Bruce In Philly

I just changed the brake fluid on my friend's '04 C4S Cabriolet...... she purchased the car used many years ago, but never changed the fluid in that time. The car has circa 60K miles on it.

So.....

1. The fluid was green.... was this original fill?
2. The fluid from the front brakes had bubbles and..... black gunk. What was this black gunk? It looked like very very fine black particulates and the color of the fluid was .... well not quite Guinness, it was dark.

"Wow, the brakes feel totally different".

Peace
Bruce in Philly

DC911S

Dirt getting past the dust and fluid seals. I've never seen green brake fluid. If you see bubbles, air must be getting in.....Anytime I do brakes, I always buy two can of BrakeClean and really scrub the pistons and seals with it and a toothbrush to get rid of the gunk that builds up. That gunk and dirt is abrasive and will eat into the seals.

BIG smoke

When I helped change the fluid in my friends 78 corvette, the fluid came out like brown play dough or pasta. It was just rusty. Still don't understand how that car stopped at all.
I'll go with rust.

Spyerx

you should have seen the fluid that came out of my 89's clutch slave cylinder.
Looked like tobacco spit.

BIG smoke

Sorry BiP I have to go on a tangent because of Spyerx

Friend Michelle was getting a few phone calls from he son. "When you coming home mum?"
After 3 or 4 of these calls, she was getting suspicious.
She came home not too late. Went to the back yard. Her 19 year old boy was over one one side with a few of his friends, they were having a few beers.
She then went over to the patio table where her other son was and his 15 year old friends.
She saw a few plastic glasses 1/2 filled. Mom in her huffy and suspectness said, "well I guess this is beer and your under age".... she took a swig.
In my best slow mo voice .... Mom DDD OOO NNN """ TTTT !
She took a swig, to prove her point.
It was not beer. The 15 year old's were experimenting with chewing Tobacco.
Thus the rusty coloured fluid on the table... that was not beer.
She lost her cookies next.


BiP - good on you for helping out your friend. I hope she helped or at least passed you tools. Or cold beers.

Marine Blue

Everything I have read is that brake fluid accumulates moisture (water) over time and this leads to corrosion of the internal components in the brake line. This corrosion becomes sediment in the fluid and the dirtier it is the more moisture was likely present. This is one of the reasons to change fluid every two years. I can believe that dust can also work its way into the system over time which adds to the darker color.

dbv1

Stock fluid gets green, if you wait long enough.

Sydneysixer

My local P dealer flushed my 997.1's brake fluid last year… the replacement fluid was/ is deep green in colour. I don't know the colour of the previous fluid as I had only just bought my car, however, the service records indicate the brake fluid has been flushed every 2 years or so.

Iceter

Brake fluid contaminated with rust is dark, like Guinness. it's not usually reddish--it looks more like dirt than rust. The rust sloughs off the internal parts and settles. Once it's out of the system and in a clear jar, you can see the particles when you shake up the fluid.

Once you get to the point where you're getting a lot of sediment out of a brake system, you'll probably want to re-flush the system once or twice to get as much of it out as you can.

Also, I have found that bleeding the system by using the pedal seems to create more turbulence than a gentle bleeding with a vacuum bleeder or gravity bleeding. Stirring up the gunk allows you to get more of it out of the system when you bleed the brakes. Of course, it also increases the risk of getting sediment in whatever valving your ABS system uses, but it's probably worth it. Most of the sediment is in the calipers, so the risk of gumming up your abs or master cylinder is fairly low, IMO.

3Series

That doesn't sound right to me. Brake fluid is amber/gold. If it's green, I'd make sure the dealer flushes the system until the fluid in the reservoir shows amber/gold.

Bruce In Philly

Wow, check out this:

https://www.gpo.gov/fdsys/pkg/CFR-20...sec571-116.pdf

The gov. eliminated colored fluid "colorless to amber". Of course, I don't know when this law came into effect and if the fluid in my friend's car was just green-colored DOT 4 from before the law.

S5.1.14
Fluid color.
Brake fluid and
hydraulic system mineral oil shall be
of the color indicated:
DOT 3, DOT 4, and DOT 5.1 non-SBBF—color-
less to amber.
DOT 5 SBBF—purple.
Hydraulic system mineral oil—green.

Peace
Bruce in Philly

DC911S

My KTM bikes use mineral oil for the clutch system and DOT 4 or 5.1 for the brakes. Mineral fluid would not work on brakes and it's a weird color. If by chance a mechanic put mineral oil based fluid in brakes then he is not too sharp a mechanic.

3Series

That occurred in 2012 or 2013. ATE Blue Racing fluid was no longer available. Track guys used to alternate between Gold and Blue so you can tell when the fluid has been changed out.

3Series

Yellow and blue make green, but it doesn't make dark green when mixing brake fluid. It's more of a bluis green and very transparent. That's my experience with ATE, Porsche Fluid and SRF brand brake fluids.

Aspen Autosports

I haven't seen a green fluid before. I have seen the fluid get a very slight tint of green after sitting for a long time. The Pentosin CHF202 is greenish but that is a PS fluid not a brake fluid.

The government passed this law about the color being clear or amber a few years ago. About 5 or 6 if I remember correctly. It was mostly due to the ATE Super Blue fluid. I guess they felt someone would put the Super Blue fluid in the windshield washer system or something like that.