By on October 15, 2014

brake fluid. Shutterstock user Nor Gal

Gregg writes:

Sajeev,

I have a 2006 Tacoma with 50K miles and anti-lock brakes. I feel it is time to change the brake fluid as a preventative maintenance measure. I have the tools and have bled numerous non-antilock brake systems and have done some research into what it would take to fully refresh the fluid. Some forum people suggest the usual bleeding procedure followed by causing the antilock feature to react by stopping quickly on a dirt road or similar circumstances and then re-bleeding the system. Also mentioned is using a code reader to actuate the antilock system.

Personally I wouldn’t mind paying for a lower end code reader if I knew it would do what I needed, but I certainly am not going to spend big bucks for one. Do you or any of the readers know what will activate the anti-lock system with minimal expenditure?

I also noticed that there is a hose about 3/8 inch ID attached to the master cylinder reservoir that appears to be the return form the anti-lock system. I could easily make up a catch container to keep the return fluid from mixing with the new fluid I would put in the reservoir.

What do you think about using DOT-4 fluid?

Thanks,
Gregg

Sajeev answers:

Because modern braking systems are a far cry from the old days, this is a time when RTFM is abso-Fing-lutely mandatory for everyone’s safety.

Either buy the factory manuals, or be a forum junkie (like reading this) as they regularly cover these concerns.  The forum suggests flushing brake fluid without the tool is no biggie, but honestly, the “correct” procedure doesn’t look that hard if you buy the right tool or its cheapy laptop alternative.

This loaded task implies you’re forgiven for taking it to a shop with the proper tools, like this cool sucky brake fluid machine. Time value of money and all that.

I can’t quickly Google the factory brake fluid for your truck, but regarding DOT 4: it interchanges with DOT 3 with a higher boiling point.  But it doesn’t keep the boiling point higher for as long as you might think. That said, everything suggests DOT 3 systems can be flushed and replaced with DOT4 and it is good idea if you flush DOT 4 on a regular basis. DOT 5 is different, its silicone (not glycol) based. DOT 5.1 is glycol, but I haven’t read anything conclusive about replacing older fluid designs with it.

Whew!

Off to you Best and Brightest, especially those with more firsthand experience in various types of brake fluid.

[Image: Shutterstock user Nor Gal]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 

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44 Comments on “Piston Slap: Liberal Bleeding, Flushing Brake Fluid...”


  • avatar
    Detroit-X

    I’ve never flushed brake fluid, in any vehicle, in about 740k miles of lifetime driving.

    • 0 avatar
      NeilM

      @Detroit-X: Then I sure as shit hope that someone has been doing it for you, for instance as part of a normal brake service. Brake fluid is hygroscopic, meaning it actively absorbs moisture (in this case from the atmosphere). This moisture both lowers the brake fluid’s boiling point and promotes corrosion in the car’s steel brake lines.

      • 0 avatar
        3Deuce27

        Critical(Mechanical) Reasons for Critical Pre-Crash Event Attributed to Vehicles

        Number of Crashes Weighted.

        Tires failed or degraded/wheels failed_ 43.3%

        Brakes failed/degraded_ 25.0%

        Other vehicle failure/deficiency

        Steering/suspension/transmission/engine failed_ 10.5%

        Unknown_ 0.5%

        Total_ 100%

        http://www-nrd.nhtsa.dot.gov/Pubs/811059.PDF

    • 0 avatar
      3Deuce27

      Reg; “I’ve never flushed brake fluid, in any vehicle, in about 740k miles of lifetime driving.”

      Luck be with you(and everybody in and around your moving vehicle ) living on the edge.

      I change BF usually every year, but never go past two years or 15,000 miles.

      If you live in hilly country or city, or drive aggressively, it is imperative to change often to reduce boiling. Same goes for pickups and vans that are often used loaded/towing, any heavy vehicle.

      Around here, race/track vehicles get a BF change every race/track weekend.

      The damage caused by rust in iron MC/BC bores, steel brake lines, and ABS modulators can be quite expensive and can result in catastrophic failure.

      Have a shop do it or buy the the equipment to do it and school yourself in the proper procedure.

