Yesterday I lost braking on my 1980 Toyota Celica GT and had the booster replaced per the mechanic's suggestion. Now my braking is back. But the front brake smokes up and the car does not really go even if I hit the gas pedal to the bottom. The mechanic has not been able to duplicate the failure. He said my front rotor and caliper need to be replaced. Is it possible that this front brake locked up problem have anything to do with a new brake booster? Or just a coincidence? Is it possible that the mechanic screwed up something when he replaced the booster? The last time I stopped my car before calling for a tow truck to take my car to the repair shop again, I heard a noise from my front brake like some metal dropping. Is it a clue for something? Thanks.
Brake fluid should be replaced every 2 years REGUARDLESS OF MILES. This is because it is hydroscopic. (absorbs water like a sponge) Once it is saturated, the water falls out of suspension and starts to corrode your brake-system from the inside- out.
It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced.
To answer your other question... if the rotor was dragging and you continued to drive, the heat must have been enormous. (think RED HOT rotor!!) This can easilly burn up bearings in the wheel and generally cause bad things to happen.
There is the slight chance that a improperly adjusted pushrod on the brake-pedal can cause a booster to drag the brakes... but usually ALL of the brakes would be dragging in this case.
Nope not following too closely - just lost all braking while stopping. The rotor break occurred during braking on a clear, warm, dry day. ABS activated momentarily and then I had no brakes at all. No skid marks, no swerving, no abs light, no squeal of the pad warning indicator, nothing. Hard pedal that I was standing on. Brakes were still above minimums.
I averaged 35-40k miles on front brakes on both my 95 and 96 Suburbans. The 10k inspection was 8 months earlier.
Hmm, losing 1 rotor or caliper should not on a modern car cause complete brake failure. Usually it's an X pattern where your opposite corners run on the same fluid line so that in a failure (as you had) you would retain braking in the other 2 calipers.
Something doesn't seem complete to this story IMO.
"It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced". so, would replacing the calipers and rotors solve the problem? Or, should one somehow drain the water first? By the way, when my brake failed yesterday, it came kind of suddenly. When I was parking in the lot, the brake pedal kind of bounced back (upwards) and I heard a clicking noise. (After that, I need to press the brake all the way down and allow a much longer distance in order to stop.) Before that, there was not much warning sign. Do brake boosters normally fail like that, rather than gradually?
Not entirely true. BMW recommends a brake system flush (and use of DOT 4 brake fluid) every two years. Many other manufacturers do as well. Regardless, I follow this maintenance procedure on all of our cars whether they recommend the service or not.
I flush every 30K miles or two years. Aside from wrecks I bought to restore, I've never had to replace a caliper or wheel cylinder EVER. Brake flush makes a lot of sense.
They have testing tools and testing strips to measure the actual chemical condtion of the brake fluid in question, In some ways this is a (go no go) UOA. (not unlike for motor oil) ( not unlike measuring your pool for chlorine/ph levels)
So for example@ $.52 (cents) per test, and 32 oz of brake fluid costing from 4 to 25., .52 cents can/might help to be appropirate and perhaps let you extended the intervals. (depends on tests and/or attitude or circumstances or any combination)
Nothing like having the facts facing you to make an informed decision.
The problem is that the composition of the brake fluid in the reservoir can be VERY different when compared to the fluid in the calipers and wheel cylinders. I have no problem believing that the fluid in the reservoir could test out good while the sludge in the caliper was eating away at critical surfaces at the same time.
Still interesting that some do, but many do not (brake flushes). Hydrostartic is hydrostatic... seems all manufacturers would recommend 2 year brake flush if it were that important. :confuse: ....just my 2 cents.
I applaud your good sense. In my case i've thought about the exact same thing but decided that it wasn't worth testing it (in my case) because I drive very hard and often in lousy conditions. For me, getting it up on a lift, flushing things out and having eyeballs on the whole system gives me peace of mind.
Brakes are, after all, the difference between a really good day and a really bad day sometimes. If I stopped in 50 feet for a truck 49 feet in front of me, well, that's pretty good but not quite good enough. :P
I'm a believer in small increments of advantage when it comes to tires and brakes. For me, in those areas there is no "overkill", whereas "super" sparkplugs or "heavy duty" oil filters or "performance mufflers" or "free-flow air filters" don't seem worth it to me for the little gain.
But those extra 12 inches of braking......yeah!
I'm so fanatic about braking that I even diss oversize wheels and tires for that reason. I feel they cut off a small amount of braking distance (depending).
