Proper method to change your brake fluid?

[Ed_Flecko]

I have a 2 part question -

1.) Since brake fluid absorbs condensation from the atmosphere, how often should one change their brake fluid? Annually, or...???

2.) To flush all old fluid from the system, I'm thinking I'll buy a brand new turkey baster from the Dollar Store (so I know I'm not contaminating the system) and siphon out most (but not all) of the existing fluid from the reservoir. Then, I'll buy a brand new can of DOT 4 fluid, fill the reservoir and bleed the brakes, wheel by wheel (right-rear, left-rear, right-front and finally left-front), with the help of a friend.

Does this sound about right?

Thank you,
Ed

 

[mclasser]

Honda says every 3 yrs, irrespective of mileage so that's what I go with on all my cars.

I've heard it said that bleeding the brakes via the pedal method can cause master cylinder failure, particularly on older cars since it's not good to let the pedal drop to the floor. I think there are TSB's for newer cars as well. Easiest & safest method is vacuum bleeding. Brake flushes are the only fluid change I don't DIY on my cars; it's nasty toxic stuff that eats paint. I gladly pay my indy to do it every 3 yrs.

 

[threeputtpar]

My general rule of thumb for cars I plan on keeping long term is:

Dot 3 fluid - every three years no mileage limit
Dot 4 or 5.1 fluid - every two years no mileage limit.

Dot 4 and 5.1 are more hygroscopic than Dot 3, thus the shorter interval.

I've done several two man manual brake bleeds and the only thing extra I would do is to put a 1"x6" block under the brake pedal so it will stop short of its full travel. I've never had to replace a master cylinder yet.

 

[Colt45ws]

I use a pressure bleeder. I used vacuum bleed for a long time, giant PITA. Hose always slips off the bleeder and then you have air, so rebleed time.
With the pressure bleeder, you just pressurize the master, and go around and open every cylinder until it runs clear. I typically use a quart bottle of oil to bleed into so I can monitor how much Im taking out, so I don't over do it and run out.
Simple and clean.
I try to do 2 years, but 3 years is reasonable. If you want, there are strips available that you can dip into your master. It measures the amount of copper present in the fluid and if there is a lot, its time to change.

 

[mk378]

Open the bleeders and let the fluid run out, or use vacuum bleeder. Do not let the reservoir run dry. If you have a vacuum bleeder you can use it to remove most of the old fluid from the reservoir first, though that is not strictly necessary. Turkey baster seems very ghetto.

You could then test drive and kick in the ABS a few times to get old fluid out of the ABS parts. Then repeat the change.

 

[The Critic]

I use a pressure bleeder from Motive. For your Toyotas, Assenmacher makes an excellent direct-fit cap.

If the pedal height and feel is not correct after bleeding, I will use Techstream or my Solus Ultra to run thru Toyota's "air bleeding" utility.

 

[Kuato]

Originally Posted By: Ed_Flecko
I have a 2 part question -

1.) Since brake fluid absorbs condensation from the atmosphere, how often should one change their brake fluid? Annually, or...???

2.) To flush all old fluid from the system, I'm thinking I'll buy a brand new turkey baster from the Dollar Store (so I know I'm not contaminating the system) and siphon out most (but not all) of the existing fluid from the reservoir. Then, I'll buy a brand new can of DOT 4 fluid, fill the reservoir and bleed the brakes, wheel by wheel (right-rear, left-rear, right-front and finally left-front), with the help of a friend.

Does this sound about right?

Thank you,
Ed


Your plan sounds great to me.

 

[Oro_O]

Originally Posted By: mk378
Turkey baster seems very ghetto cheap and effective.


Fixed that for 'ya!

Pressure bleeders do other things, but for what he wants to do, this is a sound technique to make the process more effective.

Originally Posted By: Kuato
Your plan sounds great to me.


+1.

My personal experiences agree with the time intervals for change above. I live in the PNW now, but have always been a stickler for brake performance. I find with the incredibly wet weather here part of each year, I can get two years out of a fluid swap, then feel some decay in performance after a 3rd wet winter. I could squeeze a little more time out in a drier environment I imagine, but why try? Three wet winters let me know I've got contamination in the system and to get it out to keep things up to snuff, so I do it after two.

Be careful with your bleed screws and use a flare nut wrench or 6-pt wrench when turning them, and not a 12pt.

 

[Doublehaul]

Hate to say it guys...but I've never "changed" brake fluid...ive also never had an ABS or MC failure....and i keep cars a long time! Only time i remove fluid is if changing a brake line or a caliper etc and even then its only enough to get the air out.

 

[69GTX]

I wouldn't bother with the turkey baster, especially since they don't have fine control and you could be spilling that stuff everywhere. A large syringe would be better. Just let the fluid bleed down to near the base of the reservoir then refill, and continue bleeding. It takes forever to gravity bleed. Having someone to pump the brake pedal will make it a lot faster. Don't push the brake pedal to full travel. 2/3 to 3/4 of the way should be fine.

