Repeat M/C leak from reservoir lid

[DirtyLarry]

Alright, I am scratching my head on this one. The master cylinder lid started leaking all over the freshly painted inner fenders on my ’72 C20 a while back so I picked up a new lid seal and called it good. A few days later I noticed it was leaking again so I pull off the two lid retaining springs and bent the ends over a bit to help hold the lid on tighter. I figured all would be well….nope! It started leaking again so I bought a new master cylinder from Vhatozone and ran that for a few weeks. Guess, what? The SOB is still leaking! It leaks from the lid at the forward reservoir, which would be for the rear brakes.

I don’t know what do to next other than replace the rear brake hose and maybe wheel cylinders.

Anybody ran into this before? The funny thing is the brakes work flawlessly. It is just the more you drive it the more it leaks from the lid as if it is building pressure that won't release.

The truck is for sale but I want to fix the brakes before I sell it to someone with a brake problem. The truck looks rather rough but it is in perfect running order except for this leak.