# soft brake pedal even after bleeding?



## raymilosh (Jan 12, 2005)

Hi all,
I have a mystery. I replaced the master cylinder on a 95 honda accord because when the pedal was pressed, it slowly went to the floor. It wasn't leaking outside anywhere/ consuming any fluid, so i presumed the seals inside the master cylinder were shot.
I bought a rebuilt cylinder, bench bled it, installed it and bled all the brake lines. No air came out anywhere. I thought it odd. The car does have proportioning valves, but there is no bleeder there. It does not have ABS. It is power assist with a vacuum diaphragm. 
When I was done, I started the car and tried the brakes, it stops smoothly, but the pedal is near the floor. It feels very soft and it does not feel right at all. The owner tried it and said it definately didn't feel right. 
I bled it ALOT more and still got no air and it didn't improve anything.

I removed the master cylinder, re bled it and did seem to get some air there, then reinstalled it and rebled everything. Still no air from any of the 4 wheels. The brake pedal still feels really soft.
I did the functional checks of the brake booster and it passed. 
I never did check to see if the 2 master cylinders were identical and the old one is already turned in for the core. I spoze it's possible I need to adjust the rod length, but I'm wondering if there's something I'm missing. 
Anybody know what's going on? I'm baffled and frustrated and this was spostuh be easy and it's turning out to be a big pain and i wanna be done and waaaah.


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## vallyfarm (Oct 24, 2006)

There is a chance, be it a slim one, that you have one or more hoses that are expanding when the preasure is applied. Have someone pump the brake and look VERY carefully to see if the hose swells up a little. These would be the ones made of rubber that connect to the front rotors. All others should be a hard line. But it seems more like moisture in the fluid to me. If you have bled out the brakes properly from a M/C change, all fluid in the lines would now be new, so that isn't likley either. Sorry couldn't be more help. Mike


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## agmantoo (May 23, 2003)

Ray, are you bleeding the brake by yourself or with a helper? If the pedal is spongy I would think you still have air trapped in the system. I would pump at least a small bottle of brake fluid through the system. IMO, there is air there somewhere.


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## barelahh (Apr 13, 2007)

hey,
whenever i change brakes or a master cylendar, i change the fluid completely. 
sometimes when that fluid gets really dark, i will change it out anyway. 
What happens is it gets moisture in the lines and contaminates the fluid. 
BUt the spongy feeling is probably air in the lines at a junction point somewhere. I'll almost guarantee you have air in them since you did change out that master cylendar. those lines that screw into the cylendar probably have a big bubble near the top or halfway down.

PLUS the back lines are the hardest to get the air out of. SOOOOO heres what you do.

Bleed front brakes until the fluid runs clear. then jack the back of your car up under the differential until you get the rear end up high enough to cause the air bubble to travel to the back bleeder valve. Then open the right bleeder on the back wheel. Let fluid run out til its clear then close off bleeder. drop your car back down on the ground and then bleed the left rear wheel til fluid is clear.
Then try your brakes. 
MAKE SURE you have a couple big bottles of fluid and have someone pouring fluid into the cylendar when it starts getting low. Keep it pouring until you get your fluid changed out.


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## HermitJohn (May 10, 2002)

I dont know and am not going to go look it up, but is it possible Honda used two or more different master cylinders on this model year? May look simular and bolt up same but one may need longer push rod or something?

On older cars it can sometimes be big pain when you find the car manufacturer apparently got a deal from some different part manufacturer for part of the year. I've learned hard way over the years to take the old part with you and closely examine both for any possible physical changes the replacement has. If I have to start re-engineering things I want the price difference to be worth it.


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## Beeman (Dec 29, 2002)

I'll assume you have the correct master cyl. I would plug the master cyl with the correct size plugs and then step on the pedal. If the pedal is good you're MC is fine and bled. You could also start by clamping off 1 rubber brake hose at a time with a rounded style clamp, not just vise grips, and see if the pedal improves. If you clamp off the 2 frt. hoses and you see a change your problem is in the frt., clamp the rear and it's better it's back there.
Always bleed from the farthest point and work your way closer to the MC. Also check the adjustment of the shoes if it has shoes on the rear. If the emergency brake is a standard type that activates the rear shoes activate it and see if the pedal improves.


