I recently replaced my 86 Jetta GLI's sticky rear calipers now that I'm
good and tired of having no e-brake. If it matters, I let the job
stretch over two days. I believe I had one caliper hand tightened
together last night but the other's line still unattached draining into
a jar. I finished bolting everything together today. No more than
about 1/2 to 3/4 cup of brake fluid had drained out of each side by the
time I was done.

When I went to bleed the system, I was pushing the pedal all the way
down, and noticing that even after I thought I got all the air out, the
pedal did not firm up as I expected it to. In fact, if you pushed a
little slowly it would still go all the way down. Many short strokes
would build up pressure such that the pedal would stiffen halfway down
but it would still go all the way down if you kept pushing. I stopped
messing with it, and dug up some articles about how you can wreck the
seals in the master cylinder by pumping the pedal all the way to the
floor like that with an old car whose brake fluid never gets flushed,
exactly as I had done. It made sense and I found my local Auto Zone was
still open and had a new (rebuilt) master cylinder for $30, so I got it
and put it in.

The second time I went to bleed it, I noticed two things: the pedal
still goes all the way down (with the new master cylinder, doing this
shouldn't damage anything now), and the quick pumping does not appear to
build up pressure any more. And occasionally, if I push it all the way
down quickly, I hear a squirting or sucking sound, I think in the
booster, and the pedal doesn't spring back all the way. If I floor it
again it will typically spring back after that.

So I hope the first thing is because there is still lots of air in the
lines, even though I've bled a quart or so of fluid through the system
and have clean fluid with no bubbles now coming out of all 4 bleeder
valves for 3 or 4 consecutive pumps. I hope it is not because the
replacement master cylinder has an even more horrible leak than my
original one might have had. Can someone give me an idea of how much
pumping, or waiting, or fluid, it takes to get the air out after
replacing the master cylinder? What is the most effective technique for
bleeding the brakes? How can I further reassure myself that the lack of
pedal resistance is just air?

As for the second thing, well, I don't know why it would do this --
power brake system? -- so any reassurance that I have not now broken
more than I have fixed would be appreciated.

Take the mangles out of the reply address to send e-mail.

Thanks, Peter.

Don't mean to offend you, but how are you bleeding the lines? Also,
when you let the lines drain, did you remove the cap off the
reservoir?

Darryl.

On Mon, 17 May 2004 04:37:08 GMT, Peter Stokes
<stokesmanglep (AT) earthlink (DOT) mangle.net> wrote:

"Peter Stokes" <stokesmanglep (AT) earthlink (DOT) mangle.net> wrote

Just a guess but have you followed the procedure to adjust the e brake? As I
recall on my 99.5 jetta after installing pads you eather pull the e brake or
push the pedal first but I don't remember the correct one and it's
importance was stressed. Check your Bently. Also instead of pumping out the
fluid try another method. One is to make and attatch a small garden sprayer
with fluid in it and then pump the sprayer and pressureze the whole system
and then bleed. Another procedure is attatch a small vacume pump, hand or
motor powered, to each wheel cylinder and suck the fluid/air out. Also I
think I read a quart a wheel in the bently.

JoBo

Are you getting any help bleeding it, or you are doing this all by yourself?
Bleeding should be:
With a Helper and the bleeder closed, the brake pedal is pumped a few times and
held down then the bleeder is opened observing fluid flowing through the clear
hose into a bottle of fluid. Or a one-way valve on that hose helps.
I usually open the lines one at a time at the new brake master and make sure I
bleed that before I attempt to bleed the wheels in this order; RR,LR, RF, LF.

Or a power bleeder and you can bleed by yourself easier. ;-)

Some have talked about gravity bleeding, but I think it takes longer and air
bubbles may get trapped in places. Not sure on this though. <g>

later,
dave
Reminder........
Before you criticize someone, you should walk a mile in their shoes. That way,
when you criticize them, you are a mile away from them, and you have their
shoes. Frieda Norris

All questions are fair game...thanks all for your suggestions. More detail:

First, I do not much want to buy a machine although I'm sure they work
wonderfully. I live a space constrained existence, and do not imagine
myself doing more brake work for a long time. Once this gets done that is.

The e-brake is not yet connected.

I don't quite get the garden sprayer idea -- if I were to do this to the
individual lines at the master cylinder, wouldn't I still have to bleed
it out anyway once I reconnect the lines? Otherwise I need to seal the
garden sprayer to the reservoir cap somehow...??

"When I let the lines drain...": when I left it overnight with one
caliper line unconnected, the cap might have been off the reservoir, I
forget. But not much fluid was collected, and once everything was
assembled, I refilled the reservoir before trying to pump it.

On how I did the bleeding:

I have pliers clamped (fairly gently) on the regulator at the back
holding the rocker plate on it in the position it would be if I were
driving with a ton of bricks in the trunk.

I had an assistant help me do one of two things in the three or four
cracks I took at bleeding the system:
- open bleeder, pump brakes gently several times, until no bubbles are
seen coming out, holding pedal down at end and closing valve
- have assistant push pedal down once and hold, open bleeder, close
bleeder when flow stops watching for bubbles, release pedal, repeat.

