Replacing brake fluid

[Racer57]

I've never known of anyone that did it with cars, but do any of you flush out and replace your brake fluid as soon as its no longer clear like new ?

I know motorcycle manufactures recommend it and I personally have had issues on my bikes if I let it go for a lot longer than required. It will get a lot thicker with grim and not work as it should, plus condensation and heat. With the much larger quantity and heat extremes it seems that we should. Especially on cars that sit for long periods of time.

[JS29]

Yes, Some manufacturers rec-amend doing it, I think at about thirty thousand miles. Some have used synthetic brake fluid for vehicles that get limited use.     

[Chryco Psycho]

Dot 3-4 will absorb moisture so it is a good idea to change it occaisionally

[GoodysGotaCuda]

Yes it should be changed, primarily in most and performance or heavy haul application where boiling point really matters.

Keeping water out helps with corrosion as well. That said, a very very small amount of people ever change their brake fluid.


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[headejm]

I've never changed brake fluid in 40+ years of working on cars. Not saying it's a bad idea, just saying I've never done it. I use Dot5 now and won't have to worry about changing it because over time it will all leak out anyway. 

Reminds me about the old HD joke...when do you know when to change the oil in a HD? When it stops leaking!

[JH27N0B]

There are inexpensive test strips you can buy to analyze the condition of your brake fluid.
https://www.napaonline.com/en/p/BK_7002559?cid=paidsearch_shopping_dcoe_google&gclid=EAIaIQobChMIpbPc7dSJ6QIVQv_jBx2i_ggzEAQYAiABEgLq2fD_BwE
I'd changed the master cylinder on my convertible a couple times over the 2 decades I've owned it, so figured the brake fluid was pretty well refreshed by the quantity of fresh fluid in the master cylinder each time I changed it.
When I had a shop work on its engine a few years ago, he asked me if I wanted him to change the brake line that runs across the firewall while the engine was out, since the line had overspray from when the previous owner painted the car.  I agreed to that work.  Later he told me the brake fluid was pretty ugly when he bled the system.  The calipers especially were full of sludge.
With the high price of Mopar brake parts and cheap cost of brake fluid, it's something you shouldn't ignore!
On the other hand, dealers are big on selling brake fluid flushes when your late model ride is in for service, confirm your fluid is truly bad before paying them $150 for that as it's a money maker up charge they peddle aggressively.

[dodj]

Is there a procedure to replace fluid? Like do you just open bleeders one at a time and keep adding fluid till you figure all the old stuff is out?

[GoodysGotaCuda]

Is there a procedure to replace fluid? Like do you just open bleeders one at a time and keep adding fluid till you figure all the old stuff is out?

Suck out what's in the reservoir and open all the bleeders to gravity bleed it through and keep topping off the reservoir.

You can do one bleeder at a time, if you want.


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[JH27N0B]

I think to do the job correctly you'd need a vacuum bleeder to really get all the old fluid out, but you could do a decent job gravity bleeding or having someone push the brake pedal while you open and close the bleeder screws until you get a lot of fluid out.
My concern is getting the calipers cleaned out, because as a low point in the system, that seems to be where the most debris and contamination end up.  In fact, when I worked at a brake parts company, I learned that when you do pad replacement on a caliper, you should clamp the brake hose and open the bleeder when retracting the piston back into the calipers, otherwise you push contaminated brake fluid from the calipers back up into the system, which can damage other parts including expensive ABS components.  We sold a tool for clamping hoses that looked a little like a crab claw/nutcracker with a tabbed screw band for this, which I talked one of the product managers into giving me one.
You could use a vise grips and a rag wrapped around the hose to clamp it if you are careful.

[JH27N0B]

Here's a video on clamping brake hoses.  He says not to use vise grips, oh well.
https://www.youtube.com/watch?v=YAgJpKyAR1Y
I'm going a little off topic here, no need to clamp hoses when changing brake fluid, but I thought this was something to pass along.

[screamindriver]

I run DOT 5 in the Cuda.. I bleed the system every other year... DOT 5 is purple and supposedly won't absorb water, but there is a noticeable difference in the color of the fluid that initially comes out the calipers/wheel cylinders...For the most part the master cylinder and lines stay fresh, it's just the "working areas" of the system that I see the difference... I simply have someone press the brakes and work from the rear to the front for the bleeding process..

[Cudakiller70]

I flush them using a pressure bleeder.
https://www.summitracing.com/search/brand/motive-products/product-line/motive-products-power-bleeder-kits/part-type/brake-bleeder-kits?fr=part-type&autoview=SKU&ibanner=SREPD5

[JS29]

When i do a break job, I crack the bleeder, install my piston compressor, open bleeder, and push the piston in. that pushes fluid out and i tighten the bleeder.