Master Cylinder buttons
 

I just replaced the master cylinder on my 83 300TD. I noticed for the first time (I guess) the two black buttons on the top of the brake fluid reservoir. Each one seems to be associated with the level switch connectors on the front and back reservoir sections. Any idea what these two buttons are for? They each have a spring return function of some kind.
Thanks for your help.

the black covers themselves are seals to keep dirt and moisture out, if they are cracked they should be replaced

By all means replace them, especially when trying to use a power bleeder. :eek: :eek: If they are cracked/old brake fluid will squirt right out of there when pressurizing for a bleed. Not good! :eek: I am thankful I got the pressure relieved fast enough and managed to wipe up the leaked fluid. I had to go to the stealer and pay $6 for two of those. :mad:

seals for what... and what are the internal springs for?
Thanks for the help.

dirt and moisture, the buttons inside are for the fluid level indicators

If either of those switches goes down then it triggers the "brake" light on the dash (same one as the parking brake)......so your parking brake spring needs to function properly to keep that light off while in normal operation. :rolleyes: Mine does, but the 83's pedal/parking brakes are very loose and sloppy so the light stays on. The brakes can't even hold the car on a slight grade anymore, we'll need to look into that soon..... :rolleyes:

level switch "test" buttons... very cool. I'll try them out in the morning. Thanks a bunch.