Technical WTF?

it also depends on where you live..high humidity environment would make sense to check...

 

I watched this video and of course you can’t think for people, but the ignition switch would have been the easiest cure. I have a manual fuel shutoff and a magneto kill switch In my old junky car. I practice emergency shutdown procedures before I start the car at the track.

 

^^^ This............

 

Just one of the reasons I've been using dot 5 for over thirty years now.

 

I bought a 4 litre brake fluid and went through my family's cars and after finding all the black and brown crud settled in the bottom of the bleed container, now I do it every couple of years. When you buy it in a big container, it's cheap insurance. All that brown rusty crud inside your wheel cylinders come from the small amount of water that eventually gets in there. You just need someone to sit in the car while you do the "brakes on............brakes off" bit.

 

No explaining needed

 

The owner said it cost him over $200,000! to build and in the top comment he said he only had liability on it.

 

To me, the problem is not upselling or even whether brake fluid absorbs moisture (it does), it's that too many of these quick lube places charge for things they don't do. I've seen several of these places around here charge for power steering and brake fluid flushes but not do them. I have even heard of them shorting people on the oil changes by not changing the filter and sometimes even the oil.

Your guys may be honest and are just looking for a few extra bucks or they may be total scammers, we can't see from here. I don't trust them after being in automotive businesses for 20 years and hearing all the horror stories.

 

Does brake fluid absorb as much water when the humidity level is at or under 10% (like here in Utah) vs 80-100% (like everywhere else)?

 

I am with you!

Ben

 

I change my car’s brake fluid anytime it blows a brake line, a wheel cylinder leaks, or the master cylinder leaks.

I call it after the fact maintenance, rather than preventative maintenance.

I usually make it ten or twelve years until a change happens.

 

If they didn’t open the master cylinder cap, there would be no path for moisture to enter. The more you inspect, the more you contaminate.

 

The master cylinder cap is vented to the air. If it wasn't the fluid couldn't move out of the master cylinder and towards the wheel cylinders or calipers, then move back into the master after the pedal is released. The brake fluid in the master cylinder is always in contact with the moisture in the air, and that exchange is renewed every time the brake pedal is pushed, or released.

 

Any master that has a diaphragm under the lid with “bellows” is not vented directly to the air for that reason, the bellows allow air to displace the fluid. Our older ones are definitely in constant contact with air, also part of the reason they started to make reservoirs visible, to decrease the need to open the system.

 

I suck brake fluid out of reservoir and refill every other oil change, same with power steering fluid.

Visual brake check when I rotate tires - check pads and clips, grease the caliper pins. Crack bleeders open and push out 8 oz fluid. I figure the brake fluid that sits in the calipers takes all the heat cycles, don't think it cycles thru the system well. Vacuum bleeder makes this a few minute job.

 

Ironically I change brake fluid in my mountain bike twice a year. Brake pads at least that many times sometimes more depending on conditions. I've changed brake fluid in my daily driver twice in the 9 years I've owned it and my wife's daily the same. Hot rod - not yet but, doing new brake lines etc now. After watching the 1500 horse Merc crash I'm going back through systems again before road tripping it. Good reality check. New fluids all around coming up.

 

my off topic ( euro cruisier ) requires a bi-annual brake fluid change.. so its a good idea to change it..

 

If the fluid in the master cylinder is discoloured, it is overdue for a change. The worst of the dirt migrates to the wheel cylinders or calipers. Change the fluid in the master, then pump fluid out the wheel cyls until it come clean.
A bottle of brake fluid every few years is cheap insurance.
Even systems with Dot 5 need to be flushed. Read what it says on the label.

 

In May we got a fairly comprehensive brake job on my wife's late model at one of the name-brand brake shops. I was able to ask questions concerning the parts used and warranty, etc., and watch the procedure.
Two months later in July, she was at her dealer for a simple oil change and I get the call...... "Honey, they are saying I need bla bla on my brakes. Should I tell 'em to go ahead?" My answer was, "No. You tell 'em to go to hell. You just had the brakes done 2 months ago. Remember?"
My wife is hell on brakes. She doesn't believe in coasting when approaching a red light. She's on the gas pedal until the brake pedal must be used. There's no coasting to anticipate the green hoping for a "roll-through", etc. In 6 years she's had brake service 2 times so the good news is, her brake fluid never has a chance to get too old.
(She does drive a lot of miles, though, so that also contributes to the brake job frequency.)

