Pony07

I've got some issues with losing coolant and the temperature and need to figure out just which part to replace instead of spending money on everything. My coolant is low in the tank.... I've filled it up, and it goes low but very slowly. In fact now its been 2 weeks since I added and its just a half inch below the cold add zone. There are no visible leaks and I've specifically checked around the thermostat housing which is a leak spot on many of these 4.0 V6s. Its dry.

If the cap doesn't hold pressure could that cause it to be low?

Also, something is weird with the temp. From a cold start, the temp gauge moves up toward the middle and then drops to halfway to the C. It'll stay there as long as I drive (i have a 16 mile trip each way) and then when I idle for a while it'll go back toward halfway where it should be. After 16 miles, I checked under the hood. The tank has liquid in it but feels room temperature... the upper hose is hot but I was able to put my hand around it and hold it there for at least 20 seconds before it started to feel uncomfortably hot. Shouldn't the upper hose be too hot to touch? The heater does throw hot air, but could probably be a bit hotter.

I'm not sure if all of this is related. What would cause the upper hose & tank to not be too hot?

Also another weird thing: I've noticed a whiteish chalky type of coating on the underhood insulator pad near where the front center of the engine is. This is different now because I typically keep my engine compartment very clean. Could this be residue from steam containing coolant? That would seem to indicate the thermostat housing area although its dry when cold.