This has been going on for a month. I'm totally stuck and ready to ditch the car if I can't get it figured out by this weekend, which is when I'm planning to swap... keep your fingers crossed.

Master Cylinder went out. Brakes would go to the floor and not apply pressure. Sooo I replaced the Master Cylinder and the Brake Booster at the same time, bled the brakes three times afterwards (I also bench bled the mc and put the bolt that connects to the brake pedal in the same spot as the old booster). Go to take the car for a test drive, brakes are as hard as a rock. I get a newer check valve(used though b/c Honda has them on national backorder and Napa, Autozone, Advanced, etc. don't carry them). Everything ran fine for a week, and then all of a sudden, while driving, my pads lock down on the disk. If I stop the car, and pull off the brake booster vacuum hose, put it back on and turn the car on then everything works fine until it decides to do this again whenever it wants. There are no leaks in the vacuum hose for the booster. I also rebuilt my front calipers earlier this week, bled the brakes twice, and nothing happened. There is nothing in particular that I can figure out unless my booster is bad. Do you guys have any ideas?

 

Correction: Sounds like the diaphragm valve in the brake booster sometimes may be sticking open. You may want to test brake booster function and check the pushrod clearance adjustment for the master cylinder and brake booster (see service manual) as well as the height adjustment for the pedal:

 

thanks, i'll try that tomorrow night.

so is it possible that the booster is just bad and causing that? i have a warranty on mine. if the pedal and pushrod are adjusted correctly, i can get a new booster... i didn't mess with the measurements of either one.

 

It's possible the booster is bad but, before replacing it, do the brake booster tests several times to see if you can find a defect and also check the pushrod and pedal adjustments.

 

i've done the booster test listed in Haynes and the HSM... it does what its supposed to do, until i start driving and it changes it's mind.

 

The next step would be to check the pushrod and pedal adjustments.