Changing break fluid

[jlee]

I know brake fluid is hygroscopic. Point was, brake fluid is designed to withstand being contaminated up to a certain point....just like oil is.

So if you're not "to that point" where your manufacturer recommends you change the fluid....then while yes, it's dirty...it still works fine. And when you change it, you're not going to *feel* the slightest difference. It just won't be as dirty and that far along towards the "it's too contaminated" point.

And dirt absolutely makes a difference. Ask your stuck calipers or wheel cylinders or you failed master cylinder or ABS pump how they like that nasty fluid. Water in the fluid can also hurt these parts.

I can agree with this.

The initial post lacked the "manufacturer recommends" clause you're now including, which makes a significant difference. The issue taken up with your post was the claim that "dirty, contaminated brake fluid still functions just as well as brand new clean fluid" -- brake fluid typically contains 1% water per year of service. Once you get to the 8% mark, DOT3 fluid will boil around 250f. That's pretty low!

I'm not sure what their source is, but this article claims that 95% of hydraulic brake failures (presumably on motorcycles, given the source) are caused by moisture in brake fluid.

 

[JCH13]

It's worth noting that 'street cars' get driven on a variety of roads. Some people just putter around in suburbia and never see anything more dramatic than stopping from 65mph off of an interstate. Other people routinely drive on 18% grade hills (like me) and other people drive through multi-mile mountain passes that lose 5-8k feet of elevation quite quickly (like my parents). These sorts of roads can quite easily cause brake fade and brake failure related to overheating.

It would be fool-hardy to think that one's own myopic view or experiences of driving and braking provides a meaningful argument platform in such a general discussion.

 

[jlee]

It's worth noting that 'street cars' get driven on a variety of roads. Some people just putter around in suburbia and never see anything more dramatic than stopping from 65mph off of an interstate. Other people routinely drive on 18% grade hills (like me) and other people drive through multi-mile mountain passes that lose 5-8k feet of elevation quite quickly (like my parents). These sorts of roads can quite easily cause brake fade and brake failure related to overheating.

It would be fool-hardy to think that one's own myopic view or experiences of driving and braking provides a meaningful argument platform in such a general discussion.

Yep. The last time I drove down Mt. Ascutney, I could smell brakes cooking from a car ahead. It's a fairly common odor on long grades in general (Colorado comes to mind). Stop and go city traffic is far, far easier on brake fluid.

 

[Zivic]

"Maybe" here's a picture of someone lighting a cigarette off of it. I didn't say "normal driving conditions" - I said "street car." If you're going to argue with people, argue statements that were made instead of shit you make up.

if a person with any car changes pads and chooses to bed them in, I think they could get plenty hot to boil the fluid and cause issues.

 

[OILFIELDTRASH]

I'd find a new mechanic if they told me that flushing the fluid is a waste of money. I've seen some nasty fluid come through the bleeder valves on some older vehicles. I personally don't want moisture and rust in my brake lines.

 

[Pacfanweb]

I can agree with this.

The initial post lacked the "manufacturer recommends" clause you're now including, which makes a significant difference. The issue taken up with your post was the claim that "dirty, contaminated brake fluid still functions just as well as brand new clean fluid" -- brake fluid typically contains 1% water per year of service. Once you get to the 8% mark, DOT3 fluid will boil around 250f. That's pretty low!

My original post said this:

It's done to prevent having problems caused by dirty, contaminated fluid

I would have thought that most people with reasonable reading comprehension could infer that the manufacturer specs would determine what that point actually is.

Regardless, what I responded to was whether the brakes (the pedal, specifically) would "feel" different after changing the fluid....and it won't. If the brakes felt fine with the dirty fluid, they won't feel any different with the new fluid.

 

[jlee]

My original post said this:


I would have thought that most people with reasonable reading comprehension could infer that the manufacturer specs would determine what that point actually is.

Regardless, what I responded to was whether the brakes (the pedal, specifically) would "feel" different after changing the fluid....and it won't. If the brakes felt fine with the dirty fluid, they won't feel any different with the new fluid.

Would you also have thought that most people with reasonable reading comprehension could infer that, because I never said "normal driving conditions", that I did not mean "normal driving conditions"?

Let's not play the insult game. It's never productive.

Ultimately I think we agree; the phrasing of the original post was unclear enough to get the attention of more than one person.

Old fluid will 'feel fine' until you stress it beyond its boiling point. Some people driving in bumper to bumper traffic every day may never get there, while someone who lives in the Rockies will find that point a lot earlier.

 

[Midwayman]

It's worth noting that 'street cars' get driven on a variety of roads. Some people just putter around in suburbia and never see anything more dramatic than stopping from 65mph off of an interstate. Other people routinely drive on 18% grade hills (like me) and other people drive through multi-mile mountain passes that lose 5-8k feet of elevation quite quickly (like my parents). These sorts of roads can quite easily cause brake fade and brake failure related to overheating.

It would be fool-hardy to think that one's own myopic view or experiences of driving and braking provides a meaningful argument platform in such a general discussion.

I think people under estimate how hot their brakes get. I remember one time I went to visit my folks who lived in a pretty hilly area and was driving it up and down hills like I normally drive at surface street speeds. I pulled into their driveway and the brakes were smoking a bit. Trouble with failure is that its not really a smooth drop off. You have brakes and then you don't.

 

[boomerang]

Old fluid will 'feel fine' until you stress it beyond its boiling point. Some people driving in bumper to bumper traffic every day may never get there, while someone who lives in the Rockies will find that point a lot earlier.

:thumbsup:

People tend to believe that the driving conditions they experience are universal and apply to everyone. Obviously, that's not the case.

The learning moment from this thread should be that when brake fluid is in use that is hygroscopic, it should be changed according to the manufacturer's maintenance schedule for reasons of both longevity of components and more importantly, safety. And BTW, safety encompasses both yourself and those around you.

 

[HarryLui]

The first time I bleed the brakes on "new to me" 1989 Dodge Daytona Shelby, there were big pieces of rust that came out of the system.

You bet I bleed the rest of my cars once every few years after seeing that.

A quart of brake fluid is $8. Overhaul or failure of the brake system? I don't even want to think about it.