To replace brake fluid - when & how to know if needed

That says it----

Usually it is by time, varies from different manufacturers. 2 to 3 years is within the normal range though.

You can test it with either an electronic tool, essentially a simple resistance check, or with test strips.

But, much like motor oil, you generally just do it as prevention of things further down the road.

I can tell you, from working on all kinds of things for many years, there is a difference in both pedal feel and brake performance as well as length of parts life if this is done periodically. And really, even if you do not have a fancy flush machine, gravity bleeding works fine (just takes longer). Fluid is cheap too.

I try to stick to the 2 year rule, or if for any reason I have to open the system. Brake fluid is hydrostatic so it's not good to let it go for too long or your steel lines will start to rust internally if severe enough.

I also start to think about changing it when the fluid starts to turn black.

Brake fluid

I flush my brake system once a year, is that excessive --maybe -maybe not also depends where you live -I am in Florida high heat 9 months of the year and high humidity --Water is what normally contaminates your brake fluid ie condensation-in the res. I work on BMW Motorcycles and brake fluid flushes once a year is what is called for, being that our VW's have ABS brakes I go on the once a year theory since I see alot of ABS units fail due to people not changing their brake fluid---It's Brake Fluid it's cheap and does not take long to do the flush--very inexpensive preventative maintenance. It's a hell of alot less expensive then a new ABS control unit lol

I think you can safely go 2 years. Most all the cars are like this now, 2-3 years, my theory is something to do with all the small passages in the ABS.

The fluid is cheap though. I wouldn't begrudge anyone who felt like flushing it every year. At least you'd be pretty certain the bleed screws wouldn't seize up.

I do it whenever I service brakes/replace pads, etc. I'm already at the bleeders, already have my tools out, etc. it's a convenient time for it

IMHO every 2 years irrespective of mileage.

Overkill? Maybe. But I've never had to replace a caliper in a vehicle where that's been done on a religious, every 2-year basis and brake fluid is cheap -- some vehicles now approaching drinking age.

You decide.

... Brake fluid is hydrostatic ...

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The correct term is hygroscopic. It absorbs moisture so that it can't condense on the surface of the hard lines and corrode sufficiently to perforate or otherwise cause the line to fail.

Changing the fluid replaces old fluid with fresh fluid which has no entrained moisture.

Cheers,

PH

Genesis said:

IMHO every 2 years irrespective of mileage.

Overkill? Maybe. But I've never had to replace a caliper in a vehicle where that's been done on a religious, every 2-year basis and brake fluid is cheap -- some vehicles now approaching drinking age.

You decide.

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That would be "By the Book"

It is quite interesting to see how different manufacturers view the need for brake fluid replacement differently - when I owned a 2010 Jetta TDI, the maintenance schedule did call for a brake fluid replacement every 2 years. Last July, I returned my Jetta to VW and bought a new Toyota 4Runner. The first thing I did after bringing the new vehicle home was to check the maintenance schedule and, lo and behold - no scheduled brake fluid replacements. Ever. The only thing the owner is supposed to do is to check the level of all fluids every 5,000 miles and, if needed, top them off. This makes me wonder whether Toyota knows something VW does not. And maybe it's the other way around.

soot1 said:

It is quite interesting to see how different manufacturers view the need for brake fluid replacement differently - when I owned a 2010 Jetta TDI, the maintenance schedule did call for a brake fluid replacement every 2 years. Last July, I returned my Jetta to VW and bought a new Toyota 4Runner. The first thing I did after bringing the new vehicle home was to check the maintenance schedule and, lo and behold - no scheduled brake fluid replacements. Ever. The only thing the owner is supposed to do is to check the level of all fluids every 5,000 miles and, if needed, top them off. This makes me wonder whether Toyota knows something VW does not. And maybe it's the other way around.

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I work for toyota and we've gotten away from making customers spend money on maintenance. Since they introduced Toyota care people just want everything for free. The only fluids left with service time is coolant and trans fluid. You need our scan tool to check the trans fluid btw if you didn't know it's an overflow style pan on the 4Runner. The 4runner is one of the last good products we sell.

John-TDI said:

I work for toyota and we've gotten away from making customers spend money on maintenance. Since they introduced Toyota care people just want everything for free. The only fluids left with service time is coolant and trans fluid. You need our scan tool to check the trans fluid btw if you didn't know it's an overflow style pan on the 4Runner. The 4runner is one of the last good products we sell.

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I owned the Jetta for almost 9 years, but I never bothered to replace the brake fluid. Yes, brake fluid is hydroscopic, that is a known fact. However, there is only very limited volume of air above the fluid in the reservoir, and that air is sealed off from the outside atmosphere by a rubber gasket. So, the only air the fluid comes into contact with is that very small volume between the fluid and the gasket. That was pretty much my rationale for not changing the fluid even though the maintenance schedule said I should. But since all fluids deteriorate over time, I was planning on changing it eventually, possibly after 10 to 15 years. For the same reason, I plan on changing the transmission fluid in the 4Runner at 50,000 mile intervals, although Toyota claims this to be a "lifetime" fluid if you don't do much towing. I tried to purchase a shop manual for the vehicle when I was taking delivery so that I could do this type of maintenance myself, but the salesman told me Toyota no longer offers them. When changing the transmission fluid on the 4Runner, what is the scan tool used for and how is the procedure performed? When the time comes for the fluid to be replaced, my plan was to drain the old fluid, measure the exact volume that drained and replace it with the exact same amount of fresh fluid.