I will certainly try the assistant pump pedal several times and hold,
open bleeder, close bleeder when flow stops, assistant release pedal,
repeat method if that is substantially different than what I already
did. And perhaps I just haven't been sufficiently patient. How many
valve cycles is reasonable for this, and is it important to do it
quickly? I don't think I did more than four or five cycles of valve
openings and closings on any wheel since I was never getting any bubbles
by that point, and didn't want to empty the reservoir, but maybe that
was just the calm before the storm.

I believe the reservoir cap was generally on, although maybe not screwed
down tightly, when I was bleeding.

I did the wheels more or less in the order mentioned RR LR RF LF.

One respondent mentioned a quart of fluid per wheel, I haven't run
nearly that much through yet, which makes me ask: is it kosher to feed
the mostly clean fluid you bleed out the brakes back into the reservoir,
or would a smart person just throw it away (how do you dispose of it,
like motor oil? I live in Mass.)? I have long since removed all the of
the dark cloudy stuff that was in there when I started, but I still get
the odd flake or bit of crud coming out.

Good day, Peter.

Peter Stokes wrote:
You can get "speed bleeders", bleeding nipples with a built-in check
valve for easy one-man bleeding. Check http://www.speedbleeder.com/.
They stay on the car and should not affect your "space constrained
existence". You can also get similar check valves that you insert
in-line with your bleeder hose. With both methods, I worry (perhaps
needlessly) that some small amount of air may bleed back into the system
(around the nipple threads) on the pedal up-stroke. I usually finish of
with two or three "pump, hold, open valve, close valve, release" cycles
(kind of defeats the one-man operation promised by the speed bleeders,
doesn't it?).

Throw it away. Both the Bentley and the brake fluid bottle has stern
warnings about this.

Where I live, (northern CA) you can make an appointment with the county
for hazardous waste drop-off. Whenever I have accumulated enough motor
oil, brake fluid, paint thinner etc. I make an appointment and drop it
off. It's free.

Peter,

Too bad if your first m/c (may have) failed because of bottoming out...that
is a shame.

For this new m/c, did you bench bleed it at all, or did you install it, and
then just fill it and start the wheel bleeding process?

I had an 81 Rabbit (with probably a similar m/c to yours, and probably
similar m/c available at Pep Boys/AutoZone etc.) When I had to replace the
m/c, I went through three reman units from Pep Boys before I had to buy a
new one ($110 instead of $35, and this was in 1990). The problems I had
with the reman units were that the seals at the push-rod end of the master
cylinder were not able to seal properly since the cylinder had been honed
out (as part of the reman process) The result was that although I was able
to get the thing bled, I kept loosing brake fluid rapidly but without a
drop on the ground. Eventually I discovered that the vacuum booster was
inhaling the fluid from the m/c!

So, be aware that there's a possibility that a reman won't work out and
you'll have to spring for a new one.

Good luck,
Arthur
P.S. Sorry if someone already mentioned these possibilities, I didn't read
all of the responses to date very carefully.

Sounds like I didn't bleed it for (nearly) long enough for a m/c
replacement. No I did not bench bleed the master cylinder. I bolted it
on, installed the brake lines, then popped the old reservoir on and
filled it. Bench bleeding presumably would involve just sitting it
level and pushing the piston by hand with the reservoir installed until
fluid squirts out the brake ports? Shame if that's necessary as it's a
damn sight easier to put the fittings back without the reservoir
installed. I don't think any special bench bleeding "kit" or fittings
were provided as one person suggested but I'll have a second look.


I will certainly be on the lookout for disappearing fluid once it's
together. I am crossing my fingers that this m/c is serviceable.

Thanks, Peter.

Arthur Russell wrote:

You can slightly loosen one brake master line at a time at the master and push
on the brake pedal.
Loosen it just enough to try to let the air out and barely enough to let the
fluid out with pedal pushing difficulty. So actually the line is almost bolted
down completely. ;-)
Do this to all the brake master lines.

I forgot was this a GLI with rear calipers?
You have to make sure that the are no air gaps between pads and rotors. Caliper
pistons may push out but then retract creating air gaps and making the brake
pedal travel further down.

Incorrectly installed brake shoes could create the same problem too!

later,
dave
Reminder........
Before you criticize someone, you should walk a mile in their shoes. That way,
when you criticize them, you are a mile away from them, and you have their
shoes. Frieda Norris

"Peter Stokes" <stokesmanglep (AT) earthlink (DOT) mangle.net> wrote

If you didn't bench bleed then that is most likely your problem

I don't think any special bench bleeding "kit" or fittings

I been involved in replacing about 4 master cylinders now and they all came
with explicit instructions on bench bleeding and a bleeder "kit". All the
kit consists of is two cheap plastic hoses and fittings. You hook up the
fittings to each half of the master cylinder then the hoses are routed back
into the reservoir. You then pump the piston slowly by hand until only
bubble free fluid is going to the master cylinder. The instructions on the
last master cylinder stated that #1 reason for problems with new master
cylinders was not bench bleeding them. If yours didn't come with the kit
I'd go back to where you bought it and have them pull another one off the
shelf to see if yours was just missing. I bought several auto parts over the
years that were missing parts/defective because they were previously sold
and returned to the self. In fact now that I think of it, one of the master
cylinders was missing the big O-ring for the booster end due to this.



HTH

Steve