CJ Master Cylinder Replacement Issue.
Folks, I just had to have my Master Cylinder replaced so I could pass the State Safety Inspection. The Inspector's garage installed a rebuilt one ($139.00) and it leaked everywhere! I took it back and made them install a second one. After 4 Master Cylinders I took the Jeep home and installed my own for $19.95
The bad news, my install leaked too. I read in this forum about machining the top of the Master Cylinder so I tried that, no joy.
Long story cut short... The issue with all these Master Cylinders was the lack of breather hole on the cover. I drilled a small hole on the cover, installed the rubber diaphragm, and all the leaks stopped... Looks like rebuilt covers come with the vent hole blocked, drill it out, and get back on the road!
Hope this helps!