A follow up to close this thread out. I found very little definitive information on the common rear brake line bleeding issue. I finally got this resolved but it took HOURS!!! I did the following 3 things. Moved the coolant reservoir out of the way to access the top of the ABS pump. Used my Foxwell to activate the pump while loosening each 4 lines a little one at a time and bled whatever air was in there out. All the while I had my pressure bleeder connected to reservoir on master cylinder with 20lbs of pressure. Once I new the air was out of the master and ABS pump I moved to the rear lines. There was no way to be sure all air was out of the above procedure, but I must have done the procedure 5-6 times. At the RR wheel I hooked up a clear hose and bottle to monitor the air coming out of the line. Open the bleeder and you will see a very slow trickle of fluid coming out via gravity/pressure from the pressure bleeder. I activated the ABS pump via the Foxwell 3 times. Than I would do a slow pump on the brake pedal 6 times. All the while monitor the fluid in reservoir so you don't run out. I did the same on the LR wheel. This process was painful slow and I was really wondering whether I had another problem or ???. So many small bubbles kept coming out I never thought it would end. This literally took me probably 10 hours with different interations of bleeding everything. Feel free to reach out if you have any questions. I also replaced the master cylinder thinking that was the issue.....it wasn't! But I now know how to do that. Good luck.

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Dave S.
Northeast
2003 4.6is
2005 E53 4.4
2003 E39 Msport(a REAL ONE!)
1959 Fiat 600