Rep Power: 273

I have an '02 Civic Si and had notice the travel in my brakes were more than normal and had started to go soft. I bled the brakes and no change. With the car off the pedal is firm. Press it 2 or 3 times and hold it and it won't sink. I turn the car on and it will sink. Figure it's the Master Cylinder. Had it changed, had the system bled and when I first started driving it the pedal was firm again and seemed normal, at least better than it was. After driving a few more days on the new MC I noticed my pedal dropped while at a traffic light. Pumped the brake it was firm again. Drove a few more days and it started doing it more.

I'm not sure what the problem is. I guess it could be a defective MC. Also of note, when the pedal is soft and the ABS kicks in it will push the brake pedal up. I have no fluid leaks.

Any thoughts or suggestions?

 
Rep Power: 273

54 views and not even a comment?

I've noticed the last couple of days the problem seems to get worst as the braking system warms up. First thing in the morning the brake pedal is firm and by the time I get to work it will begin getting soft. By the end of the day, after the car has sat out in the heat, the brakes will get soft off and on all the way home.

Still not getting check engine light or abs light. Is it possible there's some kind of internal leak or fluid bypassing occurring in the ABS Module? Do I need to bring it to the dealer to have them hook their equipment up to make sure the ABS module is bled in the event there's air in it?

 
Rep Power: 0

Have you rebuilt the calipers? The inner seal, not the dust seal may be worn. $3 per side.

 
Rep Power: 0

Check your rear wheel cylinders too. You must have a leak or air pocket. Why did you bleed the brakes to begin with? I assume a rotor/pad replacment?

 
Rep Power: 273

Keep in mind this is an EP3, so I have 4 wheel disc.

I originally bleed the system due to the soft pedal. It firmed up but after a couple of brakings it resume being soft and required a quick pump to firm up.

Same thing after the master cylinder replacement.

I'll be replacing pads this weekend so I'll visually inspect the boots.

Thanks.