Mine goes up to the line past 180, and the Climate Control AC Diagnostics trick shows me running at temps as high as 235 today.

What are your temps?

 

Gauges are different in a 997TT, but mine runs a tick over 175 pretty consistently. And I drove it yesterday when it was 116

 

I have a 2002 996C2 6-sp Coupe. During slower traffic on FWY it'll get about same as yours. When moving steadily, seems to live between the "0" and "8" of 180.

I'm in the East Valley.

 

Thanks for posting a reply to my question. Does your car recover and cool down when it gets that hot in say 110 degree heat.
If the outside temp holds steady my car gets hot in traffic and at stop lights and does not cool down even if I start moving again.
It will never go past the 3/4 line at the gauge but will never cool down from that point unless I head home to Carefree and the outside temp is cooler. Then it will go down a tick or two.
If I drive south on Scottsdale Road from my house, its 12 miles to the 101 interchange. My gauge will stay right in between the 8 and the 0 in 180. I stop at the light before I get on the 101 and the temp will rise and never go down. This is with CLEAN Radiators, no coolant, I'm running distilled water and Red Line Water Wetter and the radiator fan mod has the fans on both sides on high speed.
It will continue to rise each time I am at a light until it settles in at 3/4 up the gauge as shown in my image.

 

I'll have to pay closer attention, but my cooling system is stock save for new expansion tank and cap. Have had a few leaks over the years but tight as a drum right now.

It's odd that your temperature rises so quickly. How long is the wait at that light?

I drive about 5 miles to 101 every morning, then about 5 miles on 101. Temperature stays normal (between "0" and "8"). I've noticed it climb coming home in stop-n-go 101 traffic. Will try the tricks with HVAC control to know more accurately.

I think my temperature also drops back down some after driving back on surface streets after sitting on the 101.

 

I added a second bottle of Water Wetter and today drove 22 miles to work. It was 98 degrees outside and my dash gauge stayed in the middle of the 8 and 0. The climate control diagnostics never exceeded 96C, thats 204F. A/C on the whole time with center vent and recirculate, two fan speed up from the bottom. Much more encouraging. The ride home is the test, it'll be 108 this afternoon.

 

Yikes! Too hot

 

I paid closer attention yesterday, but don't have much to report. The trick with the HVAC controls doesn't seem to work on my car (2002 MY).

Traffic was usual on the way home; temp climbed a little (not beyond the "0" in 180) and moved very slowly once traffic cleared.

I remember reading about air pockets in the coolant lines and them taking a long time to clear out. Sounds like a similar issue with a rapid climb in temp. That, or a bad temperature sensor.

 

My car never went past the zero in 180 as well and the climate control coolant temp never was never above 103C thats 217.4F. It was baking hot out, my dash gauge showed 109 as the outside temp. Adding a 2nd bottle of Water Wetter seems to have done something, the coolant temp is lower.

 

Does high humidity affect an engine like it does a human? AZ is a dry heat. East Texas right now is 100 degrees, and 99% humidity. My 996 stays between the "8" and "0" on 180.

I wonder if Hell is a dry heat, or humid....

 

I am glad to hear that it is cooling normally again, but I am skeptical that a bottle of water wetter in and of itself was responsible for the fix.

I am inclined to believe that some other issue remedied itself such as an air bubble in the line blocking flow, stuck thermostat etc. It is possible the water wetter was a catalyst in helping to resolve the issue, but I would keep an eye on things for a while just to be safe.

 

It *shouldn't*. Humidity affects humans because we cool through an evaporative approach (we sweat, it evaporates, and we cool as a result). Cars cool through heat transfer; engine heat is transfered to coolant, which is in turn transfered to rad fins, which is transfered to passing air, cooling the fins/coolant, allowing them to absorb more engine heat, and so on.

The only factors that affect your engine temperature are:
- the rate at which your engine generates heat (there are a number of reasons why an engine might generate more heat than it's able to dissipate - timing, etc, (but you would probably see many other symptoms)
- the rate at which that heat is transfered to coolant - governed by the coolant temperature and conductivity of the coolant
- the rate at which the coolant system can dissipate heat - there's a lot to this one, including
* the rate that coolant is moving through the system
* the surface area of the radiators
* the volume of air moving over the radiators
* the conductivity of the radiator fins (**dirt and leaves are insulators)

 

Never took either of the Pcars to AZ but I have been there a couple of times, one while driving back a VW without A/C..... "To Die For"... AZ heat is just terrible...

-Eli

 

I took this last month (6/24) and it shows where mine is most of the time on my trips home (about 20miles one way) when it is 'warm' here in Phoenix. I have seen it climb to the right side of the 0 on surface streets.

I would love to add the third radiator and the L&N low temp thermostat so that the higher temps are held at bay a bit longer.

My seatbelt light is on because I took it off to take this picture also the airbag light is on because I replaced the driver side window regulator and tested it with the side airbag disconnected. Guess I need to go get that reset.