      And always drive like you don’t have any brakes, saves your brakes and fuel, not to mention a lot of other parts and pieces in the drive and suspension systems. Tires last a lot longer and remain more effective, especially in emergency braking and at high slip angles, because the case/sidewall construction maintains a higher integrity.

      Changing your brake fluid is way cheaper then an oil change… do it.

    • 0 avatar
      3Deuce27

      > Reg; “I’ve never flushed brake fluid, in any vehicle, in about 740k miles of lifetime driving.”

      Luck be with you(and everybody in and around your moving vehicle ) living on the edge.

      I change BF usually every year, but never go past two years or 15,000 miles.

      If you live in hilly country or city, or drive aggressively, it is imperative to change often to reduce boiling. Same goes for pickups and vans that are often used loaded/towing, any heavy vehicle.

      Around here, race/track vehicles get a BF change every race/track weekend.

      The damage caused by rust in iron MC/BC bores, steel brake lines, and ABS modulators can be quite expensive and can result in catastrophic failure.

      Have a shop do it or buy the the equipment to do it and school yourself in the proper procedure.

      And always drive like you don’t have any brakes, saves your brakes and fuel, not to mention a lot of other parts and pieces in the drive and suspension systems. Tires last a lot longer and remain more effective, especially in emergency braking and at high slip angles, because the case/sidewall construction maintains a higher integrity.

      Changing your brake fluid is way cheaper then an oil change… do it.<

      • 0 avatar
        golden2husky

        ….And always drive like you don’t have any brakes, saves your brakes and fuel, not to mention a lot of other parts and pieces in the drive and suspension systems. Tires last a lot longer and remain more effective, especially in emergency braking and at high slip angles, because the case/sidewall construction maintains a higher integrity….

        Ugh, I hope I never encounter you on the road….I drive with a moderate amount of enthusiastic activity – and love g forces around on/off ramps and gladly pay for 10% reduction in parts and tires. And I still get damn good life out of my cars and 33 MPG out of my commuter with “lotsa” pedal inputs.

        • 0 avatar
          3Deuce27

          Reg; “Ugh, I hope I never encounter you on th road”

          LMAoff! Don’t worry, if I feel like playing, you will have a hell of a time keeping sight of my rear bumper. I put my Miata sideways at least once a day, usually more then once. And on the weekends I play with one of my track cars, and one of them has 3.2 pounds per Hp. My annual tire budget would by a nice used Boxster or XKR Jag.

          The comment was meant for the daily driver looking to get the most out of their transportation funds. And when I’m not playing in the twisties, I drive very efficiently, like I don’t have any brakes.

          I always get a kick out of passing at the next light, the yahoo who passed me being in a big hurry to get nowhere fast. I don’t want his cost per mile of car ownership and fuel use.

    • 0 avatar
      Detroit-X

      My 740k miles includes about six cars over 100k, one with over 200k miles, and never a fluid change. Here in Michigan, brake parts rust from the outside in, not from the fluid side out, and we don’t have the high heat load or mountains.

      When I see an owner’s manual that says change brake fluid at anything under 100k, it sounds to me: “MFR refuses to use good parts.” Or “MFR want to pad dealer’s pocket.” Or “MFR is passing any possible future legal buck to owner.” 15k changes? Jeez. What about re-foaming the seat cushions every 10k?

      Where is the NHTSA data that says brake fluid was the cause of brake failure, and not other brake parts. Is that data from a cop with a clipboard at the side of the road, taking to a just-crashed owner?

      Duly noting severe duty exceptions, just like oil change intervals, this brake fluid thing is whatever makes you feel better. Just like hair coloring and expensive cat chow.

    • 0 avatar
      MBella

      How many calipers, wheel cylinders, master cylinders, brake lines, abs units have you replaced?

      • 0 avatar
        Detroit-X

        On the car that went over 200k, at 186k, I had both rear wheel cylinders replaced in the drum brakes. That’s it for the whole 740k history. $50 in parts. For the person who does not drive in severe conditions, has less road salt, and ditches the car in 30-50k miles, the brake fluid panic is extra goofy.

