T-stat housing and heater core nipples at the firewall.

 

Ok. I think it might be the gauge sending unit. After it been running the t stat housing gets really hot (way hotter than 120-130 degrees which you can touch). Seems like it must be reading 40-50 degrees too cold.

 

As mentioned, get an infrared point and shoot thermometer (they are CHEAP now), and point it directly at the thermostat housing.

Then you'll know what you coolant temperature truly is.

Good data = Good decisions.

 

So I went ahead and checked it with my friends temp gun. At first it was reading around 110F at the t-stat housing, with was total BS. There is no way I could put my hand on that thing (which I would if it was 110F). So I tired a couple of other spots to get a reading. The area where the upper hose meets the housing, and that gave me a temp of 140F (the truck had been sitting for about 5 minutes). I know the thermometer is accurate because we use if to tune our nitro rc trucks. I think since the new housing has a polished finish it was getting a weird reflection when trying to get the temp. This all leads me to believe my temp gauge sending unit is kaput...

 

Just giving this a bump to see if anyone else thinks my logic about what my truck is really running at is sound.