i'm testing a brake booster for suspected failure. with long and furious pumping on my mityvac i can get it to pull 2" of vac at which point if i stop pumping it bleeds off. i'm assuming this thing is supposed to hold steady vacuum but is 2" anywhere near the capacity? pedal is hard and requires pressure to stop the car but it feels like some assist is still there

ETA hose going into the booster pulls 24" of steady vacuum from the engine pump

one final edit: when the car is running , pressing the brake pedal you can hear a squeaky sound thats like air being let out of a balloon

__________________
1981 NA 300D 310k miles