Flushing Brake Fluid

[ShadowsPapa]

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.

He was talking 5.1 originally.
But no, I'd never go 5 in these due to the necessity of removing ALL of the DOT 3 fluids - or risk the possibility of running into serious trouble later.

One of these days I'll pull out my brake service manuals and get some scans/pics.......... but we're headed into town again today and it's been a crazy week of driving all over the place, sick cats, doctor appointments for me and worse.

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[ShadowsPapa]

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.

Yeah, and I've worked on those cars and trucks and when it's time for pads, the calipers and other parts are toast - etched by the acids that formed and left rings where the seals run, ripping apart the seals when pads were replaced. "but it was fine before" - well, it sort of was.......
If you want to be able to replace pads down the line and not buy calipers, too - a flush when indicated is smart.
I have master and other cylinders and calipers on my shelves I've kept to show the damage done by the crud that forms when the chemistry of brake fluid starts to degrade. Not only moisture, but acids form, there's corrosion, and you literally have etched parts - so bad you can see and feel the etching and they can't be repaired.
Depending on caliper design, it may take only pistons and seals to rebuild, but it can get pretty ugly inside.
The color in the master cylinder may look great - but it could be gray down at the calipers because there isn't a fluid flow in these like other systems. It's a flow of pressure while the fluid remains mostly static - flowing from the master down, not from the calipers up, so any crud forming down below won't be seen on the top.

 

[PuddleJumper]

Yeah, and I've worked on those cars and trucks and when it's time for pads, the calipers and other parts are toast - etched by the acids that formed and left rings where the seals run, ripping apart the seals when pads were replaced. "but it was fine before" - well, it sort of was.......
If you want to be able to replace pads down the line and not buy calipers, too - a flush when indicated is smart.
I have master and other cylinders and calipers on my shelves I've kept to show the damage done by the crud that forms when the chemistry of brake fluid starts to degrade. Not only moisture, but acids form, there's corrosion, and you literally have etched parts - so bad you can see and feel the etching and they can't be repaired.
Depending on caliper design, it may take only pistons and seals to rebuild, but it can get pretty ugly inside.
The color in the master cylinder may look great - but it could be gray down at the calipers because there isn't a fluid flow in these like other systems. It's a flow of pressure while the fluid remains mostly static - flowing from the master down, not from the calipers up, so any crud forming down below won't be seen on the top.

Ok that makes sense. Thanks for the heads up, i'll just flush it. can't hurt it, even if it isn't needed right now.

 

[ShadowsPapa]

Ok that makes sense. Thanks for the heads up, i'll just flush it. can't hurt it, even if it isn't needed right now.

Don't pay the dealer some crazy price - at least that's figured out LOL

I figure brake fluid is cheap.
I don't think it's as it was years ago with modern systems and I get Hootbro doing the testing - that's even now recommended by the makers of brake systems these days.

 

[PuddleJumper]

Don't pay the dealer some crazy price - at least that's figured out LOL

I figure brake fluid is cheap.
I don't think it's as it was years ago with modern systems and I get Hootbro doing the testing - that's even now recommended by the makers of brake systems these days.

tbh if its heavily contaminated and shit is damaged. I'll make it a warranty issue. No way a 6 month old sealed system should be damaged.

 

[Buckhorn]

So my 23' just hit 20k odo. Whew those miles flew by quick. Anyway dealer did the usual and tried to charge me 350 bucks for filters. I got the ol' mopar filters myself on amazon for hella cheaper. easy enough to do myself. But they also added that a brake flush was desperately needed and wanted 300 bucks to do that. I wouldn't be surprised if it is bad. It feels mushier than my Aunt's Rubicon and I see a lot of offroad and towing. That DOT 3 might very well be cooked. I got that fancy vacuum brake flush tool so I'll do that myself. You know what I'll upgrade to DOT5.1 for some better performance and longevity as well. So my question, How much brake fluid do i need for a full flush?

Just my 2 cents, but I think the brake flush thing is just a new fad. I bought my first car in 1966, and have driven a lot of miles, and have never flush the brake fluids on any of them. I have never done the motorcycles I've owned either. The only time there is new fluid added, is when I replace a caliper. If you are going to flush the brakes, you might as well replace the blinker fluid also. Lol

 

[Hootbro]

Just my 2 cents, but I think the brake flush thing is just a new fad. I bought my first car in 1966, and have driven a lot of miles, and have never flush the brake fluids on any of them. I have never done the motorcycles I've owned either. The only time there is new fluid added, is when I replace a caliper. If you are going to flush the brakes, you might as well replace the blinker fluid also. Lol

 

[ShadowsPapa]

Just my 2 cents, but I think the brake flush thing is just a new fad. I bought my first car in 1966, and have driven a lot of miles, and have never flush the brake fluids on any of them. I have never done the motorcycles I've owned either. The only time there is new fluid added, is when I replace a caliper. If you are going to flush the brakes, you might as well replace the blinker fluid also. Lol

Really hope you don't have an ounce of "serious" in that because it's dead-wrong and I hope no one reading this while searching for the key words "brake flush" see it and decide against maintaining their brakes.

