Suspension & Brakes - Question about flushing brake fluid. Already tried a search.

I'm going to be changing out my master cylinder because the old one went bad and also changing the fluid to DOT 4 ATE fluid, which I don't believe is supposed to be mixed with the DOT 3 or whatever is in there already. Would it be better to flush it by pushing the old fluid out with the new like you normally would, or empty out all the old fluid first with a pump or something?

I suck out all the old fluid I can, then add somenew. Then flush. You want to push out all the old fluid once you start seeing the new fluid coming out all 4 lens you know thats pretty good then fill up the MC. Just be sure you don't let the MC run dry at any point!

Dot 3 and 4 mix technical....

Here's what I do:

I go to Bed, Bath and Beyond (although I'm sure you can get these other places) and buy this:

http://www.bedbathandbeyond.com/product.asp?order_num=-1&SKU=11791182

Yeah, it's a flavor injector. Take it out, put the black "needle" in the end of it, but do yourself a favor and cut off the last half inch or so with a pair of scissors so that the fluid won't squirt sideways when you push it out.

That little bastard does a good job at sucking the reservoir dry - just keep pulling it out and put it in a plastic cup or something. Once you get everything out of the reservoir, just fill it with new stuff and bleed like you normally would.

As already stated, DOT 3 and DOT 4 (the Ate) are completely compatible, so mixing them won't hurt a thing.

The fluid is compatible. Just suck most of the old stuff out of the master (an old turkey baster works well) and put the new stuff in, then flush the lines and bleed it.

And coolformula is right, DON'T let the master run dry. :)

...don't let the master run dry unless you are cool like me and let everything leak away while your calipers are off being powder coated :jest:

Oops - good thing I don't have ABS anymore :)

you could invest in a brake bleeder kit. instead of hitting the brakes and trying to force the air down, the kit attaches to the bleeder valve, and forces fresh fluid up through the lines and into the master, the way air wants to go - up. just make sure you suck out the old fluid. and, you only need one person to do it.

Bench bleed the new master with the ATE fluid.
Install new master and bleed the lines like you would normally at the rotor/drum, once youve got all the "old" fluid out youll see the new fluid (blue, yellow/orange, whatever color ATE youve got) in whatever your using to collect the fluid.
Make sure you have someone helping so you can check that the master doesnt run dry, I usually check after 2-4 pumps of the peddle.

DOT 3 and 4 can be mixed, but you cannot mix anything with DOT 5(silicone)

Motive power bleeder! Takes about 10 mins. to flush bleed the whole system. The only true one man bleeder i've used. I used it the first time last week. I'll never use anything else. http://store.motiveproducts.com/

I suck out all the old fluid I can, then add somenew. Then flush. You want to push out all the old fluid once you start seeing the new fluid coming out all 4 lens you know thats pretty good then fill up the MC. Just be sure you don't let the MC run dry at any point!

Dot 3 and 4 mix technical....

When you do the flush part do you need a second person or just use a hand pump or whatever you used to suck the old out?

Here's what I do:

I go to Bed, Bath and Beyond (although I'm sure you can get these other places) and buy this:

http://www.bedbathandbeyond.com/product.asp?order_num=-1&SKU=11791182

Yeah, it's a flavor injector. Take it out, put the black "needle" in the end of it, but do yourself a favor and cut off the last half inch or so with a pair of scissors so that the fluid won't squirt sideways when you push it out.

That little bastard does a good job at sucking the reservoir dry - just keep pulling it out and put it in a plastic cup or something. Once you get everything out of the reservoir, just fill it with new stuff and bleed like you normally would.

As already stated, DOT 3 and DOT 4 (the Ate) are completely compatible, so mixing them won't hurt a thing.

That is a truly dam creative idea.....I may have to try that.:D

The fluid is compatible. Just suck most of the old stuff out of the master (an old turkey baster works well) and put the new stuff in, then flush the lines and bleed it.

