I just bought a new to me 97 2500 CDT (I'm new to the Dodge trucks, too) and have a question about the engine temp gauge behavior. As it warms up, the gauge comes up to the start of the normal range mark (guessing around 150; 140 is marked) and then up to the middle of the normal range (again, guessing around 180; 190 is marked). In normal driving, the needle drops to 140, then climbs back to 180 every few minutes for no obvious reason. It takes maybe a minute to drop and then climb back up again. Is this gauge a direct-read, or just another "idiot light with a needle" deal?
Any ideas?
Thanks.
Greg

 

It's an electrical guage and sounds as if it is working properly. The cooling systems are so large on our trucks and I believe they are setup to operate this way.My truck has done so since new.

 

Its normal for these cummins thermostats to cycle between 145-190<br>there is a cummins stat that doesn't cycle as much I don't have the part # handy

 

Pappy is refering to Cummins part #3934373. I changed mine, it still cycles but not as fast.<br><br>Michael

 

Since the thermostat seems to cycle between 150 and 180, would I most likely have a 150 thermostat, a 180, or something else?
Thanks.
Greg