Actually, I am with you on that.... so a can do easy would be to crack open your longest (R-R usually) and squirt a shot of BF onto the test strip. Tighten back up.
In addition, as you probably know and have probably done, you have added BF to top the reservoir, aka FRESH at the top.
Yes I think the actual testing appeals to me in that it helps the SWAGGING. So for example in your case (hard, lousy conditions etc, yada, yada) you make a good case for 2 years does not fit all!!! So in that sense, the actual test will help you make the appropriate decision: shorter, longer ,on time, on mileage, don't give a D... . (yes I was correct, no I was way off. I can extend, I feel like short, let's change this YESTERDAY!!... etc.)
Another that goes along with your thought processes , as you know BF can vary WILDLY in price: per 32/33.8 oz. (I use 32/33.8 oz as this is what it usually takes to flush a normal system)
So again IF .125 cents per oz is more than fine, THEN why buy the .78 oz designer swill? Of course, AND vice versa.
..."I'm so fanatic about braking that I even diss oversize wheels and tires for that reason. I feel they cut off a small amount of braking distance (depending). "....
Yes I sometimes cringe knowing that many folks who will "bling out" tires and rims combinations and do NOTHING to the brake system, don't even have a clue the stopping distances have just gone out the window (and hp, but that is a different discussion) .
In the brake department (consumer) I have to admit to being a tad spoiled. I have one 7 years old that stops 60-0 in 109 ft. This has been recently beaten by the 2008/2009 Nissan GT-R @ 104 feet. Another 2@ 4800# 14/12 year old Suv 's which stops in 136 ft.
Subaru is 3 yr/30k for brake flush interval according to the manual.
Also as has been said, testing the resivoir doesn't indicate what's in the lines or the calipers. I reccomend a 2 year inverval for normal driving. And for $60 give or take is it worth it not to do it?
On my own car that i push hard and track as well I use ATE Superblue and flush 1-2x a year.
Not saying that this is a valid reason to not change brake fluid, but I have never replaced a caliper or wheel cylinder EVER either, despite never changing brake fluid.
I did have Midas try to sell me such parts one time, but the dealer said there was nothing wrong and no need to replace them.
Quite the contrary, regarding time of ownership. Cars we bought new, we have kept for 12 years. I also once had a 16 year old Sentra, bought from a relative (who I think also did not change brake fluid). Not a paticularly dry climate, either...Wisconsin and Illinois.
(Recently my son did replace a leaking wheel cylinder on a 1996 Jetta that he bought used last summer.)
Oh, and I did change brake fluid once so far...on my wife's 2 year old Jetta, as it is specified in the maintenance shedule.
I'm more guilty of short term ownership but a brake flush is one of the first things I do when I buy a used car---and they ALWAYS seem to need it, too.
The corrosion brought on by water in the brake fluid is by far not the worst negative effect of this type of contamination. So, what is? Boiling brake fluid. If there is too much water in the brake system, and your brakes are hot (either from a combination of hot weather and heavy traffic, or from racing), your brakes can simply fail when the water starts to boil.
Regarding the cars you kept for 12 and 16 years with no fluid change, how do you know that the fluid wasn't ever changed, even a little? I ask because when various shops do a brake job, they typically "bleed" the brakes, and that has the effect of pushing through the worst of the contaminated fluid (water is heavier than brake fluid), and replace it with fresh(er) fluid from the reservoir.
If your car truly went 16 years with zero fluid replacement, then I guarantee you that the sludge that would come out of the bleed orifices would have absolutely zero resemblance to brake fluid.
Yes, there certainly were normal brake jobs. The 12 year cars had front done twice and rear once. Which is also the status of a 10 year old vehicle we currently have.
As I said I don't provide this as evidence that this is a good idea. Changing brake fluid was something I first heard about a few years ago, and then an attempt to sell me on it was only based on the claims of corrosion and resulting expensive repairs.
I only recently read about the boiling issue, thanks to these forums. I've kind of decided that my new policy will be to change fluid at about 3 years and 25,000 miles (when no warranty issues). Typically we have gone about 50,000 miles between brake jobs and put 8000 to 10,000 miles per year on our cars...so this will be one full flush between each brake job and then when they do a brake job, I can just ask them to replace all fluid.
I have not yet decided what to do on the 10 year old vehicle, 2 years since last brake job, which was both front and rear.
I'm also thinking I'll now periodically replace PS fluid...I recently spent about $900 on a pump and rack.