And coolformula is right, DON'T let the master run dry. :)

Sweet! I saw something about fluids it could mix with on the side and didnt see DOT 3 so I kinda assumed they weren't supposed to mix. By the way, you were who I got the fluid from. Just got here a couple days ago. Should two bottles be enough? Thanks, dude! :chug:

...don't let the master run dry unless you are cool like me and let everything leak away while your calipers are off being powder coated :jest:

Oops - good thing I don't have ABS anymore :)

This brings me to another question. Do I have to worry about if my ABS ran dry? I'm guessing no since the leak was at the Master Cylinder and it would stop once that was about empty? I lost enough that my reservoir dried up.

you could invest in a brake bleeder kit. instead of hitting the brakes and trying to force the air down, the kit attaches to the bleeder valve, and forces fresh fluid up through the lines and into the master, the way air wants to go - up. just make sure you suck out the old fluid. and, you only need one person to do it.

that sounds good but I've heard of power bleeders having a tenancy to let air by. Is that something that doesnt happen often? I'm interested but just not sure how likely it is to have an issue.

Bench bleed the new master with the ATE fluid.
Install new master and bleed the lines like you would normally at the rotor/drum, once youve got all the "old" fluid out youll see the new fluid (blue, yellow/orange, whatever color ATE youve got) in whatever your using to collect the fluid.
Make sure you have someone helping so you can check that the master doesnt run dry, I usually check after 2-4 pumps of the peddle.

DOT 3 and 4 can be mixed, but you cannot mix anything with DOT 5(silicone)

So more or less just a typical brake flush, right? Pretty much what I planned on doing but wasn't sure if there was any problem with it like weird reactions when the 2 types of fluid came in contact or something. :nod:

Oh yeah, I had one other question. What about gravity bleeding? Any particular pros/cons besides that it takes forever? Seems highly recommended by those that have tried it and doesnt need a second person AFAIK.

Yes, 2 people is better than 1. Gravity can work, just takes a long time.

If the ABS ran dry or has air bubbles, that may present a problem - that'll have to be bled using a Tech 2 to cycle the ABS (most likely).

Oh, and I also use a Motive Power Bleeder - it lets me bleed the entire system by myself.

Yes, 2 people is better than 1. Gravity can work, just takes a long time.

Well I guess that's another possibility.

If the ABS ran dry or has air bubbles, that may present a problem - that'll have to be bled using a Tech 2 to cycle the ABS (most likely).

But would it have been likely to run dry since the leak was up at the master? Also this is on an LT1 car which I believe has a different ABS module than the LS1s, dunno if that changes anything? And that power bleeder does sound good but I don't really mind taking extra time to save the ~50 bucks at the moment unless itll benefit me in some other way. Probably grab one later though.

Nice to see this thread. I've been looking at the motive bleeders and wondering if they are worth it. My brake fluid is 6 years old so I'm a little behind and changing it.

My wife's Honda is at the 3 year mark in which Honda recommends to flush the brake fluid and my F150 is also at the 3 year mark. Looks like I need to buy some brake fluid in bulk!

I use the Motive pressure bleeder shown above (the late model GM version)...

It works very well (especially for one person operation)... if you have 4 wrenches and 4 bleed tube/bottles you can bleed all 4 at the same time...

The only thing you have to be careful of is: make sure the end of it seals properly on the reservoir/cap opening otherwise brake fluid leaks out.

For the ABS (if it has gotten air in it), you need a scantool (Tech II, Genisys, AutoEnginuity) to cycle the solenoids... altho I believe it can be done manually, but it takes a lot of bleeding and cycling the ignition key.

Can anyone post the "cycling the ignition key" procedure again, for getting the ABS valves open? It was posted on one of the threads a while back, but I can't get the procedure to come up in a forum search.

Can anyone post the "cycling the ignition key" procedure again, for getting the ABS valves open? It was posted on one of the threads a while back, but I can't get the procedure to come up in a forum search.

