Hi, all.

My daughter in college drives a 2009 Saturn Aura. It's well maintained with low miles, but last week while leaving a restaurant she encountered no brakes. Her brakes were totally fine until this point. She wisely pulled into the closest parking lot. I arrived and also felt there was no resistance in the brake pedal at all. We had the car towed to a mechanic.

It was determined that both braided brake lines from the master cylinder to the ABS unit were rusted and leaking. There was no factory replacement brake line available, so they needed to fabricate one. They also noted that they could not curve the line following it's original path. The brakes are fully functional and strong now, but we noticed a change.

The brakes originally engaged relatively quickly with little pedal travel. But now in order to get the same braking power requires a good amount more pedal travel. It's essentially "mushy". Is this to be expected? The mechanic said they could possibly re-drain and fill the brake lines again to see if that helps. I drove the car and do notice the difference, but it brakes fine. It's just not nearly as responsive early in the pedal press.

What are your thoughts? Get used to it, or look into the issue more? Thanks a lot.

Chris

mushy means air in the lines generally, and bleeding should be done, at that point check the pads and rotors if they are well aged.

Since the lines broke and had to be replaced there had to be air in the system.

I wonder if they replaced the factory hard lines with rubber, which would be more mush, that and not bleeding the lines properly will get the same mush feel. Might be air in the ABS system, or anywhere.

Personally, I would source the OEM hard lines and have that installed properly.

Master cylinder seals and/or air in the brake lines. They need to do it again.

Thanks for the replies so far.

The brake pads and rotors are new as of 1 year ago. Should be good to go.

They could not source the OEM hard lines with the factory bends, so they had to use flexible lines. I think they used flexible metal, not rubber, but can verify.

I will have them rebleed the lines, check for air anywhere in the ABS system/master cylinder, and do it again.

Let me know if any other ideas/suggestions come up. Thanks!

I would agree that it hasn’t been bled completely. I have read that a change in flexible lines can affect pedal firmness but I doubt it would feel mushy or require more stroke. You’re compressing air bubbles somewhere.

Many GM cars (and a few others) from that time period and back into the late 90’s require a special bleed procedure initiated by a scan tool with bidirectional capability. This is to get the air out of the valving of the ABS unit. This will cause a low pedal even if all the air is seemingly removed by conventional means.

The procedures are similar, but often more protracted when dealing with the brake systems on hybrid and electric cars, as the ABS provides all the braking, not your foot through a traditional booster.

The brake line material should have little to no perceptible impact on brake pedal feel on a car like yours as long as they were properly formed and installed.

quote:

Originally posted by rainmaker5505:
Many GM cars (and a few others) from that time period and back into the late 90’s require a special bleed procedure initiated by a scan tool with bidirectional capability.

Yup!

Most any (Pontiac, Chrysler, Benz, Freightliner, etc...) traction control / ABS systems will need the valve/pump actuator cycled several times.

It gets to be tricky if you have an electric brake booster (I don't think these ever made it in to a Saturn) as they are bled at 2600 psi.

Either way if you are going to try to do it yourself, do not underestimate the value of good eye protection.

Changing the brake lines on any vehicle, even if using new OEM lines, requires more than one bleed to get all the air out. I do it as thoroughly as you can - pressure bleed on the MC, vacuum bleeder on each caliper, done in the proper order and with a rubber mallet to tap the bubbles out of each caliper. Even then it will require another bleed or two because there will be more air trapped in the system that's only going to move with some driving and real braking.

Thank you, all. Bringing the car back to the shop now to have the job re-done... armed with this knowledge.

It sounds like you still have air in the lines. I don't know how the new, fabricated lines are routed, but IIRC, the original braided lines made a curvature up coming out of the master cylinder. Fluid, even under pressure, doesn't like to flow uphill. Add air and it can be very difficult to bleed, even with a pressure bleeder and activating the ABS with a scanner. Good luck with it.

quote:

There was no factory replacement brake line available, so they needed to fabricate one. They also noted that they could not curve the line following it's original path.

I too have to fabricate a lot of brake lines, and this is 100% true. Factory hard lines are pre-bent by a machine and are installed before the engine, transmission and other components. Put another way, the car is more or less built around them. On the latest one, a 2003 (around here this is a new car) Malibu, I had to replace five of them (they all ran together and were equally rusted), using a total of 16 feet of line.