my engine temp gauge is weird it stands inbetween 140 and 190 then jumps down to 140 then back to 190 and so forth

 

hey that is a normal thing with the older twelve valve engine the engines then and even today cool so well that as soon as the thermostat opens and coolant flows it goes back down to the 140 due to the engine running cool to begin with. the newer pickups you do not notice due to the cluster and the pcm working together to send you a buffered temp reading so you do not see the gauge fluctuate. dont worry this is normal

 

hey thanks that helps alot

 

Ya, mine does the same thing. From what I understand, there is a new Cummins thermostat which will regulate the temp more closely to avoid the wild swings, but there's no real harm in it.