Brake pedal going down

[BootlegCB7]

Well, I did my rear drum and bled my brakes. now When I brake, the initial paddle response is tight and good. when the car fully stops, the paddle starts to drop on me, if I pump a bit it comes back up, but starts to drop again.

I bled the brake wrong probably, I just open the valve, let my friend pump like 10 times, then close it.

so should I bled my fluid again the way people posted, open, slowly pump and close and repeat again?

[OldSchoolCB7Fan]

Well, I did my rear drum and bled my brakes. now When I brake, the initial paddle response is tight and good. when the car fully stops, the paddle starts to drop on me, if I pump a bit it comes back up, but starts to drop again.

I bled the brake wrong probably, I just open the valve, let my friend pump like 10 times, then close it.

so should I bled my fluid again the way people posted, open, slowly pump and close and repeat again?

not sure if this is going to fix the problem, but its worth a shot, i've seen people open up the brake fluid reservoir and then pump your brakes while the car is on, supposedly you can get the bubbles in the brake lines to leave from there, then just put the cap back on when the pedal feels stiff again. i've done this before and it worked, try it out.

[TypeG]

there is a chance that your master cylinder is going bad, but since you just did a brake job, it's probably air in the line.

when you bleed them, do it like this: pump until the pedal gets firm, hold the pedal down and don't let it up, open, then close. pump it up again, hold it down to the floor, open and then close. repeat until you see new fluid coming out or until you are sure no more air is in the line. bleed all lines that were interrupted.

also, watch the fluid level of the brake reservoir while you are bleeding and make sure the fluid doesn't get to low. later.

[johnl]

The master cylinder is leaking. If you can't see any signs of leakage or the fluid level isn't going down then it's leaking internally. When this happens fluid (and pressure) leaks past one of the piston seals and then back into the reseviour, so you have a firm initial pedal, then the pedal sinks as you lose fluid from the cylinder back into the reseviour. You can pump it back up, but you start losing fluid from the cylinder again and the pedal sinks again.

I'll say it again for clarity, when this happens the fluid level doesn't go down as with an external leak, but it's just as much of a problem. This problem can be intermittent, or it can be constant, but it will only get worse.

It may seem no more than an irritation, but it's potentially dangerous as one of the cylinders (the MC in effect contains two cylinders, one in front of the other) isn't holding pressure and what will happen is that one of the diagonal braking circuits will operate at a lower pressure than the other, and you lose braking performance (you may also lose control in hard braking in slippery conditions because the braking force won't be distributed correctly). Not only that, but the problem could become suddenly worse at any time. You need a new MC.

[BootlegCB7]

johnl's response is what I feared, I have had sponge paddle before, never like this one cuz initial feedback is very strong. but I found some ebay mc by adler, seller claiming oem . price sounds good for a new mc, how about it?

http://cgi.ebay.com/ebaymotors/90-97...spagenameZWDVW

[JohnD1079]

i didnt read johnl's response, but it sounds like you bled it wrong. Your not supposed to pump while the valve is open, but until i read that part of your post, my intial thought was Master cylinder.

[Old School]

there is a chance that your master cylinder is going bad, but since you just did a brake job, it's probably air in the line.

when you bleed them, do it like this: pump until the pedal gets firm, hold the pedal down and don't let it up, open, then close. pump it up again, hold it down to the floor, open and then close. repeat until you see new fluid coming out or until you are sure no more air is in the line. bleed all lines that were interrupted.

also, watch the fluid level of the brake reservoir while you are bleeding and make sure the fluid doesn't get to low. later.

OK this is very close to correct, I'm sure TypeG knows what he want's to say but maybe just didn't quite type it out exactly how he wanted.

1. Fill the reservoir.
2. The brakes must be bled starting from the brake cylinder furthest from the master cylinder. This means the right rear is bled first. The left rear is second. The right front is third. The left front is last.
3. Follow TypeG instructions.
4. Just to be clear, the peddle must be held down until the bled valve is closed so air dose not get sucked back into the system!

[Old School]

.

Just to be sure re bleed the system again correctly to see if the problem is still there before you start buying parts!!!!

[irkage]

That happened to me when my master cylinder was failing.

[ChillPhatCat]

This was happening to me back when I got my car inspected... the shop said they couldn't find a problem with the brakes. Ever since I took it in the pedal has been just fine... All I can figure is that it must have fixed itself when they bled the brakes and they just didn't notice that there was air in the line.

[IBCNYA]

If your master cylinder leaks out into your brake booster and can eat out the seal in the booster. If this happens even if you replace the master, youll still have problems from the booster leaking vacumn. Had it happen to me twice. Also make sure your mechanic bench bleeds the master cylinder prior to intstalling it, this makes bleeding alot easier.

[Opticon]

Well, I did my rear drum and bled my brakes. now When I brake, the initial paddle response is tight and good. when the car fully stops, the paddle starts to drop on me, if I pump a bit it comes back up, but starts to drop again.

I bled the brake wrong probably, I just open the valve, let my friend pump like 10 times, then close it.

so should I bled my fluid again the way people posted, open, slowly pump and close and repeat again?

pump a few times, hold and open and close valve, then release pedal

[xCB7 VA SP4R10x]

there is a chance that your master cylinder is going bad, but since you just did a brake job, it's probably air in the line.

when you bleed them, do it like this: pump until the pedal gets firm, hold the pedal down and don't let it up, open, then close. pump it up again, hold it down to the floor, open and then close. repeat until you see new fluid coming out or until you are sure no more air is in the line. bleed all lines that were interrupted.

also, watch the fluid level of the brake reservoir while you are bleeding and make sure the fluid doesn't get to low. later.

X2: my brake master cylinder was bad not TOO sure of exactly what it was but i know that after i changed it, it never went bad again. every once in a while at a stop sign or light.when i
slowly applied the break it would steady its way on to the floor. but i didnt have the same problem when i slammed the brake or it was somewhat fast.if you have the same problem 99.9% sure its the brake cylinder

[js593]

johnl's response is what I feared, I have had sponge paddle before, never like this one cuz initial feedback is very strong. but I found some ebay mc by adler, seller claiming oem . price sounds good for a new mc, how about it?

http://cgi.ebay.com/ebaymotors/90-97...spagenameZWDVW

This was my exact problem. I replaced mine with a Cardone Remanned to OEM spec's. Still works great. People recommend buying it from the dealer, but everyone i know that works on honda brake systems says the remanned ones can last longer then the new, depending on how the seals last, and whatnot. I recommend re-bleeding the lines, top off the fluid, and check if you get that same sponge feeling. If you do, replace the MC - Do not drive until you do, It could fail completley at any time and cause an accident.

[bcjammerx]

dropping pedal is most often a failing master cyl.

My slave cyl crapped on me overnight...

possible that the new fluid flushed out debris that freed the inner bleed...rebuild...cheap and easy.