'79 brakes

My son's '79 lost its brakes yesterday, and we spent today fighting
this: I can't get all the air out of the left-front line. We've run
8-10 ounces of fluid through the system, which is maybe 18 inches long
on this wheel, and still there are bubbles with no end in sight. The
system must be sucking air somewhere. There aren't any obvious fluid
leaks, the flexible lines are intact, but we cleaned the entire master
cylinder area and plan to look closer tomorrow---We made a bit of a
fluid mess while replacing a line on the rear, which is where we
thought the problem was.

The other symptom is that the pedal is firm if we hold it hard, but a
soft push goes to the floor.

Last, the master cylinder reservoir squirts up if we hit the pedal
hard...is that normal? (this is why we made the fluid mess)

We rebuilt the rear brakes in the spring, including new cylinders and
one new line in back, and replaced the front pads a couple months ago,
flushing the entire fluid system. It's been working fine since. No way
am I an expert or even very experienced at this, but I'm pretty
confident we're doing the bleed properly. What should I do next?

-John O

"JohnO" > wrote in news:1165799365.568310.24160@
73g2000cwn.googlegroups.com:

> What should I do next?

Replace the master cylinder. It's bad.

elaich > wrote:

> "JohnO" > wrote in news:1165799365.568310.24160@
> 73g2000cwn.googlegroups.com:
>
>> What should I do next?
>
> Replace the master cylinder. It's bad.
>

Yep... tipoff is: light effort - pedal goes to floor, yet no leaks.

--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!

Backyard Mechanic wrote:
> elaich > wrote:
>
> > "JohnO" > wrote in news:1165799365.568310.24160@
> > 73g2000cwn.googlegroups.com:
> >
> >> What should I do next?
> >
> > Replace the master cylinder. It's bad.
> >
>
> Yep... tipoff is: light effort - pedal goes to floor, yet no leaks.
>

Good, we can handle that. Thanks guys, for confirming what--for me
anyway--was a wild guess.

-John O

Backyard Mechanic wrote:
> elaich > wrote:
>
> > "JohnO" > wrote in news:1165799365.568310.24160@
> > 73g2000cwn.googlegroups.com:
> >
> >> What should I do next?
> >
> > Replace the master cylinder. It's bad.
> >
>
> Yep... tipoff is: light effort - pedal goes to floor, yet no leaks.

Replaced the master cylinder last night, and the brakes now work
perfectly. The bigger resevoir had a bunch of gunk in the bottom, maybe
this was the remains of the seals breaking down, or what caused them to
fail, whichever. Hell, they were 27 years old!

The job was a lot easier than I expected, especially since the old
lines came off the cylinder nicely. Thanks for the help guys.

-John O