Flush break fluid for shop revenue ?

[GO.DOG.GO]

It has been recommended to me at Audi shop and Volvo to flush break fluid on a vehicle.
Being a cynical man I suspect this is 99% scam. In my younger days I work on an abused
construction fleet of pickup trucks and larger trucks and saw various break failure but never evidence
of contamination. Can someone convince me this is really necessary and not a play on
fear to generate shop revenue.

Dog

[Hugh@EuropaParts]

Brake fluid lives in a sealed system and can survive for years, but moisture from the surrounding air can work its way in through hoses and other parts of the brake system. If your brake fluid has become dirty or contaminated, it can change how your brake system operates — brake pedal feel can be affected, as can heat dissipation in repeated stops. Water in the brake lines lowers the boiling point of the fluid, so stopping ability can diminish in hard stops as heat in the system increases. In addition, over time the moisture can cause internal corrosion in the brake lines, calipers, the master cylinder and other components.

[MugelloB7RS4]

I've always done it as preventative maintenance. Its not that difficult or expensive. Overtime the brake fluid could attract moisture especially if boiled. That moisture in the brake caliper can cause rust and degrade the performance of the system. I really can't give you a quantifiable answer, but its just piece of mind for me. I'm not sure if things like stuck calipers result from old fluid that's boiled and rusted internally but its not too far of a stretch to imagine it could. Also performance could suffer if the fluid has absorbed water. You won't be getting the most optimal stopping performance. For me, even if I can save 1ft of braking distance, it's worth it and could be the difference between not hitting the obstacle in front of you and having your car written off.

For me, its just part of keeping the car in the best shape I can. If you own the car and are going to keep it, I would say flush the system. If you aren't planning on keeping it, then it may not make sense.

[Robdukes]

Good answers above. Going to do mine with next brake pad change. Picked up the schwaben 3 liter brake bleeder system to make it easier. Quick question...I have 1 liter of Typ200 fluid. Does anyone who has done this job know if this will be enough to refill the system?

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[Iwantyourcar]

I had moisture in mine. Worth a change.


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[Audibot]

I believe it's recommended every 2 years. You could go for longer if it feels fine, but as stated, it can get contaminated over time. Not a scam but the prices are usually scam-worthy

[jygesq]

audi recommends every two years to do flush, brake fluid picks up moisture . well recommended as your braking feel is improved.

[GO.DOG.GO]

Brake fluid lives in a sealed system and can survive for years, but moisture from the surrounding air can work its way in through hoses and other parts of the brake system. If your brake fluid has become dirty or contaminated, it can change how your brake system operates — brake pedal feel can be affected, as can heat dissipation in repeated stops. Water in the brake lines lowers the boiling point of the fluid, so stopping ability can diminish in hard stops as heat in the system increases. In addition, over time the moisture can cause internal corrosion in the brake lines, calipers, the master cylinder and other components.

Can you show pictures of corroded brake piston bores ?
I can t find any .
I believe that about 10 years ago shop tool suppliers developed easy to use tools
and promoted this new revenue stream for shops. Everybody rolls over in fear with concept of failing breaks.
Process is easy for a second rate shop helper to generate $250.00 and 250.00 is a very palatable cost on
a high end car.
I was advised to flush brake fluid on a 3 year old car thats never had or needed break work.
how would water or dust have entered a high pressure hydraulic brake system.
Brakes have redundant safety with spit cylinders in case of failure any way.
Every 2 year brake fluid flush is a scam.

[GO.DOG.GO]

Both brake fluid and water are not compressible. What could physically change to improve feel with new fluid ?
Do you run nitrogen in your tires ?

[Envy187]

I've always done it as preventative maintenance. Its not that difficult or expensive. Overtime the brake fluid could attract moisture especially if boiled. That moisture in the brake caliper can cause rust and degrade the performance of the system. I really can't give you a quantifiable answer, but its just piece of mind for me. I'm not sure if things like stuck calipers result from old fluid that's boiled and rusted internally but its not too far of a stretch to imagine it could. Also performance could suffer if the fluid has absorbed water. You won't be getting the most optimal stopping performance. For me, even if I can save 1ft of braking distance, it's worth it and could be the difference between not hitting the obstacle in front of you and having your car written off.

For me, its just part of keeping the car in the best shape I can. If you own the car and are going to keep it, I would say flush the system. If you aren't planning on keeping it, then it may not make sense.

+1.

These are great cars, so treat them as such.

I did the brake fluid flush recently because that's what Audi recommends (every two years). When I asked my mechanics how the liquid looked like after they were done with the service, they said it could've lasted a little longer...but you can't put a price on peace of mind.

Some vehicle manufacturers interval recommendations vary in quantity of miles/km's, but I merely follow the recommendations of my vehicle's manufacturer...and Audi recommends it every two years.

[Audibot]

Both brake fluid and water are not compressible. What could physically change to improve feel with new fluid ?
Do you run nitrogen in your tires ?

I feel you're being obstinate to be obstinate.

Brake fluid has a significantly higher boiling point than water does. So if you brake sufficiently hard, that heat has to go somewhere, and some ends up in the fluid. If you have water in the system, even a very small amount, it can boil and vaporize, leaving your pedal spongy and/or deficient. Flushing out old fluid removes most/all fluid contaminated with water so that this does not happen. As stated above, it is good part of preventive maintenance.

