Complete brake failure on two occasions

[axplayer]

It looks like one other person here reported a similar problem, but I have what seems to be a pretty serious brake issue. I have a 2009 Genesis Sedan (4.6). It has about 20K miles. On two occasions now, both about 3 months apart, I have had total brake failure at low speed, after slowing down from highway speed. Once was as I turned into a parking lot off a highway. The other was turning into my neighborhood of the highway. I was thus rolling along at fairly low speed at the point the brakes failed, but the only way to stop was to apply the emergency brake. The brake pedal pushed all the way to the floor with almost no resistance. On the first occasion I had braked a bit hard before the failure, so I thought perhaps it was an overheating issue. The second incident was not preceded by hard barking. Needless to say, this is a little disconcerting and, of course, a problem that the dealer will likely not find--although I fully intend to take the car there. I'm just trying to get a sense of whether this has happened to anyone else. Any takers? Thanks.

 

[homeofstone]

It may be a bad master cylinder or caliper leaking. Have you noticed any wet spots under the car?

 

[Mark_888]

Total brake failure is not a characteristic of over-heated pads/rotors.

 

[BacktoHyundaibychoice]

It looks like one other person here reported a similar problem, but I have what seems to be a pretty serious brake issue. I have a 2009 Genesis Sedan (4.6). It has about 20K miles. On two occasions now, both about 3 months apart, I have had total brake failure at low speed, after slowing down from highway speed. Once was as I turned into a parking lot off a highway. The other was turning into my neighborhood of the highway. I was thus rolling along at fairly low speed at the point the brakes failed, but the only way to stop was to apply the emergency brake. The brake pedal pushed all the way to the floor with almost no resistance. On the first occasion I had braked a bit hard before the failure, so I thought perhaps it was an overheating issue. The second incident was not preceded by hard barking. Needless to say, this is a little disconcerting and, of course, a problem that the dealer will likely not find--although I fully intend to take the car there. I'm just trying to get a sense of whether this has happened to anyone else. Any takers? Thanks.

To answer your question, I don't recall this happening to anyone else. Though if it HAD happened to me, the car would've been flat bedded to the dealer immediately.

 

[axplayer]

No fluids are leaking. Going to check fluid, etc. It's been a good car all around with the exception of the brake issue and an occasional memory seating hiccup.

 

[STREETS]

And is the car at Hyundai for a complete look over & diagnosis? It would have been in until problem found after #1

 

[pilotdane]

Brakes in a car rank right up there with engines in an airplane. They absolutely must work all the time.

 

[waveman]

To answer your question, I don't recall this happening to anyone else. Though if it HAD happened to me, the car would've been flat bedded to the dealer immediately.

Take a look at this thread, which you participated in. (Not faulting you for not remembering, BTW - if I had as many posts as you, I'd forget too.) I don't know how what eventually happened with the person/car in that thread, though.

 

[scottdk]

No fluids are leaking. Going to check fluid, etc. It's been a good car all around with the exception of the brake issue and an occasional memory seating hiccup.

Be sure to check all of your rims for any brake fluid on them. Sometimes you won't see any leaked fluid on the ground, but on the wheels.

Take the cover off the master cylinder and have someone else press the brake pedal. If you see bubbles...you've got troubles

 

[neptune]

I once owned a 1987 Chrysler New Yorker that had the same brake momentary brake failure issue. My wife "free wheeled" through an intersection one day. After she told me the story, I took it to the dealer who check the computer codes and reported no recorded faults. I drove the car myself for several days and it did the same thing to me! If I hadn't quickly applied the parking brake, I would have been toast! Took the car to another Chrysler dealer who ran the same diagnostics, and also reported no faults recorded. After several minutes of serious discussion, he informed me that this model's fault detection logic ignored all faults not lasting for at least 2 minutes! He was very apologetic, while informing me there was nothing that could be done to fix the issue. He was wrong about that! I drove that stinking Chrysler to an Oldsmobile dealer and drove out with a new Delta 88! Best car I ever owned!

