Brake fluid...3 years but only 11K miles. Should I replace?

[930.engineering]

Every two years for me regardless of mileage except for my classic Porsche which
I do three years on. It's getting way less miles compared to your Accord though.
Brake fluid is inexpensive, even DOT 5.1 fluid which I'd prefer on ABS equipped
cars.
Boiling fluid isn't my main concern. Brake fluid absorbs water and water causes
corrosion (inside MC and calipers). Changing fluid every 2 or 3 years is cheapest
insurance possible.

I think brake fluid replacement is over done. I have done it every ten years or so and never had a brake problem related to the fluid.

I prefer to have no brake problems at all.
.

 

[willbur]

Brake fluid absorbs water. Some people believe three years or so is the limit of safe use for a fluid. Now I use inexpensive test materials to help easily and quickly determine the fluid's condition. Some examples here, but check around ...

https://www.amazon.com/brake-fluid-test-strips/s?k=brake+fluid+test+strips

That Phoenix kit tests for COPPER- not moisture. Ford engineers visited automotive junk yards and found little moisture in brake fluid in these hulks. Copper leaching out of brake lines etc is what causes the damage.

 

[Oro_O]

The same fluid stays in the lines, you need to break the bleeders open until fresh fluid flows through them. Brake fluid doesn't circulate through the system.

Nope, not physics. Science still applies in brake systems, no free pass.

The fluid mixes, even sitting still. There are passages always in contact between the components. The fluid freely mixes over time. You can demonstrate this if you are curious doing reservoir drain/fills and measuring H20 content with test strips.

I took apart a 22 year old Volvo brake system last month, never opened before. I did it only to swap on braided lines and refinish it, not because of a mechanical issue. It had lived it's whole life in the wet PNW. It was spotless inside. Just change the fluid periodically via the reservoir.

When I was a wee bairn* and **** Nixon was prez, my dad was a professional motorcycle mechanic and very talented amateur racer. With no cage around you, brakes were the #1 system on a vehicle you serviced. And the vehicles were serviced every Sunday evening.** I'll drive a car out for a test drive with a leaking carb or fi system, but NOT with a leaking brake system. Brakes are the #1 thing I keep in tip-top shape on any vehicle of any type. And if this system satisfies me, it's good.

* - sorry, I've been watching "Outlander" recently and it's contagious.
** - Some people say "Bullitt" is Steve McQueen's best movie. I say it's "On Any Sunday."

On Any Sunday — Bruce Brown Films

www.brucebrownfilms.com

Watch On Any Sunday | Prime Video

Featuring the legendary Malcolm Smith, this Bruce Brown film is a timeless classic unmatched by todays backyard video conglomeration. Bruce Brown is a master of entertaining quality videos. His coverage of these classic events will keep you on your toes.

www.amazon.com

 

[Leo99]

I think brake fluid replacement is over done. I have done it every ten years or so and never had a brake problem related to the fluid.

Most people never do it.

 

[nomas]

How does moisture get into a sealed system ?

 

[Oro_O]

Free advice for the DIY crowd:

A minute or two in Muriatic acid will make baked-on brake dust disappear as if magic was involved. No need for hard elbow grease or sandblasting. You can literally wipe it off with a paint brush.

Full disclosure: The shield on the right is AFTER I painted it, not just after I acid washed it.

 

[Oro_O]

How does moisture get into a sealed system ?

It's not sealed THAT well. Think of it like this: A fence that will keep a goat out might not keep a mouse out.

Water is an extremely small molecule. It will work past seals that will keep almost anything else out. And hydraulic systems are not built to keep water out, they are built to keep much larger molecules IN. Just like prisons. They are built to keep miscreants IN, not out. Ever try to break INTO a prison? Not hard.

Here's an analysis of typical brake fluid; the main component is tri-ethylene monomethyl ether. Relatively speaking, goat vs. mouse in size:

Brake Fluid - an overview | ScienceDirect Topics

www.sciencedirect.com

 

[Jimmy_Russells]

It's not sealed THAT well. Think of it like this: A fence that will keep a goat out might not keep a mouse out.

