master cylinder ?

[boilrman]

I have had a spongy brake pedal for a few days and finally stopped by the parts store and they said I have a leak somewhere.

I took the lid of the master cylinder and the fluid from the front compartment started to flow out. It was full and under pressure. The rear compartment had about 1/2" of fluid in it. I refilled the rear compartment and the brake pedal has returned to what it was before.

My ? is, why was the front compartment pressurized?

I haven't pulled the drums yet to look for leaks, but I dont understand why the front compartment was under pressure.

Any help would be appreciated.

Thanks

Chad