        “Sir, at our dealership we recommend brake fluid changes every 15k miles.” Where is your test data to prove that? “Ha ha… Sir, we have no test data; we just decided this at the last sales meeting of service writers.”

        Yet another reason to avoid me I on the road, I guess; let’s review: my vehicle weighs 6000lb, won’t corner over 0.75g, won’t stop in XX feet, and won’t accelerate 0-60 in 5s to “get out me of trouble”, and I change my oil when the light comes on, risking sudden engine seizure.

  • avatar
    Gardiner Westbound

    The independent garage I patronize renews the brake fluid coincident with changing brake pads. That seems to be sufficient.

    • 0 avatar
      Speedygreg7

      That may be, but that may also be against manufacturer maintenance schedule. For our 2012 Nissan Altima, Nissan requires a yearly or 15,000 mile brake fluid flush. Sounds crazy to me, but with ABS, traction control and stability control all using the brakes maybe Nissan believes the fluid gets more of a workout than in earlier cars. I have been doing it every 30,000 miles on that car. I can’t wrap my head around 15,000.

      • 0 avatar
        Jacob

        This schedule sounds crazy. An average person will never follow it. Typically people’s jaws drop when I say that I change ATF in my cars. Most Americans think oil is the only fluid that needs to be changed. And manuals? Who reads manuals?

        • 0 avatar
          CobraJet

          I agree. My 21 year old Silverado probably had a partial brake fluid change last year when the front calipers were replaced by my mechanic at 180,000 miles. Other than that, I have never touched it.
          Same for my 07 Impala or my 02 GMC van. Transmission fluid, on the other hand, is changed in each vehicle regularly per the severe schedule. In fact, I don’t think I have ever seen brake fluid changes mentioned in the service schedule

      • 0 avatar
        danio3834

        Is that brake fluid change interval printed in the maintenance manual or is it the “dealer recommended” interval? Most manufacturers don’t even specify a brake fluid change interval as recommended maintenance.

        • 0 avatar
          3Deuce27

          Ford, for a time, recommended fresh fluid every 36,000 miles or three years, and to replace the fluid each time the brake pads are changed. Currently, however, Ford specifies no specific time or mileage recommendation for changing the brake fluid.

          As for Chrysler, the only recommendation they publish is to change the fluid every 24 months on their Sprinter van.

          A number of import car makers do recommend brake fluid changes for preventive maintenance at specific time/mileage intervals:
          Acura: 36 months
          Audi: 24 months
          BMW: 24 months, or when indicated by Service Inspection Indicator
          Honda: 36 months
          Jaguar: 24 months all models except 2009 XF (36 months)
          Land Rover: 36 months
          Lexus: 36 months or 30,000 miles, which ever comes first
          Mercedes-Benz: 24 months
          MINI 24 months
          Saab: 48 months (all models except 9-7X)
          Smart: 24 months or 20,000 miles, which ever comes first
          Subaru: 30 months or 30,000 miles (normal service) or 15 months/15,000 miles (severe service)
          Suzuki: 24 months or 30,000 miles, which ever comes first (Forenza & Reno), 60 months or 60,000 miles (Grand Vitara and SX4)
          Volkswagen: 24 months (New Beetle, City Gold, City Jetta), 36 months (all other models except Routan)
          Volvo: 24 months or 37,000 miles (Normal), or 12 months (severe service)
          Source for fluid change recommendations: Vehicle Manufacturer service information & owners manuals

        • 0 avatar
          Speedygreg7

          That is Nissan owner’s manual maintenance. I ignore everything the dealer says and refer to the manual on all services.

      • 0 avatar
        IHateCars

        @ Speedygreg – Nissan/Infinitis have notoriously undersized/bad brakes to begin with so this accelerated schedule sounds like a band-aid fix to address bad design and/or nickel & diming on brake parts….thanks Ghosn.

        Personally, I change brake fluid on my cars/trucks every 80 000 KMS (or 4 years) and every second year on my bikes as they see more extreme heat cycles.

  • avatar
    RetroGrouch

    8 years on DOT3 or DOT4 brake fluid is 5 to 6 years too long.

