slovill

Walked into the garage yesterday thinking it was going to be the first time to to turn the key after two years of work. Found a nice puddle of brake fluid on the floor . I bled the brakes the day before with the help of my gearhead daughter, so I'm guessing that prompted the problem to reveal itself (the bleeding part, not the 15 year old daughter part ).

Inspection showed fluid leaking from the weep hole on the bottom of the master cylinder. I searched the forum and think I found out the master cylinder needs to be rebuilt. I have a couple of questions about the process... BTW this is a 1964 327/300 vert w/power brakes 4W drum

The master cylinder is pictured below, along with the weep hole (yes, that is my coconut at the top of the weep hole picture, the weep hole is the moist orifice near the bottom of the picture).

So here are my Q's...

Paragon and LIC no longer have the rebuild kit - Zip does (Part#EB-210) - and it is in the third picture. Is this all I will need?

What are the 'bad' things I should look for while I have the MC apart, and are any of those bad things catastrophic (need new MC)?

I read about bench bleeding the MC on this forum, so that's covered, but after the MC is re-installed how much should I expect to bleed the brakes - I mean, does a lot of air get into the system while the MC is off of the car? I don't see how it could, but I just want to be sure.

There is a rubber seal on the front of the booster where the MC bolts on (the plunger comes through this seal) - what is this called? I think I found it from Zip (part #DB-377) (link if you want to look, but it is the fourth pic below) - is this it?

There is also a felt thing (part #ZDB 375) (link if you want to look, but it is the fifth pic below) - this does not exist on my car - does it go in front of the rubber seal (closer to the MC)?

Lastly, although the rubber seal I asked about seems to still be okay, how likely is it that brake fluid leaked into the booster? How would I know? and what do I do about it if it did?

If you can answer any or any part of these q's I sure would appreciate it. Summer is going fast, and ol' Bessy isn't.

darguy

When you have the master cylender apart and cleaned up (brake clean, not solvent) check the bore for scoring or pitting from rust. You can hone the bore like you would a wheel cylender to refresh the surface (but be careful not to bottom out the hone on the end of the bore). After it's honed you'll have to make a judgment call on the surface - you could probably get away with a few minor imperfections, but I wouldn't want to push that too far on a single reservoir master. If it doesn't pass the test, you could send it out to get repaired or replace it.

As for the bleeding, if the master never went dry there shouldn't be any air in the lines. If you're careful when removing the master (and bend the line upwards slightly after removing it so it doesn't drain), you should be able to get away with just pumping the pedal a couple of times and cracking the line at the master to get rid of the residual air (after bench bleeding the master).

If there is brake fluid at the back of the master by the clip, then some fluid probably got sucked into the booster. I'm not sure that's a real issue, but I'd clean up any goo around there and if you're ordering parts, you may as well replace those seals and such at the same time. If the leak started after the bleeding from the previous day, and you haven't started the car since, then the master wouldn't have sucked any fluid in, but some may have dribbled in from gravity.

I haven't rebuild a master in ages, but have swapped out my share of leaky masters and never had any come-backs.

slovill

Thanks for the reply. The service manual gives specs for gap around the piston, so after I hone I'll make sure it falls within spec.