Temperature Gauge

While i haven't paid much attention to this gauge it doesn't act like others i've been familiar with. Since its been cold here the trucks gauges reads mid-way when i'm driving at a normal speed when the engine is warm. When i sit at a light idle it goes down to a 1/3 of the way, and then back up when in motion. Imo, it seems a bit strange....would this be normal operation? Don't remember this happening in the summertime.

 

Interesting, you'd think you'd be getting warmer at a stoplight just sitting there at idle. If you're really curious, you can get a bluetooth OBDII reader and an app on your phone and see what your actual temperature is and see if it correlates with the gauge on the truck.

 

I haven’t noticed fluctuations, I’ll keep an eye on it as I drive around today.

 

I haven't noticed any that far. Check coolant levels.

 

What's your ambient temperature? Apples to Oranges comparison I know but the Diesel engine in my F-550 does this when it's less than 50F or if I leave it idle for more than a few minutes on cool days. My gas-powered Silverado does the same thing. To me it's normal.

 

Truck was at the dealers yesterday for its 2nd service and inspection...supposedly all was perfect. I just noticed it this morning when running an errand. Pretty sure when in warmer weather this gauge never fluctuated like now. I can tell you this truck has been cold blooded in the past taking its sweet time to fully warmup.

 

thermostat

 

I just looked at this yesterday. I have OBD fusion. It said 170 coolant temp when the dash gauge was in the middle. But it was also in the middle when the OBD said 200. It was about 28 F outside temp. Toyota says that’s normal. LOL.

 

My truck barely leaves the cold mark at idle during warm up in severe cold.

I can start it and let her run 15 min and come back to a cold engine. Gotta get the RPMs up to reach normal operating temperature in the dead of winter.

My gauge does not fluctuate once she’s warm.

 

In my experience with Ford, Chevy and Toyota most do this. I have a Scan Gauge connected in my Silverado and it's not uncommon for the Scan Gauge to read different than the dash gauge, especially when the truck is warming-up. I think the one in my F-550 Work Truck is the most egregious though; on the dash gauge I can see sometimes a 30 degree difference between the dash gauge and the Scan Gauge, at least until it goes over 200 Degree's, then the dash gauge moves pretty quickly off-center and matches the Scan Gauge.

From what I've been told most of the manufactures do this so that their Service Bay's aren't over-loaded with cars customers think are overheating because they climbed a steep grade on a warm day and the temp gauge moved slightly off-center for a minute.

 

This is exactly the case. My gauge will stay dead center from 185-230. Once it gets above that, it climbs pretty rapidly, almost hitting red at 240. This from first-hand experience staring at my gauge and also monitoring temp on my ultragauge simultaneously.

 

How cold is cold to you? The coolant temp will absolutely drop while idling in colder weather. I assume due to the mechanical fan always spinning.

That being said Ive never seen it drop enough to move the needle much (if at all). From what Ive seen (in my 2nd gen) the temp will stabilize in the mid-high 170*F range when its about 10*F outside. Normal operating temps for me is ~191

 

Jaguar had a problem with this in the 90’s so the swapped out gauges so the needle would be in the middle. LOL

 

OP you don't say where you are and what the outdoor air temp is.
Think about this for a bit:
Your truck engine's heat output is higher at road speed & revs than at idle.
When idling in cold weather the heat transfer out of the radiator is much higher than is needed, so the coolant temp will drop dramatically. Conversely, when driving at highway speed the heat output of the engine more than compensates for the heat dumped out through the radiator until a "normal" balance is achieved by the thermostat.
In other words, it seems normal to me.

 

I don't think so, i've got plenty of heat once the truck comes up to temp. If the thermostat was an issue you'd think there wouldn't be much or any heat....at least what i experienced with older thermostats in my past toyota 4 cyl trucks. Its almost like toyota over engineered the cooling system for this truck. Its strange however when your doing normal highway speeds the temp gauge reads normal mid-way, and never moves till i come to an idle then it immediately drops a 3rd of the way.

 

My gauge doesnt move at all once its at operating temp, but i do notice on my pod it will drop down to 160-70ish when sitting at a light then back up to 186ish when im on the move. -30 today for reference.

 

After reading several posts, i'm just starting to think my gauge, and sensor are picking up the variations in coolant temps as the rpms in the truck rise and drop as some posted above.

 

My 2020 Trd sport did this when we went camping 2 years ago. Was 25 degrees outside and just sitting there idling the temperature gauge kept fluctuating . My new 2023 sr5 v6 seems to do the same thing but not as drastic. The needle takes a while to get to the center and will come off center when I start idling. Takes a solid 20 min of driving after it reaches center then it will stay there and won’t be any more fluctuations

 

I can say from experience the needle doesnt get to the center idling alone when its this cold outside

Feb 4th 2023. Idled the truck on and off for a few hours while setting camp up and getting the diesel heater going. This was the best she could do, but enough to keep the cab in low 50s. Good enough to eat dinner and warm the hands between outdoor tasks