Bleeding Brake Problem

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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 3:48 pm

Ashman wrote:The calipers have now been rebuilt and the problem is still there. The only things left are the brake servo and brake lines.
And the abs module....id be inclined to now change the abs module....possible internal fault?

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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 3:51 pm

Feck it!!! I like working on cars...because im weird...if you shipped to me mate id work onit til steam came out my ears and its fixed...im in Wilts Ba13.
I reckon internal abs fault...bigpete must have hundreds of em...

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Re: Bleeding Brake Problem

Post by ChrisHolmes » Tue Mar 05, 2019 4:23 pm

would it not still have pressure even if the abs unit was faulty and also throw a code to say so?
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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 4:29 pm

Maybe...but its gotta be something...cant be mc...x4 fitted.
But when abs activates the pedal goes to the floor and the pump takes over...maybe internal fault but passes system checks....
Only a plug and few pipes.

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Re: Bleeding Brake Problem

Post by ChrisHolmes » Tue Mar 05, 2019 4:34 pm

What I would do know apart from looking for cliff or concrete wall is to make up a blanking unit with a female union on a bit folded and crimped brake pipe (ideally brazed or soldered closed) and stick on each caliper hose and bleed the system by loosening each of them in turn. If that worked then you know its massive air lock in the calipers.
With the engine off do you get any pedal resistance, however slight, when you press the brake pedal or even a bit of sponginess (spellchecked so it is a real word)
Without looking back to see I think you have done the MC test of blanking the outlets off to see if it holds pressure, if it did then it rules that out as the problem.

Addendum. Just saw the post regarding the ABS activating and the pedal going to the floor. The ABS should not activate except under hard braking which given your situation is not happening. Is it that with the ignition off the pedal is firm, but when you turn on the ignition, not starting the engine the pedal goes to the floor or is it when you start the engine that the servo cuts in and the pedla goes to the floor.
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Re: Bleeding Brake Problem

Post by warpc0il » Tue Mar 05, 2019 4:49 pm

boosted wrote:
Tue Mar 05, 2019 3:41 pm
This is weird....there is some logic in the vac line drawing fluid into booster. But that means all master cylinders would have bad seals....
Do you get a pedal bleeding up then when engine running it goes to floor?
The pressure differential from the vacuum can be no greater than about 15 psi (1 atmosphere) and is probably only a small proportion of that, as tracked by the MAP (Manifold Absolute Pressure) Sensor, not to be confused with the MAF.

The hydraulic pressure within the brake lines can be anything from 200-800psi.
This means that a faulty seal may only leak from the hydraulic system into the vacuum chamber under braking, or when attempting to create pressure for bleeding.

I'm not saying that this is the cause of the problem, just another potential line of investigation, especially as the brake booster is just about the only related component that hasn't been touched during previous attempts to fix the issue.
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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 5:23 pm

Offer stands, get the car to me with a big pete mc booster and abs module in the boot...ill fit it. Me n Brad will bleed up and will see what we got.


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Re: Bleeding Brake Problem

Post by ChrisHolmes » Tue Mar 05, 2019 5:35 pm

Can all participants come and watch the miracle being performed. Warc0il by Facebook live!
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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 5:40 pm

Not on Farcebook, happy todo a youtube...

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Re: Bleeding Brake Problem

Post by 13Black » Tue Mar 05, 2019 5:56 pm

Do we have a Turnip Translator to hand?
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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 5:57 pm

Lol

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Re: Bleeding Brake Problem

Post by ChrisHolmes » Tue Mar 05, 2019 6:09 pm

Bring a smock and a length of straw so we can sit on a fence a not stand out amongst the locals! Ooah ooah!
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Re: Bleeding Brake Problem

Post by warpc0il » Tue Mar 05, 2019 6:30 pm

13Black wrote:
Tue Mar 05, 2019 5:56 pm
Do we have a Turnip Translator to hand?
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Re: Bleeding Brake Problem

Post by boosted » Tue Mar 05, 2019 6:31 pm

Looks like i might have to get my Pitch Fork out....

