I believe this is a common problem, my '02UL brake fluid with 110k is very dark. It was flushed about 2 years ago and has been turning black since. Dealer suggested another flush but I believe moisture is coming in from somewhere.

It has been suggested that the rubber seals on the rotors need to be replaced. A rebuild kit is available and I have a mechanic willing to do the work. Question is has anyone tried this? Do I need to replace pistons in addition to parts that come with rebuild kit? Any other parts needed or advice? Thanks.

 

That's just debris & contamination from the rubber / iron / aluminum parts of the brake system, the moisture does not make the fluid black. The big problem is MOST dealers from i learned don't bleed/flush the brakes using the Techstream. They use a traditional bleed off the caliper alone using a vacuum canister. The problem with this is its not a complete flush as alot of the contaminated fluid still remains in the actuator and brake splitters. They don't use the techstream because its more time consuming and requires more work rather then just put on 4 vacuum lines and do a bleed while just standing around.

 

Where does someone find a shop using the "Techstream" system? Is it used by dealers? Independents? I would be willing to try it before rebuilding calipers and in any case planned to do a full flush after the caliper rebuild.

 

Techstream is a dealer only tool. Its typically used to diagnose issues between onboard computers to see what sensors are doing what. But it can do so much more like setting up personal perimeters, brake bleed, etc. Its too bad many dealers don't use it to its fullest potential as it's a $10k piece of equipment. (Basically a Panasonic toughbook laptop with special software loaded onto it.)

 

I have my brake fluid flushed and refilled every 30,000 miles . No problem.

 

The synthetic fluids I have in varying cars tend to get a progressing darker yellow-amber by 30K miles. 60K miles on fluid with a good seal is slightly brownish. Black is not good and especially by 30K.

Is the dark fluid present when bled from the calipers or is it at the top in the fluid reservoir? If the caliper seals are worn, you would have signs of fluid around the piston. Another symptom would be the need to fill the brake fluid reservoir. If there is no loss of fluid, the first item I would suggest is the brake fluid reservoir cap and checking the reservoir for signs of fluid leakage.

Suck the dirty fluid out of the reservoir and replace with fresh. Then if DIY, bleed the system so that clean fluid is coming out at each caliper. Don't allow the dirty fluid in the upper reservoir to be pushed through the ABS-TRAC system.

 

My brake fluid is black too, its 160k miles on the car.
I have the fully functional techstream at home, do you know what menu I have to go to do the procedure of bleeding?

 

Determining the color of the brake fluid should not be done by just looking at the exterior of the reservoir. I found that out when I removed the fluid from the reservoir. The reservoir will darken with age from the fluid and make it look dark when it really isn't. Pull some of the fluid from the reservoir to determine the actual color.

 

In my case it was the fluid, the reservoir is now the color of corona lite beer. :

 

I had the fluid flushed a few weeks ago and so far, so good. I took it to a Lexus dealer to be worked on by a Lexus Master technician (35 years Toy/Lex experience). He showed me the Techstream and confirmed that their was no "blade" (software routine) for a LS430 brake bleed. So I told him to do what he thinks best.

He suggested a through flush. In addition, he removed the master cylinder and flushed it thoroughly. He then used his machine to flush the system 3 times. The first two times, you could see the junk (dirt, debris, etc) come out. The third time was clear brake fluid, the color of cooking oil. It has been a couple of weeks and the fluid is still light and clear.

In addition, I have had some Stop-tech stainless steel brake lines sitting in a drawer for a year or so. He installed them before flushing the lines. The combination of the flush and new brake lines has improved braking performance. Nothing spectacular but a noticeably firmer pedal with significantly diminished brake fade and a more solid feel with shorter stops. I am glad I did it.

The fluid remains the color of cooking oil and I hope it stays that way. He also said that moisture enters the system through a vent hole in the cap. If you wash down your engine bay he suggests covering the master cylinder.

 

I bled mine the old fashioned way when I first picked up my 2006 LS with 89k miles. The fluid was slightly darker than fresh fluid in the reservoir. However, it was hard to tell the difference between the old and new fluid as we were flushing so I switched to some synthetic racing brake fluid that was blue. It was overkill but it looks cool in the reservoir.

 

Interesting. Just to clarify, Techstream is not just a brake tool, it's a way to hook up to the software of the car and do all sorts of things. One of them is to place the master cylinder into the correct "mode" for through bleeding. Is that right?