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Atreyou40
Novice
Sep 11, 2009, 7:10 AM
Post #1 of 14
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Brake light on
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Well, since he hasn't replied I guess I'll tell you the same story. Low brake fluid light comes on, so I look in the reservoir, and it's low. No problem, like any good little monkey, I filled it up.
Still on. So I pump the brakes a little bit, don't notice anything suspicious.
Infuriating. Light. Still. On. The pedal feels fine, car stops good, reservoir is full, stupid light is still on.
Owner's manual goes in to elaborate detail about the possibilities: "Something wrong with the brake system"
OBD doesn't apply here to at least point me in a direction, so I do what comes natural to a competent amateur mechanic - assume the MC swallowed air when the fluid got low and bleed the system (there is no indication that it's leaking fluid - in the pedal behavior, stopping power, or on the driveway).
So with the engine off, I stomped the pedal to relieve the vacuum pressure on the booster and then I bled it out - RR, LF, LR, RF in accordance with the Haynes Manual. If I hadn't read the manual, I woulda done RR, LR, RF, LF. My wife pumped three times and held as I closed the bleeder valve, and then she let off. We did this at each wheel, and I stopped to pour a spanking new bottle of Valvoline synthetic Dot III into the MC after each bleed.
Not once to I see a single cotton picking air bubble larger than a grain of sand - maybe 1 or 2, and maybe that was a grain of sand. So I'm really perplexed at this point. Because NOW the infernal light is still on, but I drove the car around the block and I feel like the pedal is too spongy, and I can NOT chirp the tires when I put the pedal on the floor.
Granted, this is a subdivision I'm living in, so I only hit about 40mph max before slamming on the brakes, but I roll for at least 35-50 feet with my Toes mashed to the floor.
If you drive it like a normal person, it seems to stop just fine. Grabs nice, is smooth, but now I'm all paranoid because before I didn't have a reason to drive around slamming on the brakes like an idiot. Now that I've done it, I'm suspicious of the master Cylinder. I had one fail in a 1979 Buick Regal when I was rolling down hill. I owe my survival to all the heavy steel in that car, and the soft little car in front of me that stopped me. Dude got totaled, I got some dings on my chrome plated bumper.
Good times - but the reason I'm posting for help is because I've already experienced a couple brake failures while driving, I'd like to avoid that in the future, especially now that I have a 3 month old riding around with me most of the time. I don't want to check the rear bumper height on the vehicle in front of me with her in the car.
So even though my pedal never slowly creeps to the floor as a couple other bad MC's have done to me, or gets terminally stiff due to a vacuum leak to the booster...
I'm gonna bleed these suckers a little more thoroughly and if it still won't stop like I like, I'll replace the MC - unless you all think that would be idiotic.
BTW - My car does not have an ABS manifold anywhere under the hood, nor does it show the dash light the manual says should appear if ABS is installed. I think I should get a little wheel lock when I hammer the pedal as hard as I can - even if I'm only going 20 mph.
I'm a blabbermouth, so I know that's too much info. Sorry if your bored, but I look forward to your help.
(This post was edited by Hammer Time on Sep 11, 2009, 7:17 AM)
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Atreyou40
Novice
Sep 11, 2009, 7:18 AM
Post #2 of 14
(3508 views)
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Re: 04 chevy impala 3.4l info board
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And By the way, my car is exactly what dude has - 3400cc/3.4L Chevy Impala. It appears to be the cheapo model, but they did put the stereo option in it with the HD Radio and the AMP.
Anyway, that's why I'm posting in this thread. Cheers.
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 11, 2009, 7:20 AM
Post #3 of 14
(3505 views)
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Re: Brake light on
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I have detached your post and used it to start a new question as you should have done. We can't address more than one vehicle in any question. It just gets too confusing to follow.
