GT500 dirty brake fluid

[XP900]

I upgraded my GT500 with the Ford Performance upgrade kit ( 6 pistons front, and rear bracket angle changes) so I basically put all new calipers and stainless steel lines on my car. This was exactly two years ago and and I flushed the entire system and used Motul 5.1. At that time I noticed the brake reservoir wasn't as clean as I would like to I did my best to clean it without removing it.
My brakes have been working great for the last two years, great stopping power and pedal firm and no play. I use my engine to do most of my braking.

I checked the fluid and it is very dirty.. The reservoir is coated with a blackish tint and the fluid has a black mixture in it....as if something like a hose was disintegrating. I have completed pulled the master cylinder and replaced the reservoir. I also replaced the clutch cable with a stainless steel one and I am replacing the clutch supply hose with a BMW piece of hose. I also have the kit to separate the clutch and brakes system reservoirs. I plan on using the new Bosch 5.1 brake fluid this time.

Anyone ever run into this and know what is causing the black discoloration to mix with the brake fluid? I know my brakes have never been overheated in this car. The only thing I can think of is that the Motul 5.1 caused the plastic clutch line or supply hose to start to disintegrate but I am guessing. Separating the systems and flushing both systems will help pinpoint where the issue is if it happens again.

 

[Black Cobra '99]

There is a thread on this issue on TMO forums. The short answer is the dirt comes from the clutch because it shares the reservoir with the brakes.
People who installed a reservoir for the clutch noted that the brake fluid stayed clean and the clutch fluid got dirty with the same stuff you're describing.

 

[XP900]

There is a thread on this issue on TMO forums. The short answer is the dirt comes from the clutch because it shares the reservoir with the brakes.
People who installed a reservoir for the clutch noted that the brake fluid stayed clean and the clutch fluid got dirty with the same stuff you're describing.

Thanks! I was hoping that was the issue. I am in the process of separating the systems now. BAD design by Ford. They saved a few bucks but screwed the owners.

 

[Race Red Boss]

I wonder how many have ruined their brake master cylinder or any other brake part (caliper pistons?) as a result? Guess the message to GT500 owners is make sure you flush your brake fluid more frequently.

 

[Robert M]

If dirt (clutch dust) was coming from the clutch/bell housing area, which has been mentioned on the forum in the past, there would be a leak in the system that is allowing clutch dust to get into the clutch hydraulic system and that would require the clutch disc dust pressure (bell housing area) to be fully sealed and greater than the clutch hydraulic system pressure, neither of which is is the case. Some have also mentioned clutch heat.......If it was that hot, the oem plastic clutch line would be melted, again, not the case.......

The reason why the clutch hydraulic system gets brown/black is because of rust, rust from the shared brake system. DOT 3 fluid attracts moisture and that moisture rusts the inside of that brake lines in the brake system........The WORST thing to do during a brake pad change is to depress the pistons back into the caliper (which is common) for a pad change, before fully flushing the system (which is not common) and push all of the rusty fluid back into the M/C reservoir. Once that nasty/contaminated brake fluid is in the M/C reservoir, it settles to the bottom and guess where it goes??......to the rear nipple that feeds the clutch M/C and down to the lowest point......the TOB and everything above in that system. The rust contamination is heavier than the fluid, every time the clutch pedal is pushed it sucks fluid into the system and gravity works, the heavier contaminants make their way to the lowest point.....

If an owner fully flushes the brake system and clutch system and keeps clean fluid in the brake system from that point forward through regular maint. with full flushes of the brake system, that will minimize the contamination of the clutch system in the future.

Below is the brake fluid for my 2008 at 600 original miles when I upgraded to Baer Extreme 6S rears. The fluid was already (at very low miles) beginning to look like tea (instead of pee)....

The rust was already starting at 600 original miles, and that brown/black rust settles in the lowest part of the system.......the clutch system......

^^^^^This is a car that has never been out in the rain (humid conditions) and has been stored in a A/C garage all of it's life. If you drive a car in humid conditions, the amount of moisture absorbed into the brake fluid is even greater. As the brake pads get thinner (through use), the amount of humid air is greater in the M/C and the moisture absorbs into the system causing more rust. The wisest thing to do is keep that contaminated fluid out of the system through full flushing.....

I would have to look back at the fluid I used in my brake system, I believe it was DOT 5.1.......but in reality, that is still a moisture absorbing petroleum based fluid that attracts moisture, the only benefit of the 5.1 is temperature, it is higher than DOT3 and DOT4. The best fluid would be DOT5 Silicone fluid that is not petroleum based and does not absorb moisture.......BUT, it is not recommended for ABS systems, so that is not an option.......

R

 

[Robert M]

It is not a complete clutch system flush, but there is a bleeder available from McLeod that attaches at the bell housing and enables a flush from the brake M/C reservoir, through the clutch M/C to the bell housing

^^^I believe through some creative clutch pedal and bleeder opening that the TOB could also be "somewhat" flushed.....

R

 

[Robert M]

double post

 

[me32]

Great explanation @Robert M .

 

[Black Cobra '99]

I don't think the rust explanation is valid.
The braking system has all stainless steel or aluminum components so where is the rust coming from?
Rust is still metal, and it will flake. The dirt described does no resemble rust at all.
Finally, this dirt accumulates fast and people have observed that. Where is rust needs longer time to form and flake. Moreover, rust will probably get stuck somewhere before it reaches the reservoir.

 

[Robert M]

I don't think the rust explanation is valid.
The braking system has all stainless steel or aluminum components so where is the rust coming from?
Rust is still metal, and it will flake. The dirt described does no resemble rust at all.
Finally, this dirt accumulates fast and people have observed that. Where is rust needs longer time to form and flake. Moreover, rust will probably get stuck somewhere before it reaches the reservoir.

If you look at the sample I showed in the water bottle, there is no "flake" in that second picture, it is tiny micro particles and a "sludge", it is fine particles and sludge, it moves freely where ever the brake fluid flows. Unlike metal that is out in the open air and does "flake", the sealed brake system is not that environment.

How would "dirt" get into the system, especially that much over time and especially in my case at 600 original miles and all the way back at the rear calipers with no leaks in the system? One explanation could be that the dirt comes in through the M/C cap vent.......but that would have to be a very dirty environment under the hood for all of that dirt to get into that tiny vent and into the system..

There are several "qualities" of stainless, 304, 316, etc., it all depends upon the quantity of rustable and non-rustable material in the stainless.......The lesser quality stainless may not rust with a "splash and dry" of water, but it will deteriorate with a constant exposure to moisture. <<<<Also to mention, this is a slow rust with fine particles, not a flaky rust like cheaper non-stainless metal. The higher the quality of stainless, the higher the cost, I can guarantee you that Ford (or any other normal auto maker) does not use the top quality stainless on the brake system of the vehicles they build, it would be too costly.

R

 

[Robert M]

I found this on the internet.....

"Exposure to corrosive process fluids and cleaners, high humidity or high salinity environments such as sea water can remove the native protective layer (chromium oxide) and can cause stainless steel corrosion. Removing surface rust from surfaces improves the appearance, but it's importance goes beyond the decorative."

Brake fluid has been rusting out brake systems for years because it absorbs moisture from the air, the difference now is the manufacturers do use a certain quality of stainless to lessen the rust issue, but the regular system maint. intervals are required to keep the system clean.

NOTE - To be honest, from what I read above, it may not be "rust", but instead an "oxidation or corrosion" of the stainless that causes the discoloration and the dark sludge shown in my second picture. That "gathering" of dark particles would not even be noticed when flushing a system, only the dark fluid would be noticed. The only reason mine showed the way it did is because I captured it in a bottle and let it settle.

R

 

[kazman]

Brake fluid changes from almost clear to dark as moisture is absorbed, the darker the fluid the more moisture content it contains.

 

[Robert M]

Brake fluid changes from almost clear to dark as moisture is absorbed, the darker the fluid the more moisture content it contains.

^^^^Yes, I call it Pee, to Tea, to Root Beer to Coffee. That is the progression.....and that is "moisture" exposed to the inner walls of the stainless brake lines......

.......and here is another internet copy and paste......

Brake Fluid is Corrosive
Brake fluid is a very corrosive substance. Even if you are topping off the vehicles reservoirs, you may spill some brake fluid onto your engine or surrounding area.

^^^So add that into the mix with the moisture exposure in the closed brake system....

Another good question......Does brake fluid turn acidic (change in ph) over time, like coolant does?

R

 

[kazman]

I don't mean to be contradictory, however, brake fluid left in an unsealed plastic container will turn dark rather quickly, especially in the east Florida humidity. No metal necessary.

I believe it's designed to do so as a telltale.

 

[Robert M]

I don't mean to be contradictory, however, brake fluid left in an unsealed plastic container will turn dark rather quickly, especially in the east Florida humidity. No metal necessary.

I believe it's designed to do so as a telltale.

I don't doubt that the fluid turns dark in the container with moisture in the air, it is the particles, contamination and sediments that concern me and their affects on sealing surfaces in the brake system......It seems that as the color gets darker, there is more particle contamination.

The brake system does not care what color the brake fluid is, but it does not work well with particles in the fluid, not to mention the brake fluid temperature degrade with moisture in the system, but that is a different discussion.

R

 

[Robert M]

I don't mean to be contradictory, however, brake fluid left in an unsealed plastic container will turn dark rather quickly, especially in the east Florida humidity. No metal necessary.

I believe it's designed to do so as a telltale.

I just happen to have a DOT4 plastic brake fluid bottle that is 3/4 empty and has been exposed to humid West Central Florida environment. I had not looked at the brake fluid in this bottle since it was new and looked like pee, yes it has discolored to a light tea color over the 5 year of being in the plastic bottle that was 3/4 full of Florida air.................but the dark fluid color we are discussing is way beyond the affect that I see in this 1/4 full plastic bottle. <<<Brake fluid color as shown below would be well within what most people feel is acceptable, as color goes......

^^^Also notice......No sediment in the bottom.......

R

 

[HKusp]

Robert rust is oxidation just for clarity sake. I know you are trying to differentiate between flakey metal rust and small particulate, but rust is oxidation.

 

[Robert M]

Robert rust is oxidation just for clarity sake. I know you are trying to differentiate between flakey metal rust and small particulate, but rust is oxidation.

True and you are right about my differentiating...Not all rust is flaky. Many times I will equate rust to steel and oxidation to aluminum. <<Not that it is correct, but that is how I think of it usually.

That water bottle I showed above laid on its side for a few months and that is why the sediment (in my 600 original mile brake fluid) is on the side of the bottle. It actually looked like a dark brown liquid with particles of rust or contaminates in it.

R

 

[XP900]

Separated the clutch and brake systems. Pressure bled the brakes with a quart and a half and fluid appeared clean the whole bleed time. I replaced the reservoir and cleaned the MC before the bleed. Brakes are clean...but I already see slight discoloration in the new clutch system fluid. At least I know my brakes are separated now and every 6 months I can flush the clutch fluid in the separate reservoir now. Thanks

 

[Robert M]

Separated the clutch and brake systems. Pressure bled the brakes with a quart and a half and fluid appeared clean the whole bleed time. I replaced the reservoir and cleaned the MC before the bleed. Brakes are clean...but I already see slight discoloration in the new clutch system fluid. At least I know my brakes are separated now and every 6 months I can flush the clutch fluid in the separate reservoir now. Thanks

Did you also get the old fluid out of the clutch system (at least down to the bellhousing/TOB line) before the separate clutch reservoir was installed with the new fluid?

If not, the old fluid in the system will discolor/contaminate the new fluid in the new separate clutch reservoir and that is why the discoloration in that side is quicker than the fully flushed brake side.

R