89 S4 auto 132K miles. My temp gauge sits at a hair under the line between 170 and 210 - so about 188F is what it's reading I think. It's pretty steady around there once warmed up, and never goes higher.

But I'm used to temp gauges that sit in the middle of their range. Is this a quirk of the 928? Or is mine running too hot? I looked up thermostats on the web and have seen temps of 188F (87C) and 181F (83C) for sale. If mine has the 87C the gauge reading would seem about right.

Are people in hotter climates switching to an 83 or should I just stop worrying?

 

Mark,

It's been hot here lately, and yes the S4 seems to read higher then most cars.
On my car, the temp gauge will be half way between mid point and 170 on cool,
days and half way between 170 and the bottom of the red on hot days.

 

My gauge moves between the lower 1/3 and the upper 1/3 .. IN stop and go during the summer it would climb near the upper third of the range, then drop back down to the 1/3 area.
Very active gauge. (it gets to 100 here in my area).

 

Mine seems to run hot, or at the least makes me look at the gauge more that I would like. I've seen comments indicating that the gauge is not as accurate as it should be? I have never overheated....

'89 S4 GP White/Black
'76 912E Silver/Black

 

Well the Porsche gauge just seems to have a funny range. The top line is 210F. In comparison, the one in my 2010 Jetta goes up to 250F!

I think I might try an 83C thermostat to see if that drops the needle a little though.

 

Do you have a "belly pan" Under the engine for cooling?
Do you have the original fan and radiator?
What type of driving? Highway or Stop-and-go?

I do know one S4 owner who put in an updated fan and it never goes about 1/4 the way; otherwise I've heard from 1/3-2/3 typically.

 

its not the thermostat, its the radiator and cooling fan effectiveness. they should all run in the mid range, and cooling fans click on just after the mid range and bring it back down to just under mid range.
see if you have air in the system when cold. (squeeze main hoses with cap removed)

 

Both my cars have 83oC thermostats. The GT has had a cooling flapectomy, and the gauge runs at the 170oF mark almost all the time. IR of the upper hose when the engine is warm is right at about 185oF.

The GTS also has an 83o T-stat, and the gauge runs at the 190 mark, IR of the upper hose also reads 185. Sharktuner says the coolant temp is 83 almost all the time, unless I've been driving like an ***, and then it creeps all the way to 85 for a minute or 2.

So the conclusion is that the temp gauges aren't real accurate.

 

This looks normal for operating temperature on a 89+ (digital cluster), temp gage in lower right...

 

borland, fantastic, that's exactly where my needle sits!

 

I think that photo was from an 89' S4. On my 90' S4, the gage hovers right around there too.

With a diagnostic tester or a jumper across the diagnostic plug, the instrument cluster's digital display will show the coolant temperature. That's covered by the Porsche instrument cluster technical manual, included in the Morehouse CDs.

 

Interestingly, the lines on the temp gauge on my 89 are labelled 170 and 210, while in that pic they are not.

When I get the car back I'll set to work with my IR thermometer

 

I assume the gage tick marks are linearly spaced.

170 F = 77 C (low marker)
210 F = 98.9 C (high marker)

That's 40 F difference between, so the middle marker would be

190 F = 87.8 C.

Since the thermostat is set at 83 C, then the pointer should ride slightly lower that the middle marker.

 

looks normal for my Euro 90 as well...I have the same guage but with numbers above. 40C left - 80C middle -100C red. I agree that the needle appears too far hot compared to other vehicles but should be fine as Borland stated.

40C left - 80C first line - 90C(implied by guage) 2 nd white line - 100C red line

 

Mine sits just a needle's width above the first white line, in the Vegas heat. And thats with the air on. My car never over heats.