Now, on your car. Where exactly are you assuming this fluid went to? You have a leak somewhere and your ignoring that fact. You need to lift the car and pull all four wheels to find out where that fluid went and you will likely find your braking problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Guest
Anonymous Poster
Sep 11, 2009, 9:05 AM
Post #4 of 14
(3499 views)
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Re: Brake light on
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Are you sure it's a "low brake fluid" light? With all those owner manual possibilities I suspect it's a "brake" system light. Now, if you don't have a leak you probably need to replace your brake pads.
No leak. and needing fluid, means your pads are worn.
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Atreyou40
Novice
Sep 11, 2009, 10:44 PM
Post #5 of 14
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Re: Brake light on
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Well - I assume that as the caliper pistons get pushed out, and the pads wear down, the fluid in the reservoir gets pulled into the rest of the brake system. Being a system under pretty serious pressure, repeated application of the brake pedal should expose where the leak is wouldn't you think? Unless you think there's a pinhole leak so tiny that the fluid is atomizing at the point of release into the atmosphere and leaving no trace.
I don't think I'm ignoring anything. Gravity puts leaky fluid on the ground, it's one of the many things I find gravity useful for. Drafts smear that leaky fluid all over the undercarriage as you roll down the road, one of the excellent benefits of wind resistance - only powered flight has proven more useful to mankind I think.
I'm not ruling out a leak, I'm just saying I didn't consider it in the initial post because the obvious places - the MC lines, the calipers and their fittings, the fender skirts, the entire underneath of the car, were about as dry as any undercarriage I've ever seen.
I did pull all four today to get at the bleeder valves, but that was with a floor jack, not a lift. It would be nice to have access to one of those.
And I read the "READ THIS FIRST" post after you moved this thread. Sorry about that, I should've linked to the previous thread with a new one, because we've thoroughly confused the Guest replier.
Hey Guest, thanks for the feedback, but the awesome engineering that went into the 2004 Impala brake failure warning system is apparently to turn on any dashboard lamp relative to the system.
Yes - there is a red "brake" light that comes on on the left indicative of a parking brake or as I've seen on most other cars some sort of issue with the system. The really irritating thing is that the computer information center that tells you when to change the oil, when the doors are open, when the hood is up, etc... constantly displays "Low Brake Fluid" on the dash. These little nuggets of info were in the original thread - as someone had the identical car, with the identical issue - but I made the mistake of not reading the "READ THIS FIRST" post.
Instead I read ANOTHER post, where a user was chastised for starting ANOTHER THREAD about the SAME THING as someone else had asked. Funny how that works, oh well.
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 12, 2009, 4:18 AM
Post #6 of 14
(3490 views)
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Re: Brake light on
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Although fluid does transfer to the calipers as the pads wear, the reservoir hold sufficient fluid to wear out a set of pads without running out of fluid as you did. Even if it did transfer down, it would certainly indicate worn out pads. I would say that you have a fluid loss somewhere and you need to find it. Look foor a stain behind the master cylinder on the booster and check the rear wheel cylinders under the dust cups if it has drum brakes in the rear. It is not normal to run out of brake fluid.
PS, If you read someone being asked not to start a second question, it would only be if the same person was posting the same question multiple times thinking they will get more answers or things just aren't moving fast enough for them.
The reasoning for moving yours was that if both you and the original poster start making responses and asking questions, nobody ever knows who is being responded to for which problem or which vehicle is being talked about.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Sep 12, 2009, 11:46 AM)
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Sidom
Veteran
/ Moderator
Sep 12, 2009, 10:48 AM
Post #7 of 14
(3478 views)
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Re: Brake light on
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Instead I read ANOTHER post, where a user was chastised for starting ANOTHER THREAD about the SAME THING as someone else had asked. Funny how that works, oh well.
Hi Atreyou40
Welcome to the forum. Looks like you have a handle on your problem and got some good advise so no real need to add anything else, even saw were you helped out someone with some good advise. Thats great, kinda what this place is all about...
I'll just clear up one small point where there seems to be a little confusion... In this thread you referred to, some people will come in and start 2, 3 or even more threads with the exact same problem. It gets way to confusing having 2 or more threads with the same problem, so we prefer one thread per problem. Without even looking at the thread you referred to I guarantee that is what happened.
