DIY – Changing the Brake Fluid

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Recently I caught up on all the car maintenance that’s been overdue for a while. It never used to be this way – everything was done by the book and on schedule. Now our toddler takes up most of our free time and when he goes to bed  we are usually exhausted and just want to unwind. I used to have time for it all but now, honestly, I’d rather go work out than work on cars when I get a minute to myself.

But the fact remains – cars need to be maintained no matter how little time you have available. For me, it’s actually much more efficient to do all routine maintenance myself anyway. Taking a car to a mechanic takes much longer than doing it in my own garage. Plus I have to rely on someone to get a ride if I don’t want to sit there and wait for hours.  So it’s not just about saving a lot of money, but also about using what little spare time that I have more efficiently.

Changing the brake fluid is something that should be done at least once every two years. It’s one of the maintenance items where mileage is irrelevant, so you can drive only a thousand miles in two years and still have to change the fluid. This is because brake fluid is hygroscopic meaning that it will absorb moisture from the air. Water in the fluid can in turn affect the boiling point and the brakes might not work as expected, which is not something you want to experience.

Changing the brake fluid is a simple and straightforward procedure if you have the right tools and know a couple of tips and tricks that I’ll share in this post. This DIY method is applicable to any car or even a motorbike as long as they have hydraulic brakes (most do). I’ve changed brake fluid on BMWs, Toyotas, Infinitis, Hondas, Nissans using the general approach outlined in this post. This particular DIY guide is illustrated with pictures from a brake fluid change on a 2003 Mercedes C320 (W203 model) – my wife’s car. It’s really no different from working on her previous Toyota Corolla yet you’d drop 2-3 times as much money on this service at a Mercedes dealer just because of the name. They don’t care that this Mercedes has 120,000 miles and that we bought it for less than what a used Corolla costs.

Doing this yourself will cost less than $10 in materials and no more than an hour of your time. In the future, you should be able to get the next brake fluid service done in 30 minutes from the moment you get the tools ready to the moment you crack open a cold one after finishing the job. Depending on the car you drive and who services it, this job would cost you anywhere from $100 to $300 plus all the time wasted driving to and waiting on a mechanic.

Tools

Refer to this page to find the item number on the list to see the exact description of each tool recommended for this DIY.

  • Car jack – item 2

  • Socket wrench or an open/adjustable wrench that will fit the bleed screw – item 8. Most of the time they are 10mm

Materials

  • Brake fluid. If you check your car manual it should say what grade is required, typically DOT3 or DOT4. I use ATE Super Blue Racing and ATE Gold brake fluid which can be used on DOT3 and DOT4 systems. *Edit. For some reason ATE Super Blue Racing disappeared from Amazon where I usually buy it. You might want to check Ebay to see if you can get it there.

Here is the first trick that will make this process so simple. The reason I use the ATE Super Blue Racing fluid is not only because it’s one of the best on the market in terms of quality, but also because of the color. It allows you to know exactly when you are finished bleeding each brake caliper without having to guess or waste the brake fluid. If you current fluid is the regular yellow/gold color then once you see the blue coming through the tubing you know you are done. The next time you bleed the brakes you would use a yellow/gold-colored ATE fluid so again, you will know when the new fluid is coming out indicating that you are done. It might sound a little confusing at this point but you will see what I mean after you finish reading this DIY.

Instructions

Warning: working on cars can be dangerous and can cause a serious injury or death. This is a write-up on how I would personally go about doing this project. I am not a mechanic and can only offer my own opinion on what worked for me. If you choose to follow these instructions you accept all risks associated with this job.

  • Park the car on a level surface and loosen the lug nuts on all four wheels.
  • Open the hood and find your brake fluid reservoir.  Note the side that it’s on – left (driver) or right (passenger).
  • If it’s on the left side, you will want to bleed the furthest caliper first i.e. right rear. If it’s on the right side you will want to start with the left rear.
  • Tools are laid out and we are ready to start.

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  • Assuming you want to start with the right rear first, you will now need to jack up the car on that side and take off the wheel. For this job, I don’t usually use jack stands since I don’t get under the car. The car remains on the jack after I take the wheel off while I bleed the brakes. I do put a ramp under the car close to the jack so at least the car would land on that instead of the floor if for some reason the jack gave out. You could also put the wheel you just took off under there instead of the ramp. I never had my Torin jack give out on me, but it certainly could happen.
  • Take a cap off the brake fluid reservoir in the engine bay, put a clean funnel in and get your brake fluid ready.

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  • Find the bleed screw at the back of the caliper. It should be covered by a rubber cap which you will take off now. In this picture you see the bleed screw exposed – to the left of “H 9” on the shock absorber.

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  • Put a wrench on the bleed screw nut and loosen it. You want it to be loose enough to be able to twist it by hand but tight enough to prevent any brake fluid from leaking.

