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I have a 2000 Buick Lesabre that I can’t seem to bleed the brakes on.
The pedal went soft on my wife. Due to a lack of a brake fluid leak on any of the lines, and the wetness behind the master cylinder, I replaced the master cylinder. Yes, I did bench bleed it.
However, after bleeding each brake caliper several times (both using the “coke bottle” and vacuum bleeder methods), I still cannot get a firm pedal. As in no brakes at all. All calipers are seated (parking brake actuators in the rear correctly tensioned, no loose pads).
The only conclusion I can come to is air in the ABS unit… which for a $450 beater car, probably totals it since it takes a $300 Tech II tool to bleed that, right?
Ideas?
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You can get the trapped air out of the ABS without a special scan tool if the pedal is spongy but the car stops.
All that’s required is a loose or slippery surface.Cautious for the safety of others and yourself, drive around a deserted gravel or wet road or empty parking lot and apply the brakes a few times.
It’s also possible on dry pavement but the speed required to get the wheels to slip to activate the ABS is higher while you brake harder.
After the ABS is activated a few times, bleed the brakes again–starting at the master cylinder.
You could have a helper pump the brakes while you bleed them.
Start at the master cylinder and bleed both lines before bleeding the calipers.If at any time the mc reservoir runs out of fluid–you’ll have to start over again at the master cylinder.
Very important to be sure that your new brake fluid is compatible with your vehicle which means Dot 3 or 4 or 5.1 but NOT DOT 5..
Silicone brake fluids are incompatible with most brake systems.Also possible is that the new master cylinder is defective.
If you’ve purchased a rebuilt/remanufactured master cylinder this is common.Yeah, it’s a duralast reman. It was pushing fluid while bench bleeding, but that means nothing, I know. I’m using DOT 3 fluid.
Too bad I broke the level sensor on the new one… even if I put the old sensor on the new one, I’m not sure they’ll take the return. Since I’m getting ready to leave the country for a week or two (work), I’ll probably rockauto a new one or something.
With the engine off there is some resistance but the pedal bottoms out. Once the engine is on, the brake booster causes that resistance to go away. Maybe I did get a bad master cylinder?
Many remans fail, even alot of the cheap aftermarket new ones fail too. If you bleed it many times at the wheel, while stomping the brakes, and master cylinder, I would assume you have a bad master cylinder. See if you can swap it out for another.
No pedal at all, that’s weird. You may have a big air bubble somewhere. I would check my bleeding technique too, you want it to go like this: (you) “Push”, (wife): Ok, (you) slightly loosen bleeder and watch for amber fluid or bubbles (wife) “pedal almost to floor” (you) close bleeder repeat that until you get bubbles, then keep it up until no bubbles, then three more cycles of no bubbles. Do them from passenger rear, driver rear, passenger front, driver front. Check the reservoir every five bleeds to make sure it’s got enough fluid.
It’s not likely the ABS system, that is in most designs completely closed off from the brake system until it’s in use. There is a small chance that that ABS system has an internal valve leak, in that case you need to cycle the ABS system for 100 thumps or so, the best way is on snow or loose gravel.[quote=”ratdude747″ post=193856]Yeah, it’s a duralast reman. It was pushing fluid while bench bleeding, but that means nothing, I know. I’m using DOT 3 fluid.
Too bad I broke the level sensor on the new one… even if I put the old sensor on the new one, I’m not sure they’ll take the return. Since I’m getting ready to leave the country for a week or two (work), I’ll probably rockauto a new one or something.
With the engine off there is some resistance but the pedal bottoms out. Once the engine is on, the brake booster causes that resistance to go away. Maybe I did get a bad master cylinder?[/quote]
While it could be the master, I’d first re-bleed the system with a helper, starting at the master cylinder lines, bleeding both MC lines, then moving on to the RR wheel, etc..
Just have a helper press the brake pedal 4 times and hold it down, then open and close the lines/bleeder screws before having them repeat this.
If that still fails to get any pedal and there are no leaks, the master is bad.
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