'87 5KCSQ brakes not releasing properly

[steinbru at vnet.ibm.com]

Ref:  Your note of Wed, 31 Jan 2001 14:58:22 -0800 (PST)

Hi Shef, I get scarce on the q-list too, but happened
to catch your post while checking on another brake
question.  Prolly by now you've gotten to the part that
is causing your problem:  the brake master cylinder.

Here's how heat causes the brakes to "self-apply":  the
vent normally open to atmospheric pressure when the
pedal is up (released) is probably blocked.  This
happens when the black sludge from old/wet/oxidized
brake fluid builds up in there.  Expansion of the fluid
as it heats up then causes the brakes to rub, which
causes more heat, and so on until the car won't move.
You can check for this when it happens 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 and the brakes release, the
blockage described is almost certainly your problem....

I can send some BTDT for coupe and 5k if you still
working on the problem.  New MC is between 50 and 80
bucks I think.  I can get 'em out and in and pressure
bled in an hour (coupe) or two (5k).  Less if I don't
drop the clip somewhere :)

I have "cleaned" things up and got the brakes working,
but the MC's only good for a couple more months anyhow.
Best (like always) is preventive maint:  bleed/flush
completely with new DOT4 every year or two, and don't
forget the clutch slave.  You have to do this anyway
when you replace the MC.  Do it good, 'cause the black
sludge that got your MC is close to getting your clutch
and wheel slave cylinders too!

Hie thee down to your local salvage yard and get a MC
reservoir cap, then to a tire shop for a stem.  Snap
the switch outa the cap, pull (with brake fluid lube)
the stem into the hole, and voila':  a pressure
bleeder --keep things under 10psi and there ya' go.
You will still need to exercise both pedals a bit,
but just a little, and you don't run the risk of having
the MC seals explore virgin territory and get roughed
up --'specially the clutch, which you probably didn't
have to replace yet anyhow.
--Gary