Flushing the brake system
- Thread starter LarryL
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Every car is a little different so if I were you, I would look in a manual on your car to see about bleeding the brakes properly. Some cars have quite an involved process. That said, the ABS pump can often be used as a partial "power bleeder." Some of the cars I've done with ABS were really easy because of this. With others, the ABS makes it a lot harder. I always like the old "gravity bleed" myself. Suck out the fluid in the reservoir, replace with fresh, open one bleeder with a clear hose into a clear container, let it bleed slowly from gravity until the fluid comes out clear and a little more, repeaton the other bleeders. If you keep the reservoir full, no air gets in, you don't need a helper and you don't trigger the proportioning valve (if equipped) to shut off one circuit of the brakes. There are other generic methods but, again, the manual on your car will warn you of any pitfalls peculiar to your system.
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If you got a willing girlfriend, wife, neighbor kid or trained pet monkey, the old pump-the-pedal method works just fine. I really like the pressure bleeder method, or rather the aforementioned people and pet monkey prefer it, because they won't be subjected to emotional outbursts of dissatisfaction.
You are right, it is quite easy to create problems with the ABS or other things. First thing is to read the manual. Unless it requires it, skip it. It does nothing to protect the most vulnerable parts of the brake system.
The manual system does work well. Always let your wife be the one pumping the pedal. Avoid excessive use and the same wife may last indefinitely. Perhaps a third person to keep checking and refilling the master cylinder. The shop manual for my Grand Am said nothing about needing to flush the brakes. It was very explicit about never running the MC dry.
Pressure bleeders work well, but must be carefully cleaned and stored between uses. Otherwise, the fluid in reservoir and lines will pick up the very moisture many so irrationally fear.
The manual system does work well. Always let your wife be the one pumping the pedal. Avoid excessive use and the same wife may last indefinitely. Perhaps a third person to keep checking and refilling the master cylinder. The shop manual for my Grand Am said nothing about needing to flush the brakes. It was very explicit about never running the MC dry.
Pressure bleeders work well, but must be carefully cleaned and stored between uses. Otherwise, the fluid in reservoir and lines will pick up the very moisture many so irrationally fear.
Anyone can bleed the brakes with ABS. But, you won't always bleed the ABS pump/reservoir which isn't an issue if you did NOT get air in the system.
If you use your ABS regularly, don't worry about it.
If you don't use your ABS, its gonna fail anyway.
A simple way to bleed is to exercise the ABS, bleed the brakes normally, and repeat. This way the ABS pump/reservoir fluid is new.
With very light pressure on pedal, some cars will cycle the ABS pump by simple spinning one tire since other three are stationary.
I prefer vacuum bleed with a pela extractor or mityvac. But, my cars have speedbleeders. Gravity bleed takes too long.
http://www.speedbleeder.com/
http://www.autopart.com/TOOLS/TOOLSMAIN/tool/T_1238.htm
http://www.mytoolstore.com/kd/kdbrak02.html
http://www.winbrake.com/eezibleed.html
http://www.motiveproducts.com/02bleeders.html
If you use your ABS regularly, don't worry about it.
If you don't use your ABS, its gonna fail anyway.
A simple way to bleed is to exercise the ABS, bleed the brakes normally, and repeat. This way the ABS pump/reservoir fluid is new.
With very light pressure on pedal, some cars will cycle the ABS pump by simple spinning one tire since other three are stationary.
I prefer vacuum bleed with a pela extractor or mityvac. But, my cars have speedbleeders. Gravity bleed takes too long.
http://www.speedbleeder.com/
http://www.autopart.com/TOOLS/TOOLSMAIN/tool/T_1238.htm
http://www.mytoolstore.com/kd/kdbrak02.html
http://www.winbrake.com/eezibleed.html
http://www.motiveproducts.com/02bleeders.html
Kestas
Staff member
So you're suggesting it's best to exercise the ABS system by activating it once in a while, such as by locking up the brakes on a safe stretch of icy road. I like that idea.
labman, i know your posistion on brake fluid replacement, and how it is NOT a substitute for replacement of rubber seals/gaskets etc in the calieprs or wheel cylinders. The fluid and seals each requre their own seperate attention.
