Just a quick question on my 1997 12v. The temp guage never seems to reach a constant temp and stay there. Once the engine gets warm and the temp get to @170-175 it will then drop rather quickly back to @150 and slowley creep back up to the 170 mark then fall again. once the truck is warm it cycles between 140-170 with in about 1min. is this normal?
Thanks
Ben

 

this is normal,these trucks have a large cooling system and when not being worked this is what happens,i use a winter front to help keep the truck warm and a constant temp when not being worked,then adjust according to load and temp......hope this helps......

 

Does the truck have the original T-stat. If not, this is a really bad problem with most replacements. There is one out there from Cummins that can correct this, but I don't remember the part #. Might be able to get it from local Dodge dealer, or maybe someone else knows it.

 

I went with the "improved" stat, it kept the temp steady but too low, went back to the old one. A lot of it has to do with the location of the coolant sensor. If you have a oil temp gauge or even a pyro you will see that their temps don't swing with the coolant temp, the block temp is remaining constant and there is really no reason for concern.