As far as adding on to an old thread with the same problem kinda the same scenario applies, we don't want to start adding advise to an old thread & new problem. But I don't see a problem with a quick "Did you ever find your problem?" message. Some people have enable the e mail response and may come back, doesn't happen often but it does happen..
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Guest
Anonymous Poster
Sep 12, 2009, 2:11 PM
Post #8 of 14
(3468 views)
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Re: Brake light on
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Well, to clear things up I did say it was "low" and not "empty".
Just to be sure, I got under the car and actually looked exclusively for leaks. There is no evidence of any leak that I could find, not even an oil system or any other system leak.
My bleeding partner is at work for now, so I'm gonna wait to re-bleed until after she gets home. In the meantime, I guess I'm gonna have to have my lunch delivered. Poo.
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 12, 2009, 2:15 PM
Post #9 of 14
(3464 views)
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Re: Brake light on
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If it went low enough to draw air, then that is considered empty. The low fluid light would have come on long before that point so if all this happened over a short period of time, then you still haven't found your problem.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Atreyou40
Novice
Sep 12, 2009, 2:30 PM
Post #10 of 14
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Re: Brake light on
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Well, you probably didn't get to it since I tend to post mini-novel's, but I did also say that the "gulping air" theory was just an outside guess.
Upon bleeding the brakes, there was no evidence at all that there was any air, anywhere in the system - except what could've been ultra-tiny bubbles or grains of sand.
Like I said - as soon as my bleeding partner gets home, I'm gonna basically try to bleed as much of the existing fluid out one sure pump at a time, and see if that doesn't stiffen up the pedal a little. If not, since there's no ABS and I can't find or produce evidence of a leak by depressing the pedal on a high pressure closed system, I think I'm gonna splurge on a replacement MC.
Since they are $149 a piece, I wonder if there's a method to confirm whether or not this is what's wrong before replacing it - any ideas?
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 12, 2009, 2:38 PM
Post #11 of 14
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Re: Brake light on
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The way to confirm it is to find out where the fluid went. If you had a loss of brake pedal without fluid loss, that would be indicative of a bad master but you do have fluid loss so you need to find it. It could still end up being a master but there will be evidence somewhere. Brake systems do not get air in them for no reason and bleeding without a repair should never be necessary.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Sep 12, 2009, 2:39 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 13, 2009, 7:54 PM
Post #12 of 14
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Re: Brake light on
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Just a note: Brake fluid will wash off clean with water making finding a leak a pill if driven in wet conditions. The big word for the type of fluid is "Hygroscopic" -- brake fluid is not an oil whatsoever! It is water soluble!
T
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Atreyou40
Novice
Sep 14, 2009, 5:38 PM
Post #13 of 14
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Re: Brake light on
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Well, I appreciate the feedback of everyone in the forum. As I stated many, many, many times, there was no indication of either fluid loss, or air in the system.
It turns out that the "lower than full" level in my reservoir was most likely the result of normal wear, and after replacing the reservoir, and thereby the sensor within the reservoir, the problem has been resolved by sensor replacement.
So - this is only the second time in my automotive repair life that a faulty sensor/indicator has driven me to to extreme lengths to identify a non-existent issue (the only other one was a bad temp gauge in an LAV-25).
Live and learn I guess - so if the system feels fine (i.e. the car appears to stop normally, no pedal travel after the car has stopped), has no leaks, doesn't give you any bubbles when you bleed it, then a $30 junkyard reservoir with the sensor is a cheap way to rule that out - or in as was my case. If there's a way to test the sensor besides replacement, I'd sure like to know it (I'm sure simply looping the connector wouldn't work - that the sensor returns a specific voltage to the computer when it's functioning correctly).
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Atreyou40
Novice
Sep 14, 2009, 5:41 PM
Post #14 of 14
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Re: Brake light on
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One more note - I did NOT replace the master cylinder because I'm just too cheap to splurge on that without being 100% sure.
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