Special procedure for flushing dirty brake fluid?

[getluky]

Ok, on to my next question - when siphoning off brake fluid from my reservoir, I observed lots of dirty particles floating around in there. I've heard that one shouldn't flush dirty fluid through the system, so i'm planning on siphoning out all the fluid in the reservoir under the cap and filter, and rinsing the filter in some new brake fluid. Once i've got new fluid in the reservoir, do I just do the normal bleed procedure and call it a day, or do I need to do anything special? I keep reading posts about how people recommend flushing the entire system out, but I also read posts about how one shouldn't ever let the reservoir run dry when bleeding brakes, so I'm not sure what to do. I'm not 100% clear on how the whole system works and this is probably adding to my confusion. Thanks in advance.

[JohnKo]

If your objective is to get rid of the dirty stuff and bleed the brakes (and not go a lot further), you definitely don't want to remove so much fluid that pumping the pedal injests air into the system. I'd say remove what you can without going too far (perhaps adding and repeating if you feel the need), then bleed and/or flush as you see fit.
Conventional wisdom is that brake fluid has a finite life, during which it absorbs moisture, and should be flushed every few years -- recommendations vary. So, depending on how old the fluid is, you should consider flushing the system, which essentially means bleeding it more and longer, until you're getting fresh fluid of of the bleeders.
If you haven't heard this already, start with the caliper farthest from the master cylinders(s) -- right rear -- and progress to the one closest -- left front. Watch the reservoir carefully and don't let it suck air, or you're in for a longer day.
Good luck!

[aston@ultrasw.c]

Originally Posted by getluky

I keep reading posts about how people recommend flushing the entire system out,

Flushing generally means bleeding the system until new fluid poured into the reservoir makes it out of each caliper.

If you do suck air by mistake it's not that bad, just work slowly and be patient.

[TRE Cup]

Before you start with this procedure, realize that brake fluid is not friendly to paint finishes. So be prepared to to catch whatever fluid comes out when opening the system. Soapy water will neutralize it pretty quickly

Also the extra travel that your master cylinder goes through , during the bleeding process, can cause the seals to fail. So don't be surprised if you get plenty of firm pedal after you completely bleed the system, only to have the pedal go to the floor subsequent to this. Why? the piston seals are used to a certain amount of travel and may have caused a barely perceptible working "groove" after many many miles of use. The extra travel from bleeding may cause the o rings to fail. So with that, let us proceed
1) Remove the reservoir from the car, clean it thoroughly, wash it, let it dry
2) open the brake hoses where they connect to the brake caliper lines and let them drain
3) disconnect the brake lines that go into the brake master. These are pushed into place in a rubber seal. Gently angle the metal tubes and pull them out. If you are careful, these seals won't be damaged
4) There is a brake cleaner spray available you can use to clean these plastic lines (they are swedged into metal where they connect to the master.) Blow air thru them to dry
5) if the rubber seals that connect the reservoir lines to the master are cracked, replace them. Most foreign car parts stores will have these seals. There is an inner groove that secures the metal tubes from the reservoir lines
6) install the clean and dry reservoir back on the lines. Make sure the overflow tube is connected and routed properly out the bottom of the car
7) connect the reservoir lines to the master cylinder
8) fill the reservoir with brake fluid. Check for leaks at the connections from reservoir to lines, lines to master
9) have someone pump the pedal while observing the flow from all four disconnected hoses. The flow will NOT be completely equal, BUT they should flow. Don't worry about running out of fluid in the reservoir at this stage. You are just flushing the master, lines, and hoses. Cycle through a couple of times
10) Reconnect the hoses to the caliper lines, fill reservoir
11) bleed the system as suggested above. RR/ LR/ RL/ LF- outer bleeders first, then inners. Don't get fluid on the pads or discs!. It may take a couple rounds to get a consistent firm pedal. Check for leaks hoses to caliper lines

Take care to monitor the brake fluid level during the final bleed. If you detect an especially low volume from the brake hoses while they are open during step 9 (not connected to the caliper lines) then I would recommend replacing them with new ones. These corrode from the inside out and cause low fluid flow / poor braking performance.
If you have aircraft style lines, we recommend replacing these every 2-3 years. The continual bending back and forth will cause the inner liner to fail on some of these. Of course this means no brakes at that corner if that happens !
Final reservoir level should be about 1/4" above the divider in the reservoir. NOT all the way to the top. Why? When the brakes get used, they get hot, fluid in the reservoir rises and goes out the overflow.
Go thru all the connections , check for leaks, check that all are tightened to spec. The brake cleaner spray is a good solvent that can be used to clean these connections and then check for leaks. You can use a nice clean dry piece of brown paper bag to do this. Dark paper= leak present

[RWebb]

do you have a home air compressor for #4?
- could use a bike pump -- be sure the air is DRY

you can make a pressure bleeder for about $10 using a pump garden sprayer - do a search for how to make it

brake fluid is hazardous waste - catch it all in a container(s) and see if an oil change place won't take it for free.

post any problems you have...

