Engine temperature varies

[Jersybehr]

I have a ‘21 RAM Laramie with a 5.7 engine. Last week I noticed the engine temperature bounced between 196 and 226 degrees during some stop and go traffic. Expressway travel was 203 to 206 degrees.
When I got home I checked the coolant level and operation of the fan. Coolant was full and after warm up the fan came on at about 210 degrees.
During warm up I felt the top hose. It got slightly warm from approximately 175 degrees. At that point I think there was partial tycoolant flow. At approximately 208 degrees the thermostat opened fully with the top hose getting hot. The temperature proceeded to drop to about 196 and then slowly went to 206 degrees. It stayed there until I turn on the AC to get the fan to come on at 210 degrees.
My question is, this nominal operation and I just was not paying attention or is this a problem?

 

[gt8684]

Yeah this is normal (not that I agree with it). I remember the first winter in my truck, no A/C running, I pulled off the interstate and the temp jumped up to 230 while waiting at the red light. Thought something was wrong with the fan, turns out that is just the temp they say is "ok"... If I recall correctly the factory stat is a 200.

 

[Jersybehr]

Thanks

 

[Jersybehr]

Next question. The research that I have done is that the thermostat can be changed to a 180° but unless you remove some of the radiator louvers it will still run around hot.
My question is this. If I change the thermostat and remove the center louvers leaving the top and bottom rows (so it won't trigger a code). With the temp down the approximately 180°, will it through a check engine code? And if it does, can I delete it without it coming back?

 

[gt8684]

From what others have said yes removing some louvers will help, but that won't change the temp that the fan comes on, so putting in a 180 stat and driving down the interstate yes the engine will run closer to 188-190... but if/when you are sitting at the red light in town it will still get up to 225 before the fan cuts on to cool it down. To change that you would need to unlock the ECU or get a programmer. Same with the check engine light, most people say they don't get it to come on and run 180 stat, but if it does with a factory ECU you can clear it, but won't mean it can't come back, if your ECU was unlocked you can then clear the code and prevent it from coming back.

 

[Bigskyroadglide]

The electric radiator fan is commanded to on with the ac, not the manual water pump mounted fan. If you run your truck in auto temp control, if you have it, your climate control system internally will attempt to keep itself at the desired temp, I say all this because it will impact engine temp.

If the electric fan, not manual is commanded to on by the climate control engine temps tend to drop and rapidly, if you run climate control in heat, then your generally not using the auto or ac functions.

If you remove. All the slats in the automatic shutters except top and bottom, it will not set a code and they will function as designed, except no slats exists and airflow is not impeded.

This doesn't impact thermostat operating temp, it just allows more airflow.

Changing the thermostat (factory is 203) to a 192 or a 180 usually will not set a code, below that its a crap shoot.

To address fluctuating temps, you need to change the thermostat, (i choose192), make certain the coolant is in the correct operating range of full, including overflow bottle (between the min.max marks), and remove grill shutters. Absent all three of these being changed, you will generally get a range of temps and all are ok.

Usually between 235 and 245, you should be concerned as the margin for error is slim.

I've spent extensive time studying on this problem as I have a supercharged 5.7 hemi. And travel routinely coast to coast and in various degrees of hot to cold.

My temps are rock solid once the engine coolant is above 192. Oil temps are another issue and I didn't address.

Oh and the wife hates auto climate control. When she wants heat it's max hot. max fan speed, so understand user input is a variable.

 

[ExpressRules]

Have you thought about it may just be the thermostat not opening correctly?? It's easy to change and low cost possible solution.