Brake question.

[Spike88]

My girlfriend recently got a 96 Chevy Blazer. She was attempting to stop when her brakes didn't stop like they should. So she thought she needed new brakes. We looked at the brakes and realized they were fine, but that there was air in the brake tubes, so we bled them. The brakes work fine now, but her ABS light is on, and when you slam on the brakes the rear wheel locks up. A friend of mine told me that it had to do with the air being in the brakes earlier and that it should fix it self, but another friend told me that she needs a mechanic to check it out. Any opinions?

[Platapus]

When it comes to something as important as brakes, I would always go to a good repair shop.

Brakes is too important to mess with.

Good luck

[August]

When it comes to something as important as brakes, I would always go to a good repair shop.

Brakes is too important to mess with.

Good luck

Very good advice this.

[UnderseaLcpl]

I don't know how much help I can be, as my own mechanical experience is limited, but is it possible her previous brake failures contributed to/caused wear on the tires that causes them to skid? It is my understanding that excessive tire wear can cause lockups that will alert the computer to display a fault light.

Any additional information would be useful.

[Spike88]

I don't know how much help I can be, as my own mechanical experience is limited, but is it possible her previous brake failures contributed to/caused wear on the tires that causes them to skid? It is my understanding that excessive tire wear can cause lockups that will alert the computer to display a fault light.

Any additional information would be useful.

The tires are actually brand new. The front ones show wear but she's buying a new set this Friday. Its only the back wheels that lock up, the front work fine.

[UnderseaLcpl]

Okay, what do you mean by "brakes didn't stop like they should?" Are they not pulsing? How, exactly, are they behaving? Is the brake pedal not funtioning like it should (i.e. depressing too far?) Is the vehicle skidding? What is the average temperature where you live right now? Are you sure you used the right brake fluid?

Even if I can't help, this information might help others diagnose your problem.
One more thing, since the front wheels provide most of the stopping power due to weight distribution, is it possible that the back wheels are locking because they are overcompensating for the lack of front-wheel traction? How worn are the front tires?

Pardon the slew of questions, but the more information, the better.

[Digital_Trucker]

I once had an ABS light come on back in the early '90s. I ended up towing the car home from the concert I missed because the car screwed up on me. When they set the car down in front of my house, I cranked it up to move it into the driveway so my crazy neighbor wouldn't hit it on his screeching way to work the next morning and guess what? The damn ABS light was out. So, my suggestion is to jump up and down on the bumper a few times to simulate the wrecker pick up and see if the problem goes away.


Seriously, I'd have it looked at by a reputable automotive diagnostician. It's possible that something that was done in bleeding the brake lines caused a sensor to trip and the ABS to stop working.

Disclaimer : The last time I was able to effectively work on an automobile was over 20 years ago and I am, by no means, an automotive expert.

[Spike88]

Okay, what do you mean by "brakes didn't stop like they should?" Are they not pulsing? How, exactly, are they behaving? Is the brake pedal not funtioning like it should (i.e. depressing too far?) Is the vehicle skidding? What is the average temperature where you live right now? Are you sure you used the right brake fluid?

Even if I can't help, this information might help others diagnose your problem.
One more thing, since the front wheels provide most of the stopping power due to weight distribution, is it possible that the back wheels are locking because they are overcompensating for the lack of front-wheel traction? How worn are the front tires?

Pardon the slew of questions, but the more information, the better.

Before they would not brake quick enough, and the pedal would be depressed all the way. After bleeding them the front brakes work fine but the back ones are locking up and sliding. The break pedal is stiffer now that we have bled the lines. Right now its actually quite cool in the 60-75's. I actually do not know if its the right brake fluid. I did not purchase it, her father did. I'm pretty sure he bought the right stuff, I was not the one who put it in either, a friend of mine did. He was also the one who bled the brakes while I pumped the pedal.

The right front tire is balding slightly the left one looks fairly new.

As a side note, apparently the brake flood reservoir had been empty at one point and the brakes had been used.

[UnderseaLcpl]

It sounds like the bleeding worked okay and that air in the lines was definetely your problem before. The temp. isn't cold enough to affect anything.
My only remaining suggestion is that perhaps there is too much fluid. That would prevent the ABS cylinders from oscillating in the proper manner. It certainly doesn't sound like you have a leak or any more air in the lines.
If it isn't too much fluid, perhaps a computer problem then, which I have absolutely no experience with.

One more thought; was there ever a time you were aware of the the rear brake pads were totally worn down? Damage to the rotors can cause excessive friction, resulting in sliding, and in extreme cases, failure of the wheel to rotate. Did you check the rotors when you checked the brake pads?

That's about all I've got. Hopefully this will be helpful or someone else can offer better advice. :salute:

Good luck

[Spike88]

The rotors were fine. She's only had the car for about a week now, and the dude she bought it from says that the drums were replaced recently. She's does not think the ABS light was on when she originally got the car, but noticed that it turned on after the brakes failed. Maybe its like my car, which has a check engine light even though we fixed the problem, just because we don't have the tools to reset the computer.

[UnderseaLcpl]

Yeah, but if your rear wheels are locking up something else is wrong. I'm sorry I can't be more help.

[August]

The rotors were fine. She's only had the car for about a week now, and the dude she bought it from says that the drums were replaced recently. She's does not think the ABS light was on when she originally got the car, but noticed that it turned on after the brakes failed. Maybe its like my car, which has a check engine light even though we fixed the problem, just because we don't have the tools to reset the computer.

From what I've been told resetting the computer does a lot more than just turn off indicator lights. The computer could be compensating for a problem that no longer exists in ways that will cause damage to the car if you don't clear the error and this problem you're having could be an example of that.

I'd definitely have a professional run diagnostics on it. That's generally a smart thing to do with any "new to you" vehicle.

[UnderseaLcpl]

From what I've been told resetting the computer does a lot more than just turn off indicator lights. The computer could be compensating for a problem that no longer exists in ways that will cause damage to the car if you don't clear the error and this problem you're having could be an example of that.


If that's true I'm never buying a car with a computer on it ever again.

[Etienne]

From what I've been told resetting the computer does a lot more than just turn off indicator lights. The computer could be compensating for a problem that no longer exists in ways that will cause damage to the car if you don't clear the error and this problem you're having could be an example of that.


If that's true I'm never buying a car with a computer on it ever again.

That pretty much limits you to cars older than 1995 or a bus pass.

These are the days we live in...

[magic452]

I am a mechanic and you have a serious problem!!!!!!
Get it serviced by a component mechanic.
Best case scenario is air in the Master cylinder or Antiskid valve.
Worst case bad valves or computer etc.
If the rear brakes lock up unexpectedly in a turn you could be in real trouble.
Get them repaired as soon as possible.

Magic452

[lesrae]

I agree that you should get it checked by a mechanic, but on the optimistic side, I used to have problems like this with my old Honda Prelude and it was caused by the ABS sensors going out of tolerance and causing the ABS to act up. It was relatively cheap and easy to repair.

Definitely see a professional though.