william sadler <wsadler@copper.ucs.indiana.edu> writes:
> The MGC has two brake boosters. Recently, when at a stop light and idling
> the brake pedal will slowly travel to the floor. IF pumped, it will get
> hard again, but slowly drop to the floor. I don't have any fluid loss.
> Is this a sign of (pick your choice) a: master cylinder problems 2) worn
> brake pads or III- bad brake shoes?
If you don't have any fluid loss (are you REALLY sure you don't?), something
funny is happening up at the booster end. I assume the wheel assemblies are
nice and dry. If so, look for seepage around the booster. Fluid does not have
to leak to the outside; if it gets into the diaphragm of the booster, it can
be drawn through the vacuum line to the engine and burned without trace. Per-
haps you could peek inside the vacuum line and see what you find.
Last time my pedal went to the floor, the master cylinder was worn; however,
it showed obvious seepage between the master and booster to confirm the diag-
nosis. Also, the wear was lateral in the cylinder due to my pushing slightly
sideways on the pedal with my right foot whenever I applied the brakes. I
found that if I temporarily used my left foot on the brake pedal (it was an
automatic trans), that would push the worn cylinder plunger from the opposite
side, and the pedal worked fine. Not recommended as a long-term workaround,
but it got me home that night.
You might try testing the pedal with your other foot to see if the symptoms
change or go away. If they go away, check the master cylinder; if they don't
change, check the booster.
Andrew C. Green
Datalogics, Inc. Internet: acg@dlogics.com
441 W. Huron UUCP: ..!uunet!dlogics!acg
Chicago, IL 60610 FAX: (312) 266-4473
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