The Wikipedia page for "brake bleeding" defines it as "the procedure performed on hydraulic brake systems whereby the brake lines (the pipes and hoses containing the brake fluid) are purged of any air bubbles." And "the same methods used for bleeding are also used for purging, where the old fluid is replaced with new fluid, which is necessary maintenance." So, it seems that there are two different things: purging the air bubbles and replacing the old fluid with new. Does one achieve both in the same procedure? Or does one need to perform them separately? Can one (or is it possible to) purge the bubble without replacing the brake fluid, for example? When a mechanic says "bleeding", normally what does he mean? By the way, do brakes fail suddenly or gradually? My brake failed without any squeaking noise or warning sign.
Flushing accomplishes bleeding; however, bleeding doesn't accomplish a flush. Bleeding means simply to open the bleed orifices (one at a time) and pump out enough old fluid to purge the brake system of air bubbles. Once the bubbles are gone, you close'er up, and move on to the next wheel. Once all four wheels are done, you top off the brake fluid reservoir and you're done.
For a brake flush, you perform pretty much the same process, however, you continue to pushing until all of the old fluid is out of the system. Obviously a "flush" takes considerably longer and requires considerably more new brake fluid.
As for why brakes can suddenly fail, geez, LOTS of ways, including but not limited to the following:
1) Master cylinder failure 2) Brake line rupture due to corrosion or damage 3) Brake hose rupture (typically due to age) 4) Brake caliper seal failure (typically due to internal corrosion from old brake fluid) 5) Brake wheel cylinder failure (same failure mode as #4) 6) Friction material loss (I had a brake pad chuck its friction material last spring) 7) Brake rotor failure (typically from being machined too thin or from internal rust) 8) Air in the brake lines 9) Water in brake fluid boiling
1 check your shop manual for the TOTAL capacity of the (your) system/ app normal bleed capacity= % of the total SYSTEM. 2. typically a normal bleeding is something UNDER a qt/lit 32-33.8 oz 2a. Of the 4 typical ends, normally bled, it is 100%. The visual guide is of course either coming out clean (then stop) or pre arranged graduated levels at each dirty end.
So for example, a VW Jetta has 5 ends that need bleeding (4 brake lines , 1 clutch line). The oem specifications call for app .2 qt/liter per end x5=(1)/33.8 oz or less than 6.76 oz per end.= app less than 100%
In either, I typically end up with app (4-10 oz) 1/8 to 1/4 qt of BF leftover.
Given the fact that actual brake fluid tests can be conducted and (actual contaminates, H20 %, usable boiling temp left) can be had for very little money (relatively) to massive bucks, it seems to be to be not unlike UOA's for motor, transmission, differential, oils. So if one IS/ARE the NYC taxicab driver/s or does daily delivery in everybody in the worlds' fav city: the hilly streets of San Francisco, CA, or is a brake pedal flogger, the more one uses the brakes, the quicker the likely hood of having to change brake fluid on a more frequent interval. So unless it is measured, or you are some of the above: really a recommendation of every 2/3 years etc. is really only a swag, preventative prescription. As with acutual motr oil UOA's, brake fluid testing is conducted by VERY few and even less % wise.
I see, and that amounts to around a quart...more or less.
Seems to be difficult to find the total capacity, I've not seen it listed under fluid capacities in any owners manuals. I'd guess a quart would be a significant portion of the total, at least if the brake fluid is not also the manual trans fluid (which seems like a very bizarre design...my kid's Focus has that too, like the Jetta that the other kid has).
Must brake bleeding/flushing be done when a brake booster or a master cyclinder or a rotor or a caliper is replaced? Is it usually done in those situations? (My 1980 Celica owner's manual doesn't say anything about brake bleeding.)
If you open up the hydraulic piping/hose, then it needs to be bled. So for instance to do the caliper, you have to disconnect the hose, air would get in the line, so you'd have to bleed it.
Replacing the rotor on the other hand, you just lift the caliper up and off and out of the way, hang it to a suspension part, replace the rotor, put the caliper back on. No mandate to bleed the caliper.
But it is so easy to bleed, I personally do it anytime I touch the calipers or am down there. Get any air or moisture collected in the caliper out.
"It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced. " - To avoid that, should one bleed/flush the brakes, i.e. getting rid of any water, BEFORE replacing the booster?
Without doing a lot of research I suspect the water in the brake fluid is dispersed throughout the contents. It is actually dispersed (dissolved) in the brake fluid. The air, dirt, water vapor finds its way in around the seals at the calipers and wheel cylinders as they move. The water finds its way in at the top around the seal on the cover of the reservoir and when its opened new air comes it.