Btw, nitrogen is used because 1. it gives a more linear behavior than air, since you've removed the >20% O2 and other gases from the equation. Additionally N2 molecules are larger than O2 and H2O molecules that pervade the air, and so are less likely to diffuse out of the rubber tire.

Regarding corroded piston bores, you can simply google to find pics. They happen. My allroad had a seized rear caliper piston. Replaced with a brand new one at the shop.

[RatBustard]

Brakes have redundant safety with spit cylinders in case of failure any way.


that's not how multi-piston calipers work. that would imply there are two braking systems on the car, which there isn't.

brake fluid is hydroscopic which means it absorbs water. you can probably get by flushing the fluid every 3-4 years, but if you extend your interval, you should test your brake fluid. you can get a tester online and keep tabs on the fluid.

[MME1122]

I bought one of these to test water content: https://www.amazon.com/gp/product/B076SC377J/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

After having the car for 2.5 years mine tested at 3%. I checked the new fluid and it came up 0%, so I have some confidence in the measurement. I got a pressure bleeder and flushed it myself since I was putting on stainless lines anyway. I think it took me about 2 hours including changing the lines. The bleeder isn't totally necessary but makes the process a lot easier, especially if you're working by yourself. Either way it's not a hard procedure to do yourself.

Corrosion I think only becomes a problem on old cars that have never had the brakes serviced. I'm thinking 10+ years probably more, I can't see it being an issue before then.

However, water content lowers the boiling point of the fluid. Just having water in the fluid won't make it significantly more compressible, but if you track the car or drive it hard the lower boiling point can cause the fluid to boil which DOES make it compressible, since you now have gas in the system. So I'd say if you drive the car hard or track it and want the brakes to perform their best all the time, or you want to complete all the service Audi recommends, then do it. Otherwise if you don't push the car much ever it's probably not necessary, or can at least be done less frequently. My car is also manual and the clutch uses the same fluid, so more reason for me to do it.

The "redundant safety" I believe you're talking about doesn't have anything to do with fluid or calipers. Most cars will have two circuits each with two wheels, so that if a line is cut or blows or something you'll still have 2 wheels with brakes. Not sure if this is the case on our cars but I would imagine it's similar.

[GO.DOG.GO]

Brake fluid flushes at 2 year intervals and nitrogen in tires are a manipulation of our obsession to take care of our cars.
it s not supported by solid performance review but its easy for any new dumb ass shop rookie to carry out and the
service manager ups the house take for the day . I guess its like copper fiber in your socks or DMSO. If it makes you believe your safer
maybe your safer but I say Audi USA should not endorse the scam.

[jygesq]

Both BMW & AUDI recommend changing brake fluid every. 2 years. I always want my brakes working at an optimal level.i I have the brake fluid flush done every 2 years.It is not a scam , but you can do whatever you want

[Silver Streakin]

All fluids are lifetime. Are you wasting money changing your oil?

[Helmet165]

All fluids are lifetime. Are you wasting money changing your oil?

And you win the internet for today

[Audibot]

Brake fluid flushes at 2 year intervals and nitrogen in tires are a manipulation of our obsession to take care of our cars.
it s not supported by solid performance review but its easy for any new dumb ass shop rookie to carry out and the
service manager ups the house take for the day . I guess its like copper fiber in your socks or DMSO. If it makes you believe your safer
maybe your safer but I say Audi USA should not endorse the scam.


Why are you driving an Audi? Don't you know it's a scam?! Go back to driving a Corolla because so they won't tell you to flush your brake fluid every 2 years... oh wait, they will too!

And copper is a known anti-microbial agent, so there is use in having it in your socks.

[GO.DOG.GO]

I change my Audi motor oil at 7,500 and transmission flush every 20,000.
Motor oil is truly exposed to contamination with excess carbon and unburned fuel that gets past rings potentially 3000 times per minute.
Legitimate science shows the need to change motor oil for preventative maintenance but brake fluid is not exposed to 3000 cycles per minute
of contaminating abrasive carbon gas and unburned hydrocarbons. The automotive repair business is bilking this emotional association of
brake fluid wearing out in 2 years like motor oil. My complaint with this is I must waste my time and money prematurely changing
brake fluid to keep my warranty enforceable. I would like to save that money for rounded out tires and a water pump some day.

[Audibot]

Sounds like we won't be able to sway your opinion. Just know that water can diffuse its way through the various hoses in the hydraulic circuit and contaminate the fluid over time.

[grovlet]

OK - to make this simple.....

#1 - Brake Fluid is hygroscopic - meaning it attracts water - so over time it more water is mixed with it.
#2 - Brakes create heat - the fluid is there to adsorb the heat - water does not absorb heat...... IT BOILS into air......
#3 - Air is bad for braking it's highly compressible - so creates spongy / slow brake pedal and effects brake piston compression

Essentially you really should change your fluid every two years regardless of fluid choice - but the better fluids are designed to hold more water and boil at a higher temperature even when water is present. If you drive aggressive it's actually recommended to change it every year. If you track your car at all even more often - some folks even change it after a heavy track session.....

Also remember we have heavy cars that require more braking to stop - so higher brake temps - meaning more chance to boil water absorbed fluids - so probably a bigger issue on the S4 vs a Mini...

http://tiltonracing.com/brake-fluid-stay-safe-and-go-fast/