Testing brake fluid for copper contamination

[exranger06]

I was looking into buying some test strips to test my brake fluid. The only ones I could find were ones that test copper levels, not moisture. The manufacturer says testing for copper is much more important and is a more reliable indicator of corrosion, and that moisture is basically a non-issue in modern brake systems. The copper contamination comes from the copper coating on the inside of brake lines. When the corrosion inhibitors in the brake fluid wear out, copper starts showing up in the fluid (supposedly).
Quote:

Then there's the mistaken belief, now earning the distinction of “urban legend,” that water is brake fluid's worst enemy and the slightest trace of it demands an immediate system flush or dire things might happen……Now, new technology and standards are finally putting the decades-old moisture myth to rest. Especially since today's Anti-Lock Brake Systems and brake fluids are designed to reduce or eliminate moisture related problems. In fact, GM, Ford and Chrysler have no recommendation for brake fluid service based on moisture because it's not considered a safety threat or service issue.


Quote:
But while car owners can stop being hydrophobic about their brake fluid, a new guideline developed by a consumer protection group called the Motorist Assurance Program (MAP), points the finger at another culprit that over time can cause serious problems with ABS components. Copper. And it's an inside job. Recent government research conducted by the National Highway Traffic Safety Administration confirmed that copper can form deposits around the sealing surfaces of ABS valves, which means your car may take longer to stop in a panic situation. Other research finds that copper levels in the brake fluid are the best indicators that the fluid's corrosion inhibitors are losing their punch and major corrosion is just around the corner. MAP puts the red-flag level of copper at 200 parts per million. Anything above, they require the fluid be flushed and replaced.


Copper vs water
New brake fluid test puts end to age-old myth

Discuss.

 

[brelandt]

Copper is the only thing we test for at work.

 

[Chris142]

Whoever wrote those articles totally missed the point. Any water in the brake fluid will lower the fluids boiling point. When the brakes get hot such as pulling a boat down a mountain the fluid will boil and the driver will lose his brakes!

 

[exranger06]

Originally Posted By: Chris142
Whoever wrote those articles totally missed the point. Any water in the brake fluid will lower the fluids boiling point. When the brakes get hot such as pulling a boat down a mountain the fluid will boil and the driver will lose his brakes!



According to the article, no significant amount of moisture gets into the brake system in the first place, so you wouldn't have any boiling fluid anyway.

 

[Billbert]

I have personally flushed the brakes on at least 10 trucks (1/2 to 1 ton models) and 2 motorhomes that have lost all braking due to boiling of the fluid. Moisture can still be a problem.

 

[1 FMF]

how does corrosion and copper contamination start in the first place? It just happens ?

 

[Stu_Rock]

Originally Posted By: exranger06
According to the article, no significant amount of moisture gets into the brake system in the first place, so you wouldn't have any boiling fluid anyway.
That's quite a generalisation. There was definitely high water content in my Peugeot's brake fluid when I bought it. That car has a bad reservoir cap design that actually funnels water INTO the reservoir!

The reservoir has the same neck as 1987-1990 GM FWD ABS cars, so I swapped on a GM cap that has a sensible seal/orifice design. With that change, copper contamination is probably more important. The car does have copper brake lines.

 

[mechtech2]

The water in the brake system [which is highly over rated] will boil no matter if it is in puddles or in suspension.

Gm says 7 years is when the brake fluid should be changed. But this is dirt , not water .
Brake systems are sealed.

 

[Kestas]

Originally Posted By: 1 FMF
how does corrosion and copper contamination start in the first place? It just happens ?

Few people know or suspect where the copper comes from -- the brake lines! They look like they're only steel, but they are actually made from a spiral-wound strip of steel (like your paper towel roll insert) that is subsequently brazed with copper. It's called "Bundy" tubing.

It doesn't take much for dissimilar metals to electrolytically plate out the copper in the brake fluid solution. This plating can wreak havoc with sensitive ABS units.

 

[yonyon]

On the up side, this can make for a fun weekend project:

Make up new steel brake lines for your car from seamless tubing. Once they've all been test fitted into place and adjusted just so, take them out, cap the ends, then paint them. Put them all back in and fill/bleed the system. Use a fluid with a good high boiling point so you won't have to worry about water for a few years. With seamless tubing you won't be seeing copper. Once all the air is bled out be sure to clean and leak check each connection and bleed valve.

 

[Kestas]

Seamless tubing doesn't have the burst strength that bundy tubing does. Without going into details of the metallurgy, seamless tubing is not safe for brake line application, which can see up to 3000 psi during panic stops.

 

[TooManyWheels]

Originally Posted By: yonyon
On the up side, this can make for a fun weekend project:

Make up new steel brake lines for your car from seamless tubing. Once they've all been test fitted into place and adjusted just so, take them out, cap the ends, then paint them. Put them all back in and fill/bleed the system. Use a fluid with a good high boiling point so you won't have to worry about water for a few years. With seamless tubing you won't be seeing copper. Once all the air is bled out be sure to clean and leak check each connection and bleed valve.


OK, I have to ask - What is a less-than-fun project in your world?

 

[mechtech2]

I don't know how all brake lines are made.
Certainly most aftermarket ones are not brass/copper coated or show evidence of spiral construction - you can see the seam.
I have not seen this on factory ones, either.

 

[Kestas]

That's because they're terne coated. Any seam you see is likely marks from drawing during final sizing of the product.

 

[Ken2]

Quote:
Bundy tube, sometimes called Bundy pipe, is type of double-walled low-carbon steel tube manufactured by rolling a copper-coated steel strip through 720 degrees and resistance brazing the overlapped seam in a process called Bundywelding. It may be zinc- or terne- coated for corrosion protection. It is used in automotive hydraulic brake lines in cars manufactured in the USA since the 1930s.

A 1969 study by the SAE recommended the replacement of Bundy tube with 90-10 copper-nickel alloy UNS C70600 (Kunifer pipe) because of corrosion concerns.[1] Kunifer pipe has since been adopted by European automakers Volvo, Rolls-Royce, Lotus Cars, Aston-Martin, Porsche, and Audi.[2] Bundy pipe retains the advantage higher rigidity, which means less volume expansion under pressure.

The Bundy Tubing Company, started in the USA, was bought in the 1980s by what is now the British company TI Automotive.
http://en.wikipedia.org/wiki/Bundy_tube

Seamless steel hydraulic tubing with working strength over 3000 psi:
http://www.hydraulic-supply.com/html/productline/prodcat/hydraulic-tubing.htm

It looks like the benefit of seamed bundy tubing is the copper coating, not the strength.

In any case, what's the point? Change the fluid regularly to prevent tubing corrosion or moisture in the fluid or any other good reason.

 

[bigdawg74]

Change your brake fluid every three years and contamination from either water or copper becomes a moot point.

 

[Kestas]

Originally Posted By: Ken2
It looks like the benefit of seamed bundy tubing is the copper coating, not the strength.

You're missing the point. The copper is there to braze the spiral wrapped steel together. And it doesn't have a traditional seam, nor does the copper coat the part.

One of the reasons for spiral wrapping instead of traditional seamless tubing is, if there is any weakness in the material such as an inclusion in the steel, the second layer of steel will keep it from bursting. This is because it's rather impossible to make defect-free steel. Plus any seams or defects in the steel won't be in the longitudinal (weakest) direction of the tube, but at an angle to the longitudinal direction. All this is important for a critical application such as brake lines, where failure of the tubing can result is serious loss of property and life.