The fluid at the wheel end shows the discoloration and dirt when bled because that finds its way in there and doesn't migrate throughout the solute. The color does not correlate with water content.
Brake fluid is cheap. I replace it occasionally. That's cheaper than buying test strips or a refractometer to measure the property of the brake fluid that can show the amount of water it contains.
I use a turkey baster to remove old fluid from the master cylinder. I refill with good. And then I start on the wheels while I'm rotating my tires.
My problem is a bleeder on a wheel cylinder that doesn't want to open. And I've round the flats on it slightly. What works to loosen a screw? Years ago I took a caliper off and took it to the machine shop where I had rotors and drums turned; they used a torch.
I use a turkey baster to remove old fluid from the master cylinder. I refill with good. And then I start on the wheels while I'm rotating my tires.
Does brake fluid circulate, like coolant or trans fluid? If I turkey baste out of the master clinder every week for about a month (refill with new), is that the same thing as a brake flush?
Bleeding the brake system of bubbles entails forcing fresh (non air-bubble) fluid into the system whilst allowing the bubbles to flow out the other end.
Thus, Bleeding and flushing is essentually the same process.
There are 3 ways to perform bleeding 1) The ol - have your wife push the brake pedal while you crack open the bleeder nipples. 2) Vacuum-bleeding (reqires special sealant on the bleeder-nipple threads) 3) Pressure-bleeding from the master-cylinder (Recommended by many manufacturers because this is the ONLY way to replace fluid in some ABS components)
BTW: Sudden brake-failure can happen when a brake-line (pipe) suddnely springs a leak and loses pressure. This is not uncommon on vehicles driven in the snow-belt where chloride is used on the roads to melt snow. Once the chloride gets imbedded in the nooks-n-crannies of your cars underbody, the corrosion continues all the time... even in the humidity of the summer.
Toyota reciently recalled 1000s of their trucks because the frame was corroding. I have seen cars sag in the middle from the chloride corrosion eating away at them underneath.
"Bleeding" the bubbles out can be accomplished WAAAY before a complete flush has been effected.
You may need to think a little broader. If master-cylinder or an ABS component is replaced, the air bubbles may not be dislodged as easilly as you think. Some manufactures even recommend bleeding the master-cylinder BEFORE hooking it up to the brake-system. (Just route the output back into the resivour and turn on the pressure-bleeder for a few minutes)
ABS components may be even trickier. On some cars, you need to hook up to a computer to "activate" the ABS pumps so they can self-bleed. (lest bubbles or old fluid gets left behind in the system)
My Volkswagen with ESP (Electronic Stabilization Program) has the ability to apply the brakes on ANY ONE WHEEL to bring the car out of a skid. The system works extremely well. Even in the snow, I cannot get the car to slide sideways.... but bleeding that brake-system requires pressure-bleeding and my laptop computer to activate the ABS system.
Once again, it's all a matter of degree. The replacement of a master cylinder and/or ABS controller is a rather extraordinary procedure, and as such, this type of a bleed is rather rare as well. The vast majority of brake bleeding operations are done following a brake job and/or following a caliper, wheel cylinder, or brake hose replacement, and only require the pumping out of a relatively small amount of fluid.
FWIW, in the combined million and a half miles that my wife and I have driven, and all of the cars that we've driven those miles in, we've needed to replace four brake calipers, four wheel cylinders, ten brake hoses, zero ABS controllers, and zero master cylinders. To take it a step further, I've maintained many-many cars over the years that were not owned by me, and while I've done lots of lower brake components (those close to the wheels), I've never even seen a car that needed a master cylinder or ABS controller.
I could not stop my 1980 Celica and hit the car in front of me in San Francisco in 1992. I was too young and did not know how dangerous it was. So, believe it or not, I drove my car all the way back to Los Angeles. (And along the way, my brake was fine.) The mechanic said my master cyclinder was bad and needed to be replaced. I don't know whether it is possible that one still can drive with a bad master cyclinder. Just curious, why people in the Snow Belt keep using cholride knowing that it corrodes cars?
Some manufactures even recommend bleeding the master-cylinder BEFORE hooking it up to the brake-system. This seems to be related to my previously asked (but not answered) question: "It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced. " - To avoid that, should one bleed/flush the brakes, i.e. getting rid of any water, BEFORE replacing the booster? But I thought one should bleed the rest of the system before installing a booster or master cyclinder. Here you are talking about bleeding the booster or master cyclinder itself. If it is a new cyclinder, there should not be anything in it, so why do one need to bleed it?
