So, I recently finished swapping out the engine on my 96 Civic. And other than a CEL for the CKF sensor not working and the car needing a tune up, everything seems fine except for my brakes won't brake as hard as they should. When driving, the pedal goes almost all the way to the floor and in park pumping the brake would normally build up pressure but it doesn't. I can keep pumping indefinitely. There does not appear to be any brake fluid leaking so I'm not sure what could cause this. The car has sat unused for almost 4 months so I drove it around to try to grind the rust off the rotors and that helped a little with the braking but it didn't help the pedal going almost to the floor. I've never tackled any repair this big before but the brakes were the last thing I expected to have to fix before this was over. Any help is greatly appreciated. Thx

 

Sounds like you might have air in your brake lines and/or your master brake cylinder is bad. I had the same issue with an integra I used to have and ended up changing the master brake cylinder to solve the issue. Check the brake fluid reservoir and make sure you have fluid in it.

 

There's definitely plenty of fluid. I was researching it earlier and people were saying the same thing, that the master cylinder may be bad or the lines might need bled, but if I never really touched the brake system much when I was working on it, would this happen? The only thing I did to the brake system was disconnect the brake booster vacuum hose (think that's what it's called ??). Could removing and leaving that hose have introduced air into the system?

 

No. Leaving the hose off would cause the pedal to be tough to push down as it would no longer have vacuum assist. Start with bleeding the brakes. Typically, a bad master will feel normal until you stay rested on the brake, like at a stop light, and the pedal will start to slowly go all the way to the floor.

 

Thx for the replies guys. When it warms up a little bit I'll try and bleed the brake lines and see if that helps. Hopefully that solves it.

 

Ok so I bled the brakes over the weekend and no change There was some air in two of the lines so it wasn't for nothing but the brakes are still not functioning at 100%. I have a theory that it might be the check valve in the brake booster hose. If the valve is stuck, and you pumped the brake with the engine off my guess is the booster would not build up pressure and the pedal would depress. whereas normally with the engine off, the pedal would stop depressing after a few pumps. This is just a guess but has anyone had to replace this hose? Not hard to replace but has changing this hose ever fixed any similar symptoms?