Green brake fluid

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Bled my brakes today and the fluid that came from the rear drums had a light green tinge to it. Any idea what would make brake fluid have a light green tinge?
 
That's the color when brake fluid gets dirty. Brake fluid gets dirtied from corrosion and seal wear. There is some copper corrosion present in brake fluid, but I don't believe that's the main reason for the color in the brake fluid.

As a kid, I used to sometimes mix black and yellow paints to end up with green. I suspect the same holds true for black contaminant in yellow brake fluid. There have been many posts about used fluid looking "green". I know my nasty fluid looks green when it comes out.
 
I think the green is from copper. The hard brake lines probably have a copper alloy layer and the brake hose fittings probably are also made of a copper alloy.

In every car I've had, the brake fluid is green when I flush it out. Some cars seem to make fluid go green faster than others. It would take only months in my mid-90s GMs, whereas the 2002 Honda and 2005 GM in the household only have a hint of green after two years.
 
Does this mean I have left it in too long that it is attacking the copper lines? It's only been 1.5 years since my last flush.
 
I too have never seen green brake fluid and I've bled many cars (and bikes) foreign and domestic.
 
Supposedly there are test strips to check for copper in the brake fluid as it is a good indicator of when the fluid has failed. There was a paper on that.
 
When I flushed the brake fluid in my 1999 Trans Am (flushed in 2005 - 6 years of use) the fluid was a dark nasty green color. My mother's 2004 Lincoln town car was the same way after 6 years of use on factory fluid. The brake fluid in my 2008 Mustang was very dark with a green tint to it as well. That fluid was only 2.5 years of use.

When a fluid get dark anywhere from green to black, it means a change it overdue.
 
My '94 T-Bird had green brake fluid prior to its first flush, as did my '97 Mark VIII. Braking performance improved dramatically when they were changed over to fresh fluid.

My fiancee's '06 Liberty had brown/black fluid prior to its first flush. Braking performance improved after the flush, but not as dramatically as the above Fords with green fluid.

I just flushed the brake/clutch reservoir on my '03 SVT Focus today, and that fluid was also brown/black. This wasn't a total system bleed so I didn't expect, or experience, any change in peformance of the clutch or brakes.
 
When I flushed my brake fluid last fall it was mostly black, but there was definitely a green tint to it. This was after 4 years and about 40K miles in a Chevy Cobalt.
 
I think there is some special blend of brake fluid that is green because I have never seen or heard of it happening. Old brake fluid turns dark brown has been my experience. I have some in an Excursion that I just bought and it is a green but not contaminated looking. It looks clear and clean other than the green color. Now someone may have put in a moisture indicator in their fluid to tell if there is water in it. When it turns a certain color is needs replacing. Maybe green is the color when it is still good or vice versa. I know that DOT 5 is purple. DOT 5 is good stuff but expensive and hard to come by. I flushed my Eclipse in 90 with DOT5 when I bought it and have had NO hydraulic corrosion problems. If DOT5 were not so expensive I would put it in everything I own.

Perry
 
DOT 5 fluid is Silicone fluid and is much too compressible for use on a daily driven car. it is intended for classic cars because it doesn't absorb moisture (therefore won't corrode the brake system). Be careful what kind of driving you do in that eclipse of yours, from what I hear, you may smash your foot all the way to the floor when pushing 11/10.
 
Actually, you WANT a water absorbing brake fluid, so less ultimate damage will occur. Do you want water pooling anywhere, or held in suspension?
 
I have run DOT5 with no issues and great improvement in boiling point for motorcycle applications. The Eclipse has great brakes and it sees 100+ MPH often. DOT 5 does not absorb water or attract water so no water gets in the system to get trapped. It does not mix with regular brake fluid. The military uses if for the same reason. It won't rot your brake system if it sits for a long time like amory vehicles tend to do. It is hard to get all the old brake fluid out of a system when putting in DOT 5 but once it is in there old fluid won't absorb anymore water. Stardard brake fluid absorbs water like mad until if becomes saturated and the water drops out of solution and forms a corrosive crud. Ethanol in gas has the same problems.

I don't know how it would effect modern ABS systems but with older systems there are NO down sides. Think of DOT 5 as Synthetic motor oil and DOT 3 as non-detergent motor oil. Brake fluid is a hold back from the 1930's. If we are using the same coolant technology we would be using alcohol in the radiator.

Perry
 
DOT 5 fluid is much more compressible than DOT 3-4. It can actually give a 'spongy' pedal or lever feel.
It will take really high heat better, however.

Historically, the military makes questionable decisions in all sorts of areas. They are not my source for info.
 
Many of the service manuals say not to change brake fluid unless the system is opened up. Honestly, I beg to differ.

Flushing all the old fluid out of a 2003 pontiac sunfire was a huge part of making it stop better.

Even more so than replacing the rear shoes..

I pay my mechanic 45 dollars, and he does it with a pressure bleeder.
 
Change conventional brake fluid often. It WILL pickup water and eventually corrode metal parts if it is in there long enough.

Perry
 
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