Water is an extremely small molecule. It will work past seals that will keep almost anything else out. And hydraulic systems are not built to keep water out, they are built to keep much larger molecules IN. Just like prisons. They are built to keep miscreants IN, not out. Ever try to break INTO a prison? Not hard.

Here's an analysis of typical brake fluid; the main component is tri-ethylene monomethyl ether. Relatively speaking, goat vs. mouse in size:

Brake Fluid - an overview | ScienceDirect Topics

www.sciencedirect.com

Liquid water doesn't even need to get in, just air that has moisture in it.

 

[slo town]

I bleed the brakes and clutch every two years max regardless of mileage. With respect to the ABS pump, I cycle it by purposely inducing wheel lockup with low speed parking lot maneuvers or aggressive braking on frost or leaf covered roads. I have a couple of places I do this and am able to lockup individual wheels.

Scott

 

[Oro_O]

Liquid water doesn't even need to get in, just air that has moisture in it.

This is true.

But O2 is a lot bigger of a molecule than H20. It can get in both ways, but H20 sitting on bleeders, seeping through caliper puck seals, through compression fittings, is the more common route. This is because the H20 molecule is highly polar and smaller. But you are correct, air contributes also and will do it over time.

 

[Jimmy_Russells]

I bleed the brakes and clutch every two years max regardless of mileage. With respect to the ABS pump, I cycle it by purposely inducing wheel lockup with low speed parking lot maneuvers or aggressive braking on frost or leaf covered roads. I have a couple of places I do this and am able to lockup individual wheels.

Scott

If you don't introduce air into the system by letting the reservoir get too low, you don't have to go through the ABS pump bleed procedure. You'll leave a bit of old fluid in there doing it that way, but it's a heck of a lot better than not changing anything.

 

[Oro_O]

With respect to the ABS pump, I cycle it by purposely inducing wheel lockup with low speed parking lot maneuvers or aggressive braking on frost or leaf covered roads. I have a couple of places I do this and am able to lockup individual wheels.

This is smart. We had some unusual snow and ice recently and I took each car out to do this; helped a lot.

03 BMW E46 330Ci ZSP

Nice. That is one of the cars on my (very) short list to get when I have more garage space. I looked at a couple about two years ago. My SIL has a 2004 Z4 and it is just pure joy to drive. I want the coupe equivalent.

 

[sk_pete]

fluid boiling point test, is one part of the biannual car check (eu)
do you have such thing there ??

 

[The Critic]

@dishdude , are you bleeding the ABS pump as well when you DIY or no?

I don't know anyone who does that, dealer included.

 

[RooflessVW]

I don't know anyone who does that, dealer included.

I have it right there on my last RO. Maybe it's because I always ask, maybe they always do it.

 

[Accent Abuser]

When in doubt, change it out

 

[eljefino]

The fluid mixes, even sitting still. There are passages always in contact between the components. The fluid freely mixes over time. You can demonstrate this if you are curious doing reservoir drain/fills and measuring H20 content with test strips.

There's the tiniest slit in the MC bore that's only exposed/ open to the reservoir when the pedal is all the way up, to let a microscopic amount of fluid dribble into the pressurize-able part of the system, to fill up the calipers to account for disc pad wear.

The first 1/4 inch of stepping on the pedal squirts half a drop of fluid up into the reservoir, then when the brakes are released that half-drop finds its way back down. Needless to say, it take a very long time for this new fluid to then disperse down many feet of 3/16" diameter line.

People should be bleeding at intervals if only because it keeps the bleeder screws free-- they rust and snap just at the time in a car's life where you're running new lines and hoses.

 

[mehullica]

Replace it according to the owners/maintenance manual. 3 years is a good time to replace regardless of mileage

 

[circuitsmith]

I change it every 3 years, regardless of my typically low ( I use the one way valve speed-bleeders.
The test strips check the fluid in the reservoir, but what does that say about the fluid down in the calipers?
For the same reason, changing only fluid in the reservoir is pointless, IMHO.
When I bleed them the first fluid coming out of the calipers/cylinders always looks the dirtiest.

 

[edyvw]

I don't know anyone who does that, dealer included.

BMW dealership does it with every brake fluid change. Simple process requiring for BMW INPA software. One man job.
I change in BMW fluid 2-3 times a year bcs. track, and don’t do that. But it is simple.