Help, pedal goes soft

[Jorgen]

This is for my friend, he has a 91 civic ex (i think)
His brake pedal is going soft while driving.
Fluid level is good.
My guess is brake master cylinder.
So do I replace the vacuum 'drum' with it?
http://tbn2.google.com/images?q=tbn:blj2DVA2xxIOcM:http://z.about.com/d/autorepair/1/0/x/S/master_cylinder.gif

You can pump it and it gets stiffer, but as you drive it gets soft again.

[MOOREOFSTEPHEN]

must have a slow leak

[zebrafantastic]

If the rotors are warped it will push away the piston as you drive, meaning you'll have to pump the breaks a few times to get it to seat. Check on that as well. Easy fix if thats the problem.

[Jorgen]

I don't think so...
I drove it around. You could pump it up and make it stiff, but it would quickly go away.
I looked for leaks, but didn't find any.

---------- Post added at 07:44 PM ---------- Previous post was at 07:41 PM ----------


If the rotors are warped it will push away the piston as you drive, meaning you'll have to pump the breaks a few times to get it to seat. Check on that as well. Easy fix if thats the problem.

Wouldn't that be obvious in the form of excessive noise or vibrations?

[Wes]

You probably just need a new BMC.

Check if its leaked into the booster.

[Jorgen]

if it has I'm guessing I will need to replace both?

[zebrafantastic]

Possibly, it's just an assumption. I drove my buddy's 02 wrx he just bought and it had the same problem; due to it's warped rotors. There werent any other blatantly obvious problems.

[kush240]

that sux, my bros car is doing the same thing, not always tho just every once in a while. id tell u to bleed the breaks but that didnt work for me so maybe it is the BMC

[Casey]

just get a new master cylinder

[Andy C]

i really doubt that the booster is bad

[Batlground Motorsports]

If the booster was bad it would make it hard to push the pedal. It won't hurt to bleed the brakes first. Its free. Check the soft rubber lines going to the calipers as well. if they are fatigued then you can get a soft pedal. If you still have a problem, replace the master cylinder, then at least you know everything else is good.

[Howard]

Booster troubleshooting. Pump brakes up then start car if the pedal goes down a little the booster is working.

Master cylinder - Pump brakes up and hold, if pedal goes down then check for leaks at the wheels and lines. If the pedal remains firm but when you release it and push it again and the pedal goes down the Brake Master Cylinder is bad

[Jorgen]

I think its the master cylinder.

[Michael]

You've bled the brakes, right?

Look it up to make sure you did it correctly, etc. If your brake pedal is soft, the typical reason, before any other, is air in the brake lines.

[Howard]

You've bled the brakes, right?

Look it up to make sure you did it correctly, etc. If your brake pedal is soft, the typical reason, before any other, is air in the brake lines.

True if the brakes were just worked on. But air does not just get into a working system. There is a problem with the brakes.

[Michael]

True if the brakes were just worked on. But air does not just get into a working system. There is a problem with the brakes.

Well we didn't get any information about recent maintenance, but car guys work on their cars, it's just assumed. I'd guess that he has just messed around with them, like you said.

[deucefawty]

It's a Honda...end of story. I agree, bleed the brakes first, it's free or at most 5 bucks and probably your problem.

[Memme]

This is for my friend, he has a 91 civic ex (i think)
His brake pedal is going soft while driving.
Fluid level is good.
My guess is brake master cylinder.
So do I replace the vacuum 'drum' with it?
http://tbn2.google.com/images?q=tbn:blj2DVA2xxIOcM:http://z.about.com/d/autorepair/1/0/x/S/master_cylinder.gif

You can pump it and it gets stiffer, but as you drive it gets soft again.


Do the words " Brake Pedal" really mean "my penis"?

And by "friend" do you mean, yourself?

It's okay man... we're here to help.

I'm almost like a Doctor. :D

---------- Post added at 12:23 AM ---------- Previous post was at 12:21 AM ----------

If it's getting soft when you're "driving", change the "cylinder"... it might be too loose...

Try the rear cylinder... if the front one is worn out.

The rest of you need to learn to read... this isn't about brakes at all... you people are so oblivious. THIS MAN NEEDS HELP... REAL ADVICE!

[deucefawty]

I see what you did there...

[Jorgen]

Memme...
that is the best advice I've had this year!

[Lonnie D]

Just drop a couple viagra's in the BMC resevoir and then problem solved.

[BigJack]

Does the car have ABS?

[silviatran]

haha u know what else goes soft?

[Memme]

haha u know what else goes soft?

You're a little late to this party... but HAI THERE! :wiggle:

---------- Post added at 08:02 AM ---------- Previous post was at 08:01 AM ----------


Memme...
that is the best advice I've had this year!

I do what I can. :goodjob:

[sullen]

ok so i see there are a few home mechanics here....

1. warped rotors do not cause you to have to pump a brake pedal. they will cause pulsatrion in the steering wheel when fronts are warped and a vibration in the chassis when warped in the rear.
2. brake booster will ONLY NEED REPLACING if it does not hold a vacuum.
3. Master Cylinders will not always show an external fluid leak. this is due to the fluid bleeding by the seal and causing an internal pressure loss.
4. if you have no clue what the hell you are talking about, you should probably refrain from posting something stupid.

that said, Jorgen, the Master Cylinder is leaking. Replace it. they're like $40

[Jorgen]

Thats what I told my friend, replace BMC.
He was supposed to call me, I dunno what he's done yet.

[sullen]

yea, i like all the BS info though. warpage causes brakes to go soft.... learn something new every day.