My '99 Accord LX (4dr, 4 cyl vtec, non ABS) just crossed the 200,000 mile mark about one month ago. At about that same time I noticed that my brake pedal was getting pretty spongy. I've repaired brakes myself all of my adult life so I didn't hesitate to take this task on. The rear drums were also squeaky so I began there. I installed new wheel cylinders and metal lines along with new shoes and hardware. I then installed a new master cylinder and new calipers, pads and rotors. When I attempted to bleed the system, I got great pressure at the wheel cylinders but almost nothing came out of the bleeders at the calipers. I then returned the master cylinder for another one and I replaced the front brake hoses. To my surprise, I'm still getting very little brake fluid to flow out of the bleeders on the calipers. The brakes won't pump up fully and if you start the ignition, the increased pressure from the booster sends the pedal to the floor. The only thing I haven't replaced is the brake proportioning valve. All the lines appear free and un-kinked so this would appear to be the only answer despite the fact that I've never had this happen before. Are Hondas know for proportioning valves failing? Am I off base with my diagnosis? Help!!!

 

Hmm.. So your rear wheel cylinders bleed well but not your front calipers.

My first step before replacing anything would've been to check the brakes and make sure that they are all wearing somewhat evenly. Then as I had it apart, I would've pressed the front caliper pistons back in to make sure they're moving properly and also make sure the slide pins both slide easily, and finally bleed the brakes..

Your concern sounds like either a caliper or stuck slide pin issue, thus the spongy pedal.

Good Luck