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[sandy]

Have you checked the brake fluid reservoir under the hood? For the TOTAL failure you describe, brake fluid reservoir and master cylinder would have to be empty and this can't be the case as your brakes came back to life without addition of fluid. I doubt you will find any signs of fluid leaking from wheel cylinders. The problem most likely is with the master cylinder...like a faulty piston seal that fails to push the fluid thru to the wheel cylinders.

Of course, my "expertise" is limited to cars of the 60's and have no idea what role the electronics (abs,etc computers) might play in this situation other than intermitent TOTAL failure often is electronic.

Be interested to hear what the solution is.

 

[BacktoHyundaibychoice]

Take a look at this thread, which you participated in. (Not faulting you for not remembering, BTW - if I had as many posts as you, I'd forget too.) I don't know how what eventually happened with the person/car in that thread, though.

I forgot my wife's birthday this year too.

 

[yellow3.8track]

Yes, even the old chevys of the early 70's had a dual reservoir master cylinder that enable on set of brakes to work even if there was a blow out/loss of pressure in the other side. For example, if you blew a brake hose to one of the front brakes there would be no pressure to either front brake due to the massive leak of fluid - but the rear brakes still had fluid and pressure from their side of the master cylinder - and the brake light in the instrument panel would light up due to the difference in pressure off setting the piston located in the system to detect partial system failure/pressure loss.

Having type all that I recently had a total brake system failure in my 2005 Chevy pickup when one of the lines from the master cylinder to the anti lock brake "box" blew out. No brakes, front or rear and no brake light to confirm I had a brake failure. Now that is a screwed up design. Had a line failed after the anti lock brake "box" (don't know what else to call it) I'd have had a brake light to tell me there was a problem in one end or the other of the system.

And even more, I once had a similar issue to what you describe in my 83 K5 Blazer. The o-rings in the master cylinder failed and I had no brakes at all. You could see little pieces of rubber o-ring in the bottom of the master cylinder reservoir. The "new/rebuilt" unit I purchased at the auto parts store also did not work. No o-ring parts in the fluid/reservoir, just no working brakes front or rear after initially bleeding the brakes and driving the K5. They worked for a couple of days and then it went out. The next replacement master cylinder lasted till I got rid of the K5 10 years later.

I was lucky in all three cases above, that I managed to have enough road to drive/roll past the cars stopping in front of me, and not hit anyone.

Good luck with yours, be careful, make them fix it right, or let them know why your next car won't be a Hyundai from them.

 

[scottdk]

Also,

Modern vehicles have a master cylinder with a primary and secondary system. If one fails there is still a second that will work, with two of the four brakes.

 

[axplayer]

Thank you for the suggestions. I will look for the air bubble issue. No signs of leaks anywhere. It will be going to the dealer right quick.

 

[Aquineas]

Brakes in a car rank right up there with engines in an airplane. They absolutely must work all the time.

+1

 

[Gambler]

Definitely take it to the dealer. You want it on record that you went there for this specific issue.

 

[triplington]

This is the sort of story that gets an electronics engineer on the company jet with a hastily packed bag and a group of lawyers flying to Detroit or wherever. If the brake mechanical's and hydraulics check out OK, it's most likely electronic. Get the service department to check and maybe replace the wheel speed sensors, check the wheel bearings for play and the spacing between the speed sensors and the toothed rotor (looks like a gear wheel behind the brake rotor around the bearing housing) The dealership should at least replace the ABS module. If it happens again, try fully releasing the brake pedal. The brake cylinder should refill with fluid and you can have another try.

 

[axplayer]

The dealership ruled out anything mechanical and decided to replace some ABS-related part. Apparently it costs a small fortune, so I'm glad it's under warranty. In the meantime, I've been living on the edge, driving the car until that part arrives. No problems so far. Thanks for the all the suggestions.

 

[Rich10]

Subaru's had a problem that may be similar to yours. On rare ocassions when braking while on a bumpy or wavy road, the ABS system could be fooled into thinking that there was wheel slippage. While the brakes still worked, the ABS system gave a pulsing feeling through the brake pedal. The key was to continue to brake normally even though the pedal feel was completely off. They ultimately had a reflash of the ABS system to make this less likely to occur. I don't know if this is what is happening to your car or matches what you have felt.