[Vwdiesel] bad brakes on 2001 Jetta

[lbaird119 at aol.com]

Repeated stomping of the brakes depleats the vacuum that the pump has created, resulting in a hard pedal.  "Shouldn't" happen but certainly can and does.  Brakes are still fine and dandy, just takes more leg effort to apply them.

  With the work done, the pedal will certainly feel different than before.  Hard to describe if it's ok or not without actually driving the car and stepping on them.  It does tend to sound like there could still be some air in the system (from how you describe the pedal).

  You've discovered the reason I don't like bleeding brakes with a pressure bleeder, mitee-vac, etc.  They work great for most people but for me, one person stepping on the pedal and another operating the bleeder has always produced the best results.  If there's air in the caliper with the stuck bleeder then you have what my now be know as "The Hayden Syndrome."  :-D  A caliper full of air will affect all of the others but not by "infecting" it.  Any air will allow a "soft" spot for the fluid to compress into rather than operate a piston.  The air won't spread but air, regardless of where it is, does the same thing.

  Line length is pretty much irrelevant since you're not actually moving fluid that whole distance.  It's like our science teacher explained electricty (electrons).  Compare it to your water faucet.  When you open it, you're not pulling water from the well but just behind the faucet, in the pipe.  Stuff just has to move that little bit and it's all a progression, not a journey.

  Although it's possiblt to damage master cylinder seals from a stomp, it's not likely.  More likely to damage something if you stomp it and it hits the end of travel.  Still, only a possibility not a likelihood.
     Loren



-----Original Message-----
From: Rolf Pechukas <rbp at 4u2bu.org>
To: vwdiesel <vwdiesel at vwfans.com>
Sent: Sat, Jul 6, 2013 2:38 pm
Subject: [Vwdiesel] bad brakes on 2001 Jetta


brought new-to-me '01 Jetta w/ 138k to trusted (on the list) TDi mechanic for 
everal jobs including new e-brake cables
e-brake was seizing when applied, would slowly release after driving - other 
han that, brakes were fine)
turns out right rear caliper also had a rusted/seizing e-brake lever; mechanic 
eplaced caliper with a (presumably) good used part in addition to new cables; 
lso 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 
mpressive if floored, but not confidence-inspiring at the top
t 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
lso bled clutch - still not improved
mechanic wanted to bleed driver's rear line, even though bleed screw seized, so 
e released and tightened pipe where it attached to caliper while I operated 
rake pedal
on test drive, performance now worse - after 2 hard brake pedal presses, brake 
edal became hard but braking greatly reduced - like brakes were 'lost'
ith 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 
echanic to sort out at his leisure
bu I am wondering:
- is it possible the used caliper swapped in was faulty? I was operating bleed 
crew during bleeding, with vacuum applied to nipple, but noisy/airy-sounding, 
uch air in line, never established solid fluid flow despite much bleeding
echanic said this was normal, that air was getting in through the threads, and 
'm sure this was true to some extent, but in the past when I bleed brakes, I 
leed until solid fluid with zero bubbles - but I bleed w/ brake pedal alone, 
ot vacuum
ront two calipers bled much more solid, w/ zero air noise/bubbles on driver's 
ide
s this just a matter of distance from reservoir?
.e. the further you are, the greater friction on the slug of fluid you're 
rying 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 
ay 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 
verything else impossible? is it possible air got into that caliper or line 
hen he did the e-brake cables? could that 'infect' the entire system?
I've never been great with troubleshooting brake systems
ould very much appreciate any thoughts from more experienced listees
thanks,
Rolf in MA
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