I have a 1997 Caravan (base model) and normally on my drive to work and my highway drives in rush-hour, the engine warms up just fine.
I took a road trip for work, about an hour and fifteen minutes of driving at basically 60-80mph the whole way. The engine never warmed up. In fact it went from being warmed up (about halfway up the gauge) to just barely above the Cold marker.
My blower only works on high, (a problem for another day) so turning on the heat for that chilly drive made the problem even worse (lost like a bar and a half of engine temp for running the heater at 75% temp, full blower, for maybe 10-15 minutes.) I turned off the heat for the last 30-45 minutes of the drive and it still never returned to normal temperature.
It's the Mitsubishi 3.0L V6, which I believe is a cast-iron block, if that helps.
It's also a 3-spd, so the engine works pretty hard to maintain highway speeds above 60, it should be producing plenty of heat. What's the best way to go about solving this problem?
(For comparison sake, in stop and go traffic, on my way into work, it takes about 20 minutes for that engine to warm up, not using the heater.)