[ron1688]

Drove the car to Vegas for the weekend. Man, it is hot up this weekend, 108 farenheit through the weekend. Anyways, i notice the temp gauge is on the 2nd line (right before the red marker)and at times will go over the line with the A/C on. Is this normal or should I be concerned?

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[flwbyu]

ron1688,



I have had the same problem here in AZ. I was stuck on the 101 with wall to wall traffic and 113 on the temp outside. My needle was pushing into the red and I was afraid she was going to go.



I do not believe that the problem is with the radiator but with the oil cooler. I have been debating adding a second oil cooler on the other side where the 968 Automatic versions have there's placed. I would only need to figure the plumbing between two.



In any event, I know that this is an issue with these cars in extreme heat running the a/c, etc. I am not sure what the end answer is other than to baby it. <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" />

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[flash]

the answer is:



100 degrees above ambient temp, or 15 degrees above the thermostat point, whichever is higher



if it is 112 outside, then you would be at the "10 o'clock" line - if it is cooler than that outside, then you are running hot



do you have the low temp fan switch?

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[SILVY968]

I run at 10:00 o'clock when HOT.

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[flash]

just so everybody knows:



bottom of the bottom red is 40 deg C or 104 deg F

top of the bottom red is 60 deg C or 140 deg F

8 o'clock line is 80 deg C or 176 deg F

10 o'clock line is 100 deg C or 212 deg F

beginning of dangerous red line is 115 deg C or 239 deg F



the general rule of cooling systems is 10-15 degress above the thermostat and/or 100 above ambient, whichever is higher



the more important issue is limiting variation in temps to 20 degree total swing



ther is such a thing as running too cool too - that gasoline combusts best, and gives the most power, when the coolant surrounding the cylinders is at 190-195 degrees F



so, right smack dab in the middle of the 8 and 10 lines is best, if you can keep it there

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[mitch968]

right smack dab in the middle of the 8 and 10 lines is best

....which is why I might go back to a stock fan switch instead of the low temp one. Maybe my cooling system is just functioning really well or the gauge is slightly off, but with the low temp switch it is very challenging to get it to go above the 8 oclock line. No matter how hard I push it on the street, it stays right around that line and sometimes slightly under. Granted, we haven't had any 100+ degree days lately and I don't spend much time in stop and go traffic. I'd imagine it would go higher on a really hot day in traffic.

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[flash]

lol - either you're lucky, or you just aren't driving it hard enough



get it up there and keep it up around 6k for a while (at least 15 minutes of never letting it down below 5k)



i will get a chance to check it on the funrun course agian in a couple of days, but usually, when i am running this type of course, and i never get below 5k, when it's roughly 85 deg F outside, i am running about 190 deg F on the water, and 220 or so on the oil - get it up over 90 tough, and i go up to 200 on the water and 230 on the oil

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[mitch968]

While I get over 5k plenty, I normally don't stay there for long enough periods of time. I know you must have plenty of twisty canyon runs out west, where you can open it up and not run into traffic for a long time. Unfortunately, more often than not I come up on slower traffic on the few fun areas along my short commute. My commute is only about 15 minutes, but I suppose I could just hold it high up in 2nd gear the whole way for no particular reason. ;-) I really need to get out more on weekends for some longer runs.

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[flash]

yes - absolutely - more weekend runs - and weekday runs, and between appointment runs - and evening runs, and on the way to the grocery store runs.............



you won't hurt anything with it running at that temp - you just won't get that last little bit of oomph (and we aren't talking about a lot here) - of course, if you aren't running up at those revs, you aren't anywhere near the peak power anyway, so it's a moot point



i'd leave it alone and drive it

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[wjk_glynn]

[quote name='flash' date='Jul 1 2006, 06:01 PM']just so everybody knows:



bottom of the bottom red is 40 deg C or 104 deg F

top of the bottom red is 60 deg C or 140 deg F

8 o'clock line is 80 deg C or 176 deg F

10 o'clock line is 100 deg C or 212 deg F

beginning of dangerous red line is 115 deg C or 239 deg F[/quote]



Yup. And that's the same for all 944/951/968 since the 85.5 944.



Graphically in centigrade...









[quote name='flash' date='Jul 1 2006, 06:01 PM']the general rule of cooling systems is 10-15 degress above the thermostat and/or 100 above ambient, whichever is higher



the more important issue is limiting variation in temps to 20 degree total swing[/quote]



Never heard it expressed that way but that seems reasonable, assuming those temperature units are Fahrenheit.



One question... where exactly does the temperature sender measure temperature? I think (or believe) its the block somewhere close to a coolant passage, but where exactly?



Karl.

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[mitch968]

The sender for the gauge is under the bleeder bolt area, 2 sender in....behind the one with the blue connector.

