Flushing Brake Fluid

[ShadowsPapa]

cus the truck is only 6m old. So i would have to do this every 20k or 6m. Plus the ABS bleed is a bitch, and i'd rather not do it twice a year

Every two years has always been the rule - well, it used to be more frequently, but with the loss of drum brakes and far better sealed systems, 2 years is what the brake manufacturers recommend.

Not sure how they can suggest a brake fluid flush on miles alone.

I'd have to look at "the book" to see what's in the owners manual, but it's typically TIME based.

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[WK2JT]

I installed speed bleeders and it makes the job super easy and fast. Shadowspapa probably knows off the top of his head, 5.1 has a higher boiling point, but is more hygroscopic… or something like that.

 

[aFatBird]

aFatbird mentioned Dot 5. That's who I was referring to.

I've used Motul 600 for years in my Grand Cherokee and Power Wagon. When i started to do track days with the bike, and then with the car. I switched to Castrol SRF.

My fault there, didn't notice it was 5.1

 

[PuddleJumper]

Just had a brake flush on my wife’s Jag. Indy shop charged a hundred bucks. Honestly to me I’d be wondering why you need a brake flush so early.

Service writer said Jeep calls for a brake flush every 20k. I haven’t check my manual to see if that’s true. But

noted. thx

 

[PuddleJumper]

I installed speed bleeders and it makes the job super easy and fast. Shadowspapa probably knows off the top of his head, 5.1 has a higher boiling point, but is more hygroscopic… or something like that.

speed bleeders?

 

[PuddleJumper]

Every two years has always been the rule - well, it used to be more frequently, but with the loss of drum brakes and far better sealed systems, 2 years is what the brake manufacturers recommend.

Not sure how they can suggest a brake fluid flush on miles alone.

I'd have to look at "the book" to see what's in the owners manual, but it's typically TIME based.

thats what i thought. i bled the ABS module with Jscan last night and the brakes feel like new. They said my fluid was dirty but it looks like super clear oil to me. If it was amber or yellow or brown then yeah i'd want to flush it. But how tf does fluid go bad before pads do?!

 

[Hootbro]

Service writer said Jeep calls for a brake flush every 20k. I haven’t check my manual to see if that’s true.

Ironically, the owners manual does not state or list anything on brake fluid service interval, just inspection of fluid levels, pads and rotors.

I have seen recommendations from 20K-50K miles or every 2-3 years. I tend to make it part of my 30K mile major service routine.

 

[PuddleJumper]

Ironically, the owners manual does not state or list anything on brake fluid service interval, just inspection of fluid levels, pads and rotors.

my gut says its fine. I find it hard to believe fluid fails before pads do. Unless its contaminated with water, but i have a feeling you'd find out real quick if it did, as soon as the brakes get hot. I do agree tho that DOT3 should be changed every 2 years if you can swing it. But i have seen people run for a decade on the fluid their vehicle came with. I think I'll actually flush when it starts to discolor. its still clear as it stands.

 

[Hootbro]

my gut says its fine. I find it hard to believe fluid fails before pads do. Unless its contaminated with water, but i have a feeling you'd find out real quick if it did, as soon as the brakes get hot. I do agree tho that DOT3 should be changed every 2 years if you can swing it. But i have seen people run for a decade on the fluid their vehicle came with. I think I'll actually flush when it starts to discolor. its still clear as it stands.

Unless you are race tracking, steep downgrade braking or doing heavy towing, most people will never know a brake fluid degradation issue for a long time if ever.

Your gut is probably right and it is fine. If you want to be anal and exactly know, you can buy brake fluid moisture test strips or buy a little electronic pen that checks the moisture content. I have and use the electronic pen below when checking mine.

https://www.amazon.com/Diagnostic-Indicators-Hydraulic-Moisture-Analyzer/dp/B0C53278WB

 

[Volt0]

I’ve never heard of flushing the brake fluid. Looking back on some of my older, high mileage vehicles, that brake fluid was pretty dark until I bled out a moderate amount. It just happened b/c, well, for no more often than I performed pad replacement, I kind of fumbled around with the bleeding procedure. Is the degradation of the fluid mostly a function of the heat dissipation near the calipers?


edit: as in, is it more common to flush in the southern/hotter states?

