Seems that there is some brake fluid getting past the seals

 

 

Think I already know the answer, but just asking in case someone thinks it could be something else.

Not sure if there is a rebuild kit for the master cylinder.

The photo is not from the right angle to see if it is indeed a leak from the master cylinder (MC) unions or between the reservoir and MC.

Rebuild kit for the MC: yes, there is on eBay. I recommend a new MC, especially if you didn't change the brake fluid periodically.

It's definitely not from the unions, but I'm going to double check that it's not from between the reservoir and MC.

Fluid changes at least every 2 years.

8 minutes ago, R_U_AFA said:

It's definitely not from the unions, but I'm going to double check that it's not from between the reservoir and MC.

Fluid changes at least every 2 years.

Then it looks like a seal has failed and the brake fluid is seeping out through the end of the MC. Remember that if fluid leaks out, air gets in.

Not necessarily so, more of a chance high up at the master cylinder than lower down in a caliper however the 6 speed concentric clutch cylinder can draw air in without ever losing a single drop of fluid even when it gets so bad that it needs bleeding every 5 miles.

10 minutes ago, J.R. said:

Not necessarily so, more of a chance high up at the master cylinder than lower down in a caliper.

That was exactly what I said too. Nobody talked about caliper.

12 minutes ago, J.R. said:

however the 6 speed concentric clutch cylinder can draw air in without ever losing a single drop of fluid even when it gets so bad that it needs bleeding every 5 miles.

6 speed concentric clutch cylinder ??? What are you talking about? The topic is about the MC on Felicia and a simple, logical observation that fluid goes out when pushing the brake pedal, then air gets in when releasing the brake pedal.

@J.R. gave an example of a component that can draw air in without that system losing fluid.

Concentric Slave Cylinder. CSC. 

It acts on the clutch mechanism when you depress the pedal to disengage the clutch.

Basic mechanics. 

Thank you for the translation of an unrelated example. If you have anything constructive to share that will help the OP fix his issue on the master brake cylinder, enlighten us. But if you are interested only in bickering, talking semantics, or throwing hateful comments, better stay away. The forum is for helping people, not a platform for people who need anger management classes.

Wow, giving an example of something contrary to your "simple logical" assertion is now a hateful comment! I will bear that in mind when responding to a topic that you participate in.

 

Anger management is a very sensible suggestion though that shows you have good introspection.

 

BTW, air does indeed get in when a master cylinder leaks, as the fluid level in the reservoir falls air comes in through the vent cap to replace its volume.

6 minutes ago, J.R. said:

Wow, giving an example of something contrary to your "simple logical" assertion is now a hateful comment! I will bear that in mind when responding to a topic that you participate in.

His initial reply had other, hateful content. It was deleted after I reported it.

It turns out that it was a small blob of grease that had flicked up on to the servo body from a previously leaking CV joint boot. The position of it right at the mating point between the MC and servo made me jump to the conclusion of a leaky MC. I'm glad I double checked and hadn't ordered any parts.

You can still see some evidence of the old leaking CV boot on the front subframe in the original photo, which I'm yet to clean up.