my car is a 87 turbo chassis . it sits every winter. i went out to the car yeaterday pushed down the brake to start it and the pedal went to the floor. NO fluid leaks ,no rusted out lines. went out there today and i have a good pedal and the car stops. now the car has new pads, rotors all the way around, the master cylinder was low a bit but it did have fluid in it. now the first time i went out the temp outside was 10 degrees F, today it was 38 . any ideas thanks

 

Sounds to me like a frozen and or frozen calipers...I would check to see if the sliding bolts to the calipers are seized...

 

Probably a bad master cylinder.

 

Check closely for leaks everywhere including at the joint between the master cylinder and the booster. If there are no leaks, the problem as dazed01 says, is most likely a failed master cylinder. In that case, the internal seal is failing and the fluid is "leaking" from the front of the MC past the seal to the rear of the MC when you press on the pedal. The symptoms you indicate are typical.

 

I have seen that problem on cars with Stainless Steel braided lines where the cover separated from the line and the cover fills with the brake fluid when you press the brake, only to have the fluid seep back when the pressure is off the brake and have the lines look normal visually.

So if you have SS brake lines, I'd look at that too.

 

Not sure why you have to "push down the brake" to start the car but anyway...
Could just be that after sitting for a while you're losing the vacuum in the booster- maybe a failing check valve.

 

well my driveway slants downhill,
thanks for all your help on this

 

I noticed whenever it's cold the brake fluid reservoir leaks, it has maybe half a cm of fluid in it and my pedal goes straight to the floor.