BigstarATX

When driving at 70 mph for an hour today I was watching my temp gauge swing between 165 to 190 back and forth back and forth. It never went past 190 right in the middle of the gauge. When I slowed down the temp went back to 140. Is this normal?

The truck generally runs cool 140ish

BigstarATX

32 views… no input?

oliver foster

What sort of input do you need? I read this yesterday and figured it really was not an issue that needed attention.

Sounds like a thermostat doing its job at highway speed.

I have taken a 5 hour long road trip in the summer and watched my temp gauge swing up and down the whole time as the thermostat opens and closes.
Theses trucks run cool. Now if your temps where reading 230, then we would have a problem to fix.

BigstarATX

Oliver! My Man! THAT”S the input I was looking for. None of my other trucks fluctuate in temp so quickly like that……. up, down,up,down,up,down. I just wanted to know if that was normal and it sounds like it is. Thanks for the info. Have a great week brother.

oliver foster

Glad to be able to ease you mind on that one.
The manual trucks I own all run cool. It is the auto trucks that have the transmission heat dumping into the antifreeze that can run warm. If a Cummins auto truck is making a lot of power and still has the loose OEM converter it - those can actually run hot.

texasprd

Temperature swing is normal on these trucks if your running unloaded. The cooling system system is sized for this truck to pull a substantial load, so when running unloaded you don't really build enough heat load to keep the thermostat constantly open. There was a revised thermostat along the line that was supposed to help with that issue.

I have an auto and get temperature swing when running unloaded.

BigstarATX

Good information guys. Again…. thank you for your experience. I was a little concerned while cruising along at 70 mph in 5th gear at 75 degrees outside. Watching the temp gauge fluctuate up and down nonstop while I drove was a tad concerning. I was literally telling my girlfriend how nice it is that the truck runs so cool at 140 that morning and then in the afternoon watching it fluctuate I was concerned.

Rare1

My 1998 automatic 2WD temp gauge stays dead center mostly. It rises a little when pulling a load uphill and I forget to downshift out of OD. I can't agree fluctuations are normal. I would say the thermostat is sticky and requires temperature excursions to un-stick it.

nothingbutdarts

Do 2nd generations run warmer? My 01 would never run that cool, I don't even think downhill it would.