On 3/24/10, Don Hanson <dhanson928@gmail.com> wrote:
> On Tue, Mar 23, 2010 at 11:58 PM, neil n <musomuso@gmail.com> wrote:
>
>> Yes. I hear a soft "whoosh" but could be a hiss. Pretty sure that part
>> is normal.
>>
>> Feel of pedal changes when booster vacuum expired. I'm just about
>> certain booster is working properly.  But.....
>>
>> I get what you're saying. Check pedal with engine off + vacuum gone
>> and see if  pedal is sinking. i.e. feels like a failed MC.
>>
>> Neil.
>>
>
>   What you're describing sounds like a faulty MC to me.  I replaced the one
> in my 84 and a little over a year later (about 20k miles)  the new one again
> started that same behavior, if I read right what you are feeling.  Mine had
> no "clunk", though.  It simply sank way too low for my peace of mind.  Also,
> mine would pump up again and then sink slowly under braking pressure...so
> the symptoms may not be exactly what you have.
>
>   Before you 'throw parts" at the problem you might want to go back and
> bleed it once again.  Be really meticulous with procedure.  Be 100% positive
> you get all the air out, for sure.  Check that your bleeder valves are in
> good condition, that you have a good fit on the tubing that takes the bled
> fluid out of the valves, put that hose down into a glass jar and make sure
> to keep the end immersed in some fluid as you bleed so that no air can
> possibly return through the bleeder valve...  If you have *any* doubts about
> whether you may have screwed-up during your bleeding procedure...go back and
> start over again--Even if it is the very last wheel and the last spurt of
> fluid......Air in the system...any at all..will cause weirdness.  You may
> have a speck of dirt somewhere in a valve or opening, too.  Use a clean
> 'catch jar' and check the fluid that's come out when you finish..
>
>   When I service brakes, I am scrupulously thorough.  The brake systems,
> while actually pretty simple, are intolerant of mistakes and less than 100%
> effectiveness, especially in a vehicle like our Vanagons, can sometimes have
> really  bad consequences.
>
>   I like to use different color brake fluid when I bleed brakes so that you
> can visually see you have fresh fluid all the way to the bleed valve.  ATE
> is what I use, which comes in Super Blue and Gold colors.  Google it or
> Pegassus racing has it mail order.  In a puzzling situation like you are
> encountering, I would bleed the clutch, too...Probably needless, but as I
> mentioned...Scrupulously Thorough..is best, for brake work.
>
>   Don Hanson
>

Thanks Don. All good tips.

Wheel cylinders, calipers almost brand new. Each cylinder and caliper
bled at same rate, so I assume no blockage.

Fronts bled at a noticeably faster rate. I found this notable as hole
in bleeder same ID as rears.

No dirt entered system.

Different colour fluid? Neat tip. Thanks.

Bled clutch again, fluid dirty. No surprise as I only bled that a
little recently, that being first time since purchase or Westy.
(hangs head in shame. <grin>)

With newly built pressure bleeder, watched stream come out of tube on
rears. Tube not immersed. But. Flow was steady, no backing up. Hose
secure to bleeder.

I have a couple things to try first before throwing parts around.   :)

Thanks very much people.

Neil.

--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"

http://tubaneil.googlepages.com/

http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines