coolant flush

guys My 03 996 C4S is more than 4 years old therefore I think it's time for coolant and brake fluid flush?? I went to the Porsche dealer to get the factory anti-freeze they told me I only needed 1 gallon??? However the manual states capacity almost 6 gallons?? Has anyone had coolant service done on their car and can confirm the quantity?? Thanks Bill

Uh oh! Get ready for the "lifetime coolant" flush debate to start up....

And you need a PST2 to flush the brake fluid properly.

Unless of course you go through brake fluid as much as us track rats!

3 gallons of antifreeze (100%) is all you need, You do not need to buy the Porsche coolant as there are plenty of other brands, such as PEAK Lifetime which work just as well and is fully compatable with what is in your car. 6 gallons of 50/50 is the easiest. You do not need a PST2 to change the brake fluid. Pressure flush works best.

To get new fluid throughout the ABS system you do.

You must be really misinformed then. Care to share who told you that a specific amount of fluid stays there and is NEVER circulated to the rest of the system at any time?

Thank you, I pride myself on being as misinformed as possible. The shop manual says it's part of a brake fluid flush. (although in my car the ABS and PSM is active so much of the time the fluid must be circulating plenty)

Actually the manual says that it's part of bleeding the breaks of if you introduce air into the system during the replacement of major components. It doesn't not state that it is required during a brake fluid flush.

No need to be a smart ***. Make sure you believe EVERYTHING the shop manual says. Remember, the shop manual is prepared for those people that have all those fancy computers (PST2 or PIWIS) at their disposal. I wonde how those of us that are DIY'er ever get anything done properly???

Not being a smart ***, just reacting to an unnecessary insult.

I didn't read carefully enough. Now I understand better.

If you think that is an insult you have some seriously thn skin when you are corrected for being incorrect. Enjoy Time to unsubscribe to this thread.

If you fill the reservoir with a different color of fluid and the fluid changes color at the caliper bleeders as you pressure bleed them, you know it is flushed completely through the system. That is the proof of a complete fluid change/flush.

That is simply not true with an ABS system.

And, just WHY is it different with ABS?

Because in the normal steady state of the system, the valving in the ABS modulator is such fluid passes from the master cylinder to the wheel cylinders, bypassing a maze of twisty little passages in the modulator. If the ABS is never activated there are places in there where the fluid could be sitting for years.

And you can't think of a simple solution to this?

Sure, get the ABS to exercise itself or use the PST2.

But that wasn't my point. I was simply saying this post wasn't completely correct in the context of ABS:

Wow, I am confused now. So the PST2 opens the ABS tracts and releases old fluids?

1999Porsche911 is correct in saying that you only need 3 gallons of the stuff IMHO I only like to use what porsche approves... If you go to your VW/Audi dealer you can pick up the same coolant that porsche uses and its half the price. G12 coolant (Red/pink color) from VW/audi part dept. Total cost was $58 for 3 gallons of the stuff. The C4 holds 5.95 gallons of the coolant

I've tried to attach a diagram of an ABS fluid circuit. It's a Bosch system, but I don't know which one. I added a blue line to show the flow from master cylinder to caliper when the system is in the idle state. Bill

I changed my brake fluid two years ago using a Motive Power Bleeder. http://www.motiveproducts.com/ Used instructions per shop manual. Worked like a champ. Don't forget to bleed clutch as well. It is part of the same system. Easy

I thought the ABS just blocks the input side of the fluid with valves, when in it is in a static state, it is completly open and fluid passes right through without residual fluid trapped?

Just in case you're counting votes (I don't really want to debate it), I flush and fill both coolant and brake fluid every two years on my cars. Brake fluid is affected more by age than mileage, and on low mileage cars that sit a lot, its hydrophilic property can cause decay in the lines and poorer brake performance (since water doesn't behave the way brake fluid does under pressure). If your car has not had brake fluid replaced in, say, four years, I'll bet a case of beer you can feel the difference through the pedal when you do it. Seriously. I use whatever stupid expensive Gucci performance brake fluid my indy recommends because I am an idiot. For coolant, I use Porsche's product. The reason is that it's simple, frankly. As Land Rover owners know, inadvertently mixing the wrong kinds of anti-freezes can cause the coolant to gel. I'm sure lots of you guys are smart enough to avoid this, but I just can't be bothered honestly.

guys Thank you all for all the info!!! I am now a bit confused with ABS PSM involvong brake flush, I thought the instruction from Renntech diy was straight forward. And it mentioned all we need is one liter for brake fluid. As for the coolant most of you recoomend 3 gallons mixing with water for 50/50 total 6 gallons. Do most of you really believe lifetime coolant on these cars??? Hard to accept!! Thanks Bill

Just follow the DYI and move on. No worries. The is no such thing as a lifetime coolant in any internal combustion engine. Leave it in long enough and your metal outlets will clog and/or the acid will eat through your engine. Use whatever coolant is convenient for you. I use the 50/50 Peak Lifetime as it 100% compatable, saves time and is as good as and a fraction of the exaggerated price of Porsche's coolant. If you would use it in your Honda or Toyota or any other late model car, it is more than good enough for your Porsche.

I personally do not open the valves in the ABS when I flush and bleed my brakes/clutch - and I own a PST2. I really don't think it is needed unless the system has had a leak and drawn in air. Or, unless you are changing to a synthetic brake fluid - where you really do want to replace "all" the fluid in the system. The coolant question and discussion can go on forever - I think if your system has been kept closed and is not contaminated in any way - then your coolant likely does not need to be changed for maybe 100,000 miles. This newer organic coolant is very good stuff. All this IMHO of course...

What "newer organic coolant" doest thou refer Loren?

wrljet, do you know what the letters in the diagram stand for? (v=valve?). After all, you made us look at it.

From the 1999 introduction of the 996 Carrera. "The implementation of a special coolant means that the coolant does not have to be changed. It must be ensured that only the coolant prescribe by Porsche is used." And from Scott Slausen on the PCA website. "Modern antifreeze is 96-percent ethylene glycol, which provides the freeze protection, and four-percent additives. The antifreeze protection is Lifetime on a sealed system. The breakdown can occur within the additives. Silicate antifreezes tend to breakdown at a faster rate than the OAT's (organic acid technology). You used to tell the difference in the two by the color. The OAT's were red and the Silicates were green. However now many manufactures like Porsche use a Hybrid OAT coolant. These coolants come in many colors , such as red, green and pink. So while they may all be 96-percent the same the other 4-percent makes all the difference. You should only top off the coolant system with Porsche coolant or distilled water. The only time the coolant would be flushed or changed would be do to contamination or engine replacement.. Scott Slauson - PCA WebSite - 5/13/2004"

What if Lifetime to Porsche or any manufacture for that matter means sufficiently past the warranty period to get them in the clear and their dealers more repair business. While keeping their customers reasonably satisfied? I for one change my oil more often than recommended. Much easier than changing engines. Same for coolant. Since brake fluid is more critical to safety I go by Porsche's recommendation since a law suit is just not worth it to them.

Here's an idea on some of it. I made these up, so take it with a grain of salt. Also, while doing the translations I see the circuit diagram I posted is for a diagonal system. I'm sure somebody in a German speaking country with access to Bosch publications could give us the exact terms. EVVL - Einlassventilvordlinks - Inlet valve, front, left EVVR - Einlassventilvordrechts - Inlet valve, front, right EVHL - Einlassventilhindlinks - Inlet valve, rear, left EVHR - Einlassventilhindrechts - Inlet valve, rear, right AVVL - Ablassventilvordlinks - Outlet valve, front, left AVVR - Ablassventilvordrechts - Outlet valve, front, right AVHL - Ablassventilhindlinks - Outlet valve, rear, left AVHR - Ablassventilhindrechts - Outlet valve, rear, right LV - Ladeventil - Loading valve SpK - Speicher / Kammer - Accumulator/reserve chamber sRFP - Selbstandsaugendrueckfahrtpumpe - Self priming return pump D - Druckspeicher - Pressure accumulator DDB - ??? pressure limiting/regulator Bill

Loren So if I decide to replace the coolant you recommend 3 gallons Porsche anti-freeze and 3 gallons distilled water from convinient stores??? Why Renntech.org don't provide instruction for coolant flush??? Thanks

I don't know what a convinient store is, but I can't believe that you would even consider putting in "regular" distilled water in your porsche. My car gets a 50/50 mix of Evian and Dasani.

How about : http://www.gerolsteiner.de/index.php?id=162&flash=1

MJBird993 Thanks for the recommendation on Evian, I'll do that!!!!!!!!!! Bill

In all seriousness, be sure to never ever use mineral water that's sold at grocery stores in the same plain jugs as distilled water. Bill