Brake Fluid change
Discussion
How often do you change your brake fluid.
I appreciate it absorbs moisture over time (hygroscopic) but every two years like a MINI service recommends?
Maybe I'm lax but mine gets changed when I replace callipers, cylinders or pipes but there again my cars tend to be older and need replacement parts.
(Oh and a change two years ago was in the region of £80, yesterday they offered it at a discounted price of around £105.)
I appreciate it absorbs moisture over time (hygroscopic) but every two years like a MINI service recommends?
Maybe I'm lax but mine gets changed when I replace callipers, cylinders or pipes but there again my cars tend to be older and need replacement parts.
(Oh and a change two years ago was in the region of £80, yesterday they offered it at a discounted price of around £105.)
The unfortunate thing about brake fluid is you can't tell it has water in it just from eyeballing the colour, whereas you can get an idea of how old petrol engine oil is from the colour.
You can get meters to measure the water content if it's a concern, however for normal everyday usage I bet most cars are operated on a "fill for life" approach... Not saying that's right, but leaving it longer than 2 years won't cause firey death by boiled fluid nor the insides of your system to rust solid.
You can get meters to measure the water content if it's a concern, however for normal everyday usage I bet most cars are operated on a "fill for life" approach... Not saying that's right, but leaving it longer than 2 years won't cause firey death by boiled fluid nor the insides of your system to rust solid.
Agree with that ^^. I suspect there's three answers - people who have their cars serviced & just let garages do it, hobby mechanics who do it for fun & the satisfaction of a job well done & everyone else who don't bother. I'm in the hobby spanners category & will be doing mine sometime this spring.
Would say it defnitely makes a difference to braking efficacy in my experience & is worth doing.
Would say it defnitely makes a difference to braking efficacy in my experience & is worth doing.
This is one of those jobs that at first glance is a straightforward easy job.
Right up until you encounter seized bleed screws, rusty pipes, cracked brake hoses and a soft pedal that whatever you do won`t firm up again.
There are a few every few years jobs that rarely get done, coolant, gearbox oil etc etc and the best one of all - airbags that should be changed at 10 years.
As OP says, I only tend to do it when opening the system for something else.
Right up until you encounter seized bleed screws, rusty pipes, cracked brake hoses and a soft pedal that whatever you do won`t firm up again.
There are a few every few years jobs that rarely get done, coolant, gearbox oil etc etc and the best one of all - airbags that should be changed at 10 years.
As OP says, I only tend to do it when opening the system for something else.
Every three years is fine, some manufacturers say two, some say three. My fluid tester lights up progressively and invariably gives a 'full house' including the red by three, so I've standardised it at that.
Joy is that nipples are rarely seized if they have been 'exercised' only three years ago... if they've never been opened in 5+ years and they're seized, it's condemnation of previous owners/garages (funnily enough main-dealer 'maintained' cars are among the worst... seems you have to ask for it to be done!)
Good practice to suck out as much as you can from the reservoir (not always possible though) to preclude that dirty fluid passing through the ABS valves,
but put fresh fluid in before you start pulling any through, you DO NOT WANT to introduce air at the reservoir. Pull 100ml from each corner and then go around again (you'll see the difference in colour) never allowing the reservoir to empty obviously. Be aware that you might not be able to see the level at both intake ports, so never assume they're both covered just because you can see that the nearest one is.
Joy is that nipples are rarely seized if they have been 'exercised' only three years ago... if they've never been opened in 5+ years and they're seized, it's condemnation of previous owners/garages (funnily enough main-dealer 'maintained' cars are among the worst... seems you have to ask for it to be done!)
Good practice to suck out as much as you can from the reservoir (not always possible though) to preclude that dirty fluid passing through the ABS valves,
but put fresh fluid in before you start pulling any through, you DO NOT WANT to introduce air at the reservoir. Pull 100ml from each corner and then go around again (you'll see the difference in colour) never allowing the reservoir to empty obviously. Be aware that you might not be able to see the level at both intake ports, so never assume they're both covered just because you can see that the nearest one is.
On my race car and my Porsche, it gets changed multiple times per year via bleeding. On my daily, I haven't changed it in 4 years and it's still showing less than 0.5% water by volume. The clutch fluid (same stuff) in my racecar was about 5 years old and that too had less than 0.5% moisture
I know the theory but in practice I don't see it absorbing quite as much moisture as I have been lead to believe.