 

[Hootbro]

Is the degradation of the fluid mostly a function of the heat dissipation near the calipers?

Degradation of the brake fluid is mainly from the absorption of moisture due to being hygroscopic in nature. When the fluid heats up from heat dissipation from the mechanical friction of the brakes themselves, the more moisture content in the brake fluid will reach a quicker boiling point which equals steam that thereby makes the pedals fade and reduces the hydraulic action force applied.

So in theory, heated brakes are not truly the cause of fluid degradation, just a symptom contributor of already moisture degraded fluid,

 

[PuddleJumper]

Unless you are race tracking, steep downgrade braking or doing heavy towing, most people will never know a brake fluid degradation issue for a long time if ever.

Your gut is probably right and it is fine. If you want to be anal and exactly know, you can buy brake fluid moisture test strips or buy a little electronic pen that checks the moisture content. I have and use the electronic pen below when checking mine.

https://www.amazon.com/Diagnostic-Indicators-Hydraulic-Moisture-Analyzer/dp/B0C53278WB

I do ford water a lot, I wheel a lot, I tow a lot. So it warrants a check with strips at least. I’ll give it a go.

 

[Minty JL]

Every two years has always been the rule - well, it used to be more frequently, but with the loss of drum brakes and far better sealed systems, 2 years is what the brake manufacturers recommend.

Not sure how they can suggest a brake fluid flush on miles alone.

I'd have to look at "the book" to see what's in the owners manual, but it's typically TIME based.

^^ Yup, I stick to the 24mos or 24k miles rule

 

[SoK66]

Service writer said Jeep calls for a brake flush every 20k. I haven’t check my manual to see if that’s true. But

noted. thx

There is no brake fluid change requirement in the factory recommended service schedule. A good rule of thumb is every five years.

I would NOT try Dot 5. There is no real benefit to it and if you dont thoroughly flush the system, which is virtually impossible, you'll have an expensive mess on your hands. Just go with DOT 3.

 

[ShadowsPapa]

I’ve never heard of flushing the brake fluid. Looking back on some of my older, high mileage vehicles, that brake fluid was pretty dark until I bled out a moderate amount. It just happened b/c, well, for no more often than I performed pad replacement, I kind of fumbled around with the bleeding procedure. Is the degradation of the fluid mostly a function of the heat dissipation near the calipers?


edit: as in, is it more common to flush in the southern/hotter states?

Trained (and some of that factory training) - we were taught (and this came from Bendix, Wagner, and others) that you flush every two years. I took some ASE tests years ago and seem to recall it being mentioned there as well.
Of course, things have gotten more complex, and hopefully, more "sealed" since then, and the use of different materials in cylinders, calipers, pads and so on would help so today they recommend using test strips or an electronic test device.

Just like we were taught in college when it was more of a "1 to 2" years recommendation, before coming down to 2 years and now "test the fluid" - Bendix to this day still says pull all fluid out of the reservoir and wipe it totally clean of all debris before flushing.
More than one tech has ruined parts by simply flushing and ended up pushing debris through the system, locking up parts down the line.

I can tell you from not only college training, but other sources, such as GM and Ford factory training, that yes, they recommend flushing and yes, even to this day - but it's now more a matter of testing than time.
It was never ever about miles when we were trained (I have some training direct from Bendix - although a tad dated these days) It was always about time.
Brake fluid isn't sensitive to how many miles you've driven, it breaks down over time and absorbs moisture over time - thus, the time factor "every 2 years".

This is from an article, the fellow - Kennedy - is a technical trainer from Bendix Corp. -

Brake fluid contains "chemicals" like most of our other fluids - and those break down with time (heat as well so a lot of wheeling and mountain driving may mean sooner flushes)

Don't just pop the pressure adapter onto the master cylinder reservoir - use something like a turkey baster to get the old fluid out and clean the reservoir.

With drum brakes, the system wasn't quite as sealed and the residual pressure check valve in the master cylinder could eventually lose the pressure held in the lines going to the wheel cylinders and changes in atmospheric pressure (lows and highs moving through) meant that some air with moisture could move into the wheel cylinders so it was really bad in those days.
Still no system is 100% perfect, and with heat and so on, even today, the fluid can and will break down.
(The brake lines in my F250 rotted out from the inside out - that thing had problems!)

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