[DRACO A5OG]

Did you have these particals after bleeding the Brakes?

I don't see why you can simply flush the brakes by placing new Brake Fluid of different color until the new colored brake fliud flows out.

You need a buddy to press on the brakes to keep air out and monitor the fluid level in the resevoir.

I would not use a DIY Pressure Pump due to the fact that if it does not have a H2o filter, it will introduce H2o into the new fluid. There is a Pump with the filter but it is $50+.

I had old yellow fluid and used blue fluid to determine when the system was completely flushed.

My 2 cents

[mike gilbert]

is ok to use synthetic fluid? if so it should not hurt the paint, right?im going to flush my system soon too and was just wondering........

[RWebb]

"if it does not have a H2o filter, it will introduce H2o into the new fluid."

- Eh? What makes you think that? Obviously, one will use a clean and dry apparatus. Where is the water going to come from?

Mike - No - generally, you can alternate Ate Blue & Yellow, or one of the others listed in the various threads a search on brake fluid will pull up

[rusnak]

yeah, dispose of solvents and brake fluid properly. I usually sneak a little bit at a time into my recycled oil until it's all gone. I'm not getting something here. You're planning to change brake lines at some point, right? Why are you sweating brake bleeding and flushing until the brake calipers and brake lines are done, and you are nearing the final stages?

I'd suction off the bad fluid with a turkey baster, then drain out the rest, change the lines and rebuild calipers, and get on with it. Be done in an afternoon.

One tip: since you are changing brake lines (I think?), you can get pretty aggresive with the old brake line, just save your hard line fittings if you can. It is not unheard of to damage the hard line fittings as well, and have to change both lines. A drop of brake fluid is a great penatrating lubricant. Or you can use PB Blaster.

[getluky]

rusnak: I'm coming around to the theory of just waiting til the end to flush the fluid out. Someone did mention to me that they'd be wary of flushing dirty fluid into rebuilt calipers, but I think it should be ok.

I'm just trying to get all my ducks in a row ahead of time, but as usual i'm stuck on basic items when I get into the job. I've been hitting the brake line fittings with PB Blaster and am currently stuck getting some of that off... trying to consolidate my procedural questions in the other thread, though. Thanks for the advice, and I certainly will look for the proper way to dispose of the old fluid.

[Superman]

All I can do is tell you how I do it. I use a Q-Tip to clean the fluid reservoir. Then, I use an old, discarded turkey baster to remove that fluid. If necessary, I might pour more fluid in, mix it up and suck it out again until I see a clean reservoir with clean fluid in it.

Then.....I actually like the gravity bleeding method. Just let it drip for a while. It won't take long before the fluid dripping out of the calipers, or the lines if you have disconnected them, to run clear. Of course, you need to watch the reservoir like a hawk.

[rusnak]

that's sort of what I'm saying. You are going to remove the calipers, or the calipers and the old brake lines. Even if you order a retreat, and save the brake line thing for later, at some point you gotta break the lines, so how do you stop all the fluid from draining out, and let some air into the system?

You are going to flush the fluid by default simply because the fluid is going to get out, unless you try to cap the lines or something. But why? Just stick a drain pan under the brake line, let all the dirty fluid run out.

I agree with suctioning as much as you can out of the brake reservoir, and then cleaning the reservoir with lint free cloth.

[getluky]

Hmm, I have the brake pedal stopped right now though, so even though I have the brake line disconnected form a caliper, it's barely dripping out into my drain pan. I'll probably end up only doing the flush at the very end of my brake job, after all the other work that has to be done.

[RWebb]

I would not flush fluid with particulates in it thru the calipers.

If it was just old or water contaminated I would not worry - it will not be in contact with the calipers long. You are going to put nice clean fluid thru immediately thereafter.

or use new, budget fluid to flush & then fill with Motul, Ate etc.

One of the Ford fluids is very good but also cheap.