Got an 84 truck (2WD, 5-speed). Have had to fill the brake fluid reservour three times in the last few weeks. I don't see ANY fluid spots on the ground where parked. Took off all four tires and inspected calipers for leaks. None! Also followed all plumbing/lines from MC to brakes. No visible leaks. Looked on floorboard below foot pedal and no leaks. Crazy! Anyone make a sugestion as to where so muc fluid could be going????
I agree with socal, I had this happen to me. The brake fluid leaks out the back of the master cylinder and gets sucked into the intake through the booster and is burned in the engine. Took me a couple of months to find it.
If your absoulutley sure its not leaking externaly then its prob around or in the brake booster. Did you do any brake work recently? If so and you had lines off and did not bleed the system alot of the air will work its way out and "seem" to consume fluid.