Weeping master cylinder cover under gasket

[MWbirdLOVER70]

Take a look at how the wire clamp holds the cap on and determine which way you'd need to gently bend it so it applies more down force. (I made the 'V' part of the wire clamp a bit more narrow.) Then remove the wire clamp and lid. Clean the top surfaces of the MC and gasket of any debris. Put the wire clamp in the vise so that you can bend it. It doesn't take much. When you reinstall the gasket and lid, you'll notice its pretty hard to snap the wire clamp over the lid. If its too tight then you bent too much.

Sounds like a plan

 

[wahya]

Reviving an old thread here, but I too had the old mc weep.
First,I noticed a bad braking response. I checked the master cylinder and the fluid looked bad (discolored). I wound up replacing mc, front brake lines, flexible hoses, brake shoes, distribution block and flushed out the rear hard lines. I bench bled the master cylinder per instructions on the new mc using the supplied port plugs.
After getting everything back together on the car, I gravity fed the lines, making sure I had the new fluid coming out of the bleeders.
I then bled the system the way I have done it in the past, with the help of my assistant (wife). Still bad response. I then gravity bled the system twice more without an improvement.
Getting frustrated at this point, I checked the master cylinder again and without thinking, I got back in the car and pushed the pedal a few times. Oh cr**, I left the cap off the mc. Luckily, no fluid on the fender. I cleaned up the little bit of a mess, put an old towel under the mc and had my wife push the pedal slowly. A bit of a fountain of fluid went up the drain in the reservoir for the rear brakes and I’m thinking that the master cylinder may have ‘burped’ a bit of air.
I think that this helped some with the pedal response. I wiped the fluid from the sides and top edge of the mc, put the cap back on and tried the brakes again. When I checked the mc again, there was fluid weeping out.
Now the interesting part. I looked at the dozen year old gasket on the old mc cap and it looked pretty good, also made in USA stamped on it. I cleaned the gasket carefully and it looks and feels like new. After putting the gasket in the new cap and pulling the wire ring over, it feels more secure, actually taking a little bit of an effort. Now the brakes feel good and I haven’t seen any weep. I am thinking the cap needs to be secure (not weeping) for the best braking. Glad I didn’t throw the old master cylinder away.