Losing Coolant. UPDATED

Posted this on Renntech today, but I would love to hear any suggestions from this group as well! *********************** ok, so this is going on a 6 month saga now.... 2004 996 C4S Bought the car in July, Porsche Certified Used. Drove home (across Canada) no issues. Sept...did a PCA autocross event. Car worked flawlessly. Driving home after the event coolant light came on. hmmm, maybe I ran it hot. It was a very cold day though. Topped up the coolant. Couple weeks later, light comes back on. Only seems to lose coolant when the engine is fully warm. Just a tick over the 80 mark (Cdn car) No puddle at my home or work. The saga begins. Porsche replaces the coolant reservoir tank (crack). PHEW. Nope....still leaking. Rate of loss seems to be increasing. A month later, Porsche roadside tows the car to the dealer in Edmonton. (I'm 5 hours away) and they say they will find and fix over xmas break (when I'm home) Get the call that the tech took the front bumper off. Found a ton of debris and crap and that there was coolant on BOTH rads. (outside) They've never seen a car kill both rads at the same time. We'll get back to you. Week later, they tell me the coolant system is holding pressure....no leaking. 4 days after that they say one of the rads has a stress crack. The replace the rad under warranty. The Tech says all is good. Car runs perfect, no leaking. Pick up my car. Drive it home (5 hours)...everything is fine. 4 days later. Coolant light is on. Top it up, open the valve. few days later....light is on again. When driving for prolonged periods now...when the engine is fully hot, I can smell coolant. Can't find from where....to where...its going. DRIVING ME CRAZY! Any other suggestions or tips? PLEASE? sean **************** UPDATE So the Porsche dealer says there is a pressure relief valve on the left front rad, or near the rad. That relief valve has an o-ring and the o-ring is shot. Fixed it in 30 minutes. Then they said they found a second leak by the coolant reservoir tank (which is brand new...so how they didn't see this leak when they replaced the coolant reservoir is beyond me) That is another small part, but they don't have it in stock. They will replace it at the end of the month when I go back to Edmonton for an autoX event. Hopefully (fingers crossed) this is be an end to my coolant issue. At least for the foreseeable future. Next is the IMS retrofit, RMS and AOS replacement. Booking this for mid May. At that point I think I'll finally feel good about my M96's reliability and can really enjoy it again!

Let's see; coolant cap, coolant tank, 2 radiaters...that leaves several coolant hoses that could be the cause. I must be lucky, I recently replaced my coolant tank and the leaks and associated coolant smell has gone away.

if you cant visually find any leaks, open up the bottom plates of the tunnel, there are more coolant lines under there... maybe there is a leak in that area. It is under cpo.... bring it in till you are fully satisfied.

So-they found coolant on outside of both Rads, but only replace one! I bet it's the other one.

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You ski mid-week you are lucky!

I just got back from a day at Loon Mtn. We skied 32,000 vertical feet in under 5 hrs., but the best part is that I got to drive 300 miles round trip in my Porsche, even though it is crusted with salt and dirt. It made my day being able to spend some more time in my lowly water-cooled car. The snow on every single trail was perfect today.

Quotes source post: 8247024

The system holds pressure because the leak is below the coolant level and the leak is very likely a small one and it takes pressure over time to squeeze out enough fluid to lower the level any noticable amount. In the meantime you can smell the bit of coolant that does make it through the hole. The hole can be small. (Noticed a small (<6? spot of coolant) under the front of my Mustang (years ago). Took it to a dealer (in the Salt Lake City area -- I was passing through on a trip). SM called to say the tech finally found the leak in the radiator. A tiny pinhole hole -- on the back (engine) side. The tech 'found' because there was a slight discoloration/stain where the coolant had been leaking out.) (Oh, both the coolant cap on my 02 Boxster and my 03 Turbo developed a leak and had to be replaced. These caps leak and allow over time water vapor to leave the cooling system and the coolant level to drop and it can drop enough over just a few days depending upon how often the car is used, brought up to temperature) that the coolant warning light can come on.) Anyhow, what you can do you help id the source of the leak is with the A/C off drive the car enough to get the engine as hot as you can get it. Stop and go driving, city driving. Highway driving not as good cause too much air flow. You want to try to get the engine hot enough the radiator fans come on. (Roughly, they come on low speed at 212F and high speed at 216F. They shut off when the coolant temp drops below 205F. If you have the A/C on they run all the time and this works to keep the engine coolant from getting as hot as it otherwise would. Leave the A/C off.) You might have to park the car and hold the gas pedal down and bring the rpms up to say 2K and hold the rpms at 2K for a minute or so. You want to hear the fans come on and ideally shut off once to ensure both are working ok. When you hear the fans come again, shut off the engine. The heat load will raise the temperature/pressure of the coolant. If there's a leak you'll find it. (I did this when I suspected a coolant leak in my Boxster. The pressure was enough to finally split the coolant tank and then I knew from where I had been smelling a bit of anti-freeze every once in awhile.) Walk around the car, get down low and sniff around. The area where the anti-freeze smell is the strongest is probably where the leak is. Shine a light in the radiator ducts from the front and behind/underneath the car. Ideally if you can arrange to take the to car to a place that can put the car in the air for you so you can look under the car, up inside the various areas that are covered by paneling, everywhere, this is the best, this gives the best chance of spotting the leak. Use your eyes. Nose. Hearing. You might hear a sizzle as coolant drops on an exhaust manifold. Check all hoses where the connect for any signs of coolant. Check around the water pump. Look carefully at the water pump housing for any whitish stain/deposit that is dried coolant. Open the engine cover and check/sniff around the tank. Tent the tank cap with foil and after a few minutes check for any condensation on the underside of the foil tent. Sincerely, Macster.

