[Vwdiesel] bad brakes on 2001 Jetta

[Rolf Pechukas]

brought new-to-me '01 Jetta w/ 138k to trusted (on the list) TDi mechanic for several jobs including new e-brake cables
(e-brake was seizing when applied, would slowly release after driving - other than that, brakes were fine)

turns out right rear caliper also had a rusted/seizing e-brake lever; mechanic replaced caliper with a (presumably) good used part in addition to new cables; also apparently one or 2 hard pipes to caliper(s) - wasn't exactly clear on that

we arrived to pick up and test-drove to find brake pedal somewhat soft - brakes impressive if floored, but not confidence-inspiring at the top
at least 2" of travel before any noticeable braking

turns out driver's rear caliper had not been bled b/c bleed screw seized

we bled 3 other wheels again; performance not noticeably improved
also bled clutch - still not improved

mechanic wanted to bleed driver's rear line, even though bleed screw seized, so he released and tightened pipe where it attached to caliper while I operated brake pedal

on test drive, performance now worse - after 2 hard brake pedal presses, brake pedal became hard but braking greatly reduced - like brakes were 'lost'
with a hard stomp, car would stop, but not at all how it should feel

because another customer was there patiently waiting, I left the car with mechanic to sort out at his leisure

bu I am wondering:

- is it possible the used caliper swapped in was faulty? I was operating bleed screw during bleeding, with vacuum applied to nipple, but noisy/airy-sounding, much air in line, never established solid fluid flow despite much bleeding
mechanic said this was normal, that air was getting in through the threads, and I'm sure this was true to some extent, but in the past when I bleed brakes, I bleed until solid fluid with zero bubbles - but I bleed w/ brake pedal alone, not vacuum
front two calipers bled much more solid, w/ zero air noise/bubbles on driver's side
is this just a matter of distance from reservoir?
i.e. the further you are, the greater friction on the slug of fluid you're trying to drag, the greater likelihood of sucking air in at the threads?

- is it possible something was damaged by hard testing? lots of pedal stomping may have blown a seal in the master cylinder? or boost assist?

- would not being able to bleed the driver's rear b/c seized bleed screw make everything else impossible? is it possible air got into that caliper or line when he did the e-brake cables? could that 'infect' the entire system?

I've never been great with troubleshooting brake systems
would very much appreciate any thoughts from more experienced listees

thanks,

Rolf in MA