Three questions re changing brake fluid

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Originally Posted By: artificialist
Originally Posted By: XCELERATIONRULES
I usually use Teflon tape on the bleeder threads to help keep air out during the process.
The only headache is constantly topping off the master cylinder.
The brake system doesn't hold much fluid at all.
Be sure to use the correct fluid,usually dot 3 or 4.
They are all not compatible with each other.

DOT4 can be used to replace DOT3, in fact I find that it lasts much longer in a DOT3 application.

But never put DOT3 in a DOT4 system, or it will easily boil the fluid.


DOT4 fluids have higher dry boiling points than DOT3, but have a steeper decline with moisture than DOT3.
 
I've used a vacuum bleeder and noticed an endless supply of bubbles which I presume is from the bleeder screw threads. Confused, I kept pumping well after clear fluid started coming through. Rock hard pedal when done.
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Missed the start of this thread but suck the MC nearly dry and refill with fresh fluid before you start anything else.
 
The gravity bleed is the easy way. It takes longer, No pumps, PSI needed. Just monitor the reservoir to make sure it has level above the master cyl. Tools needed, Vinyl tube 1/4" ID 12 to 18" long. Wrenches the open bleeder valves. Start with the furthest wheel from the reservoir. A good idea to remove old fluid from reservoir and fill fresh & maintain fluid level at all times. Bottom pistons, open bleeder, tube on bleeder nipple and let drain, a slow process but hands free & spec. equip. or buddies not needed. Do not touch the brake pedal during this process.
 
Originally Posted By: benjamming
DOT4 fluids have higher dry boiling points than DOT3, but have a steeper decline with moisture than DOT3.


The last few new Japanese cars I've bought have all had DOT3 fluid installed from new. I assume they are thinking most owners will not change the fluid regularly and DOT3 allows more consistent performance over the long term.
In this part of the world no one ever changes their brake fluid and it's not always easy to find fresh bottles on the shelves, and it's only DOT4.
 
Originally Posted By: eljefino
I've used a vacuum bleeder and noticed an endless supply of bubbles which I presume is from the bleeder screw threads. Confused, I kept pumping well after clear fluid started coming through. Rock hard pedal when done.
thumbsup2.gif


Missed the start of this thread but suck the MC nearly dry and refill with fresh fluid before you start anything else.


I did that on my Saturn and it resulted in a soft pedal. A pressure bleed sort of solved the problem. I think I'll need to bleed the ABS unit and use the GM automated bleed sequence in order to solve the problem.
 
Originally Posted By: The Critic
I've always used a Motive pressure bleeder.


How do you clean the tank out to use on different vehicles which may use incompatible brake fluids? Or does it just not matter after a good wipe-down with a rag?
 
Originally Posted By: Kiwi_ME
Originally Posted By: benjamming
DOT4 fluids have higher dry boiling points than DOT3, but have a steeper decline with moisture than DOT3.


The last few new Japanese cars I've bought have all had DOT3 fluid installed from new. I assume they are thinking most owners will not change the fluid regularly and DOT3 allows more consistent performance over the long term.
In this part of the world no one ever changes their brake fluid and it's not always easy to find fresh bottles on the shelves, and it's only DOT4.

According to auto books I have read, DOT3 absorbs less moisture, but life experience shows the opposite.

I think what happens is that DOT3 is made from really cheap stuff, and premium stuff goes into DOT4.
 
About how long, ballpark figure would it take to gravity bleed all 4 wheels. Is it something you could complete in one day can you gravity bleed more than one wheel at a time.........thanks
 
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Dot 4 is just better than Dot 3.

Pumping method will lead to failed master cylinder often times.

Remove the old fluid in the resevior with a turkey baster.

Mity vac is the easiest.

You wont be able to change the fluid in your abs pump with out special tools, but I dont think that is such a big deal.
 
Originally Posted By: Winston

Pumping method will lead to failed master cylinder often times.


How's that? The two-person pumping method is what's recommended by the Honda service manual and seems to be the old, tried-and-true method.
 
Originally Posted By: rationull
Originally Posted By: Winston

Pumping method will lead to failed master cylinder often times.


How's that? The two-person pumping method is what's recommended by the Honda service manual and seems to be the old, tried-and-true method.


I think, he’s talking about cases where the fluid was never changed and parts in the master get rusty from moisture. Since in every day operation the pedal doesn’t go all the way to the floor, parts that contact are rust free, but during the two men method flush, the pedal goes all the way to the floor and the corroded parts of in the master cylinder, that never made contact before, are now being forced against each other. This can damage seals, and scratch the mating surfaces which will lead to internal leakage.

But this is only a concern in old and neglected cars, if you do regular fluid changes there is nothing to worry about.
 
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MityVac Fluid Extractor....you can fully remove the brake fluid on all 4 wheels in about 20 minutes.

Attach it to a bleeder, pump it up, open bleeder screw. Then stand by the master cylinder and pour in fluid.

Super easy.
 
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