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  • Connect the Mityvac Brake Bleeder. It comes with different attachments and you want to choose one that creates a good seal on the bleed screw.

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  • Pump the handle a few times so that there’s vacuum in the line – the arrow on the dial will move up confirming you’ve got vacuum. Twist the bleed screw with your other hand to open it up and you should see the fluid flowing.
  • Now the most important part is to keep an eye on your brake fluid reservoir under the hood.  You want to top it off with fresh brake fluid periodically and never allow it to run dry. If you do, air will enter the system and you will spend a long time trying to bleed it out. If you are starting with a full reservoir you should be able to fill up the Mityvac container about half full, twist the bleed screw closed and top off the brake fluid reservoir. If you have a partner that can keep the reservoir topped off as you bleed the line it’s even better.
  • Keep repeating the above bleed/top off/bleed cycle until you see the new brake fluid appear in the Mityvac line. (Keep in mind that any time the bleed screw is open you want to have vacuum in the Mityvac line so that no air can enter the system).  That’s where the Super Blue Racing brake fluid comes in to make your life much easier. Assuming you had a regular yellow brake fluid in the reservoir when you started, as soon as you see the blue fluid you are done!

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  • With the Mityvac line still on the bleed screw and under vacuum, hand tighten the bolt, take off the line and tighten with a wrench. Don’t over-tighten! Here is a picture of how I usually hold a socket wrench in delicate situations like this. It’s an easy trick to prevent over-tightening. Holding a wrench the “normal” way it’s easy to apply too much torque and strip the bleed screw and/or the caliper threads.

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After that you just repeat the process on the other 3 wheels. In this case, left rear followed by right front and then left front. In the end, make sure the brake fluid reservoir is filled to the max line, put a cap on it, torque all lug nuts and you’re ready for a cold one!

*Bonus Tip: You might be able to change the brake fluid on some cars without even having to take the wheels off. On my Mini Cooper (R56 model) I can park the car in the middle of the garage and then get to the bleed screw while laying on the floor. Or you can drive the car up on ramps to give a bit more room, which is still faster than taking the wheels off. Check if you can do the same on your vehicle and if so, there is really no excuse not to DIY a brake fluid change!

8 thoughts on “DIY – Changing the Brake Fluid

  1. Oh, man, I hear ya on the kid thing. I have two boys (ages 3 and 5) and they are “high spirited.” It’s exhausting.

    Thanks for this write up. Last X-mas I had my Secret Santa get me the Mityvac kit from your link. My car is long overdue for a fluid change (I have a 2004 Malibu and it’s never had a fluid replacement) and I would like to actually give this a go – I just need to find the time.

    What do you do with the used brake fluid?

    • 10 year old brake fluid, huh? Get that Super Blue Racing in there ASAP 🙂 Are you up to date on all the other fluids? Most are cheap and easy DIYs so just get one afternoon blocked off and get it done. Although I can see how that might be pretty low on your priority list with 2 boys! I haven’t found a good way to recycle brake fluid so I’ve been adding it to the old engine oil that I take to Autozone for recycling. Probably not the best solution but it’s a small amount and I figure it’s better than dumping it in the ground somewhere.

      • Well, I guess that depends on what you mean by up to date. For example, my transmission fluid has never been changed. That’s probably shocking to you. However, I change fluids and do maintenance based on what the owner’s manual recommends. In this car’s case, it states that fluid never needs to be changed. Radiator fluid is changed every 5 years based on the manual. Following the manual has been a bit of an experiment on this car but after 125,000 miles, no issues thus far. Let’s hope she makes it to the 200k club.

        Keep these DIY’s coming. I love ’em.

        • You’re right, my definition of up to date is a bit different, especially when it comes to European cars… I personally find it suspicious that car companies like BMW increased their recommended service intervals as soon as they went to “free maintenance” plans. Don’t even get me started with “lifetime” transmission fluids… Sure, any modern car will last 100K miles with minimal maintenance. However, I like my fully depreciated cars with over 100K miles so I’m much more interested in getting them running with minimal problems to 200-250K miles… That requires a bit more TLC and a transmission fluid change once in a while (every 60K is a good start). Google “Old school BMW maintenance schedule” for a good discussion of this topic.

          Thanks for the kind words and more DIYs are on the way!

  2. This looks easy enough for me to handle! I’m overdue on both my cars. Like you say, it’s a maintenance item due based on years not miles, so my rarely used 2000 honda civic still needs the service periodically even though I don’t put more than a few thousand miles on it in a regular year.

    Thanks for the info.

    • Justin, considering that you’re retired you have no excuse 🙂 Get the right tools, go slow and safe and add another skill to your DIY portfolio! Better ROI than any stock out there, guaranteed.

  3. I just wanted to interject here…the Mityvac is applying “vacuum” to the bleeder screw, not “pressure” as you have noted, correct?

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