Brake fluid getting black FAST?

[NewC6]

The newest corvettes, the 2005's and newer, are seeing a phenomena that is new to us. That is, the fluids in both the brake systems AND/OR the clutch systems getting black very quickly. In my case, the brake fluid was black within 6 months of buying the car and the clutch fluid with one month of buying the car. There is considerable talk on the corvette forums as to why this is occurring and is it okay or not.
My take on this is that there is something in the system leaching out into the system. My guess is release agents used on the seals in the system.
So, other folks with GM products, not necessarily corvettes, are seeing this with your newer vehicles? My 2005 Murano is not having this symptom as an example of a car where this is not an issue.

 

[XS650]

I have a 2006 C6 and at 28k miles the brake fluid still looked good. I just had the dealer change the fluid last week. The service manager tried to talk me out of it because it still looked good and wasn't a scheduled maintenance. I like that guy. I know some other C6 owners without brake fluid problem too. I don't doubt what you have experienced, but it's not universal.

OTOH, AFAIK the black clutch fluid problem is universal. If you turkey baster empty the clutch MC each time you drive the car for about 10 times, people tell me the fluid usually cleans up. I'm in process on that. After that I have heard that changing the reservoir fluid every 3k miles keeps it nice. The reason people don't bleed the clutch is that there is a lot of dis-assembly required to get to the slave cylinder.

 

[stuntboy79]

I am surprised that domestic vehicles do not have brake fluid change intervals especially a sports car like the corvette. I have been working on european vehicle's for the past 11 years and the fluid is to be changed every two years as per the manufacture.

 

[sciphi]

The brake fluid on my Buick that was changed in December 2009 is dark but not black.

My old Hyundai used to blacken the brake fluid used in the clutch master cylinder very quickly after bleeding. All the Hyundai boards wrote it off as a quirk of the cars. Nothing seemed to fix it.

 

[stockrex]

dark == water?
or dark == to high temps?

why not perform a moisture analysis of the brake fluid to track if it is being subject to moisture

 

[HTSS_TR]

Originally Posted By: stuntboy79
I am surprised that domestic vehicles do not have brake fluid change intervals especially a sports car like the corvette. I have been working on European vehicle's for the past 11 years and the fluid is to be changed every two years as per the manufacture.

I agree, why big 3 ignore changing brake fluid is irritated me.

Brake fluid change interval as recommended by foreign manufactures/cars (the one I have manuals):
1994 Lexus LS400: every 3 years or 30k miles
2000 MB E430: every 2 years
2004 Honda S2000: every 3 years

The brake fluid in '94 LS400 is getting dark pretty quick, probably because the brake system is OEM (except pads and rotors) and after 17 years 260k miles the rubber seals are shedding like crazy.

The brake fluid in E430 and S2000 is staying clear after 1 year and only getting dark on year 2 and 3.

Since I have Mityvac to do oil change for E430, flushing brake fluid of any of my cars is a piece of cake, the heavy work (and time consuming) is remove/reinstall the wheels.

 

[NewC6]

Originally Posted By: XS650
I have a 2006 C6 and at 28k miles the brake fluid still looked good. I just had the dealer change the fluid last week. The service manager tried to talk me out of it because it still looked good and wasn't a scheduled maintenance. I like that guy. I know some other C6 owners without brake fluid problem too. I don't doubt what you have experienced, but it's not universal.

OTOH, AFAIK the black clutch fluid problem is universal. If you turkey baster empty the clutch MC each time you drive the car for about 10 times, people tell me the fluid usually cleans up. I'm in process on that. After that I have heard that changing the reservoir fluid every 3k miles keeps it nice. The reason people don't bleed the clutch is that there is a lot of dis-assembly required to get to the slave cylinder.


Yep, doing the turkey baster thing on the clutch and it seems to be getting better over the long run. The brake fluid darkening suprised me though, wasn't expecting that. I do have to admit that after changing the brake fluid, it seems to be staying clean longer. That's one of the pieces of evidence that tells me it is coming from the system.

 

[NewC6]

Originally Posted By: sciphi
The brake fluid on my Buick that was changed in December 2009 is dark but not black.

My old Hyundai used to blacken the brake fluid used in the clutch master cylinder very quickly after bleeding. All the Hyundai boards wrote it off as a quirk of the cars. Nothing seemed to fix it.


So the GM Buick is having the issue. Good to hear actually, means my theory may actually hold water. The Hyundai is the first I have heard of another brand having the same issues. Thank you.

