79 Master Cylinder and Brake Booster

[scoutpappa]

I did a little work a few weeks back on the back drums of a 79 Scout II with 11 1/4" drums to get the parking brake set. After tinkering and lubing and verifying action of the system I had to bleed the drums to get the drum itself back on. In doing this I naturally keep an eye on the backs just in case something is leaking. So once a week I check the mc and climb under the back to verify that nothing is wet. So what I am seeing is that the back portion of the mc is loosing an 1/8" of an inch of fluid every three weeks. Back drums are dry but it appears that the booster is leaking brake fluid. The m/c itself almost looks to be "sweating" fluid. Brakes work well (for a Scout). No noticable lack of performance but brake fluid is not the best thing to have leaking (taking what's left of the paint off of the booster). So is there a gasket or o/ring that keeps the fluid out of the booster that I need to change and now that this appears to be what is happening do I need to worry that the booster internal (diaphram) is going to go out?

 

[dkminors]

My mc had a similar symptom until I cleaned up the mating surfaces and diaphragm/seal for the mc lid.

 

[towpainter3]

The booster on a Scout cannot leak brake fluid as it doesnt or is not supposed to have any inside it. The rear seal on your m/c is leaking and its running out of the mount flange on the booster. There is a seal on the booster that seals the rod off from the m/c, but if its old chances are some fluid has leaked into your booster.
In other words its time to replace the m/c. Dont do the reman thing get it brand new from Jeff or locally. Just dont do reman they are junk.
Just got done with mine last week it got a new booster and a m/c due to the same issue.
I discovered mine was leaking and the booster was leaking due to a nagging miss I couldnt get rid of . Plugged off the vac line to the booster miss went away. Vacuum leaks can be nerve rackin!!!
The m/c seal can be checked without line removal, just pull the nuts off the booster and your prop valve bolts to allow slck in the lines and pull it forward. You'll see it instantly if its leakin.