‘05 T&C 3.3: weird temp gauge pegging

The following has happened twice now:

2005 Chrysler Town & Country extended van 3.3L with 103,000 miles started from dead cold after about 4 days sitting, then driven gently.
Engine started on first try and acts normally for about 5 miles during which coolant temperature gauge needle seems slow to climb to halfway mark, but gets there resting in its normal spot one needle width below halfway mark on gauge.

Gauge stays steady at halfway mark for about 5 minutes.
Then needle of gauge climbs very rapidly all the way to top red section and Over-temperature dinger comes on.
Needle stays at maximum high mark for 2-3 minutes,
then rapidly falls in seconds to halfway mark on gauge again.

Van then driven for 30 minutes to an hour without this happening again.

Coolant levels normal. Level in overflow tank halfway between Cold and Hot marks.
Radiator new about one year ago.
Battery new about 6 months ago.

After only a few months of use back in year 2005
factory dash gauges all went dead
and entire dash replaced under warranty.

Any ideas about what may be causing the coolant temperature gauge to do this?

Broken wire in lead to temperature sensor?
Bad electrical ground somewhere?
Sticking thermostat?

Start with a quality thermostat and make sure all the air is out.

I had one do very similar action several years ago.
Put a Mopar brand thermostat in it , make sure to bleed the air out of it .

Never a problem again and I still daily drive the van to this day

Use an infrared thermometer to see if in fact the engine is really that hot when the gauge is pegged. If it is in the 200F +/- range (assuming like most new stuff, that is normal operating temp), you have some electrical gremlin causing your gauge glitch.

Kevin

Well, like Murphy’s Law predicts,
I did a special test drive today to try to make the problem re-appear and it would not.

When the dash coolant gauge needle is on the halfway mark an IR Gun reads 209 F on the thermostat flange and Type K thermocouple probe reads 203 F at same spot on that flange.

Before I put the van back in the garage I parked nose up on a steep incline with the engine running for ten minutes to allow air to migrate to the top of the radiator.

I am thinking that on my next test run I should hook up multimeter leads to the wires of the coolant temperature sensor.

It took both a new thermostat AND a new radiator cap to fix this problem.

Original radiator began leaking at the driver’s side plastic side tank after 14 years and was replaced along with new hoses.

Original thermostat and radiator cap replaced at 15 years.

I believe I probably cannot trust the Original coolant pump
and will pay to have a dealership pro change it after reading the FSM and deciding that job needs a lift.