.... especially crow-feet wrenches that can be put on a ratchet offer better torque to remove a frozen nut. I used Neiko.
4. Use penetrant oil a day or two before.
5. Sometimes heat and or cold spray can help. I did use heat/cold technique on the nuts for the rear metal brake lines and was able to remove them.
I did not do this for the front brake lines but was able to break the nuts loose using a precision ( read as better quality) flare crow-foot wrench.
6. Wiggle the nuts back and forth till they slowly loosen up and then remove all the way. Sometimes the nut gets rust welded to the metal brake line and if care is not exercised, the brake line will get twisted and the job gets to be more ahem....... extensive!
7. Carefully finger/hand start re-threading the new hose fittings. It can take a while to get done right. Do not use a wrench/ratchet until you are sure the fitting is not cross-threaded. Doing it once or twice, one gets the feel of when the nut/fitting is going on correctly.
8. When re-threading the new fittings it helps to use new rubber gloves, or at least get any oil/fluid off the gloves to that the fitting is not slipping as you are trying to thread it on.
9. A little WD-40 on the spring locks for the hoses help the slide in easily with a few taps of a small hammer. Without that depending on the condition of the bracket and/or clip... it can be quite a task.
10. Get a stubby wrench.....it's all fine and dandy in some cases to cut a hose off and then use a socket.... but what are you going to do when you put the new hose in an eventually have to tighten the new fitting in a constrained space. I have seen some folks buy bigger wrenches and then grind/cut them down to make them stubby. I could not easily find stubby wrenches local to where I live. Tightening the hose nut/fittings on the rear calipers were an interesting, slow and painful process. It makes perfect sense to modify tools to do these specific jobs... saves time in the future.
11. Use rubber vacuum caps on the metal brake line side of the line after removing a hose. They prevent drips and loss of brake fluid nicely. Do not use the "vinyl" ones, those do not work that well.... they kind of leak/slip off.

And now more about the original problem with bleeding the brakes
a) I do not know if replacing the rear hoses solved my problem.
b) When I did removed the hoses, the metal brake lines were dripping in a similar manner to when a "gravity" bleed is being done, so I am optimistic.
c) I will be doing the brake bleed activity tonight using a Motive pressure bleeding tool.. and will post more info or status shortly.

Question: What is the inner diameter of the flex hoses? My inspection of the old hoses seemed to indicate a hose diameter of around 1.5 - 2.0 mm?
 

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Discussion Starter #18
So pressurized the Motive Pressure Bleeding Tool to 20psi with around 64 oz of DOT3 fluid.


Started bleeding RR caliper => closed when no more bubbles/air noticed
Then bled LF caliper => closed when no more bubbles/air noticed
Then bled LR caliper => closed when no more bubbles/air noticed
Then bled RF caliper => closed when no more bubbles/air noticed


The front calipers appeared to have higher pressure / rate at which the fluid came out.


However when I started the car, the pedal still seems mushy...
Is this indicative of

a) Problem with Master Cylinder?
OR
b) Still air in the system.... and more bleeding is required?

OR
c) ABS module has air in it?


I waited till what appeared to be no more air bubbles coming out.... should I wait even longer for the rears?
 

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I waited till what appeared to be no more air bubbles coming out.... should I wait even longer for the rears?
Appreciate the hard work. I have had cases where I was only able to get the air out by pressure bleeding(BMW) or only by the partner pedal pump method(F-150). Since it still feels mushy with the pressure method, try the partner pump method. Also, I've done brake work where the pedal didn't feel very good only to actually drive it and find that it was OK. Try driving it and seeing if it is actually low under real world braking before moving on to find the culprit. Just my suggestion.
 

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Discussion Starter #20
Thanks Rikkari, that is what I am going to attempt.
I am pretty sure that at no time during this entire process, did I ever let the MC run below the min line.


Will post to see how it goes.... my son needs to take the car back to University... so at some time over the next couple of days I may just have to bite the bullet and take it to the dealer....


Curious on some other data from other threads where some folks state that in addition to using the Motive pressure bleeder, they also pump the brake pedal a couple of times to force air out of the MC and it works better to get a firm pedal feel... Comments?
 
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