Brake fluid reservoirs

[Tonylong]

I've started noticing that the fluid in the two fluid reservoirs is changing level.
Every week or so the front reservoir gets lower (1/2 ") and the rearmost
reservoir will overflow when I check it. This happens cold or hot.
I presume some seal between the two is failing. There is no other abnormality in the brake
system, noises, etc.
Anybody have any input on this ?
TIA

 

[jsinga]

Start looking for a master cylinder.
Fluid is not supposed to pump between the 2 sections.
You can get repair kits, sometimes that will fix them. It just depends on if the bore is pitted badly. Aluminum gets water traped against it and really rots out in there. Take it apart and look at it before you buy a kit.
A rebuilt one was @ $80 when I changed mine. It started leaking out the back end.

JS

 

[berky2500]

As he said, go for the master cylinder, I just replaced mine, but it just wouldn't build pressure. The front and rear systems should be isolated and not cross-contaminate each other. The only common link they have is the master cylinder.

 

[jjacob12345]

Brake fluid reservoir-one should be empty?

I'm doing some brake work on my 75 vette. My master cylinder has 2 reservoirs’ of which only one has fluid. I was told that the 2nd reservoir is supposed to stay empty. In my Chilton manual they said the front reservoir is for the front brake and the rear reservoir is for the rear brake. I'm confused now. Are both of the reservoirs supposed to have brake fluid in it?? I was trying my best to bleed my brake system this weekend, however I could not get any fluid to come out of the rear brakes. I am beginning to think that both reservoirs should have fluid. Can anyone confirm this? I plan to be back in the garage next weekend.