I know the theory but in practice I don't see it absorbing quite as much moisture as I have been lead to believe.
LennyM1984 said:
On my race car and my Porsche, it gets changed multiple times per year via bleeding. On my daily, I haven't changed it in 4 years and it's still showing less than 0.5% water by volume. The clutch fluid (same stuff) in my racecar was about 5 years old and that too had less than 0.5% moisture
I know the theory but in practice I don't see it absorbing quite as much moisture as I have been lead to believe.
It would depend on climate. Tropical with high humidity and desert with almost no humidity.I know the theory but in practice I don't see it absorbing quite as much moisture as I have been lead to believe.
No one size fits all.
NMNeil said:
Think about it.
When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
Good point actually.When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
But where does the water come from? Top of reservoir sealed, pistons sealed... I know it gets there slowly, past the caliper/cylinder seals and the cap isn't really air tight but sometimes wonder how in real life
Skyedriver said:
NMNeil said:
Think about it.
When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
Good point actually.When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
But where does the water come from? Top of reservoir sealed, pistons sealed... I know it gets there slowly, past the caliper/cylinder seals and the cap isn't really air tight but sometimes wonder how in real life
Every couple of years I do. I see it as preventative maintenance - the caliper picture above is also an example of what the inside of things like your ABS pump might start to look like too.
For most people though, who only keep their cars for a couple of years, i doubt they ever bother and for daily driving it won't cause a problem in the cars useful lifetime (which will be less if stuff like this isn't sorted).
For most people though, who only keep their cars for a couple of years, i doubt they ever bother and for daily driving it won't cause a problem in the cars useful lifetime (which will be less if stuff like this isn't sorted).
NMNeil said:
Think about it.
When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
How many garages push the pistons in before doing the fluid?When the brake fluid has been fully saturated with water any more water will simply stay as water. Oil floats on water so the water will sink to the bottom and collect in brake calipers corroding them.
Changing the fluid on a regular basis is cheap insurance.
I’d say virtually none.
It will kind of get done by dilution with new fluid and also when new pads go in but the chances of both happening at the same interval are minimal.
I do my own with a Draper pressure bleeder and push the pistons in but I would bet that even a high end garage wouldn’t even think of doing it.
TwinKam said:
Every three years is fine, some manufacturers say two, some say three. My fluid tester lights up progressively and invariably gives a 'full house' including the red by three, so I've standardised it at that.
Joy is that nipples are rarely seized if they have been 'exercised' only three years ago... if they've never been opened in 5+ years and they're seized, it's condemnation of previous owners/garages (funnily enough main-dealer 'maintained' cars are among the worst... seems you have to ask for it to be done!)
Good practice to suck out as much as you can from the reservoir (not always possible though) to preclude that dirty fluid passing through the ABS valves,
but put fresh fluid in before you start pulling any through, you DO NOT WANT to introduce air at the reservoir. Pull 100ml from each corner and then go around again (you'll see the difference in colour) never allowing the reservoir to empty obviously. Be aware that you might not be able to see the level at both intake ports, so never assume they're both covered just because you can see that the nearest one is.
My 2016 981 Cayman had seized rear inner brake nipples on the 2 rear nipples. Impossible if the Porsche dealer had bled the brakes only 3 months earlier and 2 years before that whilst changing brake fluid.. Joy is that nipples are rarely seized if they have been 'exercised' only three years ago... if they've never been opened in 5+ years and they're seized, it's condemnation of previous owners/garages (funnily enough main-dealer 'maintained' cars are among the worst... seems you have to ask for it to be done!)
Good practice to suck out as much as you can from the reservoir (not always possible though) to preclude that dirty fluid passing through the ABS valves,
but put fresh fluid in before you start pulling any through, you DO NOT WANT to introduce air at the reservoir. Pull 100ml from each corner and then go around again (you'll see the difference in colour) never allowing the reservoir to empty obviously. Be aware that you might not be able to see the level at both intake ports, so never assume they're both covered just because you can see that the nearest one is.
It was ironic, given that I had just purchased the car immediately after its latest fluid change and I was changing all the bleed nipples to stainless to prevent seizing.
The OPC (was miles away from home) sent me a brace of brand new brembos, full set of nipples and new caliper bolts. That'll teach them to skimp, was about £1200 quids worth of parts!
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