That would be useful for me too. I think it was something like turn the key on for 10 seconds then shut it back off and repeat 5-10 times or something like that. I just found it earlier today and now I can't for some reason. should've bookmarked it:bang: I'm not sure if I'll need to or not but I'm guessing i should probably at least bleed it some to make sure no air got to it.

I've had very good luck with just gravity bleeding the brakes.

Put a catch pan under each corner, open the bleeder screws and walk away for a while. It takes about 30 minutes and the car needs to be relatively level, but the MC is higher than the rest of the system and will bleed out, all be it, slowly.

Once I'm happy with the bleed, I use a rubber mallett and bump the caliper to dislodge any air bubbles, then tighten the bleeder screw.

Good to go ...

I've had luck too, gravity bleeding, vac bleeding, pump the pedal bleeding.... The question some are asking, is if there is a better way, someway to get the valves open, someway to generate a little more luck that might evade a repair bill at the dealership. Especially if you are breaking loose lines upstream of the ABS module, or if the MC sucks atmosphere.

Nighthawk, do you remember the search keywords used? I've tried to search again and still can't find the key procedure.

I've had very good luck with just gravity bleeding the brakes.

Put a catch pan under each corner, open the bleeder screws and walk away for a while. It takes about 30 minutes and the car needs to be relatively level, but the MC is higher than the rest of the system and will bleed out, all be it, slowly.

Once I'm happy with the bleed, I use a rubber mallett and bump the caliper to dislodge any air bubbles, then tighten the bleeder screw.

Good to go ...
Excellent, I'll probably do that as soon as I can. Would have been tonight right after I put on the new master cylinder but I wanted to go see my nephew in the hospital. Maybe tomorrow or Saturday.

I've had luck too, gravity bleeding, vac bleeding, pump the pedal bleeding.... The question some are asking, is if there is a better way, someway to get the valves open, someway to generate a little more luck that might evade a repair bill at the dealership. Especially if you are breaking loose lines upstream of the ABS module, or if the MC sucks atmosphere.

Nighthawk, do you remember the search keywords used? I've tried to search again and still can't find the key procedure.

I found the thread, dude:D

http://www.ls1tech.com/forums/10718488-post6.html

As far as getting the ABS valves to open. Drive the car above 8-10mph and it opens the valves. You then leave the key on engine off and bleed the brakes and the valves are open. This works on all GM's.

That's the two procedures I was thinking of; nighthawk's for the bleedable module, smokin's for the nonbleedable later 4 channel. Seems like it on smokin's anyway. The post i was thinking of was in '06 or '07, i think, and was similiar to smokin's post above.
Thanks guys!

That's the two procedures I was thinking of; nighthawk's for the bleedable module, smokin's for the nonbleedable later 4 channel. Seems like it on smokin's anyway. The post i was thinking of was in '06 or '07, i think, and was similiar to smokin's post above.
Thanks guys!

Any time :D

As far as getting the ABS valves to open. Drive the car above 8-10mph and it opens the valves. You then leave the key on engine off and bleed the brakes and the valves are open. This works on all GM's.

Ive never heard of that! Thanks, dude!

Yea, it can be used on both though, if you dont want to mess with the ABS block.

So all i have to do is like drive it around the block or something at about 10 mph and park it back in the garage with the key on but engine off? Does it matter if I go a bit above 8-10 or is that just the lowest speed where they open up?

Looking at the motive bleeders, it looks like a modified pesticide sprayer. If so, it does not work as the more expensive diaphragm bleeders. I'd be concerned with intruding air into the brake fluid via aeration.

A similar yet more effective approach would be probably taking an old cap, adding a compressor quick disconnect fitting to the cap and connecting it to a low-pressure air source (air compressor biased down with regulator). Just make sure the fluid is filled in the reservoir. I wouldn't go to this extent with this though...

