Engine/Transmission (1994 - 1998) temp gauge

[Xtremewheeling]

today when i was running my truck i noticed my temp gauge moving from about 150 to 185 then back to 150 then to 185 keep doing it constantly . . up and down... any idea what might be causing this???

 

[JDLight]

Thermostat, kinda nature of the beast. Have you had the truck long? Mine has always done this, some thermostats worse than others. I currently have a updated Cummins thermostat it is not supposed to do this as bad but it still does it some. I have heard of some folks having trouble with the rubber seal around the thermostat coming loose and getting stuck holding the thermostat open?

 

[JacobsD]

Mine does it too, as does every other one I've ever driven. I call it the 180-drop because it goes to 180 and then just falls like a rock. Freaked me out the first time I saw it, on I-84 in Newburgh, NY 2 hours from home :-laf

 

[EKlem]

The reason for it is that when the thermostat is closed, the coolant circulating in the engine is warming up but the coolant in the radiator is cooling down. Once the engine coolant gets warm enough to open the thermostat, there is a large temperature difference. As the cooler antifreeze from the radiator enters the engine, you see your temperature gauge plummet until the thermostat closes again and the cycle repeats.

There are a few ways to deal with this. One is to run a winter front. If you don't tow heavy, you can run one in surprisingly warm weather. This keeps the temperature of the coolant in the radiator from dropping as much. Another way to solve it is to hook up to a big trailer but this isn't something that you can really control. The last thing that I am aware of is to strategically drill a few holes in the thermostat so that it is more sensitive. If you do a search, you can find a picture of where to do this.

 

[LandShark]

Normal.
Use your search function on this site. This topic has been covered many times. There is also a TSB from Dodge on this subject.

 

[Xtremewheeling]

So... ... this isn't something i should worry about????

 

[LandShark]

Yes. Correct. It's nothing to worry about.