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## raymilosh (Jan 12, 2005)

thanks for the replies, everyone. 
I have replaced all the fluid had it running clear.
I have rrun over a quart of fliud through the various lines. What I have not done, however, is jack up the back high or test the components by plugging the master cylinder or shutting off supply to the different brakes by squeezing brake hoses closed.
I also noticed that master cylinder core is still inside the box, so i can remove the new one and compare them. So much for an easy brake job.
The rear has discs. 
the self adjuster seems to be working, because the freeplay on the hand brake feels reasonable. I have noticed the handbrake cannot be pulled hard enough to make the car skid. Now I'm wondering if the rear brakes are glazed from riding with the hand brake engaged. 
Oh and for what it's worth, i'm pretty sure that on this car, one stage of the master cylinder runs the front left and right rear brake, the other stage works the front right and back left


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## Beeman (Dec 29, 2002)

raymilosh said:


> thanks for the replies, everyone.
> I have replaced all the fluid had it running clear.
> I have rrun over a quart of fliud through the various lines. What I have not done, however, is jack up the back high or test the components by plugging the master cylinder or shutting off supply to the different brakes by squeezing brake hoses closed.
> I also noticed that master cylinder core is still inside the box, so i can remove the new one and compare them. So much for an easy brake job.
> ...


 Since you say there is no proportioning valve it most likely is split LF/RR RF/LR at the MC. If the rear has discs what type of E-brake does it have? Some have a screw type mechanism built in the caliper that apply the disc pads as an E-brake. Others have a mini drum brake assy inside the rear rotors as a separate E-brake. 
I have little experience with Hondas but plenty with GM and other domestic brands. Of course first action is to decide if there is air in the system, once that is determined then go from there. On rear calipers with screw mechanisms it's common for the caliper pistons not to "self adjust" outward as the pads wear. This causes a very low pedal and wears frt. brakes much faster as there is little or no rear brake applied. Sometimes it's so bad you can jack up the rear and have someone apply the brakes and still be able to turn the rear wheels. On some you can remove the nut holding the arm that the brake cable attaches to and then turn the screw with a wrench to move the pistons out. If this makes the pedal come up you most likely need to rebuild the calipers or install rebuilt calipers.


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## bugeye (May 28, 2008)

does the car have a vaccum type brake booster, if so, the booster could have an internal leak and would need to be replaced


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## raymilosh (Jan 12, 2005)

This car does have the screw type self adjusters on the rear calipers. I was assuming the E brake was OK, because it still works, although it does come up a bit farther than I'm used to seeing. the other reason i assumed it was OK is because I don't feel like pulling off the calipers because I've had a hard time with the screw type self adjusters on a friend's Subaru and I was willing to pretend they were OK in order to not have to mess with them. 
Honestly, though it has been on my mind as a possibility.
I spoze I can check it tonight if it's not raining again.

the car does have a vacuum type booster. the manual listed several functional checks of it. It passed all the tests, so I've been assuming it's not the source of the problem.

I haven't tried any of the suggestions yet, (I decided ot work on the Ford 3000 tractor instead). I'll be checking on everything at the same time. I'm imagining one (or more) of these suggestions will work.


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## Beeman (Dec 29, 2002)

Apply the E brake and then step on the pedal and see if the pedal is a little higher/firmer. By applying the E brake you are "adjusting" the pad outward as the automatic adjuster should have done but stops doing it because of corrosion inside the caliper.

Now for the caveman don't tell anyone where you learned this trick...

To attempt to free up the adjuster even if temporary try this. While someone pulls and releases the E brake repeatedly Bang on the caliper with a heavy plastic hammer or a hammer and a block of wood. Sometimes this will free the screw mechanism inside.


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