vivekg

Hi,

I have about 1200 miles on my 991.2 C4S and had a strange issue last night and this morning. Started the car up last night and drove a short distance and got a low coolant warning. Temps all looked fine, drove a few more minutes and then suddenly I got a red light to pull over and replace coolant immediately and the needle had suddenly shot up to 250°F (pegged the needle). I pulled out at a gas station to go see what coolant they may have, didn't have any that matched what was recommended (what should you do in this case, what are alternatives?).

Got back to the car and checked the coolant and it was fine. Started the car up and the warnings were gone, drove the remaining 10 minutes home and no issues or warning.

This morning had almost a repeat, but this time as it pegged to 250 I was about to pull out after I found a spot (was driving to the dealer), then it just suddenly all reset and no issues and the temperature was showing 194°F again as usual. No issues and all alerts gone and no problems driving for the next 45 minutes.

Anyone seen something like this before? Taking it to the dealer on Monday morning to have the sensor checked out, seems like something is faulty and just giving bad codes.

Thanks,
Vivek

subshooter

Similar issue happened on my 981 at about 2000 miles. Took it to the dealer and coolant was low. His explanation to me was that during factory fill (apparently it is a fast fill), sometimes air bubbles or pockets get into the system and manifest themselves later on.


It didn't quite make sense to me. However, I have had no repeat issues after that fill and at 24k miles now.

vivekg

Thanks for the info. I had checked last night and this morning and it seemed okay, but I just went and checked again it is low. Will go to the nearest Porsche dealer and pick up coolant and fill up.

Bizarre!

LexVan

Vivek, you need to heed the warnings better, and stop driving the car. Better safe than sorry. Good job not adding any ole coolant at the gas station, but in the future/emergency, you would have been just fine adding a few bottles of quality bottle water from the soda case. Tap water, no. Distilled water most ideal.

vivekg

Totally agree with you. I stopped and checked both last night and this morning and it did seem fine for the coolant level so it was strange to find it low this morning.

Will be much more careful going forward.

Vivek

philg3

Had a similar problem on my 2012 Cayenne V6 -- got a low coolant warning -- temp gauge was oscillating between midpoint and highpoint, got the red stop engine now command. I was on a 400 mile trip and outside temperature was 105. Pulled over to the side of the road, opened up hood -- expecting to see steam everywhere, but there was none -- coolant tank still had fluid. I added about 8 oz water from a bottle of water, started up, and everything was fine.

Took the vehicle in, explained the problem, and the service advisor was familiar with the situation, and said that they always top off the coolant tanks in their loaners, as if the coolant gets a bit low, the scary warnings start up and mess with your mind. They did find a very small leak in the water pump and replaced it. No problem since, but vehicle has not been on long trips since. Plan to sell this vehicle when my 991.2 Turbo arrives, and keep our 2013 CD for my wife.

Checking coolant tank level periodically is a good idea.

The factory fill with bubbles explanation does sound plausible.

plenum

Not as familiar (yet) with the 991.2's, but there have been cases where coolant system warnings have been tied to seemingly unrelated system failures. The first time I had a similar warning on my '14 C4S (vacuum line to exhaust valves disconnected) it was a 95 degree summer day as I drove to the beach house. Warning displayed, and I watched the temp gauge jump-up. At the time I had no idea that this was a vacuum line issue, and quite frankly the warning scared the living crap out of me as I was freeway cruising along at 90-95 mph in a car with very low mileage at the time! But suddenly the temp dropped back to normal, and although I definitely heard the difference, nothing else seemed out of the ordinary (coolant level was just fine). I called my SA from the road, and after a couple of minutes they told me to go ahead and continue driving.... just bring the car in next opportunity. Apparently they had seen this behavior before. Again, no experience with the .2 cars just yet, but food for thought!

budrichard

I got a LOW Coolant warning in the 981B on startup last Spring which cleared subsequently as the engine came to temp and the coolant expanded.
Let car cool overnight and looked at the little coolant level indicator.
Not much vertical height to play with the little float.
Purchased Porsche Approved coolant($$$) from my Dealer, mixed and slowly added until float moved up a notch or two. Haven't had the problem since but am planning on an addition soon for this summer.
-Richard

vivekg

Thank you all for the comments and help. I did talk to the service dept and they suggested filling it, which I did. Everything seems fine and no problems at all. Though I am watching to see if it was a bubble or if there is an actual leak of some sort. So sensor or temperature issues since making sure things are full yesterday. Also, the the SA mentioned that the reason the temperature warning went away was as some of you had suggested once the coolant expanded and I was at cruising speed (on a cool day) there was enough cooling happening. It was more a problem when you get started and before the expansion happens.

Thanks,
Vivek

Jabs1542

For reference the recent issue of Excellence (#236, May 2016) has an article about the water cooled system that Porsche uses. It's a pretty good write up and though it seems obvious I learned two things in the article:

1) The plastic screw on cap that goes on the coolant refill is engineered to maintain 30 psi within the system, higher pressures bleed off - of course with a vacuum return so the plastic reservoir doesn't collapse when the coolant cools down.

2) The pressure raises the boiling point of the liquid coolant making it more efficient. The boiling point of coolant at sea level is roughly 230 degrees, the boiling point goes up to nearly 300 degrees when pressurized at 30 psi (I' extrapolating off of their data).

vivekg

Thanks for that pointer. So it definitely looks like a leak ( or is it a bleed off due to overfilling ). Will be taking it in Monday. You can definitely see the drop dropping and the pink of the spray. With all the rain we have been having didn't notice it till just now.

CSK 911 C4S

Hasn't Porsche been plagued with coolant leaks in the 996, 997 and now 991 cars?

Always seems to be some dam "O" ring.

boatracer

Vivek, what was the issue? I have a 2 month old 991.2 C4S and exact same issue occurred to me today. First time pulled over and was on the phone for work, waited ten minutes and car was fine. Drove car again a few times with zero issue and then later in evening same issue at start up.....waited ten minutes and everything was fine again.

Either way, will call dealer tomorrow.

vivekg

Hi,

So it turned out in my case there was a bit of a leak and the turning off of the warning was the system pressurizing after it reached temperature. However, since having it fixed I have had the warning light go off two more times. One was when I hit a pretty rough bump and got the warning. Checked everything and it was all fine, plenty of fluid. Second time was a hard braking and again light went off, stopped and checked everything all was fine. It feels like the sensor gets triggered by a shift of the fluid (this is me totally hypothesizing) and then it takes it a significant amount of time to recognize that it isn't a problem.

The dealer will be checking this next week.

Definitely check under the car for any wet spots or any dripping in case you have a leak as well.

Vivek

rkwfxd

I had the same thing at 1500 miles on my .1. Pulled over let it cool for five min. Light went off and drove home at 194 degrees. Let it cool and checked. I was low on coolant. Added some and haven't had the problem since. Been checking and the level is good.