Fwiw,I was never much for brake fluid changes in my earlier years. Two of my cars were 12 years old with over 200K miles and had never had the brakes bled other than what little came out with a brake hose replacement. None of those cars had any brake system degradation that I was aware of. Did a pair of brake bleeds last summer to my sig line vehicles (those fluids were probably factory fills, the 16 yr old fluid looked pretty decent....the other vehicle at 13 yrs old was first checked with a paper strip and tested "sat" for what that's worth).

 

[Doog]

I gravity bleed them and use my fluid extractor. Then pedal bleed to get the air out of the calipers. I only bleed them at pad reline time and then don't drain the whole system. I probably change out 1-1.5 pints.

 

[WobblyElvis]

Originally Posted By: Doublehaul
Hate to say it guys...but I've never "changed" brake fluid...ive also never had an ABS or MC failure....and i keep cars a long time! Only time i remove fluid is if changing a brake line or a caliper etc and even then its only enough to get the air out.


+1
GM does not recommend changing brake fluid. Why would I? Never had a problem with the brake fluid. I don't change the air in my tires either.

 

[Ed_Flecko]

Originally Posted By: WobblyElvis
Originally Posted By: Doublehaul
Hate to say it guys...but I've never "changed" brake fluid...ive also never had an ABS or MC failure....and i keep cars a long time! Only time i remove fluid is if changing a brake line or a caliper etc and even then its only enough to get the air out.


+1
GM does not recommend changing brake fluid. Why would I? Never had a problem with the brake fluid. I don't change the air in my tires either.


The alcohol in brkae fluid is hygroscopic, so it absorbs moisture from its surroundings. The problem with moisture in brake fluid is that it causes corrosion. Moisture in brake fluid begins to attack the metal in the brake system. Some modern brake systems are comprised of aluminum, which a highly reactive metal. Oxygen in the absorbed moisture combines with aluminum to form aluminum oxide (think: aluminum oxide sandpaper). This damages the metal components. Once the surface finish of hydraulic cylinders are corroded, they begin to leak and must be replaced.

At least this is my understanding.

Ed

 

[69GTX]

Any moisture from air that the brake fluid is going to absorb has to come through the exchange of that tiny vent hold on the reservoir cap. It's not much. That moisture picked up at the top of the reservoir has to then migrate through a fluid piping system that doesn't have much of any fluid movement. As I said above, my 13 year fluid in the Lincoln checked out good when tested by Monroe. I figured I should change it at least once in the car's life, so I did any ways. I would say the brakes are not quite as sharp as they were before I did the bleed...and I was very slow, methodical, and careful not to introduce any air.

 

[Colt45ws]

No, the brake fluid pulls water in through the hoses and seals. Neither of those are 100% sealed. Its impossible.

 

[slacktide_bitog]

I usually change the fluid when the pads and rotors are being replaced. Speed bleeders are awesome

 

[69GTX]

Originally Posted By: Colt45ws
No, the brake fluid pulls water in through the hoses and seals. Neither of those are 100% sealed. Its impossible.


So in the same reasoning, that contamination would have to migrate against gravity back through the system and up to the master/reservoir. Either way it doesn't appear significant. How did my 13 yr fluid check out sat? How have I avoided any brake failures/malfunctions for 40 years of driving up until my first brake bleeds in 2016? I guess I was lucky.

I guess it would make sense to bleed some fluid out of each end of the system during tire changes & rotations / brake services.

 

[Colt45ws]

There is some fluid flow in the system, yes. More so with ABS.

 

[DBMaster]

I bought one of those electronic testers for brake fluid. Assuming it's accurate, you push a button and dip it into the M/C. It reads out the moisture content in the fluid and you change when indicated. I think the two person bleeding method is probably the reason I had to replace the M/C on my 89 Accord every 100K miles. I changed the fluid every 30K as recommended by Honda. In retrospect I think that is excessive.

 

[Doublehaul]

I worked on cars professionally for a long long time and never heard of let alone saw people changing out brake fluid...and I am ASC certified in brakes! Its absolutely true that brake fluid does absorb moisture...but in a closed system with very little fluid movement you may be looking for a problem that doesn't exist.

I get that BITOG is the most anal-retentive forum in existence but i guarantee you that nobody outside of a very select few change their brake fluid. Where are the catastrophic brake failures and TSBs? Is this a service thats recommended by any OEMs? Im not trying to be argumentative...just curious.

EDIT...i see the gent above me had a OEM recommendation to change every 30k. Maybe this is something I've honestly just missed over the years?

As always YMMV.


In all seriousness we should have a classified section for used car sales...we have the worlds BEST maintained cars!!!