Brake pedal to the metal

[mvande]

My daughter had a couple lines break on her 95 GA last summer and lost all her brakes and fluid, fortunately she was in the driveway when they let go and was not involved in an accident.
I replaced the lines, refilled the master cylinder and blead the system. Everything was fine the brakes worked well after that.
She has since moved to San Antonio, I'm in Indiana, and she is calling with a problem with her brakes. Occasionally, 3 times in a month, when she is pulling into a parking space she will press the brake pedal and it will go to the floor with no brakes, the second pump is fine with a harder pedal than normal and plenty of stopping power. She has plenty of fluid in the master cylinder, and was not able to see any leaks. The first time it happened I thought that maybe an air bubble left from when I had replaced the lines might have worked it's way through the system and caused problem, but now after it's happened a couple more times I'm wondering what else to have her look for. She has pretty good mechanical sense, but not enough to make her own repairs but any ideas would be helpful that I could pass on to her so she may have a better idea as to what to communicate to a repair shop.

[coupe]

My guess is an air bubble working its way around the lines.
Either that or its time for a new master cylinder which is very possible given the age of the car.

[RazorDX]

My girlfriend's 95 Taurus does the same thing (more often though). It has been said that there was air in the line, but I'd never heard about the master cylinder. Being that hers only does it once in a while I'd agree about it being a bubble. I think my girlfriend's is the cylinder, seeing how it does it every drive. Good luck fixing it, and when you do please post what fixed it. I'm sure others are having the problem too, and I'm sure others will.

[rixGAphx]

I don't know on teh Taurus, but the GA's have bleed screws ON THE MC to bleed the tiny (1cc?) volume of air that remains trapped in them.

Mvande:
You are right, that is NOT the way that 'air in the lines' behaves.

I don't know what the others are talking about, but they're way off.

If the daughter's foot 'went to the floor', then I'm 99% certain the mastercylinder has a faulty seal inside.

She has ABS, right?
Her '95 has a very goofy connection port for the computer, and that computer controls the ABS. Special connectors/equipment are necessary to 'read' the ABS module when putting things back together.
Have her go to a reputable, chain-type brake specialist with lots of equipment.

If no ABS, then any decent shop can do the job.

But I'm very suspicious of the ENTIRE brake system.
It is quite unusual for brake lines to fail.
Were these the steel tubing lines, or the rubber flexlines at the front wheels and rear axle?

If the rubber flexlines, then I wonder if there isn't some petroleum product in the brake fluid, like solvent or such.
This slowly 'eats' the special rubber inside of brake systems, and these symptoms (failed lines, now a failed MC) are the expected result of such contamination.


Standing by,
-Rick

[1CoopGT03]

Get the power brake booster checked also.

[pokesmot]

Originally posted by rixGAphx

It is quite unusual for brake lines to fail.


I guess where you live because there is minimal rain it would be very rare for brake lines to fail, but all it takes here is a couple winter seasons with some salt on the road, and voila! rusted / leaking brake lines.


it almost sounds like a master cylinder problem problem to me.

here is an excellent article to check out:

http://autorepair.about.com/cs/troubleshooting/a/bl302a.htm

[mvande]

Wow, thanks for all the responses, interesting that no one has experienced this problem though. That kind of leads me to believe that it may still be a bubble running through the system as it is so eratic and not something that seems to be a common occurance.
I told her to get her roommate to pump the brakes and to listen for air leaking which may indicate a faulty booster. If she can't find anything my son will be heading down there in a few weeks. I think I can coach him through the bleeding process which I think may be worth trying again before heading to the shop and laying out the big $$.
It does have ABS so I appreciate the suggestion to use a shop that will have the proper tools to diagnose and fix it right.
One last note, the car spent it's entire lifetime, until last August, in Northwest Indiana, big road salt users, both rear lines had major rust only around the areas where the plastic clamps were on the lines. I would guess the road grime and salt would get under these clamps and never really dry out.
I'll update when I learn more.

[SE2000]

Originally posted by mvande
My daughter had a couple lines break on her 95 GA last summer and lost all her brakes and fluid, fortunately she was in the driveway when they let go and was not involved in an accident.
I replaced the lines, refilled the master cylinder and blead the system. Everything was fine the brakes worked well after that.
She has since moved to San Antonio, I'm in Indiana, and she is calling with a problem with her brakes. Occasionally, 3 times in a month, when she is pulling into a parking space she will press the brake pedal and it will go to the floor with no brakes, the second pump is fine with a harder pedal than normal and plenty of stopping power. She has plenty of fluid in the master cylinder, and was not able to see any leaks. The first time it happened I thought that maybe an air bubble left from when I had replaced the lines might have worked it's way through the system and caused problem, but now after it's happened a couple more times I'm wondering what else to have her look for. She has pretty good mechanical sense, but not enough to make her own repairs but any ideas would be helpful that I could pass on to her so she may have a better idea as to what to communicate to a repair shop.

Since it happens intermittently, I would say you have a bad Master Cylinder.
For Razor, I'd say you do have air in the line.

For air in the line, The first time you press down, the pedal is low, quickly let up and repress. If pedal is normal, you have air. If it goes low, MC is probally bad.

And brake lines go bad all the time. Brake fluid absorbs moisture and can coorode the lines from the inside as well as outside corrosion

[Nighthawk243]

Originally posted by rixGAphx

But I'm very suspicious of the ENTIRE brake system.
It is quite unusual for brake lines to fail.

Standing by,
-Rick

Depends on where you live. If you are in a northern part of the US where road salts are heavily used, it is quite common. My brake lines broke when the local garage was replacing my rusted through fuel lines... they had also been eaten away from oxidation.

[HeyDace]

Sounds like a bad master to me. One way to check is pump the peddle a couple times and keeping moderate pressure on it feel for a slow, gradual pedal drop. Air in the system will feel spongy the first or second time the pedal is pumped then become firmer.
I would inspect the booster seal where the master mates for any fluid, if so replace the booster also.

[rixGAphx]

in a northern part of the US where road salts are heavily used, it is quite common.
My brake lines broke when the local garage was replacing my rusted-through fuel lines...Thank you all for the lessons of the snow belt. I had no idea that's what happens to steel lines.
I was born in Buffalo and moved to Cleveland. I guess that's one more reason why the folks moved us here in the '50's.
* * *

'Air bubbles' don't just float around inside a closed hydraulic system, then occasionally cause low pedal or spongy pedal.

True, if the air entered at the wheel cylinder, it would gradually 'float' to the highest part of the tubing it can reach.
BUT, every time the pedal is pushed, the fluid in the line is pressurized and that bubble compresses (causing the spongy feel).
There aren't any nooks or crannies for a bubble to hide and therefore have no effect.

-Rick