Does the ABS unit have to be 'run' to properly flush the brake fluid? If so, is that something that can be done with a VAG cable?

I don't think you HAVE to run the ABS pump to flush all the fluid... You only need to run it if you opened the system at the pump. And yes you need VCDS to run the ABS purge cycle.

I believe you would need to actuate the ABS unit if you let air in the system while you're bleeding it, too, so be careful and watch the res.

soot1 said:

It is quite interesting to see how different manufacturers view the need for brake fluid replacement differently - when I owned a 2010 Jetta TDI, the maintenance schedule did call for a brake fluid replacement every 2 years. Last July, I returned my Jetta to VW and bought a new Toyota 4Runner. The first thing I did after bringing the new vehicle home was to check the maintenance schedule and, lo and behold - no scheduled brake fluid replacements. Ever. The only thing the owner is supposed to do is to check the level of all fluids every 5,000 miles and, if needed, top them off. This makes me wonder whether Toyota knows something VW does not. And maybe it's the other way around.

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Toyota (and the others) know you'll get out of warranty before the calipers (or worse, the master and ABS pump!) are damaged by corrosion due to moisture being absorbed by the brake fluid if you never change it. Thus it is not on the "maintenance schedule" since it will not cost them money (it'll cost you instead!)

Brake fluid is hygroscopic and everything in a brake system operates on pretty tight tolerances. Corrosion either makes things in the system stick or leak and thus require replacement. If you've had a failed caliper apart that has not had the fluid changed regularly it's pretty obvious what happened to it and why it failed. The system is NOT "sealed"; it can't be because as the pads wear the level in the reservoir must fall somewhat (the pistons are further out in their bores.) The cap on the master does slow the exchange of air in that space but cannot prevent it entirely.

A can of brake fluid is a few dollars and with a pressure bleeder it takes under 30 minutes to flush and change the fluid. Done correctly no air gets into the system and thus you don't need to purge the ABS pump either. Not doing it every two years means you'll get to buy brake components; doing it every two years means the OE brake components will likely last the lifetime of the vehicle.

You choose.

Genesis said:

Toyota (and the others) know you'll get out of warranty before the calipers (or worse, the master and ABS pump!) are damaged by corrosion due to moisture being absorbed by the brake fluid if you never change it. Thus it is not on the "maintenance schedule" since it will not cost them money (it'll cost you instead!)
Brake fluid is hygroscopic and everything in a brake system operates on pretty tight tolerances. Corrosion either makes things in the system stick or leak and thus require replacement. If you've had a failed caliper apart that has not had the fluid changed regularly it's pretty obvious what happened to it and why it failed. The system is NOT "sealed"; it can't be because as the pads wear the level in the reservoir must fall somewhat (the pistons are further out in their bores.) The cap on the master does slow the exchange of air in that space but cannot prevent it entirely.
A can of brake fluid is a few dollars and with a pressure bleeder it takes under 30 minutes to flush and change the fluid. Done correctly no air gets into the system and thus you don't need to purge the ABS pump either. Not doing it every two years means you'll get to buy brake components; doing it every two years means the OE brake components will likely last the lifetime of the vehicle.
You choose.

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There are many components and systems in the 4Runner that require servicing both during and past the warranty period, yet they are mentioned in the maintenance schedule (the schedule stops at 120,000 miles). Toyota could have put the first brake fluid replacement at 3/36 and every 2 years thereafter in order to avoid paying for this service item, but they didn't. Also, if not changing the brake fluid causes serious corrosion of the metal components that are in contact with the fluid, reasonable person would assume that, due to the low cost of the fluid and how quickly the procedure can be completed, this is not a cost issue, but rather a safety issue, and that it would be addressed by Toyota in the maintenance schedule. Toyota's design team instead chose not to require periodic replacements of the fluid, and I am pretty sure Toyota's lawyers had the final say in this matter, being fully appraised of potential consequences of a ruptured brake line.

I am not trying to dispute your own personal experience, and if you make a living working on cars, you certainly have a lot more of it than I ever will, I am merely trying to understand Toyota's rationale. If Toyota tells me to change the oil and oil filter every 5,000 or 10,000 miles (depending on driving conditions), the air filter every 30,000, to rotate the tires every 5,000, to lubricate the U-joints every 30,000, etc., etc., all that with the intent to keep the vehicle running smoothly for as long as possible, why would they omit replacing the brake fluid if it were so important to keep the brake system from failing? It would be interesting to hear from owners of new vehicles of other brands what their maintenance schedule says about brake fluid replacement.

Check out Russel Speed bleeders. They have a check valve built into the bleeder valve and coating on the threads. Makes brake bleeding a snap for one man and prevents air getting into system.


Using these is far more simple and faster than using my Motive pressure bleeder.


About $20.00 per vehicle.

FWIW, I've used a mason jar with two nipples soldered to the lid, one plumbed to a electric vacuum pump, the other to a brake nipple. Turkey baster to remove as much brake fluid as possible, refill to the brim with fresh, the go around and pull a vacuum on each nipple after opening it until the fluid comes out clean. Have to make sure the MC is refilled after each wheel. Hopefully that will pull fresh stuff through the ABS.