Since I haven't had the coolant drained out in months and it's done this ever since I've owned it, I'm assuming that there is no bubble in the coolant.

So I'm ordering a Cummins T-stat soon, hopefully.

 

So what did you find out?

 

interesting thread. i have been going through this for 8 years with my 82 with 97 cummins in it. i would be willing to pay for a fix. 3 cummins stats and no change. 40 years in the business and have never seen an engine i couldnt get hot until i ran into this. called cummins tech 3 times they told me it couldnt do that, couldnt help. now i dont feel so alone.

 

The Cummins T-stat fixed it!

It may have not been just the T-stat itself, but the fact that the gasket was chewed up really bad on the old one when I took it out. It was basically allowing water to bypass. Don't really know why it ended up that way when it got installed.

In 30 degree weather, I can get up to 180 within 15 minutes of driving, even less if the truck has been plugged in. The dual jiggle pins in the T-stat help keep the temp gauge from seeking as much when it opens and closes. It gets to 180 and stays right there until I'm done driving. First time it's ever been like that. And now both my temp gauges correlate with each other perfectly.

 

Good to know, thanks!

 

wish mine was that simple