Air in the ABS Valve? Time for a pro?
 

2003 R53. . . I replaced the pads & rotors on all four corners a few weeks ago. No braking issues afterwards. Then, a corroded line broke and all hell broke loose. The brake system appears to have run dry after the line rupture. I replaced the left and right main brake pipes- from the front of the floorpan to the rear calipers. I installed stainless braided hoses at all corners. I installed a new master cylinder and reservoir. I installed a new brake vacuum line with check valve because the OEM one broke. I bled the system using the Motive pressure bleeder. I allowed the stream of brake fluid to flow until no bubbles were present after 10 continuous seconds. The timer would reset after each bubble. During bleeding, I followed the "ventilation" process in the Schwaben BMW/MINI scan tool. I don't have any leaks, drips, or detectable weeps, the reservoir is at the max level. No brake warning lights, either.

After what I thought was a successful bleeding process, I test drove the car. The pedal would travel to the floor without slowing the car. The car would stop after 2-3 pumps. On the 2nd and 3rd pumps, the car would drift left than correct itself- like the DSC was kicking in. I did a few 45-0 quick stops and the car would behave the same way- a slight drift left and a mild correction. The braking felt the same with and without DSC activated. I haven't tried bleeding the brakes after the test drive.

At this point I'm thinking that air is in the ABS valve and a trip to the mechanic is warranted. , , unless one of y'all would be kind enough to point out obvious things I'm overlooking.

The Foxwell NT510 scan tool (I have the Schwaben brand version for MINI/BMW models) lets you do a lot more dealer level stuff
than most generic scan tools.
You can activate the ABS valves with it while bleeding. There are some other scanners that do this, too.
It's not very expensive at about $200.
It wasn't hard or lengthy to do.

I also have the Schawben NT510 tool. I'm totally new to BMW/MINI maintenance. I followed the tool service\chassis\ABS-DSC...\ventilation\replace master cylinder instructions. . . bleed, vent, repeat. What I'm unclear about is if the tool holds the ABS valve open while fluid is flowing during the bleeding process, like I've read about for the INPA program. Or, if the vent process is suitable for releasing small amounts of air during a fluid flush when the lines remain closed, but not as efficient for a major failure when a lot of air is introduced in the system.

I'm ~30miles away from an independent BMW service shop, 35 to the MINI dealer, and ~50 to Detroit Tuned. At this point, I'm thinking I'll burn through more brake fluid than what I'll get charged for a flush & fill. The obvious downside is the dodgy drive to the shop.

I've been told you bleed the brakes, then use the tool to activate the ABS (it pulsates the unit quickly for a few seconds to evacuate air), then bleed again.
Not sure if you activate once then do second bleed on all 4 wheels, or activate before each second bleed (I did the latter).

I chucked in the towel and made an appointment for a brake flush at the independent shop. Once benefit I see is that they'll be able to flush out any old fluid in the ABS valve. . .and the brake saga will be over. . . and they'll probably point out a bunch o' "oh by the way" service/maintenance recommendations. My appetite for buying, dl'ing, and fumbling through INPA is quite low at the moment. I just want the car back on the road for the end of summer and autumn driving.

After a swipe of the credit card for a brake flush service, the Mini Scoocher is back on the road. The culprit was air in the ABS valve. I'm glad the shop didn't cite any brake work issues during the multi-point inspections. The inspection reported findings typical for its age and use.

I use an Autel Maxisys Pro OBD2 scanner, that allows you to bleed the abs. I am sure there are some less expensive units that will allow you to do this.

Nice tool, I'd probably have one (or equivalent) if I were in to flipping cars

In a pinch, you can sometimes get the air to move from the ABS to the lines by engaging ABS a few good times on gravel or dirt. Do that a few times then bleed as normal, and, if you're lucky, that will help.