  • avatar
    Crabspirits

    In the fleet that I manage at work, EVERY piece of equipment gets brake fluid changed on a yearly basis. I use a super easy procedure of sucking it out of the reservoir with a vacuum pump. Unless your calipers/wheel cylinders are extended out due to low lining or other reason, this takes care of MOST of the fluid.

    I understand some will balk at this half-assed approach, but the failure rate of my brake system hydraulics went WAY down (almost none) since I started doing it 5 years ago. Eventually the fluid will port back up to the reservoir and mix around with the new. The more frequent servicing offsets the effect of any lingering old fluid. Brake fluid is cheap anyway. You could do this even more often, as it only takes two minutes to do.

    • 0 avatar
      Jacob

      Supposedly, there is little mixing going on in the brake fluid due to thin lines, but then replacing the fluid in the reservoir is inexpensive. I replace the fluid in the reservoir before doing the bleeding because that speeds up the process.

    • 0 avatar
      28-Cars-Later

      Crabspirits this is a brilliant approach and it answered the questions I had on the subject, thx.

      • 0 avatar
        SCE to AUX

        I like the sound of it, too. But I really prefer flushing the lines if I can.

        However, the last time I flushed brake lines (this summer), one last pedal push drew air through the empty reservoir ([email protected]#$%^), and I had to start over.

        • 0 avatar
          DeadWeight

          This is an issue I’ve experienced multiple times, also, no matter how careful/thorough I was.

          I sort of lean towards Crabspirit’s approach for my daily driver cars. I realize brake fluid absorbs moisture, and that there’s time-decay in addition to use-degradation affecting the brake fluid, but for a sensibly driven daily driver, I find it hard to belief that a vacuum out and replenish won’t get the essential nature of the job done 98% of the time.

          Also, unless someone is towing often, or driving 25,000 miles a year, regarding a moderately driven daily driver, I find these brake fluid change intervals of every two or even three years to be overkill.

          Finally, I once had a mechanic whom I deemed competent tell me that brake fluid color can actually reveal a lot of immediately useful information at lesst in terms of identifying clearly fried fluid. He said that, generally speaking, as long as the fluid was closer to its original light color rather than amber or darker, assuming it find’t have any sediment or fouling, it was likely okay, and that brake fluid will turn darker even just from absorption of ambient moisture.

    • 0 avatar
      danio3834

      That’s a decent, quick, one-man approach. Whenever I open up the hydraulic brake system on vehicles or at pad/rotor replacement, I power-bleed the entire system until all the fluid is new and clean. That is unless it’s got sketchy looking rusty bleeders as is common after a while here in the rust belt.

    • 0 avatar
      nickoo

      That’s how I do mine. Yes its half assed, but it’s better than air in the lines.

      absolutely mandatory: buy a brand new bottle of brake fluid every single time you add it, it goes bad very quickly by accumulating moisture the second you open the bottle. That and heat from excessive braking are what wear out brake fluid.

    • 0 avatar
      krhodes1

      Changing the fluid in the reservoir is better than nothing, but probably not a lot better. Brake fluid being hygroscopic, the water in it WILL migrate throughout the system.

      Every vehicle I have ever owned has had a change interval of 2 or 3 years. With a Motive pressure bleeder ($50), this is a 10 minute task once the wheels are off. For my cars that I change to snow tires annually, I do it annually. Why not? The wheels are off anyway. And opening the bleeders every couple years makes sure they actually DO open when you need them to.

      That last one is really the best reason of all to do this, especially in salt country. Nothing sucks more than having to replace a brake line or hose or MC on an older car, and then having to replace a couple calipers too because the @#[email protected]@@# bleeders shear off because they have not been touched since the thing was new. And the really tiny ATE bleeders I replace every other bleed cycle. Those things are tiny and made of sillyputtium.

      • 0 avatar
        3Deuce27

        All good points_krhodes1

        I pull the bleeders and clean them and run a tap through the bleeder bore, then use the appropriate anti-seize when reinstalling bleeders.

        In rust country, I would no doubt have a much stricter maintenance regime, even for my throwaway $1,000 Winter daily driver.

