replacing brake fluid

[philippeF]

Hi all
How shall i replace my braking fluid ?
what is the volume to replace ?

(with an unaccurate english....)

Many thanks
Philippe
from France.

[atlporsche]

Not being sure of how knowledgeable on car maintenance you are I will make this very basic.

Get a friend to help with this (spouses/girlfriends work great)

Open the reservoir that holds the reserve fluid. fill it full with the new fluid.

Each caliper has a two bleed valves on it. You will need to open an close these valves as we go (picture help someone?)

Start with the wheel that's farthest from the master cylinder. (usually the passenger side rear) Connect a hose to the nipple on the valve. You will need a wrench to open and close the valve. With your spouse/girlfriend in the driver seat have them press on the brake pedal, then with them pressing the pedal down, open the valve, watch fluid run into the hose (and a catch can) The fluid should be murky and brown. Repeat until the fluid appears fresh (like the new fluid you put in the reservoir).

Periodically check the level of fluid in the reservoir. This is VERY IMPORTANT. if you let the reservoir run dry, you have to start over.

Do the outside valve first then the inside valve.

Repeat for the next farthest wheel (drivers rear) then passenger front, then driver front.

if you have any questions or need clarification, let me know.

steve

[atlporsche]

you'll need about 750 ml...

sjd

[Rot 911]

Or obtain the following:
One Motive Power Bleeder, which can be found here:http://www.pelicanparts.com/cgi-bin/autocat/load_page.cgi?page_number=1&bookmark=3&model=911E&currsection=brakes

One can ATE Blue brake fluid.

Using the power bleeder (and once you have one you will never go back to bleeding the brakes any other way) push the new blue fluid thru each brake line until you see the blue fluid come out each wheel cylinder. That way you know you have flushed all the old fluid out of the system.

[sammyg2]

750 ml sounds about right, I know I can do the whole job with a liter and have a little left over. Just go until the stuff cleans up. On mine I used a turkey baster (old one, not the wife's) and sucked out the old fluid from the reservoir first, no sense pumping old fluid through the system if you don't have to.

[Glasgow 911SC]

just expanding the theme a bit. In Wayne's 101 projects, he states that silicone fluid isn't recommended for street use but in various magazines it has been highly recommended (paint safe, no moisture etc). What are the problems with using it?

[makaio]

I believe the reason DOT 5 (silicon) is not recommended is it absorbs water more easily than type 3 or 4. . THat's what I have heard at least.

[ChrisBennet]

Philippe,
To bleed your brakes by hand you'll need a partner:
1. Remove as much of the old fluid as you can first. A turkey baster (like a giant eye dropper) works well for this.
2. Fill reservoir with new fluid. Here in the US, Castrol LMA and Valvoline SynPower are good choices for daily drivers. The SynPower is synthetic but it is not silicone. Silicone=bad.
3. Put a BOX WRENCH on the brake caliper "bleeder" nipple. Place one end of a tube over the nipple and the other end in a bottle to catch the used fluid. Start with caliper furthest from master cylinder.
4. Have the "Driver" press gently on brake pedal and then say "Open".
5. "Bleeder" opens/loosens bleeder nipple and watches fluid come out.
6. Driver presses brake pedal down slowly and when pedal is near floor, stops moving pedal and says "Close".
(Don't press pedal all the way to floor. Don't press pedal fast or hard.)
7 "Bleeder" closes bleeder and says "OK, pump again"
8 Driver gives pedal a couple of pumps and then repeats steps starting at #4.

Continually check level of brake fluid in master cylinder.
Bleeder nipple do not have to be very tight. Tighten them like you would tighten a faucet.

Why this way?
You don't want to make the master cylinder operate at the end of its travel in the part of the bore that doesn't get used because it may be corroded or pitted and this will tear or scratch the rubber seals. The only way this can be avoided is for the "Driver" to control the process. Only the driver knows the position of the brake pedal. An added benefit of this method it that if you are having the wife press the pedal she can tell you what to do so your aren't going against the normal chain of command.
If you press the brake pedal fast you can cause cavitation in the fluid i.e. make bubbles in the fluid.

