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Discussion Starter · #1 ·
It has been a long time since I've been on the forum, but came back to see if I could get an answer on an issue that has been bothering me. Last December I bought a 2021 SRT (new) as a third vehicle for us to use some around town and to our lake house. (It fits easily in the garage, is fairly small compared to our other vehicles, etc.) My issue is coolant temps. I'm an exceptionally anal retentive sort and do all of my own PMs, and other light maintenance. When driving the Jeep, normal cruising temperature is 203 or 204 degrees. This isn't terrible, but probably about 5 degrees warmer than most other modern vehicles I've owned - no big deal. When in traffic, or at a long light however, the doggone thing will climb as high as 221 degrees before the fan kicks on to start bringing it down. I don't like this in the slightest. It stresses the heck out of me. I realize that modern vehicles are engineered to operate warmer due to emissions, but this swing just isn't "cool" with me (pun intended). Conversely, our 2021 Escalade operates between 197 and about 206 on the high side...and of course my 6.7L Powerstroke, well heck-it is a diesel...I can sit in traffic forever. I've tried the search function here on the forum, but have found nothing specifically about this issue.
 

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I think what you're experiencing is fairly normal. I geek out on fluid temps and love that we are able to track the temps of a lot of items. In any event I usually find that once the vehicle (a 2018) reaches operating temps, the coolant fluctuate between about 204F and abouy 220F. You've got a big displacement engine with I feel is a frontal area that's a little too small to direct enough cool into the car. I assume, however, the jeep engineers have taken this into consideration. I have another vehicle with a bigger displacement engine than it was initially designed for and oil/coolant temps can also get pretty high.
 

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Discussion Starter · #3 ·
You are spot on with respect to the small frontal area, and this of course isn't lost on me. I just thought they'd engineer it so that the fan would come on sooner to keep it closer to normal temps as opposed to letting the thing get to 219-221. Like I said, our Escalade (2021) with 6.2 L has a pretty small window-operating temp range; it is just a matter of when they have that fan programmed to come on...
 

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I totally agree. Though the charger/challenger likely have a smaller frontal area. I suspect that this was taken into consideration when the 392 was under development. I guess what I'm saying is that although the engine runs hot vs other v8 engines, my money is on the engineers taking this into account during development. Most companies do both hot and cold weather testing, so they're stressing the engines more than I am. My only evidence to support my conclusion--which is admittedly flimsy---is that other than faulty water pumps, I haven't read about a lot of heat-related issues.
 

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Not sure what engine you are running, but our wrangler with the 3.6 penastar runs all day long at about 223. It has been as high as 240's while climbing mountain grades. According to the manuel, this is normal operating temp range. The first time it went into the upper 230's, I thought I was going to need a change of britches.
 

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My ‘17 GCSRT runs at the same temps as yours. I was worried at first, but after 40,000 miles with no issues, I don’t even think about it.

If it really bothers you that much, you could get a 180 degree t-stat and a Diablo tuner, but it will be pricey since I believe you’ll need to also purchase an unlocked PCM. You‘d be looking at spending around $1000.
 

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Discussion Starter · #7 ·
Everyone's responses are appreciated. My last question (and you just know the dealer won't do this) but...I suspect that they could easily modify the high side temperature trigger point downward to, say, 210 degrees. Problem is, I know they will give me some excuse why they can't...
 

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Everyone's responses are appreciated. My last question (and you just know the dealer won't do this) but...I suspect that they could easily modify the high side temperature trigger point downward to, say, 210 degrees. Problem is, I know they will give me some excuse why they can't...
Why do you want to? It's engineered to run at that temp. Lowering it won't help anything. All 3 of our Jeeps (17 Summit 4x4 Hemi, 17 SRT, and 2020 Trackhawk) all run in the temp range you're indicating. So it's perfectly normal and designed to run at that temp.
 

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Thermostat OEM I believe is 203F operating Temp. Putting Aftermarket Thermostats in without a tune to also account for them Pisses these things off. They are Tuned/Programmed to achieve that operating temp for Closed loop fuel status and other things Making them run cooler with out accounting for that they can run rich etc. My 2012 SRT runs around 215-220 all day.
 
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