      • 0 avatar
        cbrworm

        This is essentially what I do. I use a motive power bleeder for the brakes and do every vehicle every two years. I do the clutches by hand.

  • avatar
    JMII

    Here is my take: the reason for activating the ABS system is some brake fluid is in there and just flushing doesn’t get all of it out. Seems like overkill however as there can’t be that much your missing compared to the overall volume in the entire system. DOT4 has a higher boiling point which is a good thing, but it tends to attract more moisture which is a bad thing. Thus the reason DOT4 needs to be flushed more often. Brake fluid should be flushed every 2 years regardless because of the moisture issue and general heat cycle damage. As mentioned above my Nissan too uses the brakes as part of the vehicle dynamic control system (aka anti skid, traction control, stability, etc, etc) so they may be called upon more often then “normal” (IE when YOU push the pedal).

    I gained a whole new respect for brake fluid after putting my car on the track. Slowing down repeatedly from 100 MPH fast enough to engage the ABS and DOT3 soon becomes boiled and worthless. Granted on a daily driver you aren’t pushing braking system anywhere near those limits, but when it comes to brakes why would you take short cuts / cheap out? Rotors and pads are easy to measure the wear rate but with fluid you can’t really tell if its “good” or not.

    • 0 avatar
      krhodes1

      I boiled the brakes on a several year old rental car in the Black Hills of South Dakota once. I NEVER, EVER want to repeat that experience. I really don’t enjoy cold sweat showers, and any faster and it would have been a “code brown” event.

      • 0 avatar
        3Deuce27

        Yes! The pucker factor is quite pronounced in those situations.

        A few years back, I was coming down hill from Greenhorn Summit(Cali Hwy_155 near Bakersfield) in my 1-ton crewcab with a camper and loaded 20ft equipment trailer. That hill is very steep so as a precaution, I started off in compound low gear, but the revs built to quickly, so had to shift up, soon I noticed that the brakes were fading, so I pulled off in a chain-up area. The brakes were glowing bright red and sparking, easily seen in the bright sunlight and the fluid was boiling.

        We waited about four hours into evening for the brakes and fluid to cool before attempting to finish the decent. Even then, I had a discussion with my son about him bailing out if the brakes started to or completely fail. I wouldn’t have that option as my vehicle, uncontrolled, would run down into Wolford Hgts and probably land on a house, and like a pilot with a wounded bird, I had to stay at the wheel to hopefully minimize damage to property and person.

        All turned out well, but I was amazed how long it took for the rotors to quit glowing red that night. We had a good time waiting, sitting in lawn chairs and barbecuing, while watching Airforce jocks do mock dog fights overhead.

        After that episode all the brakes had to be rebuilt and fluid changed. And, it turned out that the Trailer braking activation system was only partially working(electrical ground), causing or exacerbating the situation. After that experience, I changed to Semi-truck trailer/RV equipment trailer connections with blades instead of round pin contacts, and wired a direct ground from the ground buss at the battery. Now all my trailers have that set-up, though, it should be noted, that heavy duty round pin connectors should work as well, certainly better then the lighter duty light vehicle connectors.

  • avatar
    Roader

    Depends on the climate. Here in the desert West the air is very dry. Never had a problem braking on multi-mile 7% downhill grades with 20-year-old factory fluid.

  • avatar
    hudson

    I always find these sorts of arguments funny. I live where it’s moist nearly all year around. I know more people that don’t touch the fluid than do.

    As far as I’m concerned, you’ll get away with out under normal circumstances. But, doing it at all, regardless of ‘completeness’ or schedule, is cheap insurance.

  • avatar
    3Deuce27

    My early comment… still missing.

  • avatar
    Scoutdude

    As long as you never let the reservoir run dry doing the conventional method of bleeding the brakes is fine on an ABS equipped car. If you have a turkey baster suck out all but a little of the fluid first, then refill and bleed until you get clear fluid. The best time to do it is after you’ve installed fresh pads. Do it on pads that are getting thin and you are going to need to use that much more fluid to get all of the old fluid out of the caliper. Typically the inlet is near the top and the bleeder is always at the top so the old fluid in the bottom of the bore will more than likely mostly stay there.

