Am I running too cold?

[Jerry Bransford]

I would not put any t-stat below 180 in anything. Mine runs around 190 with a 180 t-stat and there there is no enrichment. At around 160 there is quite a bit of enrichment. Once in closed loop it will not vary A/F much if any. Narrow band O2s don't have enough range to allow it.



Maybe higher emissions? I've passed tailpipe emissions tests with 2 different cars with 180 t-stats so ¯\_(ツ)_/¯



I have not had any issues in 2 years even in winter, but Tennessee winter is more like Colorado fall.

What do you have against running the specified/correct 195 degree thermostat the engineers programmed everything around? You do realize the engine will run the same temperature on a warm or hot day with a 180 or 195 degree thermostat right? It definitely won't run any cooler on hot days with a 180 than it would with the correct 195.

 

[Turdworlder]

If its correct stant thermostat you have to drill a bypass hole

 

[Brianj5600]

If it passes emissions, In my experience there is a small power advantage in cooler water temperature with stock settings. Above 204 degrees the mapping reduces power. At around 215 it gets a little more aggressive in reducing power.

The bean counters decided that knock sensors are too expensive. The PCM is capable of supporting a knock sensor so the savings is a couple of wires and sensors. That savings caused the powertrain engineers to go ultra conservative with calibration.

For people altering factory settings to tune for performance, cooler combustion chambers allow more cylinder pressure with out knock. I never run less than 180 degree t-stat to keep wear down.

What do you have against running the specified/correct 195 degree thermostat the engineers programmed everything around? You do realize the engine will run the same temperature on a warm or hot day with a 180 or 195 degree thermostat right? It definitely won't run any cooler on hot days with a 180 than it would with the correct 195.

I don't think the engineers did a very good job on the 4.0L performance wise. My only guess was to meet emissions? Poor quench, low compression and lazy ignition timing are my top complaints. I have addressed the ECM settings and will fix the other 2 this winter.

My experience with engine temperature mirrors DylanM345. The only time I see 210 is hot days idling on the trail. It drops back down below 210 once I start moving and the rpm goes up. This is my normal.

 

[KingCarGuyZ]

I don't think the engineers did a very good job on the 4.0L performance wise. My only guess was to meet emissions? Poor quench, low compression and lazy ignition timing are my top complaints. I have addressed the ECM settings and will fix the other 2 this winter.

I will agree that Jeep engineers did not push the performance envelope of the 4.0 much at all, perhaps for emissions. But I think more likely for longevity.

These engines are bulletproof, known to go to 300,000 and Keep on kicking. Mine has 250,000 and is happy as a clam. If you do got to increase compression and timing and such. Keep in mind that these were not designed as Short term high-performance race engines, but more as reliable tractor engines for the long haul. Does that mean that you can’t get more HP out of it? No. But do your really need 400HP on the trail? Or would you rather know it’s gonna take you back home no questions asked?

 

[Brianj5600]

LOL @ 400hp. Why do you talk in such extremes? There is an enormous gap between a race engine and a tractor. I have no intention of putting 300,000 or 200,000 miles on it. I doubt I'll put 100,000 miles on it in the next 20 years. I am not trying to do anything crazy, just correcting what I see as flaws and add some displacement. Power production will likely be moved lower in the RPM range. I'm looking for enough power to pull my off road trailer in the mountains and no more.

 

[KingCarGuyZ]

LOL @ 400hp. Why do you talk in such extremes? There is an enormous gap between a race engine and a tractor. I have no intention of putting 300,000 or 200,000 miles on it. I doubt I'll put 100,000 miles on it in the next 20 years. I am not trying to do anything crazy, just correcting what I see as flaws and add some displacement. Power production will likely be moved lower in the RPM range. I'm looking for enough power to pull my off road trailer in the mountains and no more.

Choose 400 cause it’s the highest I’ve heard of a AMC straight 6 making, though it’s deffinetly true you can make small trade offs, it’s a scale. Sounds like you have a plan that will work we’ll for you. Curious to see how it goes.

 

[EricT77]

I have a trail dash that tells me my temps. I was able to tell when stuff needed replacement, when it started creeping to 212° then to 217° I replaced everything with Mopar parts, and now in the central Fl. heat I hover around 199 driving, to 206 at stop lights. Only shows just under 210 on gauge. This is stop and go traffic.

 

[Rubicon88]

Dash gauge display might be canted some.

It wouldn't bother me s but.

Quit stressing and run it.

 

[Brianj5600]

I thought of a downside...heater not as warm.

 

[D M]

Just an update, I installed the Stant 195°F thermostat and it fixed my problem, she now runs at 210 operating temp. Thanks

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