Picked up a '97 3500 CTD 5-spd Dually the other night. I'm so glad I'm back in a Cummins, especially after driving that Powerjoke I had. As for the Dodge, all is well, everything works and everything seems fine aside from needing a new set of front tires.

This morning I installed a BHAF and removed the silencer ring from the HX35. These are the ONLY mods on the truck, and I've literally got less than 200 miles on it since I bought it.

I was headed to a job interview at around 1pm today and noticed the water temperature gauge climbing to 190-degrees. Once it hit 190, it backed down to operating temp. Then it kept doing it the entire trip and back...and still does it now. It never goes over 190, but it is constantly fluctuating between operating temp and 190. Acts the same way at idle, driving around town, and on the freeway.

What can this be? Fan, Thermostat, Sensor....??? Hopefully someone here can point me in the right direction before I start spending money on stuff that isn't the culprit of this pesky little issue.

Thanks in advance

 

What do you consider operating temp? The stock thermostat in my 99 is a 190 degree. It will climb to 190 and never come off. When I first got the truck it would only get up to 160 because of the bad thermostat.

 

Cummins says,

THE COOLING SYSTEM USED ON THE CUMMINS DIESEL ENGINE EQUIPPED VEHICLES PROVIDES THE CAPACITY AND PROTECTION OF THE HIGHER GVWR AND GCWR RATINGS AVAILABLE ON THESE VEHICLES. OWNERS SHOULD BE ADVISED OF THE NORMAL SLOWER WARM UP AND LOWER ENGINE OPERATING TEMPERATURES ASSOCIATED WITH DIESEL ENGINES.

THE COOLANT TEMPERATURE GAUGE WILL FLUCTUATE ON DIESEL ENGINE EQUIPPED VEHICLES. IT IS INFLUENCED BY VEHICLE LOAD, OUTSIDE AMBIENT TEMPERATURE AND EXTENDED IDLE TIME. THIS FUNCTION IS CONSIDERED NORMAL

 

change the thermostat, if it still does it you probably have no problem

 

Yeppers....If its not the thermo you should be alright. Mine did the same thing. Bounced from 190 to 160 often... Friends said it was either thermo or just outside heat or load doing it... I somewhat ignore it nowadays...

 

Cool, thanks fellas.