Brake fluid-- DOT 3 ???

[Max Hubrich]

Here are some pictures I took today as I prepare for my upcoming sojourn.

I changed the brake fluid in my rig exactly 10 months ago (Nov 9th) and have a total of 1268 miles since the change. I have been sitting in Maine since May 12th and have not driven in any weather that has been hot, or even warm. In fact I was running the heater enroute to Maine. The winter was spent at home in eastern NC.

Here is the Picture--- I'll explain----- And a question at the end.



Left to right--

-- DOT 3 fluid - 3 qts needed.

-- Fresh fluid from the DOT 3 container. It's in a cut off water bottle.

-- Next two water botthes are holding the fluid removed from the master cylinder reservoir. It actually held 3 of these bottles, full.

-- The large plastic jug holds the fluid removed from the calipers. I pumped each wheel 6 times, starting with the RR, LR, RF and LF.

The removed fluid looks terrible!

What's going on with this stuff and how often do we need to change it ??

PS: I also showed the tools I needed to do the job. The combination wrench is 10mm- I used the box end only. The clear plastic hose is 3/8" OD X 1/4" ID, about 30" long. I drilled a hole in the bottle to hold the tubing firmly as I maneuvered around underneath the coach to prevent spills. The funnel was used, of course, to refill the MC reservoir. The turkey baster was used to evacuate the MC reservoir.

[DriVer]

Forensics is everything!

Thanks for taking the time to document your fluid change.

[oemtech]

Max,

Although the fluid looks bad it may not be as bad as you think. But, unless you have some way to test it you really don't know. The best way would be to send it someone like Blackstone Labs. I check mine with some test strips.



Speaking of test strips... At the Texas Boomer's Labor Day rally in Burleson, TX I installed a set of Speed Bleeders and did flush/bleed for Jerry Curtis (JC2). I tested his 3 year old fluid and it tested bad. The test scale is 0, 10, 30 100, 200 & 300. Jerry's tested at 200.

0-100 = Test are regular intervals
100-200 = Test at oil change interval
200-300 = Replace

Now, you know why I change every year... Cheap insurance.

[JC2]

And this is what it looked like.

[mrschwarz]

What do the test strips test for? How do they work?

The color of brake fluid is irrelevant. It's the boiling point that counts. While DOT 4 brake fluid's dry boiling point is only marginally higher than DOT 3, its ability to absorb moisture with less effect on its boiling point is much better. I would think that with the amount of time that a motor home sits, this would be something that would be worth the extra expense.

[oemtech]

Quote:

Originally Posted by mrschwarz What do the test strips test for? How do they work? The color of brake fluid is irrelevant. It's the boiling point that counts. While DOT 4 brake fluid's dry boiling point is only marginally higher than DOT 3, its ability to absorb moisture with less effect on its boiling point is much better. I would think that with the amount of time that a motor home sits, this would be something that would be worth the extra expense.

The test strips check the cooper content instead of the moisture. Read about it Here. You may also what to check the Resources Tab for more info.

[mrschwarz]

I looked at the web site that was recommended. It speaks at great length about dissolved copper and rust inhibitors, but does not speak about brake performance, other than copper deposits and ABS. It doesn't address vapor lock, moisture absorption of brake fluid, and decreased brake performance due to lower boiling point.

I tried to find an objective 3rd party evaluation of the Brakestrip product and couldn't find one, other than the testimonials from repair shops about how many brake flushes they were selling because of the product. I also couldn't find the research that they cited on their web page.

They did claim that an industry trade and lobbying group (MAP) was a standards setting organization, but I have always thought of SAE (Society of Automotive Engineers) or a group like that set the standards, not an association of repair shops.

One place on the web site spoke about 'pockets of moisture' in the fluid. It also referred to fluid as hygroscopic, which means it attracts and absorbs moisture. I don't think you can have one with the other. If it absorbs moisture, would it absorb the 'pockets of moisture'?

I can't speak for the science of dissolved copper in brake fluid, but if the main concern is the ability of the brake system to stop the coach, a conversation that doesn't include the boiling point of brake fluid, which has a direct relationship with brake system performance, is incomplete, in my opinion.

For myself, without any 3rd party verification and no correlation drawn between boiling point and dissolved copper, I would assume that this is more of a sales tool than anything else, though I could be wrong.

I would more likely follow the manufacturer's recommendations (Volvo recommends that brake fluid be flushed every two years, for example).

[Max Hubrich]

Oemy--


I guess i'm looking at the copper effect in my brake fluid.

Where do you take your sample for the strip test? I guess directly from one of the calipers-- not the MC reservoir. My samples show the dramatic difference between the caliper fluid and the master cylinder fluid which has not yet been exposed, in any appreciable amount, to the metal piping of the brake system.

[DAN L]

Quote:

Originally Posted by oemtech The test strips check the cooper content instead of the moisture. Read about it Here. You may also what to check the Resources Tab for more info.

oemy,
thanks for the post.
very good info that i didn't know about.
i wish the article explored the differences in dot 3.0, 4.0 and 5.1.
it has been my experience that motul dot 5.1 has the least amount of corrosion resistance, but highest boiling point.
castrol 4.0 seems to have the most corrosion resistance but i don't know why.

[oemtech]

mrschwarz,

The test strips are just another tool... If you really want to know the real condition of your brake fluid send a sample to a testing facility like Blackstone labs. Testing tools can run $350 for a hand held version to $9,000+ for automatic tester.

I think part of the reason you don't see any comments from the consumer is they don't use test strips and most never change the brake fluid unless they have brake work done. When was the last time you or anyone else change the fluid in your car or truck?

Here is another source for info AA1Car Library.


Max,
I test both... Master Cylinder and Caliper. But, you have to test the caliper fluid before you get any of the new fluid into the catch bottle.

The bottom line is... Change your brake fluid at least every 2 years. For me I change every year as the cost is low... about $12 to $15 for 3 qts of brake fluid.