Was told brake flush should be done every 2 years

Status
Not open for further replies.
Originally Posted By: Stanley Rockafeller
Originally Posted By: expat
Originally Posted By: chevyboy14
this is the best way to check brake fluid and antifreeze!! get a multi meter and put positive in the fluid and ground on a metal object if the fluid reads .03 volts consider doing it soon . at .04 it needs done asap. that is the absolute most sure fire way that i know to check it.


Hum...... Can anyone verify that?


Yeah, it's pretty accurate. The mulit meter method is pretty well-known. Heck if you want a DIY you can look on youtube and I'm sure that you can find some step by step instructions to get it done.


? Would the metals of the vehicles brake system and chassis provide the dis-similar metals required to provide the drive to power this voltage leakage test?

And if there is no standardization of the differences in electro-negativity then some vehicles would have a high drive force, while other had a low drive force.

As an example think one vehicle has a drive potential of 1.2 Volts, while another may have a drive force of 0.12 Volts for this test.
 
Last edited:
Originally Posted By: JimPghPA
Originally Posted By: Stanley Rockafeller
Originally Posted By: expat
Originally Posted By: chevyboy14
this is the best way to check brake fluid and antifreeze!! get a multi meter and put positive in the fluid and ground on a metal object if the fluid reads .03 volts consider doing it soon . at .04 it needs done asap. that is the absolute most sure fire way that i know to check it.


Hum...... Can anyone verify that?


Yeah, it's pretty accurate. The mulit meter method is pretty well-known. Heck if you want a DIY you can look on youtube and I'm sure that you can find some step by step instructions to get it done.


? Would the metals of the vehicles brake system and chassis provide the dis-similar metals required to provide the drive to power this voltage leakage test?

And if there is no standardization of the differences in electro-negativity then some vehicles would have a high drive force, while other had a low drive force.

As an example think one vehicle has a drive potential of 1.2 Volts, while another may have a drive force of 0.12 Volts for this test.


....wot?

AFAIK, the method I was taught was to immerse BOTH the pos and neg terminals from the mulitmeter into the fluid. The reading it gives you will indicate how much the fluid is able to conduct electricity. The better connection, the more water in the fluid (the worse it is).
 
I can understand a hydraulic fluid that is free from moisture being a non conductor.

And I can understand a hydraulic fluid that has water molecules being able to conduct some electric current.

However if you are immersing two similar metals in the hydraulic fluid, similar metals should not act as a battery in such a setup, and if the meter is on the voltage setting, there should be no voltage indicated.
 
Originally Posted By: Stanley Rockafeller
I once invested in a "motive power bleeder" for my e30 and after one use did I realize how much of a joke it was.

Sure it operated correctly and I had fresh fluid in it etc. but after using it on my car with my older brother who is a mechanic, he noticed that we could get the old fluid out of the bleeders FASTER by merely having one person in the car pressing the brake pedal down while the other guy went around from wheel to wheel cracking open the bleeders and flushing them clean (making sure to keep the res. full of course).

Another method I learnt was simply doing a "gravity" bleed. It can easily be done by one person and requires no special tools. Just jack up each side of the car and remove each wheel and then open the bleeders and let them bleed clear. Then close off that valve and move onto the next wheel. Also making sure to always keep an eye on the res. to avoid air from entering the system.

After learning these two methods, I quickly went and sold my motive bleeder to a porsche owner. He thought he was getting a deal HA!


Don't know why you think power bleeding is a joke, this is how most professionals bleed brakes. It's easier, faster and only requires one person.
 
GM says 7 years with a new car.
I'd do 2 years or so because I do it myself, and takes only a few minutes.
I am not worried about water, which is not an issue, but debris.
If you have water problems,fix the entrance.
 
20 years now, other than bleeding when new brakes put on and changing the fluid in the reservoir a few times a year I have never had the fluid flushed in my 20 year old Camry. Brakes appear fine.
 
I just opened the master cylinder on my daughter's car last weekend and the brake fluid looked black. I've never seen brake that dirty/contaminated. I wonder if it's ever been changed. I am going to do a fluid change this weekend...
 
Before I owned Hondas, no owner's manual ever told me to exchange brake fluid. My former '97 Cadillac had the original brake fluid as far as I know, all the way until my brother sold it two years ago. Brakes were "fine", but probably far from optimal.

I exchanged the original fluid in our MDX last year. What a dramatic difference that made in pedal feel and brake response. I plan to exchange the fluid in our CR-V this winter.
 
Quote:
Don't know why you think power bleeding is a joke, this is how most professionals bleed brakes. It's easier, faster and only requires one person.

If your just changing the fluid there is no need to bleed them, there is no air in the system.

Just remove as much fluid as possible from reservoir, fill it with new fluid and open each bleed screw one at a time till clean fluid comes out.
Keep a check on the reservoir so it doesn't go empty.

No need to push the brake pedal or anything else, in fact pushing and releasing the pedal poses a risk of getting air in the system if the bleeder wasn't tightened before the pedal is released.
Gravity is the best and easiest way to do this job.
 
Most old cars change their own fluid whether you like it or not from time to time, through blown wheel cylinders, calipers, lines, hoses and the like. Probably not often enough, but better than nothing.
 
I lost brakes once due to black brake fluid. Since then, I change it every two years.

My focus, if I still have it, will be 2 years old in the spring. I'll be flushing out the fluid then.

I also believe that running the original pads down to nothing (taking 10years) and never flushing the fluid contribute to calipers that end up hanging at the piston when new pads are put in.

