jeffruby

So i have a 96 accord with a h-22 swap and my brake pedal bleeds all the way down to the floor when pushed. No leaks and no fluid being used. Could this be the booster maybe?

Schmitey

With the engine off, pump the brakes and see if the pedal gets firm and STAYS FIRM. Now start the car...if the pedal is sloppy and will not get firm again then its a bad brake booster.

JDM_DC4_Fanatic

not always true. It could be a mad master cylinder. Sometimes the o-rings in the lines will let the fluid flow back into the resivoir. You wont see leaks, the level wont go down, but the pedal will be mushy.

Schmitey

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDM_DC4_Fanatic &raquo;</TD></TR><TR><TD CLASS="quote">not always true. It could be a mad master cylinder. Sometimes the o-rings in the lines will let the fluid flow back into the resivoir. You wont see leaks, the level wont go down, but the pedal will be mushy.</TD></TR></TABLE>

hence the emphasis on STAYS FIRM (that's assuming it was bench bled correctly from the start)


Modified by Schmitey at 9:00 PM 6/26/2007

JDM_DC4_Fanatic

the brake booster will never make the pedal as firm as when the car is off. So, even when the car is off, the pedal can still be firm with a bad master cylinder. Its when the extra pressure from the booster is applied and the car is running, that the pedal never gets hard.

Its extremly rare that the brake booster will fail. However, the most common symptom of a bad booster is when the pedal is rock hard all the time, as if the car is shut off, bu it doesnt have any braking force. This happens because the booster doesnt multiply your brake force, and the only pressure that is being applied is by foot. Similiar to pressing on the pedal with the car off and trying to stop the car at speed.

Schmitey

f*ck it. Its ******** like you that made me leave this site to begin with. You gotta have the last say on everything...every post I make. You're not telling me anything I don't already know. I'm simply trying to help the guy out one step at a time...for starters I just wanted to know if the pedal ever gets firm when the car is off. I don't proclaim to be an expert, but I post on the stuff I know about. Why complicate things if the original poster doesn't know anything about leaky master cylinders or brake boosters? I'm just trying to find the symptoms that they have. And a bad brake booster will give you a sloppy pedal only when running...saw one a few days ago.

I gave this site an honest second chance after taking over a year off. Most everyone is awesome and the old experts like touring accord are still around. Its always the one or two asshats that ruin the experience.... I like being able to help people! But its just not worth it at the cost of someone busting my ***** on every post... I even managed to work on the anger management since the last go around...its still just not worth it to me. Later all!




Modified by Schmitey at 9:34 PM 6/26/2007

jeffruby

JDM_DC4_Fanatic

I dont think you know what you are talking about. I'm not trying to be an ******* or anything, but lets look at the facts.

you said<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schmitey &raquo;</TD></TR><TR><TD CLASS="quote">With the engine off, pump the brakes and see if the pedal gets firm and STAYS FIRM. Now start the car...if the pedal is sloppy and will not get firm again then its a bad brake booster.</TD></TR></TABLE>

This is not true. If the booster doesn't work, the pedal will always stay firm. The booster is supposed to multiply the braking force of you foot, making it easier to push the pedal. Now, the opposite of that would be, your foot moving all the force...which means hard pedal. So, lets think about this. How would a brake booster cause a mushy pedal if it wasn't working properly?

Lets even use your example.
The car is off. You pump the pedal, it gets hard. Now, if the car is off, there is no vacuum going to the booster, thus it is to active at this present time.

Now we start the car, you pump the pedal, it stays firm. The engine is on, this means that there is vacuum being created by engine, so the booster should be working. Now you can pump the pedal easier. This is a properly working brake booster.

If the brake booster wasn't working, like when the engine is shut off, why would the pedal be mushy? Wouldn't the pedal be firm? like when the car is off?

I'm not trying to be an *******. I'm trying to help the OP. You gave him incorrect advise, although you are trying to help, and I give you an A for Effort, your advise is not helpful if its the wrong advise. Whats worse, is people who are not knowledgeable, or misinformed passing on their misinformation, and it spreads like a cancer across the forum.

So, please, point out to me where I am being an *******? I'm quite curious

Mjfan12

my mushy pedal was due to bad fluid. feels great now.

Bruce Banner

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mjfan12 &raquo;</TD></TR><TR><TD CLASS="quote">my mushy pedal was due to bad fluid. feels great now.</TD></TR></TABLE>
Was your fluid dirty?

livermore

I just went through the same thing but it turned out to be the new MC I installed was defective. Besides a bad mc, air in the lines and leaks, I've seen frozen caliper pins and binded adjusters in rear drums cause a low pedal too. Assuming that everything else is mechanically sound, I'd plug test the mc. Can't hurt. If it's good, put the lines back on and bleed the system. Kill two birds with one stone. If it's bad your half way to taking it off. good luck

wingback44

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mjfan12 &raquo;</TD></TR><TR><TD CLASS="quote">my mushy pedal was due to bad fluid. feels great now.</TD></TR></TABLE>
Same here.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bruce Banner &raquo;</TD></TR><TR><TD CLASS="quote">Was your fluid dirty?</TD></TR></TABLE>
Mine was.

cam22a

What is "plug testing the mc"? Take the lines off and plug the holes somehow to see if the pedal still goes down? Any suggestions what to plug the holes with? Will fingers be enough? ta

JDM_DC4_Fanatic

your fingers wont hold the pressure. To do the plug test, you need 'caps' to put in place of the lines. Go to a parts store and ask for a Brake Master Cylinder bleeding kit, they should be in there.