Draining old brake fluid

I am about to switch the brake fluid but I am a bit confused how to get the old brake fluid out of the brake fluid reservoir. I removed the lid and the strainer underneith but there is still the floater and some plastic parts making it very hard to put a hose in there. Is it possible to remove more stuff or do I need a very thin hose to be able to drain the brake fluid? Robert

You just bleed it out of the calipers. Keep topping it off until the fluid comes clear.

If it isn't clear from the above, you will never have 'empty' brake lines. When bleeding the brakes, you push out the old fluid with the new fluid until it is completely replaced... Wayne over on the Pelican board just posted up a collection of technical how-to articles for the 996, including one on bleeding brakes. Pelican tech articles here

Not a porsche, but the same process (ignore the clutch part). http://lambodiy.blogspot.com/p/bleed-brakes.html

Robo, I drilled a hole in the lid and pressurised carefully and drained it out that way. Keep topping up and after half a litre or so, I coyld see the new fluid. Started at the back outwards side of caliper and then forwards closer and closer. Just make sure it never goes dry...but the reservoir has quite a large volume. New lid required afterwards. Save the old for next time

Ok, thanks. I was aware of that I have to bleed each brake caliper to remove the old brake fluid from the brake lines. My thought was just that I could empty the reservoir before adding new brake fluid and start bleeding by putting a hose in the reservoir and suck it up. It just seems safer compared to bleeding it out from one caliper since then I wouldn't risk running dry on brake fluid in the reservoir... Robert

I guess you could take a turkey baster and suck some out but the best way is to bleed the brakes with a power bleeder and go from caliper to caliper. That is the only way to be sure all the old fluid is out. And don't forget the caliper and bleeder screw sequence order.

Robert, its fairly large and I was worried too, but drain away half a cup at a time and check the reservoir, then you see how "fast" you drain it and build confidence. Start by topping it up the cap level. Sometimes seeing new from old fluid is hard, usually there is a small colour difference. Bleed the outside caliper first, then the inner. Do right rear, left rear, right front and finally left front. After one week, Porsche dealer has still not been able to supply a new cap...I should have ordered online instead no panic, old one is sealed up but still... Mike

Motive speed bleeder is $55. Worth every penny.

I know exactly what you are trying to do. These are the tools I use. The trick is to attach a short skinny straw from a juice box, which will pass through the plastic slot to suck fluid from the bottom of the reservoir. Make sure you dont suck too much to introduce air into the ports. You will see new fluid coming out from the calipers MUCH faster with this method.

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YES! That is exactly what I mean! Where did you find the "tool" bottommost in your picture? Is it from a car part dealer? Or is it generally used for something else? I couldn't find a small enough "tool" to suck up the brake fluid at my dealer... Robert

I got it from eBay...just search for "ear syringe" 4oz, $10. I just pasti dip the rings, easier on my fingers. It works really well. The soap dispenser actually served me well for 10 yrs and it's free and light. Just use a wide mouth jar to squirt out the fluid.

Search for a post of mine about flushing the brakes. I used a syringe to pull old fluid out then used a power bleeder to refill. Someone had posted numbers for how much to let out of each caliper if the color of old and new fluid is too close to tell. I can't link properly with this app.

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I've been using ATE brake fluid which makes it easy since it comes in both blue and gold. Just keep bleeding until the other brake fluid color comes through.

I've used a turkey baster to remove most of the fluid from the master cylinder then a vacuum bleeder and compressor to draw the fluid out from each of the calipers. It's important to keep the master cylinder full of fluid, and the bleeder I have comes with a little kit that automatically keeps it full.

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this is what I do too

Timely discussion, I just bled my brakes yesterday...or attempted it anyway. First if you have not done it before don't make my rookie oopsie and miss the hidden second bleed valve on each caliper. Per recommendations I purchased a Motive Power Bleeder and found it extremely easy to use. Get the one with the European cap. They are very reasonably priced at $55. With it empty I pumped up to 20psi then opened the rear right caliper bleed valve and bled until the fluid in the reservoir was about empty but not completely so as to introduce air. From there I filled the Motive with fluid and proceeded. There are plenty of youtube videos on the Motive if you are curious what it is and how to work it. Something else I found is if you can get a small tube, there is a slot on the aft side bottom of the insert in the reservoir that it will fit into and go to the bottom. From there you could always siphon the fluid out.

Nice info. I am borrowing a friend's pressure system to do my brakes next weekend, so this is really helpful.

No turkey baster will fit in the 996 reservoir. I use a Motive, and alternate Blue/ Gold also. But I bleed the old fluid out the front driver side caliper. Why drive the old fluid out the back? You can easily see the reservoir while doing the front, and then add new fluid and bleed the front until color change. THEN do the normal sequence, and a short re-bleed of the front if you are worried.

I believe the capacity of our cars is somewhere in the neighborhood of 400-600ml. can't remember specifically off the top of my head. when i flush I will use one of THESE and bleed 2 500ml bottles through the system. Brake fluid is relatively cheap, and this is an uber easy way to go about flushing the system. Plug in air hose, put nipple on bleeder valve, crack the valve, keep reservoir topped of, close valve, change caliper, repeat.

+1 on the Mityvac kit. Works great and makes bleeding (both sides of the calipers) very easy. They have a kit to keep the master cylinder full while bleeding making it even easier still.

My 2$ worth, use the syringe with a small flexible tube as described and a pressure bleeder, pressure bleeder is better than vacuum in my opinion, it forces any air through the system and don't forget to do the clutch as well, all part of the same system

I really don't understand why people just don't pump the old brake fluid through the brake lines and out the calipers. Amazing something so trivial has already taken two pages of discussion. My $.02

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Concur. Bled mine last week. The wife got to spend some quality time with the car pushing the pedal up and down. I am also using ATE blue.

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+1 The rest is a waste of time. fun story: I did a brake job on my dad's '07 Tahoe that had ~ 95k miles on original brakes. Below is what the rear fluid looked like after a few seconds of air came out of the bleeder. I definitely didn't need Motul blue to decipher the new and old fluid. lol

oops double post

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I agree to an extent, I use a vacuum bleeder since I can do it myself without an extra person pumping pedals, and it is a lot less messy. otherwise like you said, new in the top, old out the bleeders. As far as the brake fluid in your fathers tahoe being easy to differentiate,yes that is, bu for those of us that do flushes more regularly it can be a little more difficult to differentiate. I do mine usually once a year or so in my P-car since I tend to drive on it hard, then every 2 years on my and my fiances other vehicles.

For me, my wife doesnt really want to sit there an hour pumping away (if I get an hour's worth of quality one-on-one time with her I want her pumping something else if you know what I mean )). secondly, creating a vacuum usually means it sucks air in the threads on the bleeeders. Never been able to get that to work reliably to ensure no air in system. Ymmv and .02c yada yada Mike

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Oh yes, for all my cars I go between Motul & Motul blue for ease of bleeding since I change it so often. I had ordered blue for my cars and figured I would make life easy on myself and give the Tahoe some good fluid (vs. some cheap over the shelf fluid) and go blue. Definitely wasn't necessary.

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Motul on a Tahoe? Man you have the $500 Monster Speaker Cable syndrome. j/k

The typical brake system fluid capacity is less than 500 mL (16.9 oz) and you should be able to complete a full flush/fill with 1 liter of fluid. That said IMHO it's not a bad idea to 1.5 liters (3 bottles of Motul, AP Racing, Torque RT700, etc) on had just in case you need a little more than 1 liter. Much easier to have an extra bottle that doesn't get opened than to get almost done and find you're a little short. I would suggest that spending a bit extra on fluid for the Tahoe is not at all analogous to the "Monster Cable Syndrome." There are some very real advantages to a higher performance brake fluid in terms of the lifecycle of the fluid, the additive package of the brake fluid and the overall system health and longevity. Particularly if the Tahoe is being used as a tow vehicle. No body (or very few) questions a person spending a bit more on using a premium motor oil to increase engine life and internal component longevity but folks never to seem to have the same thought process when it comes to the brakes. Just my $0.02

There's a difference in how and what applications the various brake fluid manufacturer and formulas are targeted for. I've generally found that high performance fluid like Motul and high end Castrol has excellent boiling points but sacrifice a bit of the moisture resistance found in other brake fluids. It's fine if you plan to flush it more often but the typical person will only flush it every few years or never. In this case, I'd rather have those people use a nice OTS brake fluid that will not absorb moisture as much. my $.02

Just to make you guys think.....we all know that the 996 Carrera (C2) bleeds at rt rear, left rear, right front than left front. In my Porsche Work Shop Manual it says to do the C4 rt rear, left rear, left front and rt front. Now why would that be?

@alpine003 there is a serious misconception about the rate moisture uptake by brake fluid with the only real difference in the uptake rate being between DOT 3 vs DOT 4 brake fluids. i.e. for a given time period a DOT 4 will uptake slightly more moisture than a DOT 3 under the exact same conditions. That said the DOT 4 fluid will still have/maintain higher performance characteristics than the DOT 3 fluid. Although none of the major brake fluids state this, the acceptable shelf life of a DOT 4 fluid is 24 months and all the European auto mfgr's that I'm familiar with state the change interval for the is also 24 months. While I can't state that this will not happen, the possibility of a DOT 4 fluid to have enough moisture uptake to result in it denigrating in performance to that of it's stated Wet Boiling point is extremely slim. Brake fluid just doesn't absorb moisture that fast. All that said, I would suggest the idea that you want the brake fluid to have a reduced rate of moisture uptake is completely wrong. In fact you DO want the brake fluid to uptake moisture as quickly as possible. The reality is every braking system will allow moisture in. If the brake fluid doesn't absorb the moisture (as in the case of a DOT 5 SBBF will do) the moisture would sit there, separate from the fluid, creating a potential opportunity for premature boiling. Brake fluid should uptake the moisture as quickly as possible so as maintain the highest performance of the fluid/system. I know this will seem to go counter to the conventional wisdom however I would suggest the conventional wisdom is a bit mis-guided. Even in a high humidity environment scenario the brake fluid just isn't going to absorb enough moisture and will not absorb fast enough for the rate of uptake to become a mission critical impairment

I see what you're saying but given the moisture is not as detrimental in making a car stop, the same thing can be said for having high boiling point fluid for normall street vehicles. Sure there might be those few times when you could maybe benefit from it. Even in towing situations, unless you are panic stopping at every stop light, I just don't see the use of exotic or high end brake fluid making much of a difference, especially since on the road your tires are likely to be the bottleneck. Look at all those Tow Trucks/Busses/Semi's using "regular" brake fluid and they are doing just fine. For me personally, I think it's a bit wasteful and/or unneeded to be putting exotic or boutique high end brake fluid in anything but racing or high performance cars.

@alpine003 Thx for your thoughts. I would submit this debate and your viewpoint is much akin to the non-car people out there that believe washing the car once every 3-6 months and a wax job from the drive through car-wash once a year is sufficient to keep their car looking "decent." However I would bet that most of us car-guys in the P-car community shudder at the thought of maintaining our cars' finish in such a relaxed manner. We know that 30 yr old P cars can still look great with the original paint if quality car care products are used with care, diligence and on a frequent schedule. In the same manner the above example will play a role in the longevity and quality of the auto's appearance over time, the quality of the additive package in the brake fluid (which has a significant impact on the fluid's resistance to corrosion, resistance to the fluid going acidic [in many fluids going even more acidic] lubricity, low temperature viscosity, etc.) will determine how the lifecycle of the EPDM of the caliper's pressure seals. i.e. when do you need to rebuild the calipers or in a more dramatic fashion, when does the brake pedal go to the floor because the seals will no longer seal the pistons? The same goes for the engine oil. I'll bet you don't use the AutoZone $3.99/qt 10W-40 for your Tahoe. And yet consider all the fleet vehicles that are maintained with the least expensive fluids available. That doesn't mean that using the cheap stuff is in the best performance and/or longevity interests of the vehicle. Just my thoughts...

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No one said anything about Autozone but yes I do use "Walfed" from Walgreens. I also don't mind using OTS Valvoline or Prestone brake fluid for street cars. I think they'll survive. FWIW, I'm still on original calipers without any rebuilds on my '74 BMW as well using the "regular" stuff. But this is a Porsche forum and we all like to overthink, over engineer, over use parts and such. That is the enthusiasts way.