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1996 LX. When at a stop, the pedal fades and the car starts moving. Have never replaced entire fluid, just top off when bleeding. Any ideas?

 
Rep Power: 103

I had a 91 Civic do that, it was a rusty rear brake line. I ignored it and eventually the brakes went out/pedal hit the floor.

I had that happen in a second car as well. This time it was rear wheel cylinders. After enough fluid seeped out it eventually emptied the fluid reservoir and the pedal didn't stop the car anymore.

 
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Put new wheel cylinders on the rear about 4 months ago after I broke a bleeder. Brake lines arent crusty and it isnt loosing fluid. Only 80K miles. Im assuming water in the lines is compressing.

 
Rep Power: 512

water is essentially incompressible, so that wouldn't be the case. If I had to guess, you have an internal leak in your master cylinder.

 
Rep Power: 518

Pedal sinks to the floor but there is no fluid loss: Master cylinder is bad, internal failure.

 
Rep Power: 0

Pedal hasnt gone to floor, but I havent been sitting that long. SHould I simulate an extended period on time sitting in the drive to see if it eventually goes to the floor?

 
Rep Power: 103

in park, when you step on the brake and hold hard pressure on the pedal, how far does it go? does it just slowly go down like 1/2" and then hold that height?
in park, if you blip the throttle and then step on the brake while the rpm's are still falling, when you step on the brake the same way does the speed of pedal drop increase?

 
Rep Power: 518

"Floor" is more of a description of the feeling rather than the pedal actually going that far down. Maybe i should have said 'scary low' or something?

It may sink 3/4 of the way down then hit the secondary where you still have 2 wheels with working brakes that might slow the car down.