Josh(PA)

My 2017 base 991.2 had a very odd overheating issue today and I'm curious if anyone else experienced a similar issue. About 3 weeks ago I had my water pump replaced due to a weeping leak (the standard issue). I've driven the car a few times maybe 100 miles since the service. Today I took it to my office on a ~25 mile drive and all was good. From there I went to the grocery store, which was about a mile from my office and everything was still totally normal. I was in the store for about 10 mins.

When I left the store, I got literally a quarter mile away and the water temp had climbed to 250 and I got a water temp overheat warning on the dash. I was able to immediately pull into a parking lot, shut the engine down, open the rear cover and run the heater. The oil temp never got above 198 so I'm not too worried about damage (should I be?)/ The water temp came back to about 200 in a few minutes. The weird thing (besides how quickly the water temp shot up) was the cooling fans above the engine never kicked on. I also didn't hear any radiator fan noise from the front of the car. I looked under the car and everything was dry, so it didn't dump all the coolant somewhere either.

After it cooled, I restarted it, to see if maybe the water pump was stalled and the restart would get it turning again and drove the 1/4 mile back to the grocery store lot. In the 90 seconds it took me to make that drive the water temp went from 192 to 248. Experiment over, I shut it down and called my dealership to arrange a roadside assistance tow.

Does anybody want to postuate the cause? I should have info tomorrow when their service department can check it out.

polobai

You more than likely have air trapped in the system causing a false reading.

OCNYPORSCHE

Sounds like your dealer needs to make sure they did everything correctly. Which dealer in PA?

B Russ

Burp the Baby

Wujohn

After I had my water pump replaced, a few days to a week later (I would guess) I took my car to the store and this happened. Temps shot up to 250 and got red warnings to pull over. Fans were going crazy. Dealer had to replace a few more parts outside the pump I believe because coolant got into a vacuum line or something like that. Take it back to the dealer...I can call mine up to confirm exactly what they did if you need.

Jack F

Did you check the coolant level?

Josh(PA)

That was the part that surprised me the most. None of the fans were turning. Thanks for the offer to check with your dealer, lets see what mine says and if I need any info I'll reach out.

I thought it mght be an air bubble, but would that cause the water pump to lose prime and not continue to circulate the coolant or does the bubble get trapped at the thermostat and cause a hot spot there?

I didn't check the coolant when I got it back from the dealer (my mistake) and didn't yesterday after the incident as it was hot. I was surprised how fast the temp rose. I've had water pump failures on my BMWs and you have a couple of minutes to get it to find a good place to pull over. Is the speed that it gets hot a byproduct of being rear engine and not getting as much airflow around / over the engine?

Also Re: Towing - I read through the manual and it looks like there aren't any special issues with towing a RWD manual 911 as long as the flatbed ramp isn't too steep that the nose doesn't clear. Are there any special precautions that 911 needs for tow transport? I had the tow arranged through the dealer so they had a shop that they were happy with come and pick it up. Just wondering for future reference.

CarlJ

Likely trapped air as said. Had some similar issues on my Cayenne after a water pump replacement and radiator flush. Never hurts to have the dealer recheck their work though.

OCNYPORSCHE

See it worked for 100 miles. If it were air, I believe you would have it overheated much before the 100 miles. I would ask did the dealer replace the water pump or just the seal. Mine was changed, but ai have not used it alot. I just drove it home. If there was air, I think it would have overheated on the way home (about a 15 mile drive).

arter

The engine heats the oil first and then it transfers the heat to the water to be carried to the radiators.
As your oil was not getting very hot the engine was not over heating ( and thus the fans didnt go on).

The too hot water seens to be a fault in a sensor or more likely circulation ( needs to be completely burped).
When I had my water pump replaced, I also had to go back to the dealer again to have them burp the system again.

SF Neunelfer

RE Towing..
I had mine towed recently due to a rear tire blow out, a tire plug blew. The tow driver asked if I was comforatble pullin the car on to the flatbed, with his direction. More than happy to do it. He then strapped each tire down, with a strap that went around the top of the each tire. I left the car in N and back off the ramp once it was at location. The tow driver only touch the wheels on my car. All safe and sound for the 50 mile trip.

Your experience may vary, but the strap around the tires, I liked.

Josh(PA)

Thanks for the replies on 'burping' and towing. arter's comment about oil temps driving cooling fan logic makes sense and helps me feel a little better about what I was experiencing. Whether they burp it or fart it, as long as they purge whatever air is left in the system and everything works as normal going forward, I'm happy.

Wujohn

Just curious, were your fans in the wheel wells spinning? Mine were going crazy but I don't recall if the engine fans were going at all.

Never thought of burping the system - I wonder if my SA said additional parts needed to be replaced to avoid having to admit getting air in the system. That sounds like a noob mistake to make.

Norge911

Isn’t there a way to vent system on these cars. I know the 997 had a spring on the cap, so you drove or idled car got with vent opento burp system, you would check expansion tank so it didn’t go empty if there was air. If low. Refilled and repeat.
Is there no vent valve on the 991?

Josh(PA)

I didn't hear any fans spinning, which i listened for and was surprised to NOT hear, but I didn't look specifically in the wheel wells. I did lay down and look under the car for a pool of coolant.