I thought you might find this read informative if you haven't already read similar literature: Brake fluid FAQ he has some references at the bottom of the article, so this info isn't all bunk.
To answer the OP, unless you have the specific scan tool to activate the ABS modulator, the best way to flush out both the ABS mod and the 'regular' lines is to activate the abs a few times and re-bleed/flush. Thats how i'm doing it on my 94 civic ex abs coupe. There is a procedure for me to bleed the abs mod seperately, i just haven't gotten around to it.
I personally like to use the two man method to get air out and gravity bleed from there on. The key when using the two-man is to use slow slow slow pedal strokes, and slow on the let-off of the pedal. Also remember to close the bleeder screw before lifitng up the pedal so the chance of air getting 'syphoned' back in is minimized.
I thought you might find this read informative if you haven't already read similar literature: Brake fluid FAQ he has some references at the bottom of the article, so this info isn't all bunk.
To answer the OP, unless you have the specific scan tool to activate the ABS modulator, the best way to flush out both the ABS mod and the 'regular' lines is to activate the abs a few times and re-bleed/flush. Thats how i'm doing it on my 94 civic ex abs coupe. There is a procedure for me to bleed the abs mod seperately, i just haven't gotten around to it.
I personally like to use the two man method to get air out and gravity bleed from there on. The key when using the two-man is to use slow slow slow pedal strokes, and slow on the let-off of the pedal. Also remember to close the bleeder screw before lifitng up the pedal so the chance of air getting 'syphoned' back in is minimized.
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By the way, the pressure bleeder can be combined with the pedal-pumping method.
Regarding ABS systems: The ABS control unit on some vehicles may require the unit to be cycled during bleeding. Luckily that's not the case on my Audi.
labman will be happy to hear that one of the brake piston boots on my fron brake has just torn. I'll have to install a new seal/boot. I'll take some pictures to show off the over 9 year old caliper and piston. I don't have compressed air available, so instead of "blowing" the pistion out on the workbench, I think I'll try to squeeze it out with pedal pressure (with a piece of wood instead of brake pads in the caliper). Any advice on how to avoid a mess with paint-eating brake fluid, doing this job ghetto-style?
Regarding ABS systems: The ABS control unit on some vehicles may require the unit to be cycled during bleeding. Luckily that's not the case on my Audi.
labman will be happy to hear that one of the brake piston boots on my fron brake has just torn. I'll have to install a new seal/boot. I'll take some pictures to show off the over 9 year old caliper and piston. I don't have compressed air available, so instead of "blowing" the pistion out on the workbench, I think I'll try to squeeze it out with pedal pressure (with a piece of wood instead of brake pads in the caliper). Any advice on how to avoid a mess with paint-eating brake fluid, doing this job ghetto-style?
You can tap on the back of the caliper with a rubber mallet and the piston sometimes falls out. This would be a lot less messy than squeezing it out like you describe while still hooked up to the hydraulic system. You can buy these plug things for your brake hoses at Autozone, they're little black plastic things 2 for $.99, it will help reduce the amount of fluid that drips. Do not use clamps to 'clamp-off' the brake hose.
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It's unlikely the piston will fall out. It requires usually quite a bit of pressure to force it out -- enough to turn the piston into a lethal projectile. I'll give it a shot anyway, because trying won't hurt. I got plugs for the brake lines. I wasn't gonna apply tourniquets.
My plan is to remove the caliper carrier, the rotor and the pads. Then I'll put the caliper carrier back on, put a piece of wood in the space between piston and caliper, put a plastic bag around the whole thing to catch the brake fluid. Then step on the brake... There are no painted parts on the caliper and other brake parts.
My plan is to remove the caliper carrier, the rotor and the pads. Then I'll put the caliper carrier back on, put a piece of wood in the space between piston and caliper, put a plastic bag around the whole thing to catch the brake fluid. Then step on the brake... There are no painted parts on the caliper and other brake parts.
