Temperature gauge creeping past 90

[David's8]

Well, everyday is a learning day. I hadnt appreciated the potential issues with viscous fans and the temperature sensitive clutch engagement mechanism. I found this article helpful:
http://www.freeasestudyguides.com/pe...an-clutch.html
The failure of the viscous fan mechanism could be your issue.

[RICKY D]

On my last 8 I knew the viscous fan was gone because it sounded like an old Mitsubishi shogun when up to temp and constantly runnIng.

I plugged in the my OBD11 dongle earlier and cycled through the sub menus. I didn't realise there was something for coolant temps

anyway on idle and up to temp, the gauge indicated 90 degrees but was actually 99 degrees according to the app. When driving the gauge remained at 90 but the app indicated the car was running between 103 to 104 degrees. It spiked at 105 but then went down to 104 again. The whole time the gauge remained at 90

[mattylondon]

Originally Posted by RICKY D

anyway on idle and up to temp, the gauge indicated 90 degrees but was actually 99 degrees according to the app. When driving the gauge remained at 90 but the app indicated the car was running between 103 to 104 degrees. It spiked at 105 but then went down to 104 again. The whole time the gauge remained at 90

Nothing wrong there, that's how VW/Audi designed it. The engine can work within a specific temperature range. So owners don't get worried with a constant moving temp gauge they fixed it at 90c when it's within this design range. So for it to move to 95c is odd. Worth keeping a check on but could be down to the recent hot spell.

[27litres]

Experienced as I am in driving my car in 40°+ temperatures, I can say that the temp gauge on the S8 will rise very slightly above the 90 mark on extremely hot days (35°+), but only in traffic or at low speeds.
Moving at good pace, the speed settles and stays on 90°, even at 42° (the highest temperature I've driven in since owning the S8 - some mild summers recently ).

With the climate control on automatic (ie. Aircon on), the aux fan runs at slow speed constantly (nearly inaudible). It will turn off on Econ mode and then run purely on temp settings.
The trinary switch will of course trigger higher fan speeds as the engine temperature rises, which may be the 'trigger' David is hearing at 94°.
Different markets may trigger this differently of course, though I don't see why they'd bother when you could potentially drive it to a hotter climate...

[RICKY D]

Thanks all for your input.

I'll definitely keep an eye on it and report back if anything changes. I may look to change the coolant temp switch as a precaution too.