Brake Bleeding Problem

[garrett.fell]

What kind of setup did you use
to pressurize the reservoir?


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[JCL]

Originally Posted by Ashaman074

I suppose this is pretty typical of any modern AWD vehicle, but it was a frustrating bit O' learning for sure. Thanks again to everyone who helped!

any modern ABS vehicle, AWD doesn't impact it.

Glad you got it sorted.

[SlickGT1]

Nice, crazy for sure, but something we expect these days with modern cars and DIY.

[Ashaman074]

Garrett, if I had it to do over again, I would have bought one of the pressure bleeding systems. But I actually modified a cap from another BMW (2002 M Coupe) and threaded a NPT fitting into it. I set the compressor regulator just under 30 PSI and attached it. It worked, but I had to move fast to keep it from depleting the reservoir again.

[garrett.fell]

Cool. I was thinking of making something similar. You're suggesting it really pushes the fluid out quickly? Maybe when I make mine I'll put something in-line to cut the air-volume down a bunch (like a little block in the middle with a little hole drilled in it. Much like a cylinder leak-down testing tool).


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[squidzilla]

Ughh... and I was thinking that flushing my brakes myself would be a safe DIY for someone like me. Now I am not so sure.

[Ashaman074]

It really SHOULD be easy - just don't be stupid like me and let it go empty!

The whole brake job & bleeding was a cakewalk and over quickly. It was the aftermath of my carelessness that caused all the headaches. Honestly, even just gravity bleeding would have worked; it is just that it takes SO LONG that it is easy to get distracted/forget to check up on it.

Power flushing is super-fast, the fluid flows from the bleeder in a stream. Using this rigged setup the entire reservoir would have been depleted in just a couple minutes if not watched carefully. If you do it, make sure you use a regulator, not a valve. A regulator limits total pressure, a valve would limit the volume of air but still allow high pressure to build up eventually.

DIS says to use 2 bar pressure (~30 psi), exceeding that can damage components I would imagine.

[admranger]

Just buy a Motive pressure bleeder and you'll be fine bleeding brakes as long as you keep fluid in the pressure bleeder.

Also, Ashaman, try activating ABS in some deserted parking lot (wet or sand/gravel help). That'll shake things up good in the ABS module. I like to do this from time to time to keep the system 'fresh' and it is fun.

Good luck!

[LVP]

Originally Posted by Ashaman074

Thanks RajB - I actually stumbled across this information in your original thread and it was helpful. I had another go at it last night (day 3) but this time with pressurizing the reservoir - that seems to be key.

After doing so a lot of air came out of the system, particularly at the pass/rear bleeder. It is better now; which is to say I have resistance/fairly firm pedal with the key off; but with the engine running it is still going pretty much to to floor. So while terrible, it is an improvement over day 2.

I am going to repeat the process again this evening hopefully, and maybe it will improve again after making another. It is interesting that I don't think I have seen any air from the fronts, it does seem as though it is the rears that are the issue.

What is the device on the floor? Seems awful robust for a mere catch can...?

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Aha, got it:

http://www.liquid-levers.com/shop/pr...79ee83f1f1f157

___

Thanks!

Did a complete pad and rotor swap. When pushing in the caliper piston, I opened the bleed screws to let the fluid out that way. Did a pressure bleed and ran clean fluid through - no pedal pumping, reservoir never ran dry, no line was ever cracked. Pedal is mushy with engine off, but gets to a firm spot (standing on it with both feet and all I can leverage). With engine on and some level of consistent force on the pedal, it sinks slowly to the floor. I have seen all the posts and it looks like a thorough bleed with the software is in order, but I am at a loss to actually explain what has happened.

Any insight from the experts? This is messed.

Thanks.

[Ricky Bobby]

Go in a parking lot and slam the brakes to activate ABS once or twice. That should run fluid through the module good. Then bleed again if needed