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Discussion Starter · #1 ·
Hi all - I just replaced my rear brake hard lines (subframe & fuel tank out too to access factory routing 馃槫), and I can't complete the job as for some reason my brakes won't bleed and I have no/very little brake pressure.

I'm using the 'one man' technique, submerging 1 end of the tube in a container of fluid. I pump the pedal a few times and get a solid stream of fluid in the tube, however after waiting ~30s a steady stream of bubbles appears and runs for about 5mins. I've repeated this several times for about 1hr, going through almost a gallon of fluid, and it feels like something is wrong and it shouldn't take this long to get all the air out, even though I've replaced the whole line! Should I just keep going?

The pedal will build pressure with a few pumps when the car is off, but goes to the floor when started. The "bleeding" I've attempted hasn't made a difference here.

I'm fairly certain there's no leaking fluid anywhere, but would a very small leak that's hard to detect cause this problem? Should I have another look?

First time posting here in several years, I and my car owe this community a lot! Thank you!
 

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E30M3 Race F10 535 R1150Rt M Coupe
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If you look at the cross section of the inside of the tubing, it doesn't hold much fluid.
You had the lines off (should have capped) and now likely the DSC pump is dry.

You'll likely need INPA to activate the pump to get fluid through.
 

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Discussion Starter · #3 ·
If you look at the cross section of the inside of the tubing, it doesn't hold much fluid.
You had the lines off (should have capped) and now likely the DSC pump is dry.

You'll likely need INPA to activate the pump to get fluid through.
Followup - I ended up getting a helper and tried the usual 2-man bleeding method, and took a suggestion from a friend (career Ford mechanic) to "cross-bleed" (FL > RR > FR > RR), and it worked! Brakes are tight, and all ABS/DSC dash lights turned off within 1m of normal driving.

I was hoping my ABS pump didn't run dry for the reasons you stated 馃槄 I did my best to keep the master topped up during work!

I also think I was a bit deceived by the pedal feel when stationary, the pedal feels much firmer than I thought it would when actually driving.

Thank you!!
 

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E30M3 Race F10 535 R1150Rt M Coupe
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11,875 Posts
I'd also suggest to find a gravel lot and have a few fast stabs on the brakes. Making the ABS & DSC system go nuts. This will purge any (?) trapped air in the system back to the master reservoir.
 
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