    • 0 avatar
      johnny ro

      Dont do it after the break pad replacement. Do it during the pad replacement (sort of).

      What I mean is open the bleeder while pushing the piston back in, so it does not jam fluid back upstream. Let it come out then finish the bleed job after pads are in.

  • avatar
    SCE to AUX

    I can’t see a compelling reason to spend money on a special tool to activate the ABS, when the fluid you’ll flush from doing so is minimal.

    A conventional bleed and flush – or even Crabspirits’ cheapo approach – at 2- to 5-year frequency will keep things fresh enough.

    Spending a lot of money to be a purist isn’t worth it. There are so many other nefarious forces at work against your vehicle; flushing every last cc of old brake fluid annually isn’t going to change its life or safety whatsoever.

    It’s things like repeated road salt application to your brake lines that is a greater long-term risk.

  • avatar
    Mikein08

    A friend of mine who is a decent shade-tree mechanic says that he will
    work on anything that makes a car go, but won’t work on anything that
    makes a car stop – he entrusts that to professionals. So, my advice is,
    get a trained professional to flush your brake system.

    • 0 avatar
      3Deuce27

      Your friend has to consider liability and, if, he has insurance, the policy may not allow brake work, or brake work with out ‘ASE’ certification.

      Anybody who has a decent mechanical aptitude, is certainly capable of performing brake work after doing due diligence(model information) on their particular vehicle.

      The only time I let a ‘professional’ do my brake work, I had a catastrophic failure returning the car home from the dealership. It nearly cost me a beautiful 356 Porsche.

      Last year my Dad had a complete brake job on his 300C by the Chrysler dealer. I drove it home and told Dad that the right front caliper was dragging. He didn’t do anything about it and this Spring, both front brakes were acting up so he finally took it back. Had to replace Calipers/rotor/pads. Cost him $600.00. They said he should have brought it back right away, which is true, but his hearing is bad and felt all was ok. So much for professionals.

    • 0 avatar
      Power6

      That sounds dumb, there is nothing to be afraid of with proper procedures on brake systems. I wouldn’t trust the average mechanic to do brakes with any car I care about. Brakes are a huge profit margin item and you will get bottom of the barrel cheap parts tossed in quickly…next sucker in bay 4. You have to have a really trusted mechanic or pay the dealer prices to get a good brake job. There are a lot of finer points to a good brake job that most shops skip.

      If you do it at home you can do it right. Just using some slight performance oriented pads and bleeding properly with a good fluid like an ATE typ200 (RIP Superblue) can take a mediocre braking system and make it better. Doing this on my old Lexus for example made a big difference in braking feel and performance. Any of my true performance cars would never get a corner shop brake job.

  • avatar

    I think flushing every 1 to 2 years is a little crazy. Yes it attracts moisture but it takes a while I remember when I worked for a dealer group in the 90 ,s it was a running joke among the techs that vw actually printed a schedule. I think part of the reason was you usually had to open the brake system for service every 50k miles or less which meant at least part of the fluid got changed. My wife’s Durango is the only car I ever took out fluid that looked like crap most look very good. My Toyota pickup. Had brand new looking fluid when I did a brake job at 160k. So yes change it but I have to imagine every 2years is a bit crazy

    • 0 avatar
      3Deuce27

      It is not just a boiling fluid problem when brake fluid collects water.

      The moisture collected, due to gravity, sits at the bottom of the bores in master, brake, and caliper cylinders(also clutch systems). If those bores are iron, they start to rust, eventually causing seal failure and can significantly harm the equipment making them not rebuildable.

      When you have seen as much of this damage as I have over the past fifty years, you change your brake fluid.

  • avatar

    BMW, before the fallacy/travesty known as “Lifetime Maintenance”, recommended every two years. What comes out isn’t clear, so for the guy with 700k plus, you are running sludge….

    I get to mine every 3 years or so. A quick flush till clear when doing pads/discs is usually adequate. I stick with OE fluid, not because it is the best, but why introduce questions…also, I’m not smarter than the OE, usually.

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