Yesterday I finally got around to flushing out DOT 3 Prestone for asian cars brake fluid that I put in a few years ago with some new Supertech DOT 4 fluid. I purchased 1 liter but ended up going back to the store and buying one more liter after I started seeing black stuff and particles coming out when I went to do the drivers side (front left).

I'm just wondering why the front left brake had so much crud in it when the others were fine. I ended up using a total of about 1 liter and about a quarter of the second 1 liter bottle total for all of the system. At that point I saw no particles coming out and was coming out clear for a while before I stopped. I used the pumping the brake flush with a simple catch container and vinyl hose. I rarely used the brakes aggressively so am thinking that the master cylinder (piston) or whatever you call it had some crud building up on it from its lack of hard use or maybe some scale building up on brake lines or some decaying particles.

Why did I have so much crud in the last nipple flush? Does the fluid push all the crud to the last leg?

Also, it would be nice to know how much fluid to take out of each nipple. I was waiting for a major color change when flushing from old to new fluid but was hard to tell when to stop. Isn't it possible to measure the length of each brake line and figure the fluid capacity for each nipple so know when to stop when it reaches that volume or is all of the fluid mixing like an automatic transmission does?

 

The crud and green color is from braking down copper in the system. Why it's from the left front, closest to the copper? Maybe it's in the master and you might keep flushing the other lines and get green fluid there too. You may have done this, before you flush it out, suck out the reservoir completely and wipe it spotless, then fill it and start the flushing.

At work when we flush we use half a liter per car. When I buy a used car I keep flushing until it's clear, On my old Yukon I used 2 gallons. I just used a liter flushing my TSX clutch fluid, I suspect the previous owner never flushed it.

 

Yes, used a syringe and got out all the stuff in reservoir first and wiped clean before adding the new fluid. The greenish color was there visible when I emptied the reservoir.