Flushing the brake system

[Matt89]

As usual, things are going along great until someone who knows a little science chimes in. Bah!

Funny, I forgot the difference even though I remember covering it in junior high, AND high school AND college. Probably won't forget now...

 

[Warstud]

I didn't see mention of de-pressurizing the ABS system. Well anyway make sure you do that first by pumping the brakes about 30-40 times before working on them.

 

[LarryL]

Has anyone used one of those vacuum pumps that attach to the bleed screws? I've left messages at Mityvac every day for a week and a half and they evidently don't do customer service or answer phone messages. I also sent an e-mail today. So, anyone used one of those pumps?

 

[BearZDefect]

A vacuum pump might work well on the bleeder screw, or it might not if it sucks a lot of air through the loosened threads of the bleeder screw. In my experience the latter (sucking more air than fluid) happened more often (10 out of 12) than the ideal case where it just sucked fluid.

 

[moribundman]

I tried a vac pump and didn't like it at all. For one-man operation, the pressure bleeder offers by far the most convenient solution. You don't even have to top off the master cylinder reservoir, because the pressure bleeder does it for you.

 

[nobadges]

Speedbleeders are awesome.

I change the fluid in the master at every oil change.

 

[Ken2]

Look for an industrial hardware store in your area for an internal pipe wrench. For really hard to find items, I use mcmaster.com.

I don't worry about flushing the ABS part of the brake system unless the system has been contaminated. I keep the fluid in good condition with 2 year fluid flushes, and the fluid never gets bad enough to worry about a small part of the system.


Ken

 

[vizvo]

moribundman writes:

quote:

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I saw internal pipe wrenches online, but where might I find one locally?

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I've seen them at Home Depot in the plumbing section. In fact they even had a packaged set of 3 different sizes. Not expensive either.

 

[moribundman]

Thanks for the tip regarding Home Depot. We don't have one in the city and I only checked my neighborhood ACE Hardware shops. I got the deer-in-the-headlights look.

 

[nobadges]

You can make your own vacuum pump quite easily.
I made one to change the transmission fluid and it provides plenty of vacuum to bleed the brakes.

I used a hand air pump that is used for blowing up air mattresses and other inflatable stuff. It’s a high volume pump….not like a tire pump. The cylinder in this thing is like 4” wide and 12” long.
It has a blower and a sucker connection on it.

I connected the vacuum port to an empty glass bottle with a piece of heater hose. The idea is the glass bottle and the heater hose will not collapse under the vacuum. From the glass bottle (the collection container) I ran a length of clear vinyl tubing.

Put the clear vinyl tubing into whatever you need to drain (bleed valve, transmission dipstick tube, p/s reservoir) and work the pump 1 or 2 strokes.

Works like a charm.


Also…a note on the gravity method of changing the fluid:
That won’t get the fluid out fast enough to get rid of all the air (if any). Small air bubbles can continue to float upwards if the fluid is draining that slow.

With speedbleeders you can pump the fluid out just as fast as you can pump the brake pedal.

 

[Kestas]

I've made the same setup using a glass jar, clear tubing, and plumbing through the lid. It's just like a hookah and takes up less space on the shelf. Put the correct end in your mouth and vacuum the fluid through the other.

I get too much air going past the bleeder screw threads to do any effective vacuum bleeding, so it's used mostly for vacuuming the master cylinder fluid or the power steering reservoir.

 

[bmwtechguy]

I change/flush the brake fluid with DOT4 every time brake pads or shoes are changed. I figure I'm already there and it does not take that much time to get some new fluid in there. It's not really neccessary to use an ABS controller or to change out every last drop of fluid in the ABS pump/module. If you just use the normal 2 person bleed or some special 1 person setup for bleeding, you will still be getting nearly all the fluid out, except for a few cc's that will be trapped in the ABS secondary circuits of the pump/module. This old fluid will just mix with the much larger volume in the rest of the system the first time the pump is activated. A method I used in a pinch that requires no special tools: find a clean, regular spray bottle with a small diameter pickup tube. Slide the tube down in the reservoir however you can get it in there to the lowest point on each side. Then just spray the old fluid back into the bottle. It takes just a few minutes to nearly empty the reservoir of the old, hydrated fluid. Then pour in your DOT 4 fluid and bleed all 4 bleeders till fluid comes out the new, lighter color at each bleeder. Try to keep enough fluid in there to not suck it dry while bleeding. Refill reservoir and you've changed nearly 100% of the fluid in the system. Easy and cheap preventative maintenance for your ABS brakes.

 

[rpn453]

I bought a vacuum pump at Princess Auto for $25 and I've bled 3 cars with it so far. Seems to work fine. I haven't had any problems using it.

unDummy, I like that method. I think I'll start doing that next oil change. So far, I've just bled when doing brake pads. Maybe I'll do a little PS fluid each time as well. I'll just pick up a second vacuum pump kit for oil applications next time they're on sale.