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Re: Bleeding Brake Problem

Post by nightfire10 » Tue Mar 05, 2019 6:36 pm

Shouldn't say too much as I'm from Dorset lol Image

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Re: Bleeding Brake Problem

Post by V8 Power » Tue Mar 05, 2019 6:53 pm

You have nothing on Evesham. During Asparagus picking season (locally known as grass) people dress up as asparagus spears and roam around the town.
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Re: Bleeding Brake Problem

Post by Ashman » Tue Mar 05, 2019 9:49 pm

With the engine off, if you pump the pedal it gets somewhat hard but if you then leave it for a few seconds it will loose pressure and the pedal goes straight down. With the engine on the pedal goes to the floor instantly even when pumped.
The abs module has been sent to a brake specialist and the mechanical half of the module was replaced and the electrical side was tested and is working.
What i've done so far is discs, pads, bleed screws, slider pins, seals, pistons removed, cleaned and refitted (they're in good nick), fitted braided lines, abs module rebuilt (brake specialist), tried 4 mc's, bled the system multiple times and it's also been to Mazda and they have no idea of the cause.
I've also contacted multiple rotary specialists and none of them have ever seen this issue.
The only things that are left untouched are the brake servo and the lines themselves.
As for taking the car anywhere, that's unfortunately not an option.

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Re: Bleeding Brake Problem

Post by Ashman » Tue Mar 05, 2019 9:53 pm

warpc0il wrote:
Tue Mar 05, 2019 2:50 pm
You've already disproved all the likely causes of the problem so now it's time to check the unlikely ones.
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Re: Bleeding Brake Problem

Post by ChrisHolmes » Tue Mar 05, 2019 10:08 pm

Have you bled each of the brake lines at the nuts where they come out of the ABS module?
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Re: Bleeding Brake Problem

Post by Ashman » Wed Mar 06, 2019 4:08 pm

Yes, we've bled at the mc, the abs and the calipers.

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Re: Bleeding Brake Problem

Post by RenesisRaceBuggy » Wed Mar 06, 2019 11:13 pm

Is there a diagnostic cycle in the dealer software or similar that will cycle the ABS unit? Some ABS systems won't prime at all unless the valves are cycled in the right order at high frequency and usually it's through command via the manufacturer diagnostic software.

I would also, if you haven't already, try a vacuum bleeder on all the calipers and on the lines from the ABS unit - it will generally show any leaks to air much more easily than pressure bleeding as it removes the seal pressure and you'll be able to see it coming through the line even if it's dissolved in the fluid.

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Re: Bleeding Brake Problem

Post by Ashman » Thu Mar 07, 2019 4:28 pm

I bought a vacuum bleeder but it made no difference. Mazda also bled the system themselves and nothing, i'm assuming they cycled the abs (if that's possible through their software). I did bleed directly on the abs module but without the vacuum bleeder, i just used pedal pressure.

I have another servo on it's way and once this rain stops i'll remove the one on the car and take a look. I'm half expecting to hear brake fluid sloshing about inside.
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Re: Bleeding Brake Problem

Post by RenesisRaceBuggy » Thu Mar 07, 2019 6:23 pm

But you wouldn't get fluid in the servo without the rear master cylinder seal leaking, and you've had new M/C's on it, no?

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Re: Bleeding Brake Problem

Post by Ashman » Sun Mar 10, 2019 12:13 pm

Yeah i've tried 4 separate mc's all with the same result.

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Re: Bleeding Brake Problem

Post by Ashman » Tue Mar 19, 2019 2:17 pm

The servo has been replaced and we bled the brakes again and although the pedal is fairly hard, it will still go to the floor immediately. We've now replaced everything except the copper lines which Mazda said were not leaking. No idea what to do now... #-o

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