brake problem

My car is a 94 prelude and my problem is brake. I just noticed whenever I step on my brake pedal, it will stowly go down all the way to the floor. it only happens when my engine is running and it doesnt do that when its not running. My car has ABS brake but it doent show any trouble code. Any expert out there can tell me why?? Thanks for any help.

u have to bleed ur brakes u have air in the lines or possibly a hydraulic leak from the rear wheel cylinders or the master cylinder sometimes the leaks cannot be detected so goodluck

u have to bleed ur brakes u have air in the lines or possibly a hydraulic leak from the rear wheel cylinders or the master cylinder sometimes the leaks cannot be detected so goodluck

my girlfriends ride has the same problem. but just like ghjtang said, brake pedal slowly goes down to the floor only when engine is running. blake pedal is normal when engine IS NOT running. is that mean air gets in the lines or master cylinder leaks only when engine is running??

My car is a 94 prelude and my problem is brake. I just noticed whenever I step on my brake pedal, it will stowly go down all the way to the floor. it only happens when my engine is running and it doesnt do that when its not running. My car has ABS brake but it doent show any trouble code. Any expert out there can tell me why?? Thanks for any help.

Is your breake fix yet? I want to know because I also drive a prelude and my brake is doing the same shit.

yea the only problem it could be is a leaky wheel cylander or maybe air in the lines but most likely it is leaking fluid check the brake fluid level and if its low or empty fill it and watch it and if it goes down within a short amount of time its leaking break fluid and when a car is off the break system does not ever work properly in any car if you pump the brake while its off it will go hard.

my girlfriends ride has the same problem. but just like ghjtang said, brake pedal slowly goes down to the floor only when engine is running. blake pedal is normal when engine IS NOT running. is that mean air gets in the lines or master cylinder leaks only when engine is running??


check rear wheel cylinders and if not master cylinder is bad take a uv light and check under the master cylinder and if you see residue then theres your prob. because i had aal the same symptoms you guys had so i went crazy trying to fix it finally i fixed it by changing master cylinder.. also the brakes work on engine vacuum so with the car off its gna feel hard but as soon as engine is on then the brake booster works and makes braking alot easier but what happens is if theres a hole in the system when you push the brakes the pressure is gna drop and the pressure will not be returned hence the soft pedal

I have the same problem with my lude. and probably there are 57,000 people around the world who drives prelude have the same problem. I already replaced my master cylinder and replaced my brake fluid from all the wheels. I dont see any leak and my brake cylinder is always on full level. But my brake pedal still slowly go down to the floor. what else do I need to check thats causing this problem?

check rear wheel cylinders and if not master cylinder is bad take a uv light and check under the master cylinder and if you see residue then theres your prob. because i had aal the same symptoms you guys had so i went crazy trying to fix it finally i fixed it by changing master cylinder.. also the brakes work on engine vacuum so with the car off its gna feel hard but as soon as engine is on then the brake booster works and makes braking alot easier but what happens is if theres a hole in the system when you push the brakes the pressure is gna drop and the pressure will not be returned hence the soft pedal

soft pedal means that the hydraulic system has a air leak or pressure leak main spot master cylinder and so you know that it wont be soft with the car off because it uses the brake booster and the brake booster is powered by engine vacuum and one more thing im not trying to step on anyones toes but the major no no is reviving dead threads they are defined as more than three months old anyways you also have the rear wheel cylinders which are located in the brake drum also did you open a brake line like take a brake hose off or run really low on fluid because you mentioned that you changed your master did you remember to bleed the whole brake system including the master

My car is a 94 prelude and my problem is brake. I just noticed whenever I step on my brake pedal, it will stowly go down all the way to the floor. it only happens when my engine is running and it doesnt do that when its not running. My car has ABS brake but it doent show any trouble code. Any expert out there can tell me why?? Thanks for any help.

damm.. 57,800 people around the world have brake problems like yours???iwonder if alll these people drives prelude?

It's a common problem. Just get a friend and bleed your brake system.


Remove the top of the master cylinder reservoir.
Using a turkey baster, suck out as much of the old dark inky fluid as you can.
Clean any sediment out of the reservoir with a clean, lint-free rag. (Do not spill any brake fluid on any painted surfaces, it will remove the paint immediately.)
Fill the master cylinder with clean brake fluid.
Replace the top of the master cylinder reservoir.
Pump the brake pedal several times (15 or more).
Using a box wrench that fits the bleeder bolt, loosen the bleeder valves, but leave them closed. (A little penetrating oil drizzled on the bolts the day before will help to loosen them).
Using a piece of clear plastic tubing (aquarium tubing works fine), push one end of the tube over the brake bleeder bolt.
Put the other end of the tube into a small, clear bottle with an inch or two of clean brake fluid in it. (This will keep air from being sucked back into the brake cylinder.)
Put a piece of 1 x 4 lumber or some other "spacer" under the brake pedal to prevent the pedal from traveling too close to the floor.
Remove the top of the master cylinder reservoir.
Top off the master cylinder reservoir with fresh fluid.
Replace the top of the master cylinder reservoir.
Have your helper sit in the driver's seat and slowly depresses the brake pedal with an even force and hold it down. The helper should shout "down" when the pedal is down as far as it will go.
Starting with the rear passenger wheel (back right for righthand drive cars), turn the bleeder bolt to the left one quarter-turn. Old fluid and air will go down the tubing into the bottle. When the fluid stops, close the bleeder valve.
Shout "up" to your helper, who at this point should remove his foot from the pedal allowing it to move up.
Repeat this process until new, clear fluid comes from the bleeder tube. (After every five (5) times the brake pedal is depressed, top off the master cylinder reservoir with fresh fluid. Never let the reservoir get too low, or air will be sucked into the master cylinder.)
Tighten the bleeder bolt.
Repeat steps 14 to 17 on the left rear wheel.
Repeat steps 14 to 17 on the right front wheel.
Repeat steps 14 to 17 on the left front wheel.

I have a 94 prelude type s that the brakes are locking up after being driven a few miles and the pedal gets rock hard need help to figure this out

I have a 94 prelude type s that the brakes are locking up after being driven a few miles and the pedal gets rock hard need help to figure this out

My pedal never gets soft until I bleed the front again. The mechanic that I took it to said that the brake fluid is contaminated and has blown out the seals in the calipers and the master cylinder. Can this be true?