Date: Wed, 24 Mar 2010 06:45:29 -0700
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Proper Brake Pedal Feel/Travel?
In-Reply-To: <c4e7c5f91003232358y29a33573u8ff206598d016d57@mail.gmail.com>
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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
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