 

[mechtech2]

Black brake/clutch fluid has been WAY overheated, or particulate matter from seal material.
There is not much else in there to go wrong.

 

[sciphi]

The hydraulic clutch on my old Hyundai was actuated entirely outside the transmission. Not a lot of heat on it. Everybody guessed it was degrading the rubber line, yet nobody's line broke from degradation. Not after 10-15 years for the 1996 Elantras...

My Buick's rubber brake lines are original. Most folks on the GM H-body boards are running the original rubber lines, even with replacing rusty steel lines. The lines separating internally isn't unheard of, either. That's more common with the cars in their teen years age-wise, although it's happened to newer (lol) cars too.

 

[dailydriver]

Originally Posted By: XS650
I have a 2006 C6 and at 28k miles the brake fluid still looked good. I just had the dealer change the fluid last week. The service manager tried to talk me out of it because it still looked good and wasn't a scheduled maintenance. I like that guy. I know some other C6 owners without brake fluid problem too. I don't doubt what you have experienced, but it's not universal.

OTOH, AFAIK the black clutch fluid problem is universal. If you turkey baster empty the clutch MC each time you drive the car for about 10 times, people tell me the fluid usually cleans up. I'm in process on that. After that I have heard that changing the reservoir fluid every 3k miles keeps it nice. The reason people don't bleed the clutch is that there is a lot of dis-assembly required to get to the slave cylinder.


Yes, I believe it is called the "Ranger method", for Corvette Forums member Ranger (one of the first to put a C6 Z06 in the 10s PURE stock).
The only reason I do not like this method is that one must pump the pedal (and therefore put unnecessary wear/strain on the stock master cylinder) sooooo many times for it to work properly and bring the old fluid up from the slave cylinder.
Now if I had a metal alloy, super heavy duty racing master cylinder like a Tilton, or the Tick Performance models, it might not matter.

I also use VERY expensive brake fluid for my clutch and brakes (Motul RBF 600), and prefer to not waste this stuff at ~$20.00 a half liter!

This is why during my last clutch change, I installed a remote stainless steel line with a one person speed bleeder on the end to the slave cylinder bleeder tube inside the bell housing.

Life is simple now.

 

[dparm]

Originally Posted By: mechtech2
Black brake/clutch fluid has been WAY overheated, or particulate matter from seal material.
There is not much else in there to go wrong.



This.

 

[NewC6]

Originally Posted By: dailydriver
Originally Posted By: XS650
I have a 2006 C6 and at 28k miles the brake fluid still looked good. I just had the dealer change the fluid last week. The service manager tried to talk me out of it because it still looked good and wasn't a scheduled maintenance. I like that guy. I know some other C6 owners without brake fluid problem too. I don't doubt what you have experienced, but it's not universal.

OTOH, AFAIK the black clutch fluid problem is universal. If you turkey baster empty the clutch MC each time you drive the car for about 10 times, people tell me the fluid usually cleans up. I'm in process on that. After that I have heard that changing the reservoir fluid every 3k miles keeps it nice. The reason people don't bleed the clutch is that there is a lot of dis-assembly required to get to the slave cylinder.


Yes, I believe it is called the "Ranger method", for Corvette Forums member Ranger (one of the first to put a C6 Z06 in the 10s PURE stock).
The only reason I do not like this method is that one must pump the pedal (and therefore put unnecessary wear/strain on the stock master cylinder) sooooo many times for it to work properly and bring the old fluid up from the slave cylinder.
Now if I had a metal alloy, super heavy duty racing master cylinder like a Tilton, or the Tick Performance models, it might not matter.

I also use VERY expensive brake fluid for my clutch and brakes (Motul RBF 600), and prefer to not waste this stuff at ~$20.00 a half liter!

This is why during my last clutch change, I installed a remote stainless steel line with a one person speed bleeder on the end to the slave cylinder bleeder tube inside the bell housing.

Life is simple now.

Good to see someone else has heard of the Ranger method. You must also be aware of the data he generated concerning clutch dust in the fluid. While I think he did honest analysis, my gut says something else is going on and though the clutch fluid DOES get very hot, I am not sure clutch dust is the entire answer. I would do the mod you talked about but my goal is to keep my Z06 pure stock looking forward to the day I may sell it.

Thanks for the input.

 

[NewC6]

Originally Posted By: dparm
Originally Posted By: mechtech2
Black brake/clutch fluid has been WAY overheated, or particulate matter from seal material.
There is not much else in there to go wrong.



This.

I think you are correct.