Corrosion protection in brake fluid

[MolaKule]

Originally Posted By: Barnaclebob
Is there any way that my fluid could test at such low copper levels ~30ppm after over 4 years in service from the factory? That has me scratching my head.

Since I now have a mixture of mostly DOT3 and a little DOT4 i may just replace it because I can't use a refractometer to determine moisture content anyway.


I am not sure what the infatuation is with copper indicators.

As Gmorg said, brake fluid contains metal ihibitors, which include copper corrosion inhibitors, which ameliate copper corrosion buildup until those inhibitors are used up and no longer effective.

Flush your brake system every two to three years so moisture buildup doesn't reduce boiling point, and new inhibitor additives are refreshed.

Sleep well.

 

[Bill_G]

Originally Posted By: MolaKule
Originally Posted By: Barnaclebob
Is there any way that my fluid could test at such low copper levels ~30ppm after over 4 years in service from the factory? That has me scratching my head.

Since I now have a mixture of mostly DOT3 and a little DOT4 i may just replace it because I can't use a refractometer to determine moisture content anyway.


I am not sure what the infatuation is with copper indicators.

As Gmorg said, brake fluid contains metal ihibitors, which include copper corrosion inhibitors, which ameliate copper corrosion buildup until those inhibitors are used up and no longer effective.

Flush your brake system every two to three years so moisture buildup doesn't reduce boiling point, and new inhibitor additives are refreshed.

Sleep well.


It makes me feel better that someone of the stature of MolaKule concurs with us "blissfully ignorant" types.

 

[The Critic]

Originally Posted By: Lubener
Originally Posted By: HosteenJorje
Just replace brake fluid every two years.


Exactly. Why screw around. One hour and you can bleed the whole system and be done with it.


Not all cars are easy to flush - properly. I've driven a lot of cars that have had their brake fluid flushed by the dealer or an independent garage (usually a tire shop that uphold it), and the brake pedal feels softer than before due to air being left in the system (vacuum bleeders are notorious for this if you don't each corner gravity bleed for a few mins).

The copper test may be on to something, but there seems to be more discussion lately about the water percentage being less important. Most drivers don't experience conditions where the lowered boiling point will really become an issue, so the corrosion inhibitors are of a greater concern.

 

[MolaKule]

Most brake lines are stainless steel are they not?

So what materials from what brake component(s) could possibly be contributing any copper?

The only component I have ever found that contained copper was a custom copper alloy (brass) fitting, and the fitting was not leaking.

 

[SHOZ]

The copper would be coming from the brake lines. Most brake lines are a nickle copper alloy now a days.

 

[dailydriver]

Maybe this is why the producers of the Torque RT700 fluid make such a big deal over their product's supposedly superior "reserve alkalinity" over all of the other premium/boutique racing brake fluids, including the 'king', Castrol's React SRF??

 

[cronk]

Originally Posted By: MolaKule
Most brake lines are stainless steel are they not?

So what materials from what brake component(s) could possibly be contributing any copper?

The only component I have ever found that contained copper was a custom copper alloy (brass) fitting, and the fitting was not leaking.


I wish most brake lines were stainless steel!
Here in the rust belt it is not uncommon to have to re-plumb brake lines on an 8-10 year old car due to rust. Most manufacturers use steel lines, some are plated or coated to prevent corrosion. I've been saying for years I wish all the manufacturers used stainless brake tubing but I'm sure its a cost thing. In this safety conscious world we live in, you'd think it would be mandatory!
When I replace brake lines, I use a product called "Poly-Armour, it is coated in PVF plastic to prevent corrosion. It also is much easier to bend than regular steel line, it is a combination of steel with copper brazed into it.
Stainless tubing would be great, but it is expensive and much more difficult to bend and flare.

 

[Barnaclebob]

I ended up bleeding the brakes today since I have no way of telling how much moisture has been absorbed and I was having trouble believing the copper strip test I did a few weeks ago. The fluid that came out was pretty brown but that may not tell you much. I'll probably just go with the 2 year interval since it was so easy and a bottle of brake fluid is $6.50.

Someone needs to tell Nissan to use the same bleeder fittings front and rear...

 

[Trav]

Originally Posted By: SHOZ
The copper would be coming from the brake lines. Most brake lines are a nickle copper alloy now a days.


Not by a long shot, only a few higher end car use it OE same with stainless.
NiCopp, Cunifer and other nickel copper lines are becoming a favored aftermarket replacement especially in winter salt areas but plain steel and plastic/powder (some Euro) coated steel are by far the most common.