(Stuck) thermostat issue...?

[Ronin]

My '22 Hellcat is just under 3K miles and 2.5 years of ownership. I've noticed on more than one occasion, and most recently when I drove it the other day, the coolant temperature varying significantly. I typically drive it with the gauge dashboard on displaying oil temp, coolant temp, IAT and transmission temp. Daytime temps here are currently in the high 70s/low 80s.

My mods are in my signature and the only engine modification is an OCC, no tune, etc. I don't recall the exact temperature of the stock thermostat but thought it was 200 or something...? The temp sweep of the gauge is 170-260 and the 12 o'clock appears to correspond to 215 degrees.

The other day I was on the interstate for 10 minutes or so when it appeared to fluctuate rather wildly, and hit 2 o'clock hashmark/230 degrees momentarily before rapidly dropping to the 11 o'clock/200 degrees then back up to the 12 o'clock/215 degrees. Cruise on, constant speed, minimal load increase, etc.

I've noticed it do this before and found 220+ readings to be rather alarming, especially when I'm not doing anything remotely demanding. The rather wide and abrupt temperature fluctuations have me thinking it's a wonky thermostat, but was curious if anyone thinks it could be something else.

Both reservoir levels are where they were when I bought the car and there's no discernable loss of power, etc. Just the coolant gauge doing a jig while all the other gauges are reading nominally.

I know there's no benefit to swapping out to a lower temp opening thermostat without the benefit of tuning to adjust the fans. It gets crazy hot here in the summer, well into the 100-teens and seeing this happen the other day when it's relatively mild out was a little disconcerting...

Thanks in advance for thoughtful/helpful replies!

 

[06SRT10NR]

My '22 Hellcat is just under 3K miles and 2.5 years of ownership. I've noticed on more than one occasion, and most recently when I drove it the other day, the coolant temperature varying significantly. I typically drive it with the gauge dashboard on displaying oil temp, coolant temp, IAT and transmission temp. Daytime temps here are currently in the high 70s/low 80s.

My mods are in my signature and the only engine modification is an OCC, no tune, etc. I don't recall the exact temperature of the stock thermostat but thought it was 200 or something...? The temp sweep of the gauge is 170-260 and the 12 o'clock appears to correspond to 215 degrees.

The other day I was on the interstate for 10 minutes or so when it appeared to fluctuate rather wildly, and hit 2 o'clock hashmark/230 degrees momentarily before rapidly dropping to the 11 o'clock/200 degrees then back up to the 12 o'clock/215 degrees. Cruise on, constant speed, minimal load increase, etc.

I've noticed it do this before and found 220+ readings to be rather alarming, especially when I'm not doing anything remotely demanding. The rather wide and abrupt temperature fluctuations have me thinking it's a wonky thermostat, but was curious if anyone thinks it could be something else.

Both reservoir levels are where they were when I bought the car and there's no discernable loss of power, etc. Just the coolant gauge doing a jig while all the other gauges are reading nominally.

I know there's no benefit to swapping out to a lower temp opening thermostat without the benefit of tuning to adjust the fans. It gets crazy hot here in the summer, well into the 100-teens and seeing this happen the other day when it's relatively mild out was a little disconcerting...

Thanks in advance for thoughtful/helpful replies!

OEM s 203 deg
watched the digital gauges to see if the temps roam in the same range as the analog gauge?
any codes pop up in the IC? maybe P0218 [thermostat, coolant level/quality]? P010# [water pump temp sensor]? others?
heater working properly?

thermostat - $55-75, 20 mins to swap, been there, done that
temp sensor - forgot the cost, been there as well, had a local shop figure this one out and replace
heater core issues - $$ and pain in the ass to replace, clogged hose in/out of the core, not as expensive, but still a pita. dealer service dept extended warranty repair, so only cost me $100, plus many months of concern about all the dash/interior deconstruction needed to get to the fcker

 

[Ronin]

OEM s 203 deg
watched the digital gauges to see if the temps roam in the same range as the analog gauge?
any codes pop up in the IC? maybe P0218 [thermostat, coolant level/quality]? P010# [water pump temp sensor]? others?
heater working properly?

thermostat - $55-75, 20 mins to swap, been there, done that
temp sensor - forgot the cost, been there as well, had a local shop figure this one out and replace
heater core issues - $$ and pain in the ass to replace, clogged hose in/out of the core, not as expensive, but still a pita. dealer service dept extended warranty repair, so only cost me $100, plus many months of concern about all the dash/interior deconstruction needed to get to the fcker

Thanks for your response, I appreciate it!

The digital temp gauge matches the sweep/response of the "analog" one; I remember that as soon as you asked.

I did NOT check the codes before posting, shame on me, but after checking there weren't any...

I swapped out the IAT gauge for the I/C coolant temp so the next time I'm out and about I'll see if it behaves similarly.

I'll likewise check the heater too, as unpalatable as that sounds! Just like my home it never gets cold enough here for me to turn it on, but I'll manually do so on it's next highway speed trip.