hey guys. I just put in a thermostat cause my truck was changing temprature radically. It would bounce between the two middle lines on the temp gauge.. you could just watch it jump up and down. I put a new thermostat in thinking that would cure it. Now on the initial start up when the truck reaches temp rature it goes way up over the the thirde line until the stat opens. then drops off real quick to the second mark on the gauge then still bounces between the two. I mean you can watch it change as you drive.. it just isn't like it used to be. Any Ideas of what my problem is????

 

Where did you get your thermostat? From a car dealer or Cummins. They are built differently. Mine did the same as yours until I put in the Cummins one, and now it is rock steady. Mine you, hang on to something while you ask for the price. Cummins charges about $50 for theirs.

John

 

jeeze, its a napa one and it did look alot diffrent

 

WC, how about filling in your truck info in your signature? It'll help with your questions.

The trucks with the cross flow, will go up and down until you reach a steady operating temp on the highway.

 

Redleg, there I updated it for you let me know if you need anymore information about the truck

 

Don't try to go cheap for engine parts, get the right stuff from Cummins.

 

You have an up and down flow radiator. The temp should stay constant. I converted mine to the later radiator, but it's a chore and takes a buck or two.

My gauge fluttered initially. I pulled the wire from the thermocoupler on the engine. It was on there loose. I cleaned it and squeezed it a bit with plyers to tighten it up. Gauge has been good since then.