nighthawk15

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?

coolformula

iTrader: (21)

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....

MeentSS02

iTrader: (11)

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/prod...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.

Sam Strano

iTrader: (41)

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.

MeentSS02

iTrader: (11)

...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

Oops - good thing I don't have ABS anymore

EchoMirage

iTrader: (3)

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.

smokin97

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)

WhiteRhino

iTrader: (6)

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/

nighthawk15

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?

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

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!

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.

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.

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.

nighthawk15

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.

smokin97

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

MeentSS02

iTrader: (11)

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).

MeentSS02

iTrader: (11)

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

nighthawk15

Well I guess that's another possibility.

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.

ws6pewter

iTrader: (1)

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!

joecar

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.

RedZ99

iTrader: (1)

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.

nighthawk15

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 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.

mitchntx

iTrader: (14)

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 ...

RedZ99

iTrader: (1)

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.