I recently did a master cylinder replacement and caliper rebuild on my 1990 740 16v, and things where going fine until I test drove the car and found there was still a lot of air in the brakes.

Bled the master cylinder at the bleed screw, while having an assistant pump the pedal and hold, while I cracked open and then closed. Also did both fittings at the master cylinder the same way.

Then, moved on to the wheels, and bled all 4 using a pressure bleeder. However, I discovered that my pressure bleeder seemed to be putting tons and tons of tiny air bubbles into the lines (when I pump the tank up, apparently the air is bubbling thru the fluid in the tank and frothing it up). So, I switched to the old trusty manual method of having an assistant pump, hold, crack the bleeder screw, close the screw, repeat, etc.

I have now forced almost a GALLON of brake fluid thru the system, and there is STILL air in the brakes. I'm at the end of my rope here.

Any suggestions? Do I need to crack open the fittings at the ABS modulator, and see if there is any air here? Or do I bleed another gallon of brake fluid through and hope for the best?

Thanks!
R.O.
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R.O.