Kestas
Staff member
I have shop air to blow out the caliper piston. For those that don't have shop air, using the brake pedal to push the piston out is an accepted (but messy) practise.
For either method - to avoid a mess and to avoid projectiles - pack the area with rags.
For either method - to avoid a mess and to avoid projectiles - pack the area with rags.
First, suck out [clean turkey baster - watch for spills] as much fluid from the master cyl as you can, then refill with new fluid. Do this a number of times and you will have a much better system when bleeding.
The best news is that this [done repeatedly after driving each flush] will probably negate the need for a bleeding, unless there was air in the system to begin with.
It made my clutch [hydraulic shared reservoir] and brakes work better, and my personal car only had 25,000 miles on it.
The best news is that this [done repeatedly after driving each flush] will probably negate the need for a bleeding, unless there was air in the system to begin with.
It made my clutch [hydraulic shared reservoir] and brakes work better, and my personal car only had 25,000 miles on it.
Not true. Have faith in osmosis.
How many 100's of times do you step on the brake pedal in a month? That fluid moves back and forth back and forth back and forth, mixing all the time.
The brake fluid is hygroscopic. This means that the waterless new fluid in the master cylinder will pull moisture from the rest of the braking system. I've never seen 'settling' in the calipers that some have complained about. Its mixing in all of my cars and ones that I maintained.
I siphon/refill my master cylinder at every oil change(3x a year). A brake bleed after a brake job yielded almost clear fluid from the wheel cylinders. And, I haven't lost a hydraulic component since I started doing this. Replacing/rebuilding wheel calipers, wheel cylinders, master cylinder, and ABS pumps costs too much time and money.
It also feels good to pop to hood and notice a crystal clear master cylinder reservoir. It shocks everyone that sees it. My PS also gets the siphon/refill treatment. That fluid always also looks great.
If you start a simple siphon/refill program, you won't have crappy old fluid anywhere.
How many 100's of times do you step on the brake pedal in a month? That fluid moves back and forth back and forth back and forth, mixing all the time.
The brake fluid is hygroscopic. This means that the waterless new fluid in the master cylinder will pull moisture from the rest of the braking system. I've never seen 'settling' in the calipers that some have complained about. Its mixing in all of my cars and ones that I maintained.
I siphon/refill my master cylinder at every oil change(3x a year). A brake bleed after a brake job yielded almost clear fluid from the wheel cylinders. And, I haven't lost a hydraulic component since I started doing this. Replacing/rebuilding wheel calipers, wheel cylinders, master cylinder, and ABS pumps costs too much time and money.
It also feels good to pop to hood and notice a crystal clear master cylinder reservoir. It shocks everyone that sees it. My PS also gets the siphon/refill treatment. That fluid always also looks great.
If you start a simple siphon/refill program, you won't have crappy old fluid anywhere.
When I worked in the brakes shop, we had a tool that gripped the inside of the piston. If you have an internal pipe wrench it may work. Wedging anything inside the piston might work on one worth saving. Our procedure, shop air with rags in the caliper, the tool as above, the test bench where we could pump high pressure fluid in. Nothing ever resisted that. It was largely useless however. In nearly every case, if shop air didn't do it, the piston was shot and it would have been cheaper to buy a rebuilt caliper. I have also heard of fitting the caliper with a Zerk and pushing it out with a grease gun.
The ABS on my car engages itself briefly during the first initial acceleration after startup as a self-test. It waits until the car is going about 10MPH to do it.
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labman, an internal pipe wrench might work. I actually didn't know that tool but I looked it up and it looks like it might work.
Kestas
Staff member
The osmosis question could be answered if somebody would exchange the fluid in the reservoir with blue fluid, then take note of what they see next time they flush their brake fluid at a later date. I'll keep an open mind to this issue until we find out one way or another.
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Five hardware stores later I realize that I'm not the only one who's unfamiliar with internal pipe wrenches. Everyone tried to sell me a nipple extractor instead. I saw internal pipe wrenches online, but where might I find one locally?
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