Plus, if you never bleed the brakes ... the bleeders are near impossible to get out after 10 years .
 
Last edited:
I would get some test strips and see if it really needs to be changed. 3-4 years is good measure but only a test strip will tell you if you really need to change it or not.
 
Originally Posted By: chevyboy14
this is the best way to check brake fluid and antifreeze!! get a multi meter and put positive in the fluid and ground on a metal object if the fluid reads .03 volts consider doing it soon . at .04 it needs done asap. that is the absolute most sure fire way that i know to check it.


Except that besides under a dead short, many multimeters will read close to 0.03V just from the instrument noise, even with a good fluke.
 
Brake fluid should be flushed every 2 years - but that service is not specified by all manufacturers. My Volvos and Mercedes stipulate every 2, and every year if the car is driven in the mountains/hard.

Given the expense of components in the system, keeping fresh, moisture-free fluid in there makes sense. Given the degradation in boiling point (and potential for loss of brakes) with moisture, the safety reason is compelling.

But, Carnoobie, the whole description you provided in the post is garbage...full of strange and un-needed steps. You can flush them yourself, using an assistant and a wrench...easy, and cheap, you'll be out the cost of 1 QT of fluid. All you're doing is using the Master cylinder to pump fresh fluid through the lines and through the calipers/cylinders...in some cars, you can even do it with the tires still on...depends on the bleed screw location on the calipers and/or cylinders...
 
Last edited:
Originally Posted By: mongo161
I use the turkey baster method twice each year with the Pennzoil Dot 3 that I picked up at big lots. Once before winter and once before summer. I remove all of the old fluid from the reservoir and replace it with clean fluid, after I wipe out the reservoir with clean paper towels.

Fresh Fluid is better than Old fluid any day of the week.

No Problems. I have the brake lines bled every 2 years.

BTW....I perform the turkey baster maneuver on the Power Steering reservoir twice a year.....with Mobil 1 synthetic ATF. I have some short piece of clear plastic tubing that I retro fit, securely, onto the turkey baster so I can get the reservoir as empty as possible.


I have been doing the same as you for many years and it has worked well for me. I do this every engine OC.
 
Usually the manufacturer's maintenance schedule is the best guide. It's almost always the time, not the mileage.

Many Europeans are at two years. If you're tracking the car, it's more often than that. Cars without fluid schedules that eat lots of pads are a blessing in disguise.

Pressure bleeding is the best way and the pro's way. Pedal pumping tends to damage MC seals on older systems once a bore ridge develops on them.

Here's a tip for the shade tree Motive user: Fill the MC reservoir and just use the motive for air pressure ONLY. Just don't let the reservoir drain empty. MUCH cleaner, works fine.

Unless you can get probes into a caliper bore, the conductivity test is useless. Same thing with the turkey basters. The fluid doesn't circulate or cycle back. All the intruded moisture winds up in the calipers and drum cylinders, where it can flash steam and voila, NO brakes.

A good flush starts at the bottom, where all the contamination is.
 
Originally Posted By: Volvohead
All the intruded moisture winds up in the calipers and drum cylinders, where it can flash steam and voila, NO brakes.

A good flush starts at the bottom, where all the contamination is.


So, from a theoretical perspective, what is going on here? Water and brake fluid are attracted to each other, which is why they get together in the first place.

But you are saying this only happens at the wheel, implying that once inside the system, moisture loses interest in seeking brake fluid. I don't mean to sound sarcastic, but logically, this sounds like the line in My Cousin Vinny, about the laws of physics only applying on a certain person's stove. Or maybe gravity keeps it from migrating upstream, even though it really wants to, chemically. Could you elaborate?
 
No, perhaps I should elaborate.

Moisture can intrude from many points in the system.

Although absorbed from multiple points, it tends to reach its greatest concentration in the lower reaches of the system (along with all the other system contaminants - dirt), where it is more prone to flash boiling events.

The hygroscopic nature of most fluids (except the silicone based ones) certainly helps disperse it some. But if you ever played the conductivity test with the first shot out of a bleeder valve, the values there are much higher than what you'll see at the reservoir in many instances. That's why I don't trust the meter test up top.

All that absorbed moisture does in the upper system is corrode and wear parts.

In the lower end, it causes braking failure and accidents.

I'm coming from a garage and field perspective. But DOT 4 fluids also tend to be more prone to hygroscopic failure than the old DOT 3 types, according to folks more educated on these matters than I. That may also explain why today's high performance braking systems sometimes can't go on for 10 years on the same fluid like a '75 Caprice might have.

These folks have a nice little white paper that does a fair job on the various fluid types and how boiling points become compromised:

http://www.stoptech.com/technical-support/technical-white-papers/brake-fluid

The bottom line is that the worst condition fluid generally is at the bottom of the system, where conditions are the harshest.
 
Status
Not open for further replies.

Similar threads

P
brake fluid change required to pass PA inspection?
3 4 5
Replies
84
Views
3K
IveBeenRued
Dborch41
2020 Silverado 1500 brake flush confusion.
Replies
4
Views
558
The Critic
Number_35
Friend Got An Outrageous Quotation From A Chain Muffler-And-Brake Shop
4 5 6
Replies
112
Views
5K
Arc
B
Changing Oil Every 2 Years?
2
Replies
37
Views
2K
50yr Street Mech
donnyj08
Brake Maintenance and Chinese Parts
Replies
3
Views
286
thetricky
Back
Top Bottom