Wtf

This is two months after regular thermostat and water pump replacement. Is this normal? And, yes, I know....I should have gotten low. But, a normal 180ish stat should do the job. I live in Denver, this, elevation and heat (summer) is constant. But this seems too much for the 180. I may answer my own bullshat by saying I did not purge the system well. Render this post useless at this point. Thoughts....

That's about 10f high regardless of thermostat. How do the radiators look? Ever clean out between the rads and ac condenser?

Is that at idle or driving down the road or both? If temp is normal going down the road, t-stat is probably not the issue.

Quotes source post: 18988824

You answered your own question.

A low temperature thermostat is almost never a good answer to any cooling problem. (but yeah, like you said -- you've got some air in there)

If that's after moving at low speed I don't see an issue. 996 temp gauges move around a bit. Not like modern gauges

Have you fans tested for both left and right and both high and low fan speeds. It's very common to have fan resisters fail and cause high coolant temps in certain situations, and a failed fan motor on one side is certainly possible...

automotive engines as well as air compressors, etc. are designed to operate at 100 degrees above ambient. Your driving in 96 degree heat seems to indicate you are running at 100 degrees over outside temperature, but by all means check your radiator fans.

Quotes source post: 18988846

All clean. I pull the front bumper cover off often, and always vacuum the rads out. This temp is after driving some. I do see it bounce a few degrees, but yeah. I also think I answered my own question a bit. I need to purge the system. I will report back after that if changes occur. I also agree that a low temp stat should not be necessary, and in fact, are truthfully not recommended. Car needs some heat to be efficient. Thanks to all.

Quotes source post: 18988824

For my car, this is normal. On my �99, this last white line is 97-98C and will trigger low speed fans. Check your DME temps and look for the ECTS reading with a Durametric or ODBII Bluetooth device and app to verify.

Quotes source post: 18989591

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Quotes source post: 18989591

I have the LN low temp stat in my 3.6^3.8 rebuild. The temp stays SOLID at the gap between the 8&0. I had my durametric in the car all the way through break-in, the low temp stat seems to work great, with the old one the car would heat up more.. I also have 3 rads now so at highway speed the fans never turn on high.. Remember that this was the first water cooled high volume car they built, not hard to believe that they might have been off 5 or ten degrees "f" when trying to cover all environments. IMHO whats most important with all AL engines is temp consistency and the stock stat runs the temp up and down 10 to 15 degrees. Expansion and contraction is not your friend.. FWIW,, I know several top shelf Porsche mechanics and they all run low temp stats in the 996

There's a good reason why mechanics aren't engineers. That sort of anecdote carries no weight for me. You've changed so many variables at once that drawing any sort of conclusion from what you've done is impossible. Changing the threshold as to when to open the thermostat to be lower isn't going to markedly change the variation in temperature the engine sees. I'm not saying that you're not right, it's certainly possible that it is a bad design and that the optimum temperature is lower (or that a lower temperature carries less risk for head cracking/etc for M96.0 cars, etc).

Quotes source post: 18990311

So I manage buildings with very very large water cooled and heated systems, I have to manage heat rejection a lot... megawatts of it I get how it works.. LOL Your right The thermostat is one piece of the system, you have a electric fan set, radiators with different delta T and a AC system changing the delta T as well. Heck driving through shade makes a difference.. FWIW, This isn't just a Porsche thing, Honda's and other cars are HORRIBLE for this, the ECU turns the fans on way hot, and then keeps them on way too long. so the cycle can be from 175 up to 215 and back which is horrible on head temps and expansion rates. . On my daughters honda, and Only messing with the thermostat and fan trigger setpoints, by lowering the thermostat 5 to 10 degrees, and lowing the fan setpoint its very easy to get to where the engine just runs at a nice constant temp, if I can stick between a number 185 to 190 I'm super pleased. Got a nice 2MPG out of it as well. (little 1.5 half vtec Fit) Interesting side note, the cylinder layout of a honda looks almost identical to the 996 just 4 cylinders. Thats pretty much where I'm at now in the 996,, less than a 10 degree swing from low to high in normal operation, the car never did that with the stock parts. I think it all starts from,,, The thermostats temp rating, was the easiest way to let consumer know what they were getting, the actual spec should be a volume to temp ration based on pressure, orifice size and temperature, but its too many numbers for most folks to digest, and as we notice not really needed in "most cases" You'd be putting something long winded like 1gmp @ X-PSI @ XdegreesF to 5gmp @ X-PSI @ XdegreesF, and with the number of different cars that share thermostats the parts definitions would get insane. Most engineers use the pulley size to tune it in and if its close enough for the girls we date, well they are happy. So all stats are pretty much labeled with the temp where they achieve wide open volume based on their design, remember we don't really know the opening temp unless you test one in a glass beaker on a burner so you can see the moment it opens, and its not like the wax pellet tech is rowdy when it opens.. The 195 and up thermostats were used to reduce emissions, they have no other benefit IMHO. I've noticed in dealer parts listing quite often there is a US spec thermostat and a World or EU thermostat. also,, how many times has someone said,,, My 996 is running way too cold? The top half dozen Porsche rebuilders I could find when I was shopping all recommend the lower temp stat, none really push the 3rd radiator except for track or continuous higher altitude operation, or like Porsche who added it to Tiptronic equipped cars.. I'm a big fan of using the fan capacity as well as the thermostat control as a tandem in making engines run nice. Been working out for me for the last 40 ish years..