"If it is a new cyclinder, there should not be anything in it, so why do one need to bleed it? "
What you are trying to do when putting a new cylinder into your system is to first put fluid where none has been and then equalize it. This would require adding fluid. Then if it has not been bled in a while, ya might as well bleed all four (brake cylinder) positions. Since you have just added new fluid, you bleed till the new fluid comes out of each of the cylinders at the business end of the normal four positions.-importantly it is a further procedure to purge possible air bubbles introduced during R/R aka opening a close system. Does that give you further information in answering your concerns?
"Does that give you further information in answering your concerns? " I guess so. I am not familiar the relationship between the master cyclinder and the 4 brake cyclinders. But I guess what you mean is bleeding (i.e. flushing the air bubbles or water out from the brake fluid in) the 4 brake cyclinders, not the master cyclinder (or the booster). That is, it is the 4 brake cyclinders that "has not been bled in a while", not the master cyclinder, which is new. The brake fluid may enter from the master cyclinder, but where the air bubbles/water are purged from really are the brake cyclinders, or the calipers. Regarding my original question: whether one should bleed the calipers _before_ replacing the booster, now I guess the answer is: one should do it after. As you said, one may introduce air in the fluid when replacing the booster, so one needs to bleed the whole thing after the booster is installed. Perhaps my mechanic forgot to do this and it caused the piston in the calipers to get stuck and I had to get my calipers replaced too.
I am sure you already know this shipo ... but for those reading this that do not know... the REASON that you have replaced LOWER components of the brake systems over the years is as follows.
1) Brake fluid not changed every 2 years can get saturated with water. 2) Once saturated, all it takes is a change in the ambient temparture to make some of that water fall out of suspension. 3) Now "raw" water droplets are in the brake system and they migrate down to the lower extremities of the brake system. 4) These water droplets sit in and start rust on the smooth-bore of the wheel-cylinders.
Brake fluid is hydroscopic ON PURPOSE to protect the metal parts of your brake system. As it gets saturated with water, its ability to protect diminishes to the point were "raw" water droplets form in the hydrolic system.
There is a type of brake fluid which is NOT hydroscopic. It is called "DOT5" and is essentually liquid silicone. HOWEVER, using DOT5 fluid also eliminates the protection from moisture that DOT3 and DOT4 brake fluid provides. Thus DOT5 brake fluid is only really useful in racecars where the fluid gets change several times a year.
And DOT 5 silicone fluid gets air bubbles in it when poured into the system. It then is more problem to get the air out of the system than with DOT 3. And when the fluid heats up, the air expands, and this becomes compressible. You want un-compressible fluid is a brake system. Push on a brake with air bubbles, the bubbles compress down, and the fluid does not push against the hardware to apply the brakes.
DOT 5 is difficult to work with, per what I understand.
Dot 5 is also completely incompatible with Dot 3 and Dot 4. Dot 5 is considered "contaminated" if there is ANY Dot 3 or 4 still in the system, and the reverse is true as well.
How do I keep bleeder screws from corroding and freezing? I just had to replace caliper with a reman partly because the bleeder screw had frozen up.
Too, what's the right thing to put outside the rubber isolators but inside the metal ears of the calipers. Mine had rusted up so that the replacements didn't have enough room to go in. These are on an H-body GM 1998.
"If the system came with DOT 3 (and I don't know of a car with anything else), keep DOT 3 in it. Unless you are going full-bore racing..."
Hmmm, well both of my BMWs came with DOT 4, and I'm pretty sure that both of my VWs and both of my Audis came with DOT 4 as well. I'm also pretty sure that most if not all higher performance European car marques require DOT 4. That said, your comments about staying with fluid that is compatible with what came in any given car is extremely wise.
Comments
It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced.
To answer your other question... if the rotor was dragging and you continued to drive, the heat must have been enormous. (think RED HOT rotor!!) This can easilly burn up bearings in the wheel and generally cause bad things to happen.
There is the slight chance that a improperly adjusted pushrod on the brake-pedal can cause a booster to drag the brakes... but usually ALL of the brakes would be dragging in this case.
I averaged 35-40k miles on front brakes on both my 95 and 96 Suburbans. The 10k inspection was 8 months earlier.
Hmm, losing 1 rotor or caliper should not on a modern car cause complete brake failure. Usually it's an X pattern where your opposite corners run on the same fluid line so that in a failure (as you had) you would retain braking in the other 2 calipers.