 

My OT tow vehicle has 140,000 klms (about 90,000 miles) and I've only just had a service and was told that by the next service it will need disc rotors and pads. Sounds good to me as they are the original ones that the car was built with in 2014. I tow my race car trailer all over the place and the secret is it's a manual gearbox so I use the gears rather than ride the brakes.
At that last service they did the moisture test on the brake fluid and it was 1% so they left it alone.

 

On my OT cars, I have the shop I use do the flush thing. I forget the interval. I also do the coolant and transmission flushes when they are recommended.

 

First question which popped into my head: I wonder if brake fluid can be dried? I used to be into homebrew fuel ethanol in a big way, and drying ethanol was something which came up from time to time in discussions. Consensus was, you can readily achieve 4% water with distillation, and up to 10% water is actually beneficial for combustion, so why bother? But that's moot: how would you go about drying brake fluid, without harming the rest of the constituents?

Second question which popped into my head: could a brake fluid conductivity meter be installed permanently to a car? I've got a thing for gratuitous gauges, especially if they're mismatched. The look is 1928 for "this means business." So, an analogue ohmmeter on the dash? Use a brake fluid tester to determine the dial markings. I see pen-type testers available here from about US$9.

 

I think I would have to throw the BS flag at 10% water in the system. That would make your level rise in the master cylinder. These are closed systems that aren’t constantly exposed to air. That includes an opened container of brake fluid; as long as you aren’t opening the lid every day, how does the water get to it? If you think the lid leaks, store it upside down and I guarantee no fluid will come out if tight.

 

I’m sure some moisture enters threw the rubber brake lines and seals. There is microscopic pores in some things like rubber and plastic.

ever set a plastic bottle of muriatic acid on a metal shelf? It starts to rust the shelf within a couple years.

 

LOTS of things can be measured, some easily, some a bit more complicated. With the right tools and knowlege you can quickly find out a lot about the condition of a car and its systems.

Supposedly, a submarine builder has said something it being impossible to build something that doesn't leak, it's always a matter of how big leaks you can accept.
When I put my bikes away for winter there's good pressure in the tires, when I take them out again in spring there's considerably less pressure in them. They're "sealed", they still leak over time.

 

actually i do own a repair shop

 

Today's times. I have noticed in my lifetime now 74 years old, you have to be more careful than ever with Any business/service you deal with. I have become cynical, a result of my life experiences. The world seems to be set on kill money wise and sadly women are an easy target. I have stated this before, Honesty, Integrity, Courtesy, Respect has taken a huge dive for the worse. It's been my experience in later years, when you find a good reputable business/service they are very busy, you have to get in line and wait. And to agree with you I have never changed brake fluid in any vehicle ever owned exception adding brake fluid if bleeding brakes after my DIY brake job. Wisconsin is a high humidity state, a rust belt deal salt wise, I'm talking, many cars/miles/years.

 

if dot 5 does not absorb water when moisture ( humidity condensation etc_) gets in it must be a little bubble of water at a low point in the lines

 

That's what I was taught in architecture school. It's technically possible to make something 100% leak-proof, but it's likely to compromise other design considerations, be enormously expensive, and fail relatively quickly. A better long-term solution is probably 99% or even 95% leak-proof, and then you anticipate and deal with the leaks.

Consider for example the hydraulic system in the Citroën DS19. Its durability comes from it not having hydraulic seals at all, so its operation isn't reliant on the efficacy of seals. It's a lot more feasible to maintain a 99% leak-proof condition indefinitely than a 100% leak-proof one. So the Citroën system is designed to be consistently <100% leak-proof, and to recover the leakage via a low-pressure recovery circuit. That's why a DS will slowly settle down onto its bump stops when parked.

 

Like I don't have enough things on my plate without going and looking for more things to do. There are a kazaillion cars on the road that have never had "preventitive maintenance" on their brake fluid and still going strong well after 100k miles. I have to wonder about the accuracy of testing fluid at probably the main point of moisture influx......the opened cap at the reservoir. How could that possibly tell you what moisture might be trapped somewhere in the system beyond all those bends. Remember how hard it sometimes is to get air out of a system......so how do you know its giving you a reading thats correct for the whole system? I hate bleeding brakes......so I'll just take a chance that the fluid will last till I change the brakes and add whats needed during the repair process. Many of us own multiple cars, and I sure ain't gonna go looking for some problem that isn't giving me a problem. Too much other stuff waiting on me already..........