"duckbill" <ltcauth13@nospam.cs.com> wrote
> Over the past few weeks the brake pedal on my 95 Civic Ex
> (195,000
> miles)with ABS would sometimes sink a little at stoplights
> and statrted
> feeling a little funny the first time I applied them
> lightly in the
> morning. My first thought was to bleed the brakes. And,
> while bleeding the
> brake pedal yesterday, I lost all pressure and the brake
> pedal consistently
> went to the floor.
> I had placed a piece of wood under the pedal so the
> brake stroke would be the same.

The piece of wood won't prevent a person from pushing so
much brake fluid out of the system that air is introduced
via the master cylinder reservoir becoming too low.

ISTM that's what happened, and the air entering via the
reservoir enters both "sides" of the brake system. I messed
up a couple of years ago during a routine brake system
drain/fill/bleed and had the same thing happen (pedal went
to the floor while bleeding brakes; but I /know/ I let the
reservoir get too low and introduced air). I re-did the
bleed, and all was well. (There were and are no problems
with my master cylinder.)

> The search feature of this wonderful forum
> led me to purchasing a master cylinder. The problem is
> now fixed.

I think you fixed two problems: An internal leak in the
master cylinder (fixed by replacing it completely) and air
introduced to the system (fixed by doing a thorough bleed
after replacing the old master cylinder).

> What I don't understand is how a master cylinder could
> fail so
> completely because you have two seperate hydraulic brake
> systems? When my
> pedal went to the foor, it meant I had lost both of these
> brake systems.

I think it meant you introduced air into both systems, in
this instance.

> There were no external leaks, and I never had to add brake
> fluid.

You did add brake fluid at some point during all this,
didn't you?

> Had one
> of my brake systems failed a while back and I was not
> aware of it? Thanks
> in advace of any thoughts on the issue.