Something doesn't seem complete to this story IMO.
-mike
By the way, when my brake failed yesterday, it came kind of suddenly. When I was parking in the lot, the brake pedal kind of bounced back (upwards) and I heard a clicking noise. (After that, I need to press the brake all the way down and allow a much longer distance in order to stop.) Before that, there was not much warning sign. Do brake boosters normally fail like that, rather than gradually?
Yet it is never recommended to do so in owners manuals.
Best Regards,
Shipo
They have testing tools and testing strips to measure the actual chemical condtion of the brake fluid in question, In some ways this is a (go no go) UOA. (not unlike for motor oil) ( not unlike measuring your pool for chlorine/ph levels)
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So for example@ $.52 (cents) per test, and 32 oz of brake fluid costing from 4 to 25., .52 cents can/might help to be appropirate and perhaps let you extended the intervals. (depends on tests and/or attitude or circumstances or any combination)
Nothing like having the facts facing you to make an informed decision.
Best Regards,
Shipo
Brakes are, after all, the difference between a really good day and a really bad day sometimes. If I stopped in 50 feet for a truck 49 feet in front of me, well, that's pretty good but not quite good enough. :P
I'm a believer in small increments of advantage when it comes to tires and brakes. For me, in those areas there is no "overkill", whereas "super" sparkplugs or "heavy duty" oil filters or "performance mufflers" or "free-flow air filters" don't seem worth it to me for the little gain.
But those extra 12 inches of braking......yeah!
I'm so fanatic about braking that I even diss oversize wheels and tires for that reason. I feel they cut off a small amount of braking distance (depending).
In addition, as you probably know and have probably done, you have added BF to top the reservoir, aka FRESH at the top.
Another that goes along with your thought processes , as you know BF can vary WILDLY in price: per 32/33.8 oz. (I use 32/33.8 oz as this is what it usually takes to flush a normal system)
So again IF .125 cents per oz is more than fine, THEN why buy the .78 oz designer swill? Of course, AND vice versa.
..."I'm so fanatic about braking that I even diss oversize wheels and tires for that reason. I feel they cut off a small amount of braking distance (depending). "....
Yes I sometimes cringe knowing that many folks who will "bling out" tires and rims combinations and do NOTHING to the brake system, don't even have a clue the stopping distances have just gone out the window (and hp, but that is a different discussion) .
In the brake department (consumer) I have to admit to being a tad spoiled. I have one 7 years old that stops 60-0 in 109 ft. This has been recently beaten by the 2008/2009 Nissan GT-R @ 104 feet. Another 2@ 4800# 14/12 year old Suv 's which stops in 136 ft.
Also as has been said, testing the resivoir doesn't indicate what's in the lines or the calipers. I reccomend a 2 year inverval for normal driving. And for $60 give or take is it worth it not to do it?
On my own car that i push hard and track as well I use ATE Superblue and flush 1-2x a year.
-mike
The ATE BFT 320 brake fluid tester
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Others
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I did have Midas try to sell me such parts one time, but the dealer said there was nothing wrong and no need to replace them.
(Recently my son did replace a leaking wheel cylinder on a 1996 Jetta that he bought used last summer.)
Oh, and I did change brake fluid once so far...on my wife's 2 year old Jetta, as it is specified in the maintenance shedule.
I also lube my caliper slides at the same time.
Regarding the cars you kept for 12 and 16 years with no fluid change, how do you know that the fluid wasn't ever changed, even a little? I ask because when various shops do a brake job, they typically "bleed" the brakes, and that has the effect of pushing through the worst of the contaminated fluid (water is heavier than brake fluid), and replace it with fresh(er) fluid from the reservoir.
If your car truly went 16 years with zero fluid replacement, then I guarantee you that the sludge that would come out of the bleed orifices would have absolutely zero resemblance to brake fluid.
Best Regards,
Shipo
As I said I don't provide this as evidence that this is a good idea. Changing brake fluid was something I first heard about a few years ago, and then an attempt to sell me on it was only based on the claims of corrosion and resulting expensive repairs.
I only recently read about the boiling issue, thanks to these forums. I've kind of decided that my new policy will be to change fluid at about 3 years and 25,000 miles (when no warranty issues). Typically we have gone about 50,000 miles between brake jobs and put 8000 to 10,000 miles per year on our cars...so this will be one full flush between each brake job and then when they do a brake job, I can just ask them to replace all fluid.
I have not yet decided what to do on the 10 year old vehicle, 2 years since last brake job, which was both front and rear.
