Brake fluid change!??

Tight fitting lid on reservoir. Absorbs water from where? Have not seen a vented system on a new car in decades.
If one takes the time to consider how a hydraulic brake system works, before too long you realize there are all kinds of sources for moisture to reach the brake fluid.

Consider the brake pistons. At least one on each wheel, with many cars having two or four per wheel and some having more. There is a seal on each of those pistons. I'm assuming it is by design that the piston seals allow a small amount of brake fluid to pass by. But regardless of whether it is by design or not, the brake fluid on the outside hydrates, and when you press on the brakes, that piston seal swipes by the hydrated brake fluid. And this occurs every time you press on the brakes. Times the number of pistons in your brake system.

Any belief that the brake fluid reservoir is sealed, is based upon a lack of understanding. I work in an industry where sealed vessels are paramount to the successful functioning of key components of our products. We have a saying that reminds us of reality. There are two kinds of sealed pressure vessels - one that has leaked and one that is currently leaking. Anyone that understands the failure mode of Takata airbags will also understand this principle. And the cap on a brake fluid reservoir is nowhere near as sealed as an airbag inflator.

Moisture gets in brake systems.
 
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Tight fitting lid on reservoir. Absorbs water from where? Have not seen a vented system on a new car in decades.
It absorbs water from the environment. Most say through the rubber hoses through heating and cooling cycles from hot and cold brakes. The rubber isn't a perfect seal, has microscopic pores. Takes a little while for it to absorb fluid. That's why most cans of brake fluid have specs for wet and dry boiling points.
 
If one takes the time to consider how a hydraulic brake system works, before too long you realize there are all kinds of sources for moisture to reach the brake fluid.

Consider the brake pistons. At least one on each wheel, with many cars having two or four per wheel and some having more. There is a seal on each of those pistons. I'm assuming it is by design that the piston seals allow a small amount of brake fluid to pass by. But regardless of whether it is by design or not, the brake fluid on the outside hydrates, and when you press on the brakes, that piston seal swipes by the hydrated brake fluid. And this occurs every time you press on the brakes. Times the number of pistons in your brake system.

Any belief that the brake fluid reservoir is sealed, is based upon a lack of understanding. I work in an industry where sealed vessels are paramount to the successful functioning of key components of our products. We have a saying that reminds us of reality. There are two kinds of sealed pressure vessels - one that has leaked and one that is currently leaking. Anyone that understands the failure mode of Takata airbags will also understand this principle. And the cap on a brake fluid reservoir is nowhere near as sealed as an airbag inflator.

Moisture gets in brake systems.
Quit confusing people with facts.
 
my rant goes to the bleeding pump that I recently purchased online; I was ready to do the fluid change when I realized I do not have appropriate connection; the pump came with 1/4" connection but the connector that fits Honda comes with a 3/8" piece; now I have to figure where to find 3/8" connector and hopefully have everything at one spot for next time

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that sucks...thanks for posting this thought. I was looking at the ARES bleeder last night and almost pulled the trigger, but was concerned about the connector.

pretty easy job though right?
 
that sucks...thanks for posting this thought. I was looking at the ARES bleeder last night and almost pulled the trigger, but was concerned about the connector.

pretty easy job though right?
yeah i got to look for right connector at Ace Hardware, Northern Tools or at Harbor Freight one of these days

the job it self is not hard at all once you finish the first car; I'm thinking doing it every 2 years from now on because its a cheap insurance for your brakes performing well

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The seal engineers in our company explained to me that sealing is accomplished with the very thin layer of fluid at the seal lip, which moves. This fluid is open to the elements. This is where moisture would migrate into the brake fluid.
 
If one takes the time to consider how a hydraulic brake system works, before too long you realize there are all kinds of sources for moisture to reach the brake fluid.

Consider the brake pistons. At least one on each wheel, with many cars having two or four per wheel and some having more. There is a seal on each of those pistons. I'm assuming it is by design that the piston seals allow a small amount of brake fluid to pass by. But regardless of whether it is by design or not, the brake fluid on the outside hydrates, and when you press on the brakes, that piston seal swipes by the hydrated brake fluid. And this occurs every time you press on the brakes. Times the number of pistons in your brake system.

