On the freeway stuck in stop and go traffic for about 45 min the tempt creeped up to about 230-235 (just shy of the 3/4 mark). This seems high to me but I found conflicting info. What kind of temps do these trucks see. I have about 400 miles on this truck since I bought it. Only temp spike I have seen was in heavy traffic with front and rear AC on. As soon as it gets moving and has air flow the temp drops!

 

had the same exact problem with my denali. I replaced everything I could. I love in PHX so the ambient ground temps would soar. I found nothing that helped it. I did us ICE in the antifreeze and it helped a little bit. Also when I used super unleaded it helped a bit too.

 

Such are the problems when buying a used vehicle. You got to go through everything to be sure that you're ok.
It's 15 years old, so just about everything on it needs to be checked.
I'd start with a good system flush and a new TStat. Replace Hoses as necessary.

 

That's probably where I will starts. The fan clutch seems to be ok, so I will do the flush and t-stat.

 

As long as the Fan turns freely when cold, and you can hear it "roar" occasionally after stopping forward motion.
You don't have to do everything at once, just nibble at it as budget allows. Many of our users on the Board here, are running well over 200K miles.
You bought a piece of equipment that can last you a lifetime, if taken care of.

 

I cant figure out how to post something for everyone to see. Can someone please help?

 

You just did it !

 

So I was looking online and saw someone post something interesting about the water pump and thermostat. Since this truck is new to me I don't know the maintenance history. They said that if the thermostat had 2 holes on the top of my he housing then it mounted to the original water pump. If it has 1 hole then the water pump has probably been changed to a new style. Below are photos of mine (single hole) and 1 from a video I saw online with 2 holes. Does this info sound reliable, would your guess be it has a newer water pump?

Ok so I was only able to up load one photo but the other t-stat doesn't have the empty hole at the top of the housing.

 

Make sure you have the heavy duty radiator fan thermostat. I have seen some people change them to the non A/C one because with the heavy duty one, the fan gets a lot louder.

 

I assume you are talking about the fan clutch and not the thermostat?