M5 Expert (>4000)
Join Date: Aug 2002
Location: Raleigh, NC
Thanked 1,503 Times in 1,027 Posts
I'm about to do this soon and I was thinking about the best way to get the air out of the new hoses. I can't activate the ABS pump so I was thinking of replacing the lines, then going for a drive and activating the pump by slamming on the brakes a few times. That should move the air pocket from the hose downstream to the rest of the circuit, which will then come out once I bleed the brakes.
Why would need to worry about the ABS pump activation if you do not introduce air upstream of the unit? You can mitigate the flowrate of fluid out a connection by filling the reservoir all the way to the top edge and tightly sealing it with plastic wrap stretched over the top and secured with a rubberband. Keep an eye on it to make sure that the reservoir doesn't leak down too far when you have a line open for replacement. Alternatively, you can use one of those tools to hold the brake pedal depressed just enough to block the inflow ports, and I suppose almost no fluid will run out.
Hence, just do one or some version of above, replace all the hoses, and flush the system well. (and then still get stuck with the mr bock issue, lol).
2019 M2 Competition 6MT LBB, slicktop
2011.5 M3 sedan 6MT Silverstone, slicktop: Dinan front swaybar, Eibach rear swaybar, pins-out-max-camber-up-front, Dinan exhaust, Michelin PS4S, Apex EC-7 9.5/10.5x19
2007 328i wagon Silver/gray: Eibach 28mm front swaybar, E93 M3 rear swaybar, 219M M3 wheels, Michelin PSAS3+
1975 CanAm 125MX2: Stock, original owner