Are you guys just going by what the dash gauge is reading ?, if so, that's not right.
The temperature gauges on these trucks at normal operating temperature tend to read on the cold side of normal.
On my truck at normal operating temperature my gauge reads 2/3rds of the way up between cold and the center mark on the gauge, so by looking at the gauge you would think its running cold, when its not, its normal.

 

I did not realize that. I'll go take another look. When I start my truck, there is a sound like liquid being quickly sucked into something (loud gurgling) for a few seconds, then no sound at all. Any idea what this might be?

Yes, I was basing it off the readings on the dash gauge.

Also wondering if my battery is going dead. When I turned the key a few days ago, it would crank with no hesitation. Over the last day or so, it hesitates for a second, then cranks. This morning it was 42 degrees, and there was a distinct hesitation, then it cranked and the gauge went up to the mid-mark (i.e. normal).

 

The gurgling is air going through your heater core. You have air pockets in your cooking system and/or low on coolant.

 

Is the process the same on a truck for getting air out of coolant as a bike? Start it with the radiator cap off and watch it burp bubbles out until they stop?

 

Yes, although everyone here will tell you to park the truck on a 30º incline (nose up) to get it to burp properly.

 

I parked at an angle with a good bit of 'pucker-factor'..... and STILL had air in the heater core. (poor heat.) I ended up taking the hoses off, and back-filling it, to make SURE as much of the air as possible was out. Now, the heater will cook you out.

 

I like it when 2 "issues" are connected. It was chilly this morning and I could feel warm air coming out, but it wasn't hot. With fall / winter approaching, I would prefer to have hot air. I have a fairly steep hill in my hard where I can park the truck see if I can get the air out.

How do you backfill coolant?

 

I separated the heater hoses, passenger side at the 'joint' in about the middle of the valve cover. Drivers side I took off from the steel pipe coming out of the water pump. Prop the p side hose so it was pointing up, held the d side hose up, with a funnel in it, and poured in some coolant, until I had coolant coming out the other hose. Had my wife hold the hose up while I reconnected the p side, fill d side some more, pinched it off, and reconnected it. Nice, toasty warm cab.

Another option would be to pick up a 'flush and fill' cooling system kit. Install one of the T's (with the cap) RIGHT after the outlet of the heater core. (drivers side is outlet) Start the truck up, and crack open the cap, let it bleed until you don't get any more air out. Should be golden.

Remember to top off the cooling system either way.