I'm also thinking I'll now periodically replace PS fluid...I recently spent about $900 on a pump and rack.
Does one achieve both in the same procedure? Or does one need to perform them separately? Can one (or is it possible to) purge the bubble without replacing the brake fluid, for example? When a mechanic says "bleeding", normally what does he mean?
By the way, do brakes fail suddenly or gradually? My brake failed without any squeaking noise or warning sign.
For a brake flush, you perform pretty much the same process, however, you continue to pushing until all of the old fluid is out of the system. Obviously a "flush" takes considerably longer and requires considerably more new brake fluid.
As for why brakes can suddenly fail, geez, LOTS of ways, including but not limited to the following:
1) Master cylinder failure
2) Brake line rupture due to corrosion or damage
3) Brake hose rupture (typically due to age)
4) Brake caliper seal failure (typically due to internal corrosion from old brake fluid)
5) Brake wheel cylinder failure (same failure mode as #4)
6) Friction material loss (I had a brake pad chuck its friction material last spring)
7) Brake rotor failure (typically from being machined too thin or from internal rust)
8) Air in the brake lines
9) Water in brake fluid boiling
Best Regards,
Shipo
1 check your shop manual for the TOTAL capacity of the (your) system/ app normal bleed capacity= % of the total SYSTEM.
2. typically a normal bleeding is something UNDER a qt/lit 32-33.8 oz
2a. Of the 4 typical ends, normally bled, it is 100%. The visual guide is of course either coming out clean (then stop) or pre arranged graduated levels at each dirty end.
So for example, a VW Jetta has 5 ends that need bleeding (4 brake lines , 1 clutch line). The oem specifications call for app .2 qt/liter per end x5=(1)/33.8 oz or less than 6.76 oz per end.= app less than 100%
In either, I typically end up with app (4-10 oz) 1/8 to 1/4 qt of BF leftover.
Do you mean that, typically, if you get front and rear brakes done at one time, that probably all brake fluid has been replaced?
Seems to be difficult to find the total capacity, I've not seen it listed under fluid capacities in any owners manuals. I'd guess a quart would be a significant portion of the total, at least if the brake fluid is not also the manual trans fluid (which seems like a very bizarre design...my kid's Focus has that too, like the Jetta that the other kid has).
(My 1980 Celica owner's manual doesn't say anything about brake bleeding.)
Replacing the rotor on the other hand, you just lift the caliper up and off and out of the way, hang it to a suspension part, replace the rotor, put the caliper back on. No mandate to bleed the caliper.
But it is so easy to bleed, I personally do it anytime I touch the calipers or am down there. Get any air or moisture collected in the caliper out.
The fluid at the wheel end shows the discoloration and dirt when bled because that finds its way in there and doesn't migrate throughout the solute. The color does not correlate with water content.
Brake fluid is cheap. I replace it occasionally. That's cheaper than buying test strips or a refractometer to measure the property of the brake fluid that can show the amount of water it contains.
I use a turkey baster to remove old fluid from the master cylinder. I refill with good. And then I start on the wheels while I'm rotating my tires.
My problem is a bleeder on a wheel cylinder that doesn't want to open. And I've round the flats on it slightly. What works to loosen a screw? Years ago I took a caliper off and took it to the machine shop where I had rotors and drums turned; they used a torch.
Will PB Blaster work?
2014 Malibu 2LT, 2015 Cruze 2LT,
Does brake fluid circulate, like coolant or trans fluid? If I turkey baste out of the master clinder every week for about a month (refill with new), is that the same thing as a brake flush?
I remove the several ounces of fluid at the top so when I add fresh from the can, the fluid at the top is mostly new instead of old mixed with new.
2014 Malibu 2LT, 2015 Cruze 2LT,
Thus, Bleeding and flushing is essentually the same process.
There are 3 ways to perform bleeding
1) The ol - have your wife push the brake pedal while you crack open the bleeder nipples.
2) Vacuum-bleeding (reqires special sealant on the bleeder-nipple threads)
3) Pressure-bleeding from the master-cylinder (Recommended by many manufacturers because this is the ONLY way to replace fluid in some ABS components)
BTW: Sudden brake-failure can happen when a brake-line (pipe) suddnely springs a leak and loses pressure. This is not uncommon on vehicles driven in the snow-belt where chloride is used on the roads to melt snow. Once the chloride gets imbedded in the nooks-n-crannies of your cars underbody, the corrosion continues all the time... even in the humidity of the summer.
