2008 Cayenne S

[Cayenne1992]

Hello guys,

 I have a doubt with the Cayenne, I've been having an issue that i dont know if its normal. The car sits at 80c or 180f normally but after a 40 min ride the temperature rises a bit then goes back to normal. The temperature rises when i drive to a stop or driving very slowly. Also when coasting downhill on the highway the temperature drops to around 60c or 140f. Is it normal? 

I attach a picture of the temperature when it rises

Edited September 17, 2017 by Cayenne1992

[ekstroemtj]

Temperatur range which is totally normal. No reason to worry 

[lewisweller]

I would say the rise is normal but the drop to 60oC identifies the thermostat is stuck open as the engine temperature should be maintained at 80oC all the time and not less. I would hazard a guess your engine takes a long time to warm up? Classic stuck open thermostat symptom. 

The thermostat is designed to open partially at 83oC I believe and fully open at 87oC. The dash gauges is also not very accurate! 

If you have the AC on the temperature is maintained more strictly from rising as the fans are already running. If the AC is off the engine coolant will rise to around 87oC then fall back to 80oC in a cyclic manner. 

As long as it doesn't over heat I wouldn't worry about it. 

 

[Cayenne1992]

Thank you guys for the reply. Yes, you're right, with AC on the guage rises just a bit. I also thought of a bad thermostat, but if its stuck open why does it still "overheats" past 80c?

[lewisweller]

6 minutes ago, Cayenne1992 said:

Thank you guys for the reply. Yes, you're right, with AC on the guage rises just a bit. I also thought of a bad thermostat, but if its stuck open why does it still "overheats" past 80c?

Its not overheating, it is designed to open fully at 87oC and the fan also cuts in to maintain that temperature from rising and invariably drops the temp back to 80oC fairly quickly. 

 

As I said stuck open is not a big issue, stuck closed is! 

[Cayenne1992]

yeah sorry for the term, that why I used the " ". Thanks again for the help

[abbottrace]

Hey you stole my Post , I took a picture just like yours, and had the same questions.

[ekstroemtj]

Just a sidenote from my side.

i was / I am facing same issues already long time. Same as described above. Water pump changed, thermostat changed. Still the same. 

Thats why I recommend to do a professional refill of coolant. This engine is well known for keeping some air pockets and only vacuum refill can solve this. IMO

Edited September 28, 2017 by ekstroemtj