Well, I never had any of the brake lines open. I just removed the old fluid from brake reserevoir and filled it with fresh DOT4 and bled all four calipers. fluid came out nice and no air that I can see. I am leaning towards the MC but I may take it to a shop to pressure bleed it. I do have a brake bleeder by MOTIVE the kind that attach to the MC reservoir and uses a built-in pump with a gage. I don't like it and I think it's a POS. I douby if the booster is bad. They leak if they go bad and I don't have a leak not to mention the amount of pedal force you'll need to stop the car.
Meza

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Meza
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer