Coolant System questions - post leak

Hey guys, I have some questions on the coolant system on my '99 996 C2. A few days ago, I had some straight-road fun in my car (The Maxflo mufflers are pure-pleasure ) and then soon I saw the LED at the higher end of temp. gauge blink. I looked up the manual and it said about low coolant level or the fan not working. And then shortly after getting home, I noticed that the car had wet itself with the Green stuff. It was dripping profusely around the driver side rear wheel, and on the driver's side exhaust. The engine temperature was higher than normal, but not alarming. I waited for the engine to cool down and opened the coolant expansion tank to confirm that it was indeed the coolant that leaked. It looked as if the coolant had leaked out from the expansion tank opening as there was spillage around the opening on top. I had lost ~1.5 litres of coolant and refilled it with distilled water. I suppose this shouldn't affect the concentration a lot. I did some driving (mostly highway) after filling with water and found the temperature to be steady, normal and the red blinking LED vanished. However I am getting a solid red light before starting the car (Ignition key position) and it goes away when I start the engine. I will have to get the car serviced in a while as part of regular maintenance. I did read through some older threads in this issue and had some questions. I had this issue occur previously after a spirited drive a few months ago too, and I had to refill ~3/4th litre with distilled water. Also there was a scheduled maintenance done shortly after that which flushed and replaced the coolant. To me it looked as if the coolant had escaped out of the opening (cap). If the cooling system is a pressure-operated one, which I am most certain it is, then could the increase in pressure be the reason to trigger the leak? My expansion tank looks to be stock, so does the tank's cap. I have read in other threads that these 2 components do seem to wear off (cracks etc). I don't know if my cap is the updated model or the old one. Mine is blue (I don't think its colour-coded) and I'll have to check for the part number to know. Is flushing the coolant a DIY job. Can it be compared to an oil-change in terms of complexity? I suppose it would be easier on my mind to flush and use the same Green coolant (which is the old coolant I believe - need to know where to buy this). I also remember reading somewhere that its a 50-50 mix of coolant and distilled water. I will need to address this issue of the leak sooner or later, or I am not going to be able to explore the higher rpm's :P So if the tank will have to be replaced, how complex would that be? DIY job? Thanks in advance for your replies. Happy Holidays folks! Shyam

IIRC, the 99-01 tanks are more expensive (250+ vs 02+ 996's), the engine can be lowered just a bit to be able to replace it. The coolant tank cap should end in 03- or -04 to indicate the newer version. If yours ends in -00 or -01 then it's the older version which tends to allow coolant to slowly leak out when under pressure. Porsche coolant is not cheap, I'm not sure if the Audi/VW coolant could be used. I used to keep a close eye if the temps on my C2 used to creep up in traffic. I'd turn on the AC and could hear the front fans start to run and temps would slowly creep down. Also, if your front condenser/radiator area has debris clogging the fins, overheating is inevitable, even if you're running on open roads and not allowing good airflow up front. FWIW, I replaced the coolant cap on my 00 C2 cab, but paid my indi to change out the yellowing tank and refill the coolant and check the system. No probs after that.

You should: (1) refill to the proper level and monitor, (2) find the leak, could be the cap or the expansion tank, or one of the hoses on the left side of the engine, (3) don't waste your money on a flush and refill until you find the cause of the leak...there is always a reason and you have to find it, (4) to speed things up have it pressure tested, replace the faulty part, then follow the procedures for flushing and vacuum filling. Good luck!

Thanks a lot guys. My coolant expansion tank cap was the old model (00). I have ordered the new updated cap from Pelican Parts. I had refilled the tank with distilled water soon after the leak. I haven't pushed the car after that, only regular driving. Everything seems alright now. Temperatures are within limits, and I don't feel any degradation in performance as well (shouldn't expect any). The coolant stuff that leaked was green in colour, but the stuff in the tank now (after a few drives and the water and existing coolant having mixed well) is yellow. Is that how it is supposed to be? I'm a DIY guy within my capabilities - I certainly cannot lower the engine and then replace the tank by myself (if the tank is found to be the culprit). I'll get the coolant system checked up when the car goes in for its maintenance.

Once again, thanks for your inputs guys. It is the coolant expansion tank that has cracks. I replaced the coolant cap, and still there was some amount of dripping, but much lesser than before. So looks like the old cap was also an issue. I am getting the tank replaced, coolant flushed and in the meantime, will also check the radiator grille for debris collected over Fall last year

while at the shop, have them "pressure test" the cooling system to make sure hoses/lines, pump, etc. are fine

When you change the tank make sure you flush the coolant and change it to the "new pink". Pentofrost is a staggering $46 per gallon but the best out there. Dont buy into the "use any antifreeze" BS. I just completed a total coolant system flush on my 996 because I know "lifetime" coolant is nonsense (4 or 5 years max). Not that hard to DIY really. Im posting the 996 coolant flush with Airlift DIY on Renntech.org now.

Karazyk, thanks for the DIY stuff you've been posting. It is very much appreciated.

Shy and Key, Thank you for the kind words. My DIY coolant flush and vacuum fill is here on Renntech. http://www.renntech.org/forums/tutor...6-maintenance/ (you may not be able to see it until its approved by admin) Hope its ok to mention renntech?

@kromdom - yes the test came back fine. It was just the tank (possibly the cap also, which I replaced anyways) @KrazyK - thanks for the DIY posts And yes, I am having the coolant flushed. My car had the green coolant - stuff that the factory used to use years ago, esp in Europe; or its prolly some generic antifreeze that the prev. owner chose to use Either ways, I am getting it updated it to the latest pink stuff.

Quotes source post: 10117820

Factory fill was always a pink color (Pentosin G12, now known as Pentofrost SF). Here's another how to posted by myself: https://rennlist.com/forums/996-foru...-question.html

MM, I believe factory fill was yellow for awhile before pink. Either way mine now has the nice new pink stuff from Pentosin. Nice writeup BTW but maybe misplaced. They are harder to locate if not in a dedicated thread/forum. Check out Renntech when you can.

Quotes source post: 10118155

Renntech has helped me through quite a bit, although I've only recently gotten into "passing-it-on" as far as knowledge goes. I may end up posting a few things, but I always forget to take pictures and when I'm done, I'm done (I'm not going to redo the work for pictures sake). I think I should try harder.

Yes, I too read in a few places that the factory used to have the Green/ Yellow-Green coolant until a few years ago. Apparently, the green dye they used had some not-so-green stuff. Quite a few old cars had the green coolant as stock until Porsche switched to the new one. That said, guys at the shop (Powertech) were stumped when they saw that my car had the green one.