Master Cylinder Acting Up

["Frank Bakanau" <FBAKANAU@xxxx>]

I've replaced the wheel cylinders on my C-300 and flushed the system and
replaced the fluid with silicone type. (I like the silicone brake fluid
cuzz it does not absorb moisture which we have a lot of here on Oregon.)
But after I drive the car a bit, the petal gets very hard, the brakes drag
and the stop lights stay on. Hmmm.... So I just crack the fitting loose on
the master cylinder, I get squirt of fluid and all is fine for a while. I
suspect it's a check valve problem in the master cylinder, but before I go
tearing into it, anyone have sage advice?

Frank