-Chris

[sammyg2]

I heard the DOT5 (silicone based) brake fluid is non-hydroscopic so that it does not absorbe moisture, but it feels ""spongy". Never used it, just what I've heard. Sounds like someone is telling us a story :-)

[ChrisBennet]

Originally posted by sammyg2
I heard the DOT5 (silicone based) brake fluid is non-hydroscopic so that it does not absorbe moisture, but it feels ""spongy". Never used it, just what I've heard. Sounds like someone is telling us a story :-)

Normal brake fluid is hygroscopic (attracts moisture).
Silicone brake fluid is synthetic but sythetic fluid is not necessarily silicone. Castrol SynPower (and I'm guessing Motul 5.1) are non-silicone synthetics. They are referred to as a "DOT 5.1" fluids.
Silicone is non-hygroscopic which is nice because it can sit for years at a time in a brake system. This makes it great for Army trucks being stored for years for example.
Silicone has a couple of bad characteristics. It (supposedly) will trap moisture in a system that previously used "normal" brake fluid causing corrosion. It (supposedly) is also is harder to bleed. I guess the "champagne" bubbles tend stay suspended in it.
-Chris

[Superman]

Pressure bleeders are the best. Vacuum bleeders are next. Both can be operated by one person alone. If you've never done this, it might be best if you can find a friend to help, who has done it before.

One more tip: To save time, get a cheap or discarded turkey baster (clear plastic tube with a rubber bulb at one end, used to suck drippings out of baking pans for turkeys, roasts, etc), and suck most of the fluid out of the reservoir first. Be careful not to such so much out that air is allowed down into the brake master cylinder. Carefully fill the reservoir with fresh fluid before you begin. Mark the baster with the word "POISON," or perhaps the french equivalent, and place it in a box with brake bleeding tools.

[billwagnon]

I tried a pressure bleeder (it was my dad's). It forced brake fluid out the overflow tube on the reservoir - what was I doing wrong?

[sammyg2]

Thanks for the correction, Hygroscopic. Gotta remember that.

Billwagnon, The reason your overflow tube puked out fluid when you used a pressure bleeder is because that's what it's supposed to do. You need to do one of two things:
either plug off the breather hose during pressure bleeding, or use it to pressure bleed the system. I haven't done the second method, but the way it was decribed was to put some plastic wrap or something under the cap to completely seal it and then hook up the pressure bleeder to the hose.

[Gordo2]

Having recently bought the Motive Powerbleeder and purged mine I have to say buy one, you will be amazed and will sing it's praises as well.

I haven't bled brakes in years because I used to dread it. This thing couldn't make it any easier.

I will let you know how the Casterol DOT 5 holds up after I run it for a year or so. I didn't research and bought what looked like the best (I'm a sucker for marketing and name brands).

I think the ATE blue would be nice for my next change. The stuff I put in was clear, I think the old stuff was gold (darker color). I ended up running a bunch of fluid through my system (1 & 1/2 of the big brake fluid containers) just to be sure.

Gordo

[old seventy six]

After all the technical information this may sound strange but the best way to learn to bleed brakes or do other basic maintenance is to ask the local Porsche club for help. You'll probably get lots of volunteers who'll gladly show you. Once you've seen it done it's easy.

[philippeF]

Thanks for your feedback, all

clear and accurate.........

regards from France

Philippe

[s_wilwerding]

Does anyone have any experience with the Speed Bleeders that Wayne sells on this site (the bleeders with check valves so you can do the bleeding w/o assistance)? Would anyone have reason to believe that they would fail?

I don't know if I'm comfortable having a check valve in my brakes, but if anyone else has good experience with these, I may give them a try.

[Greg White]

OK areal basic question? Do you have to jack up the car and remove the wheels, or can you do this job with the wheels on?
Greg realbeginner White

[s_wilwerding]

Originally posted by Greg White
OK areal basic question? Do you have to jack up the car and remove the wheels, or can you do this job with the wheels on?
Greg realbeginner White

I believe you can do the front wheels just by turning the steering wheel all the way over in one direction. I believe you have to take the back wheels off.