chevyboy07

well i got my civic about 2 months ago,and after about 2 weeks of driving it its had brake issues. sometimes they dont work. the pedal will go alllllll the way to the floor,but i let off and push them again and they work fine. i've been a mechanic for a long time,but this has me dumb founded. not low or even losing fluid,just to put that in there. need help please!

hioto

Have you done a brake flush? Might be air in the system or a master cylinder failure.

Cozzimoto

you could check the Brake Booster and see if there are any hose leaks coming from it to the intake manifold. if the pedal goes all the way to the floor that tells me you got no pressure in the booster, so you might want to check that out too.

iim1rmg

Sure sounds like air in the system.

Pump the pedal a few times. Do the brakes come up and feel OK? If so, you likely have air trapped in the system and need to bleed it out.

How does the brake fluid look? It should be close to clear and not brown or opaque. If it does not look clear and you don't know how long it's been in there, it's time to change it and flush the system anyway.

If the problem persists after that, it is probably the master cylinder going. Crudded up fluid will eventually ruin brake wheel-cylinders, calipers, and master cylinders. As a general rule-of-thumb the brake fluid should be changed and flushed every two years, and using a Low Moisture absorbent brake fluid (like a DOT-4) will help.

As DOT 3 gets old, it absorbs moisture. That will cause rust in the system and a cruddy brown color to the fluid. If it gets enough moisture, and the brakes are used, they will heat up to the point that the moisture boils. This can introduce air bubbles in the system that that act like little shock absorbers. When you press on the peddle, it compresses the trapped air instead of operating the brake caliper/cylinder like a good hydraulic system should. If you pump the brakes, it will compress the bubbles enough to work the brakes and bring the pedal up.