master cylinder question (how-to reply)

[Steinbru@vnet.ibm.com]

Ken,
just BTDT.  It will get worse:  eventually heat will cause the brakes to
"self-apply".  The vent normally open to atmospheric pressure when pedal
up is probably blocked.  Check by loosening the brake lines at the MC,
one front and one rear.  A small amount (several drops) of fluid may
come out as pressure is released, so keep a rag handy.  If pedal
pressure is reduced, the blockage described is almost certainly your
problem too.

I removed my MC and flushed w/ fluid until the problem went away.
However, the MC began leaking within 2mo.  I'd recommend you just
replace it and be done with it.  I got a rebuilt for a bit over $80.

Keep everything scrupulously clean!  Remove four brake lines, remove two
nuts and washers holding MC to booster, remove cap and set out of the
way.  Remove o-ring (vacuum seal for booster) from groove, you may or
may not need it again depending on replacement MC.  Pop the reservoir
off the old MC and clean out with new fluid and mount on new MC.

Before assembling, you need to bleed new MC as recommended for your type
and fill reservoir before mounting (keep the fluid off your paint).
Fluid will drip, but this helps keep air out of the system.  Newspaper
under the car will keep your floor/driveway clean and over your fender
will keep your paint safe.  Wash everything down with lots of water when
the job is complete.

Position o-ring (if needed) and put MC on the two studs.  You need to
keep your thumb over the nipple that goes to the clutch MC until you get
the hose on.  Thread all brake line fittings onto the MC, then tighten
all lines.  Make sure o-ring is in the groove and tighten the two nuts
w/washers to the booster.  Top off reservoir and you should be done.  I
got no air in the system doing it this way, but if you do you will need
to bleed the brakes.
--Gary

--REFERENCE--------------------------------------------------------------------
From: Ken <kkeith@qnet.com>
Subject: master cylinder question

Hey folks,

1.  What does a failing master cylinder act like?  What are the
symptoms?

I pulled the brake (vacuum) booster off my 4ksq and put it on my C-GT
to see if it would make the pedal 'softer', but it's the same.  I think
it'll only get worse.

(My brake pedal is very hard, and basically feels 'unassisted' at all.)