Tried and true two-man method is probably the most economical approach with very good results if followed correctly.

It just hit me; don't the factory MC caps say "use dot 3 or 4"?

Yeah, if you search around here you'll find pro/con arguments on using low cost pressure bleeders or vac bleeders; I'm pretty sure those posts are still readily found, unlike some ABS bleed posts from awhile back. The kinda "burping" the MC by bumping or setting overnight has appeared to tighten up my brakes before, at least on simpler non-abs or 3 channel type systems i've worked on, after a MC replacement.

Nighthawk, if you follow the advice these guys are giving, I think you will be fine.

I know people here bang on you to "do the search"; unfortunately the good people that provide this site can only shake so much cash out of sponsors like Sam and Steve's companies. I guess it can only go so far in saving past information.
My hat's off to the mods, sponsors, site owners, and fellow members!

So all i have to do is like drive it around the block or something at about 10 mph and park it back in the garage with the key on but engine off? Does it matter if I go a bit above 8-10 or is that just the lowest speed where they open up?

Nope, its ok if you go faster, 8- 10 is just the lowest speed that they will open at. I usually back out of the driveway and up the street a little bit, then drive into the driveway and I can get started right away.

Looking at the motive bleeders, it looks like a modified pesticide sprayer. If so, it does not work as the more expensive diaphragm bleeders. I'd be concerned with intruding air into the brake fluid via aeration.

A similar yet more effective approach would be probably taking an old cap, adding a compressor quick disconnect fitting to the cap and connecting it to a low-pressure air source (air compressor biased down with regulator). Just make sure the fluid is filled in the reservoir. I wouldn't go to this extent with this though...

Tried and true two-man method is probably the most economical approach with very good results if followed correctly.

I think I understood the important parts of that:razz:

It just hit me; don't the factory MC caps say "use dot 3 or 4"?

Yeah, if you search around here you'll find pro/con arguments on using low cost pressure bleeders or vac bleeders; I'm pretty sure those posts are still readily found, unlike some ABS bleed posts from awhile back. The kinda "burping" the MC by bumping or setting overnight has appeared to tighten up my brakes before, at least on simpler non-abs or 3 channel type systems i've worked on, after a MC replacement.

Nighthawk, if you follow the advice these guys are giving, I think you will be fine.

I know people here bang on you to "do the search"; unfortunately the good people that provide this site can only shake so much cash out of sponsors like Sam and Steve's companies. I guess it can only go so far in saving past information.
My hat's off to the mods, sponsors, site owners, and fellow members!

For sure, dude! Man it really would be nice if the search worked better though.

Nope, its ok if you go faster, 8- 10 is just the lowest speed that they will open at. I usually back out of the driveway and up the street a little bit, then drive into the driveway and I can get started right away.

Very nice. That's a pretty kickass trick:chug:

The Motive is definitely NOT a diaphragm bleeder - essentially, it is a modified pesticide sprayer.

FWIW, I've never had problems with introducing air bubbles into my brakes or clutch with it - it operates at a pretty low pressure.

Yes, maybe the Motive is a modified pesticide sprayer... it would cost me more than $60 in time to chase down all the needed bits and to hack into my wife's pesticide sprayer when instead I could be cruising to the beach with her... :nod: so in my mind I saved time and money... :cheers:

And some of us don't have assistants to help with. :nod:

I operate mine at 10 psi, that's all you need, and I have swapped/bled my brake fluid in a quick/efficient manner and have never had problems with air being dissolved into the brake fluid (this only happens at higher pressure).

I wouldn't use an air compressor for several reasons:
- if you mis-adjust the regulator, you will blow the reservoir apart,
- without a diaphragm (like was suggested), you may introduce water into the brake fluid.

Thanks for allowing me my comments...
:cheers:

...