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[flash]

how the heck did you get that pic to fit there? all the ones i try to grab, even with file sizes below 200k, end up in thumbnails



and yes, farenheit - can't remember exactly where i gleened that bit of info though - it's something that i picked up along the way over the last 30 years of tinkering, that has been reinforced a number of times by others in the know

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[flwbyu]

The first thing I did when I got the car to Phoenix was replace the regular "Prestone" coolant with Phosphate Free and Distilled Water. I also had them replace my radiator fan switch, heater control valve, replace water pump to pipe hose, replace the heater control valve to pipe hose, replace the radiator drain plug and replace the resevoir cap.



This made a huge difference but according to the diagram above, I have hit that 115 degree mark many times. When I travel up to flagstaff and come back to phoenix, I hit that 115 mark and stay there for quite some time. I am of course going through 6 percent grade climbs, heavy traffic, etc both up and down. I cannot tell you how many times I have lost all the coolant out of my 944 making this run back and forth and I had an extra large radiator installed into it. Always Fun! <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[wjk_glynn]

[quote name='mitch968' date='Jul 2 2006, 09:17 AM']The sender for the gauge is under the bleeder bolt area, 2 sender in....behind the one with the blue connector.

[right][post="23597"]<{POST_SNAPBACK}>[/post][/right][/quote]



Thanks.





[quote name='flash' date='Jul 2 2006, 09:40 AM']how the heck did you get that pic to fit there?  all the ones i try to grab, even with file sizes below 200k, end up in thumbnails[/quote]



The image is not attached. It's a URL insertion pointing to my site.





[quote name='flwbyu' date='Jul 2 2006, 09:50 AM']Well, According to your diagram, I have hit that 115 degree mark many times before. When I travel up to flagstaff and come back to phoenix, I hit that 115 mark and stay there for quite some time. I am of course going through 6 percent grade climbs, heavy traffic, etc both up and down. I cannot tell you how many times I have lost all the coolant out of my 944 making this run back and forth. Always Fun!  <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />[/quote]



That kind of regular overheating doesn't sound good. I think a fully operational cooling system should be able to keep you below 115C even in those conditions so long as you weren't acclerating hard all the time. But then again, maybe all cars experience overheating in those conditions.



When I first got my 944S2, it ran a bit hotter than I liked. A radiator cleaning (removed is cleaned off all of the exterior road grime, also an internal flush), new pump, etc., dropped the engine operating temperature by 20C. It was a big improvement.



Karl.

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[flwbyu]

wjk_glynn,



I think the combination of extreme heat here in the desert along with various other factors of everyday driving can be quite taxing on that 4cyl. I know it has always been a struggle with the 944 which has gone to greener pastures. <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[Renalicious]

My oil temp varies between 80 and 100, though never actually touching the lines. On a steady drive it'll sit at around 85-90, even on hot days like today when it was about 27+ celcius. Durring traffic or spirited driving with lots of 3000+ rpm stuff, it'll be over 90. The fans come on once it reaches 100.



And speaking of that, I've been under the impression that if your oil temp is high (around 100), and you're about to turn the car off, it's better to wait for the fans to come on and cool the rad / oil down and let it all circulate before shutting off the engine. Or is it ok to turn it off anyways?

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[flash]

lol - i wish my oil temp was that low, but then, i think you meant water temp - can you clarify that one?



the oil temp doesn't have a correlation to the fans

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[patkeefe]

Can anyone tell me where the bleeder bolt is? I know where it's supposed to be, but on the Cab it has just a solid spliced hose in there...no bleeder. The car is running at the top line before the red (100C) at 4k RPM in 90F ambient. I'm going to Watkins Glen this weekend, and am concerned. I think I'd better address this. The fans are coming on between the two white lines; seems normal.



Pat

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[sasilverbullet]

I just drove to Dallas Sunday evening in 102 degree ambient heat, and HIGH humidity...with A/C on of course! (duh!)



Using the diagram above, It once briefly 'touched' the 100 degrees centigrade line. Most of the time it was a little more than halfway between the two white marks.



I run Mobil 1 15W-50 and change it about every 4,500 miles or so...



Because of this thread I am now AT EASE about where it's running! But I'm going to look into installing a second oil cooler.



FLASH - think you could put together a 'kit' that has all the stuff we all need to add a second oil cooler? I'm sure you'd have a lot of takers...

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[mustanghusker]

I live in the Dallas area and we have been burning up here recently. If I am on the interstate running 80 or so in 6th my temp stays in the middle, around 90. However, when my wife and I were driving around last weekend looking at homes (a never ending search), I had to shut the AC off a few times for fear of getting too hot...I was well above 100, pushing 115. The car just loves to suck in some clean air and cruising at 15 mph with 105 degree heat just doesn't work I guess.



After reading all this I am happy to know that my car is "normal."

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