I got the engine warmed up and the top hose is hot and the bottom hose is still cold. It seems like it is taking a while to get heat across the radiator. Around town I'm fine. In the mountains on the highway I get warm (little over 200) when going up the mountains (not towing). Didn't used to have this problem but started last summer. I'm pretty sure I have a bad plenum gasket so the repair kit is on the way. I just put in a new radiator with a flush about 2 months ago. I have a 180 thermo but replaced it several years ago. Not sure if it is that or maybe the water pump that is not moving as good as it used to. The truck has 165,000 miles on it. Any idea?

Oh, and I have a ticking noise coming from the right front. Not sure what that is now. *sigh*


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Hot upper hose shows a working thermostat. What happens if you take the cap off (cold) and then start it up and let it get warm? Do you see coolant flowing? If the flow is weak ... water pump.

 

I don't really notice any movement. It's at the top. When I pull out of the driveway I can hear it move thru the core. When the radiator was replaced (it exploded) I remember it took a while for them to bubble out the air. The cap is holding pressure. When I open it to the first notch, I hear air. On the way to work this morning (14 miles), the radiator was warm only half way across. After getting home (ran heat on high the entire way) it was hot on drivers, warm in the middle, and easy to the touch on the pass side. Cap was easy to touch and bottom hose was cool.

 

i'm thinking your t-stat is not opening up all the way. try putting in a new 180*. test in a pot of water on the stove before install, using wifey's cooking thermometer. they love it when you do that. if its still doesn't do right, temporarily remove t-stat and see what happens.