Any belief that the brake fluid reservoir is sealed, is based upon a lack of understanding. I work in an industry where sealed vessels are paramount to the successful functioning of key components of our products. We have a saying that reminds us of reality. There are two kinds of sealed pressure vessels - one that has leaked and one that is currently leaking. Anyone that understands the failure mode of Takata airbags will also understand this principle. And the cap on a brake fluid reservoir is nowhere near as sealed as an airbag inflator.

Moisture gets in brake systems.
Just another opinion:

"
Q: What about moisture in brake fluid?
Interestingly, moisture is not the main contaminant that causes brake system problems, though thought to be the main problem by many industry professionals. Research by the Ford Motor Company indicates moisture contamination of brake fluid was approximately 1% in test vehicles that had been in service as long as 7 years. Moisture testing is recommended only for severe-duty vehicles."

 
Just another opinion:

"
Q: What about moisture in brake fluid?
Interestingly, moisture is not the main contaminant that causes brake system problems, though thought to be the main problem by many industry professionals. Research by the Ford Motor Company indicates moisture contamination of brake fluid was approximately 1% in test vehicles that had been in service as long as 7 years. Moisture testing is recommended only for severe-duty vehicles."

A lot of the time you’ll see decades old crystal clear brake fluid with a green tinge from all the copper floating around.
 
For what it's worth, I've driven several vehicles well beyond 200K miles...and a couple past 300K miles and never changed the brake fluid in any of them. Never had any issues.
I am not too worry about the brakes however I am worry about ABS valves modules getting hit by junks when the calipers piston are push back in the calipers
 
I am not too worry about the brakes however I am worry about ABS valves modules getting hit by junks when the calipers piston are push back in the calipers
If that is a concern, you can avoid it by opening the caliper bleeder screw before you push the piston back in.
 
If that is a concern, you can avoid it by opening the caliper bleeder screw before you push the piston back in.
I think this "concern" was invented by a journalist for an aftermarket trade publication. I have yet to read any OEM service information that suggests opening the bleeder screw during piston retraction.
 
If that is a concern, you can avoid it by opening the caliper bleeder screw before you push the piston back in.
I agree its feasable however pushing on the piston and manipulating the bleeder screw at the same time can lead to the need of bleeding air from the system , sometimes I have more thumbs than fingers :)
 
I do a low-hassle method that works great.

Every year I change the reservoir fluid with DOT 4. The fluid mixes pretty quickly after driving and you get a little less than 1/2 new fluid in, no risk of air from bleeding (via screws; very common). Since I live in the Seattle area now I do this annually regardless of mileage (as low as 3/4k on some vehicles). Works great. If you want a higher % new fluid in at once, just repeat it once a week for a one or two weeks.

In your case, I would do it twice, then once a year.
That doesn't get the fluid sitting at the calipers. There is really no substitute for a proper flush. Replacing just the fluid in the reservoir still is a good idea and I do it every other oil change or so. I have a digital tester that tells me the % of water in my fluid and it never gets above 1%.
 
I usually do a brake fluid flush every 3 years or when the brake linings are swapped out, whichever comes first.
Speaking of which, my parents are due for one, I’ll do that in a few weeks.
 
That doesn't get the fluid sitting at the calipers. There is really no substitute for a proper flush. Replacing just the fluid in the reservoir still is a good idea and I do it every other oil change or so. I have a digital tester that tells me the % of water in my fluid and it never gets above 1%.
I don’t think much fluid mixes in a brake system except for what’s in the lines, modulator/actuator and wheel end cylinders. A hydraulic brake system is normally “open” until the master cylinder is applied to “close” the circuits.
 
By brake fluid test strips on Amazon. On my car, after 3+ years fluid was significantly enough degraded - not dead, but well spent. My car's manual calls for replacement every 2 years.

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Thanks. When you stated "degraded" did you mean due to moisture or copper? Would like to know. Most ppl change brake fluid thinking its moisture when its really leached copper that is harming the brake components. After the first flush, less and less copper leaches out so longer between flush intervals, IMO.
 
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That doesn't get the fluid sitting at the calipers. There is really no substitute for a proper flush. Replacing just the fluid in the reservoir still is a good idea and I do it every other oil change or so. I have a digital tester that tells me the % of water in my fluid and it never gets above 1%.


Yes, yes it really does. It mixes fully in the system. This is a physical property of homogenous liquids, no way around it.
 
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