I would check the heater coil - the system may hold pressure because the valve to the heater is not open - once open, it leaks. That would also explain the smell in the cabin.

I would ask the dealer specifically if when they replaced the reservoir tank if they replaced the cap. I can't imagine them not doing it but it is a common failure point and a $5 fix ($50 at the dealer). Or, maybe if they did replace it it is a defective cap? A cheap thing to rule out.

Thanks for the replies. The code on my reservoir cap ends in .01 so I guess I'll order a new, updated cap. However, the entire reservoir assembly is dry to the touch...all the time...and there is no evidence of liquid anywhere near it in the engine bay. How does one check the heater coil? The issue I have with continuously just bringing it to the dealer is the fact of how far away they are. Since buying the car in July, I've had to take it to Porsche 7 times, at 1000 Kms roundtrip overtime. Not that resale value is my primary concern, but the value of these 996's is definitely tied to their mileage more than their age. So the far that I've taken the car from 96000 Kms to 113000 Kms in 6 months would lead to a disturbing forecast of mileage accumulation over the next couple years. I bought a 911 partially because of their extremely high rate of reliability. I guess there should be an asterisk next to that claim excluding the 996 series. I will have to find a way to get the car up, take off the front bumper and the under side panels and manually search for the issue myself and then TELL Porsche what to fix... sean

FWIW...... when I spilt coolant on my engine, the smell didnt go away for awhile.... It took about a month for the smell to burn off. Maybe that is what you are smelling since you cant find the leak.... give it time, drive it more and see if the smell continues.

Heater coil is my vote as well. Way up in there and hard to get to. There are also about 50 ft of hoses...so it could be a hose anywhere between front and back. Supply, overflow, etc. Thermostat could be leaking? Have you checked your oil on last oil change to see if there is coolant in there?? Has the dealer removed the protective covers under the car and see if there is a collection or obvious spot where coolant is dripping. Walk around the car and smell it once it starts smelling...is it stronger in one area of the car or another? Front , Back , Middle, Top, Bottom. Ask a woman to help, they have much better noses than we do. Maybe it's time to take it to an independent porsche mechanic?

I had to replace my rads, too. Corrosion from brine getting absorbed by the crap the PO allowed to accumulate between the rads and AC condensers. This is the biggest maintenance demand for a winter-driven 996, IMHO. The only thing I can add to the suggestions others have made is to look closely at the coolant lines. That's something a flat-rate dealership shop might not be too excited about doing. But I just had a pile of hoses replaced on mine, and you'd be amazed at how mushy many of them had got after ten years. A pinhole leak wouldn't be remotely surprising. Good luck!

Any of the hose fittings. I just got a new radiator. Pressure tested for hours fine. Took it out for a spin and the hose popped off. While driving, you get spikes of pressure as the thermostat opens and closes. So your leak is occurring under these circumstances, not just simple pressure.

Not a bad theory. I had to go back once after having my hoses changed for just the problem you describe.

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When my 02 Boxster's coolant light flashed and I found the tank near empty there was no signs of any coolant around the tank, no signs of any wetness around the tank, nor anywhere else for that matter. I added fluid -- quite a bit -- that tank is huge -- and drove the car but checked the level more often. Upon opening the lid I'd notice a bit of condensation around the rubber seal that the fluid bay has which seals against the underside of the trunk lid. No signs of coolant leak again but the cap had some stains that were characsteristic of coolant drying. I replaced the cap. My car's cap part number ended in 00 IIRC. I think I got an 03 cap. Leak solved. Same sort of symptoms/signs with my 03 Turbo. It was covered by CPO warranty and the tech just replaced the cap when I mentioned the coolant tank level low and the cap had some signs of water condensation around it. Sincerely, Macster.

thanks for all the suggestions. Updated with new info.