08 Silverado Overheating!!

[Doug_Scott]

Maybe so but why the F would I sit in my truck in 90 degree weather without ac on? I don't have that much time on my hands to play around to see. When I'm comfortable in my truck, heat on in winter and air on in summer, my trucks all hold tight at 210 or just shy.

 

You say your truck does not fluctuate when idling with the a/c on. I suggested that if you wanted to see what the OP was asking about it would require you to sit with the truck idling without the a/c on. Did not ask you to do that as a normal condition all the time. I see the OP has posted that what I suggested did in fact reproduce the issue he reported. If you would have tried it, you would see the same thing the OP saw. You chose to not want to try due to (what I can only think) the fear of sweating. Does not matter now, OP is happy with the answer he got, and even tried what was suggested to replicate his issue.

[Jsdirt]

.....

 

The engine temp should be cold after 5 hours shouldn't it?

 

Maybe my gauge or temp sensor isn't working properly?!?

 

When I lived in Phoenix, I could come out 10 hours later & still have a 140° V8 engine, but, the low temp of the night was 99° - all depends on outside temps as to how fast it cools down. Out there my El Camino regularly hit 265° in traffic, & even 240° at the drive thru. Engine never missed a beat in the 12 years I owned it too ... but that was the 350, and a different time.

 

Seems like your truck is behaving normally. Like I said, if it's not puking coolant I wouldn't worry about it to much. If it's still cause for concern, install a cooler thermostat, and/or drain the coolant & run this waterless coolant. It's VERY spendy, but handles some high temps & protects your engine in the process. Haven't used it myself but I've researched it enough to find very few negative comments on it. The coolant will outlast the truck. http://www.lubricationspecialist.com/evans-coolant/evans-hdtc-waterless-coolant/