[AgnosticRaptor]

Update #2:

I ordered a pair of metal plugs (M12x1.0) for the master cylinder so that way I could do a quick test without having to remove it from the car just yet. Removing the fluid lines from the MC and inserting in the plugs, I decided to go about testing the brake pedal feel in two ways:

1. With the car switched off
2. Switching the car on, letting it run for about 5-10 seconds before turning it off.

Testing the brake pedal with the MC plugged and the car switched off produced a tight pedal - though I'm unsure of how tight the pedal should feel (comments/advice would be helpful here). Furthermore, unlike when I had the lines hooked up normally to the MC where the pedal could build pressure via the brake booster and become hard as a rock, it now maintains some level of stiffness, but still has a bit of slop and doesn't build pressure at all. What does this mean?

Onto the test with the car turned on...the pedal was as squishy as ever (would still rise back up, but the same audible air sound and squishiness I've been experiencing throughout this bleed job). Again, it wouldn't pump up to pressure either. Same when I turned the car off, still wouldn't pump up to pressure like it usually did before plugging the MC.

I'd like to point out that in both conditions, the brake pedal didn't "drop" under its own weight, or fall to the floor after applying a set pressure with my foot. The main issue is that it just failed to build any pressure while testing the MC.

Would love to hear any comments/thoughts/feedback/advice etc.

 

[AgnosticRaptor]

Update #3:

Currently benchtesting the MC, and it appears that the primary port has a continuous, and steady stream of air bubbles in it that simply cannot be flushed out by bench bleeding. The secondary port, however, is free of bubbles and has excellent, pure fluid flow.

Would this mean that the primary piston seal has failed and the MC should be replaced?

 

[AgnosticRaptor]

An update...

After spending a lot of time trying to track down the correct ABS module for the car (and then having a junkyard ship me the wrong one), I've finally replaced the ABS module and bled the entire system again.

This has fixed only one of the two issues I had: I am now able to consistently bleed fluid out of the driver's rear wheel no matter if I start the car, leave it sitting, pull fuses, pull the battery etc. Woo! It previously wouldn't bleed (or only bleed intermittently) so that's nice.

However, when I do start the car, there is still zero brake pedal feel while the car is running. You can practically press the pedal down with your fingertip as it requires zero effort to do so. Turning the car off will let me pump up to a rock hard pedal again, and I can still bleed all brakes like normal, with no air bubbles and consistent fluid flow out of each caliper.

So now I'm really not sure what to make of this.

I've replaced the master cylinder and the ABS module. I know my brake booster is working correctly. Rear brake flex hoses and calipers are new and there's no system blockage or anything of the sort. Yet I still have no pedal feel and the car is not suitable to drive.

What gives? Any recommendations to try from here?