hey everyone. trying to figure out the best way to cool my old cummins down. the previous owner put a 3200 governor spring and a fuel pin in it and turned up the pump. its still got the lagmaster.... after driving it and getting it up to temp, my temp guage jumps from the middle to the 2/3 mark, back and forth, i assume as the thermostat opens and closes. im sing the truck for towing so i want to get this figured out. should i turn down the fuel? new thermostat? turbo?(not really in my budget at the moment) or shouldn't i be concerned? Thanks!!

 

The gov spring, pump mods, fuel pin, etc don't have much effect on your operating temps, they change your egt's more than anything.

What you are seeing on the temp gauge is completely normal. I had the same fear as you when I first got my truck, as the wide, sweeping fluctuations of the temp gauge is unlike any truck (diesels included) that I have ever owned. I was assured by Cummins techs as well as members here that this is completely normal for a 12V.

I will say, however, that you will definitely need a good set of gauges (like NOW) if you plan on towing with the fuel cranked.

 

good to hear. i've got boost, egt, and trans temp guages in it already. Thanks alot!!!

 

No worries mine does the same thing.

 

Mine does the same too when loaded up, temp gauge all over the place. I can really notice the fan when it kicks in, especially on a hill. It's almost as though Mopar designed it to work like a jet engine and "pull" the truck up the hill.