NOT A FAD:
It dates back to at least the 1960s and has morphed as brake systems have changed (used to be said 1 to 2 years, now it's 2 years or test the fluid)
I can tell you as a former brake person, still in it as a hobby, you are quite incorrect in it being some "FAD". Even Bendix, Kelsey-Hayes and the other brake companies trained us in decades past.

Really bad advice:
You are giving horrible advice - or sarcasm which too many may take seriously.
It's a very real thing. As I recall, it is even mentioned in ASE cert training materials. (I've taken many of the tests but never went after certification - it never mattered to me where I worked and then changed careers)

You may have countered your own "no need" thoughts right here:
If you had to replace a caliper - perhaps it's because you didn't flush the fluid and it was ruined due to acids and sludge formation.


I've worked o more brake systems than you've seen in your life - I promise you, it's no fad. Been around for over 50 years.

 

[ShadowsPapa]

tbh if its heavily contaminated and shit is damaged. I'll make it a warranty issue. No way a 6 month old sealed system should be damaged.

Unless totally abused, no way a 2 year old system should have any damage.......... yeah, you can ruin brakes very easily, that's why there's really no guarantee of life on brake parts, but it takes some effort to do so.

 

[Buckhorn]

Serious about everthing but the blinker fluid.

 

[ShadowsPapa]

Serious about everthing but the blinker fluid.

Then you are pulling shadetree stuff out of some ...........

I can't even count the number of brake parts I've seen trashed due to lack of simple maintenance. Ideally, a well-cared for brake system should only ever need pads or rotors, or seals after a long time.
I was trained on brake flushing in the 1970s so it's no fad. It's been discussed in college courses, factory training, books, articles by the major brake manufacturers and experts for decades.
Almost every caliper or wheel cylinder that I've ever replaced could have been saved with periodic flushing. They were destroyed by acid etching. I've seen cylinders with gray to gray/brown sludge in them on cars only a decade old.
But people figure it was the bad caliper or whatever - and just keep on swapping parts on, never understanding it all could have been prevented.

Just curious - did you say you worked your way through college doing brakes, steering and suspension work. Or learned it all in a back yard?

If you had to replace any calipers, I'd bet that they were damaged due to lack of decent fluid.

Why do you think there are testers, test strips, and instructions all over the place on brake hydraulic system maintenance?

 

[ShadowsPapa]

This is from an ASE article - and it's always been true, and is one reason people need to think not only of the moisture situation but the chemistry of brake fluid. It's NOT just a glycol substance - there are other things in it that control viscosity, pH and other factors, including preventing corrosion and so on - so going only by "water content" alone isn't great, either.
Anyway, this from ASE -

What kills rubber parts is when the additive package breaks down. The additive package controls the pH of the fluid and the viscosity. If the brake fluid becomes unable to control the pH or other corrosive elements, the rubber and metal parts will deteriorate over time.


That's a quote from the people who "certify" your mechanics/techs.

 

[WILDHOBO]

Do not use Dot 5. It's silicon based. When mixed with other brake fluids. It will gum up.

If you want to use a good Dot 4 brake fluid. Something like Motul 600, or 660. If you want to be a baller. Castrol SRF.

A '23 with 20,000 on it. I would just bleed the brakes to firm up the pedal if it feels soft. 50,000 miles. I say go ahead and flush using new brake fluid. I wouldn't use anything else. You don't know how other products with react with the ABS module.

The dealer wanting to do a flush for $300 at 20,000 miles. They found a sucker.

Agreed. I replaced my rear brake lines at 47k. I added lots of fluid during the bleed. Everything that came out looked just fine. I was liberal about the bleed, because I was fine with replacing lots of the old fluid, but I certainly didn’t do a full flush. I used almost a liter. I stuck with dot3. I’m not risking fluid problems in these jeeps by changing types. Too many horror stories.

 

[WILDHOBO]

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?!

My scanner supports abs bleed on this truck, but I’ve been so far unsuccessful in getting it to do it. I will say my brakes feel great, and I did a snow packed road “bleed”, by engaging abs by repeatedly hitting the brakes on slippery stuff. But I really would like to get the scanner abs bleed to work. I bought the specific scanner for that purpose. Do you mind sharing the steps you took? I did do a mechanical bleed first.

 

[Hootbro]

Serious about everthing but the blinker fluid.

You sure you do not want to double down on the blinker fluid?

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