'66 Brake Master Cylinder Leaking

[Rob A.]

I was working under the dash and noticed brake fluid leaking out of the rubber boot where the pedal connects to the master cylinder. Should I assume this indicates the brake master cylinder needs to be removed and rebuilt? (I was hoping that maybe there was a repair that could be done without removing it...not in the mood to bleed the brakes)

[Geoff C.]

I don't think you can avoid it. But Merry Xmas

or any other politically correct, gender vague, religious agnostic, color blind salutation.

[Jim T.]

Re: '66 Brake Master Cylinder Leaking

Rob I have removed a master cylinder and capped the brake lines. Rebuilt the master cylinder and installed it after proper bench bleeding. What I did was install the brake lines loose and remove the master cylinder cap and let gravity take over letting fluid leak out of the fittings protecting the drip area of the frame. Tightened up the fittings and had good pedal. I am not saying this will work for everyone, but it did work for me. A must is a good bench bleed to remove the air from the master cylinder.

[Rob A.]

Re: '66 Brake Master Cylinder Leaking

Jim,

Thanks for the info, maybe I'll have the same success. I've bled a '67 master cylinder, using the bleeder valves. How exactly do I bleed a '66 non-power master cylinder without them?

[Mike McKown]

Re: '66 Brake Master Cylinder Leaking

Run a line from the port in the MC to the reservoir and let it squirt in the reservoir. A parts house can sell you a short section of made up tubing or they also sell plastic fittings with a hose nipple and a short length of hose.

[Mike McKown]

PS

Pump the piston with a screwdriver or other suitable tool until air quits coming out of the end of the tubing, It would be best if you submerged the end of the tubing below the level of fluid in the cylinder.

[John H.]

Re: PS

Like this, but you'd only use one fitting and hose.

[Rob A.]

Re: '66 Brake Master Cylinder Leaking

Mike,

I gotcha, I remember doing that with my '67, even though it had bleeder valves. I still have the bleeder kit. Should I automatically have the master cylinder sleeved, while it's out, or leave it up to the repair shop? The brakes worked fine and the pedal was very firm. If it weren't for the leaking on the inside of the firewall I would not have known there was a problem.

[Rob A.]

Good Picture....Thanks John *NM*

[Mike McKown]

Re: '66 Brake Master Cylinder Leaking

If that were my cylinder, I'd run a green Scotch-Brite through the bore and shine it up. If you see pits or grooves in it, it's time to sleeve or replace it. A few small pits probably won't hurt anything. No grooves.

You can spend $25 or so for the kit or you can sleeve it and spend $125 to fix it. Your time and money.

[Rob A.]

Thanks...I'll clean it up and see how it looks *NM*