Friday update:
Yes, the truck has a thermostat
I honestly like that you guys are assuming I know nothing about engines- one of you might ask about something I have never heard of
Please continue to do so. I appreciate the help and the suggestions.
I have a recirculating burp bottle, but it is in the garage. Because I am going to install that bottle there is currently no hose on the overflow fitting.
Picked up a thermostat, thermostat gasket, radiator cap and magnetic oil pan plug today. A pressure tester was a hundred bucks so I passed on that
Will install them tomorrow.
For tonight, I filled the radiator [the truck sat all night], and left the radiator cap off. Turned the manual override for the fan ON. Started the truck and smoked two cigarettes. The needle never moved.
Turned the heater, the defroster and the heater blower motor all on high. Smoked another Camel. No change.
Put the original cap on and tightened it down. Turned off the manual override for the fan. The needle climbed slowly to the mid-range on the gauge [normal position for this truck] and stayed there.
Got out to check if the thermostat had triggered the fans [mostly deaf, here]. The fans were NOT running.
The overflow on the radiator, however, was puking water like crazy. The water coming out was nowhere NEAR boiling.
The radiator was not hot. It was not cold, but certainly not hot enough to be spewing water.
Maybe the fan's thermostat is fine, and just the radiator never got to a temp to activate it?
Read a lot of info on the net last night and learned that way over half of the cooling problems are caused by the water thermostat and the radiator cap. So for $16 I am going to install them.
Any other ideas about what [and how] to check?
Thanks,