I found the thread, dude:D

http://www.ls1tech.com/forums/10718488-post6.html

Good job finding the link, thanks... :cheers:

Joe,

I understand where you're coming from. I wasn't suggesting to make one out of a sprayer...just that is what it looked like to me. I wouldn't go making one either. Regarding aeration, pressure isn't a factor. Most sprayers actually pump air through the fluid as well as have a mixer paddle. The pump is in the center and has a check valve at the bottom of the pump which is submerged into the fluid. When it's pumped, you're creating air bubbles. Correctly designed pressure tanks use a diaphragm whereas air is separate from the fluid.

Though I'm not suggesting this either but it a compressor would work...Condensation shouldn't be a concern as the compressor wouldn't need cycled. The amount of air volume needed would be about the volume of a large balloon. Running it through a filter would take care of water anyways. No different than painting a car. If you already had the compressor setup, a quick disconnect male fitting, female union, seal and an extra cap would be all that is needed...these are easily located at the auto parts store.

If I had to choose between the two, I'd probably pick the air compressor method. The best method is using a diaphragm bleeder, the two man method is probably most convenient. Regarding not having another person, that is what you're wife is there for....if you're just changing the fluid, its about an hour job with another person. The wife just has to push and hold until you tell her to release...she shouldn't be getting dirty:-).

Have a great day guys!

Steve,

Oh, I see what you're saying... (about sprayer and about compressor).

So the sprayer may introduce bubbles by means of the pump mechanism... I'll take a closer look at mine... (...I'm always learning, I'm glad I spoke up...:D)

Can the sprayer be modified to have a diaphragm...?

Yeah, my Mrs has helped me before... it doesn't work too well, lol, she thinks it's a social event "yak, yak, yak, are you listening, yak, yak, yak"...:owned:...having a one-person method = priceless... :D

Correct. Typically when you create air bubbles, you're aerating the fluid.

A basic example would be a fish tank pump aerating the water to add oxygen for the fish to breath.

In your setup, you probably are aerating the fluid (assuming the pump works as the same fashion as other pesticide pumps). Granted, you're probably drawing the fluid from the bottom of the tank...air bubbles would eventually rise. I'm just thinking out loud at this point.

I think attempting to modify your current pump would not be worth the time or effort for reasoning as you've discussed previously. If it is working for you, that is what matters most. The diaphragm style pump is realistically the best method assuming you want a pressurized system. I've never attempted to use an air compressor as I've discussed...but it should work as well and much less expensive (for the folks who pinching pennies). The key to using a compressor would be ensuring you do not run out of fluid from the master cylinder. You could probably bleed two calipers before removing the cap and adding fluid again.

Ok, i went to do the thing today where you drive the car above 10 mph and turn the key off but leave the engine on then it hit me......how in the world would that work? You have to turn the key off to stop the engine on our cars AFAIK. Did I miss something? Well I went on to try gravity bleeding the brakes and cycled the ABS occasionally while doing so hoping that would cause any air to be pushed through. Well if it did its somewhere else in the system now because the pedal is still spongy but not quite as bad. I'm gonna try bleeding the ABS and bleeding the system again tomorrow and see if that fixes it. Steve, your ABS delete kits are really looking attractive.:D

Ok, i went to do the thing today where you drive the car above 10 mph and turn the key off but leave the engine on then it hit me......how in the world would that work? You have to turn the key off to stop the engine on our cars AFAIK. Did I miss something? Well I went on to try gravity bleeding the brakes and cycled the ABS occasionally while doing so hoping that would cause any air to be pushed through. Well if it did its somewhere else in the system now because the pedal is still spongy but not quite as bad. I'm gonna try bleeding the ABS and bleeding the system again tomorrow and see if that fixes it. Steve, your ABS delete kits are really looking attractive.:D

If you SLOWLY turn the key in the off direction, the car will shut off but everything else will be lit up and still "on". You dont even have to bring the key back to a "click" aka the next position. Then wait a second or 2 and return the key to the on position and it will be good to go.