Engine/Transmission (1994 - 1998) Coolant temp gauge readings

[RProvence]

I have a 97' 2500 4x2 auto. The temp gauge moves between 140 and 190 constantly while driving. Thought it might be the thermostate so I replaced. Still have symptom. Could this be sending unit or something else. It is not overheating and the coolant level is good.

 

[BigPapa]

RProvence,



Welcome to the TDR! I was told that the temp swing is normal with our engines. Mine has done it since I bought it used over 100K miles ago with no ill effects. It is caused by the cycling of the thermostat open and closed.



That said, I have read some posts where some members think that this fluctuation could be to blame for blown head gaskets and even some cracked heads. Seems like I recall reading somewhere in the TDR Magazine a statement from Dodge or Cummins to the effect that it is normal. Word also has it that Cummins came out with a new thermostat which greatly reduces this effect.



Scott

 

[Joe G.]

Normal. You can spend quite a bit of money and time trying to defeat it, but it doesn't hurt anything. Kind of natural considering the amount of coolant in the radiator when the t-stat opens. It's worse when it's cold than on a hot summer day. Mine did it for 130K miles then it stopped swinging. I got suspicous and pulled the t-stat. It was in bad shape. It was original equipment from when I bought the truck. The rubber cover had split and was jaming it slightly open. I bought a new one at NAPA. Back to the swinging and I'm confortable with it again.