Coolant temp fluctuating???

[HammerHead]

Hears a video, Oil temps went from 221°F to 195°F. Coolant only drop 6°

 

[Wild one]

Hears a video, Oil temps went from 221°F to 195°F. Coolant only drop 6°

I could see that.As soon as the fan's turned on ,the coolant that flows out of the heater core is going to be a lot cooler and will drop a lot farther and faster then the engine coolant temp will.A lot smaller quantity of coolant to cool,so it'll cool quicker,then it probably flows out to the engine oil cooler/heater.

 

[joshuaeb09]

Hears a video, Oil temps went from 221°F to 195°F. Coolant only drop 6°

This is pretty normal behavior from what I've seen on both of my Hemi's before dropping to 180 T-stats. The heatercore bypasses the T-Stat so it can keep pulling heat out of the motor even when the T-stat is going to start closing to fight it and keep the main loop coolant temperature up. If the data I've seen on the Truck 6.4 configuration is correct the stock T-Stat is 216 (WTF). That being the case it's pretty easy for that heater core to do some work getting the oil temps down.

 

[Supercoupe1]

I have a 2012 1500 with the 5.7 HEMI. I was stopped at a light for two cycles and the temp light came on. I observed my temp gauge near the red. When the light changed, I pulled over immediately, the light shut off and the temp gauge started dropping. I began monitoring it and it was fluctuating between 190°-248°. Normally it would fluctuate between 188°-206°. I'm guessing the thermostat must be going bad because I've never seen my temp gauge so high.