Toyota reciently recalled 1000s of their trucks because the frame was corroding. I have seen cars sag in the middle from the chloride corrosion eating away at them underneath.
Well, sorta, kinda. It's a matter of degree as "Bleeding" the bubbles out can be accomplished WAAAY before a complete flush has been effected.
Best Regards,
Shipo
You may need to think a little broader. If master-cylinder or an ABS component is replaced, the air bubbles may not be dislodged as easilly as you think. Some manufactures even recommend bleeding the master-cylinder BEFORE hooking it up to the brake-system. (Just route the output back into the resivour and turn on the pressure-bleeder for a few minutes)
ABS components may be even trickier. On some cars, you need to hook up to a computer to "activate" the ABS pumps so they can self-bleed. (lest bubbles or old fluid gets left behind in the system)
My Volkswagen with ESP (Electronic Stabilization Program) has the ability to apply the brakes on ANY ONE WHEEL to bring the car out of a skid. The system works extremely well. Even in the snow, I cannot get the car to slide sideways.... but bleeding that brake-system requires pressure-bleeding and my laptop computer to activate the ABS system.
FWIW, in the combined million and a half miles that my wife and I have driven, and all of the cars that we've driven those miles in, we've needed to replace four brake calipers, four wheel cylinders, ten brake hoses, zero ABS controllers, and zero master cylinders. To take it a step further, I've maintained many-many cars over the years that were not owned by me, and while I've done lots of lower brake components (those close to the wheels), I've never even seen a car that needed a master cylinder or ABS controller.
Best Regards,
Shipo
Just curious, why people in the Snow Belt keep using cholride knowing that it corrodes cars?
This seems to be related to my previously asked (but not answered) question:
"It is possible that your brake system had some water in it which migrated down to a caliper when the booster was replaced. " - To avoid that, should one bleed/flush the brakes, i.e. getting rid of any water, BEFORE replacing the booster?
But I thought one should bleed the rest of the system before installing a booster or master cyclinder. Here you are talking about bleeding the booster or master cyclinder itself. If it is a new cyclinder, there should not be anything in it, so why do one need to bleed it?
What you are trying to do when putting a new cylinder into your system is to first put fluid where none has been and then equalize it. This would require adding fluid. Then if it has not been bled in a while, ya might as well bleed all four (brake cylinder) positions. Since you have just added new fluid, you bleed till the new fluid comes out of each of the cylinders at the business end of the normal four positions.-importantly it is a further procedure to purge possible air bubbles introduced during R/R aka opening a close system. Does that give you further information in answering your concerns?
Regarding my original question: whether one should bleed the calipers _before_ replacing the booster, now I guess the answer is: one should do it after. As you said, one may introduce air in the fluid when replacing the booster, so one needs to bleed the whole thing after the booster is installed. Perhaps my mechanic forgot to do this and it caused the piston in the calipers to get stuck and I had to get my calipers replaced too.
1) Brake fluid not changed every 2 years can get saturated with water.
2) Once saturated, all it takes is a change in the ambient temparture to make some of that water fall out of suspension.
3) Now "raw" water droplets are in the brake system and they migrate down to the lower extremities of the brake system.
4) These water droplets sit in and start rust on the smooth-bore of the wheel-cylinders.
Brake fluid is hydroscopic ON PURPOSE to protect the metal parts of your brake system. As it gets saturated with water, its ability to protect diminishes to the point were "raw" water droplets form in the hydrolic system.
There is a type of brake fluid which is NOT hydroscopic. It is called "DOT5" and is essentually liquid silicone. HOWEVER, using DOT5 fluid also eliminates the protection from moisture that DOT3 and DOT4 brake fluid provides. Thus DOT5 brake fluid is only really useful in racecars where the fluid gets change several times a year.
DOT 5 is difficult to work with, per what I understand.
Best Regards,
Shipo
Too, what's the right thing to put outside the rubber isolators but inside the metal ears of the calipers. Mine had rusted up so that the replacements didn't have enough room to go in. These are on an H-body GM 1998.
2014 Malibu 2LT, 2015 Cruze 2LT,
If the system came with DOT 3 (and I don't know of a car with anything else), keep DOT 3 in it. Unless you are going full-bore racing....
Hmmm, well both of my BMWs came with DOT 4, and I'm pretty sure that both of my VWs and both of my Audis came with DOT 4 as well. I'm also pretty sure that most if not all higher performance European car marques require DOT 4. That said, your comments about staying with fluid that is compatible with what came in any given car is extremely wise.
Best Regards,
Shipo