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I'd like to update a different thread I made here discussing towing techniques. Someone said max heat but WITHOUT the A/C on. Care to comment on why AC -vs- not? I want to make sure I really understand this stuff... lol
If you're already running hot, the fan is already running at a high duty cycle, so turning the AC on doesn't accomplish anything. The reason you want the AC on is engage the fan earlier - at a lower coolant temp - to keep it from running hot in the first place.

Mark

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Found this on a different thread:
Due to numerous variables and operating conditions, the
information the customer is seeking is unavailable.
The temperature gauge shows engine coolant temperature.
Any reading within the normal range indicates
that the engine cooling system is operating
satisfactorily.

The gauge pointer will likely indicate a higher temperature
when driving in hot weather, up mountain
grades, or when towing a trailer. It should not be
allowed to exceed the upper limits of the normal
operating range.

Low end of normal is about 105 °F.
High end of normal is about 255 °F.
According to available information, transmission fluid temperature can be
20 °F hotter than the engine coolant temperature.

Jonathan D. Sanders
Fiat Chrysler automobiles (FCA)
Mopar Headquarters

The temperatures given as 'normal' are way out of whack. If you are at 105 anytime other than during warmup then you have a bad thermostat, and if you are at 255 then you are at the point of venting coolant. Those are allowable temporary operating limits, not normal operating range.
 

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The temperatures given as 'normal' are way out of whack. If you are at 105 anytime other than during warmup then you have a bad thermostat, and if you are at 255 then you are at the point of venting coolant. Those are allowable temporary operating limits, not normal operating range.
I agree 255 doesn't look "normal"
Mine 233 at idle doesn't look "normal" to me, but something tells me i will see higher numbers with the summer heat.
I have another "hot running" motor a 2.0 liter port injected Hyundai- that thing is hot at idle~ 226 probably for emissions purposes but as soon as there is load on the motor temp drops do to thermostat electronically controlled by the ECU.
Literally going up the hill the engine is colder than at idle. Nice and simple.
 

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The Heart Rate will likely indicate a faster rate
when living in hot weather, up mountain
grades, or when towing a child. It should not be
allowed to exceed the upper limits of the normal
operating range.

Low end of normal is about 1BPM
High end of normal is about 255BPM.
According to available information, skin temperature can be hotter than the internal temperature.

Jonathan D. Sanders
Fiat Chrysler automobiles (FCA)
Mopar Headquarters
 

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so I have had simial issues and sicovered a few things.



1. Grill guards will affect temperatures especially JK's with automatic transmissions and A/C due to the extra coolers mounted on the front of the rads.


2. 3.6 pentastars run hotter and suffer from heat soak. This is why every other FCA car/truck has a rad twice as big. this is why the JL has a higher speed rad fan and use the A/C system to cool the Gen 2 pentastar's. The gladiator has more open grills for the increased towing.



3. programing is bad for the electric fan especially on the 2014's.


4. OAT. It is my belief that the OAT is not as good for heat transfer compared to the old green stuff.


To combat heat I would do the following:


1. take off the grill guards/ engine cover/ rear hood seal if your doing any towing or long mountain passes/ hot summer days.


2. flush coolant system several times and go back to old green stuff (cheaper and easier to find).


3. change out tstat/ housing. Doorman has one I noticed on rockauto. havent got it yet but I have had very good luck with thier products


3. Change electric fan settings. This will require a $500 programer. Stock fan settings dont engage till 225F unless you turn on A/C. I have been looking at this one: https://www.amazon.ca/Superchips-3874-Flashpaq-F5-Programmer/dp/B017J7SFZI/ref=au_as_r?_encoding=UTF8&Make=Jeep%7C42&Model=Wrangler%7C356&Year=2014%7C2014&ie=UTF8&n=6948389011&s=automotive&vehicleId=1&vehicleType=automotive


Changing it to engage at 210F should be optimal.


4. SWITCH YOUR OIL TO 5W30 SYNTHETIC!!! fca had to switch to 5w20 due to the caf standards back in 2012. This motor was developed to work with 5w30. early pentastar's in 2011 even had 5w30 listed on the oil cap covers.
 

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Unlees Superchips has changed something dramatically, that tuner will not alter the fan start temps on the 3.6s.

Mark

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so I have had simial issues and sicovered a few things.
Where in the world did you get any of those ideas? All are incorrect, except for the Gladiator cooling system upgrade but that is because it is rated to tow over 7,500 lbs. Maybe removing the grill has some effect, but if you are at that point then you really need to find out what's broken in your cooling system.
 

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Where in the world did you get any of those ideas? All are incorrect, except for the Gladiator cooling system upgrade but that is because it is rated to tow over 7,500 lbs. Maybe removing the grill has some effect, but if you are at that point then you really need to find out what's broken in your cooling system.
LOL! Having done a bunch of that stuff, though for different reasons than cooling, I can attest that most make no difference in coolant temps, at all. I'd never consider a grill cover, but did run for awhile without an engine cover. No difference. Same for opening the largely fake vents in my Rubicon X hood. I also switched to 5w-30 to quiet the racket on startup, which it did do, but it had no effect on coolant temps. I've not switched coolants or swapped thermostats. I can't imagine why anyone would do the latter if the OEM one is working, which mine is.

Turning down the fan start temp - essentially matching what you found to be the 4wd behavior - absolutely does help in most driving situations. It can't be accomplished with the tuner the previous poster mentioned, and will not help if the rig is driven hard enough in the right conditions. For that there's no substitute for cooling capacity.

IMHO, there's also something to the airflow issue, but I'm not referring to simple obstructions. Just from reading here and talking to friends with more stock bumper setups, it seems like the stock plate/dam/cover below the bumper does a better job of keeping air flowing through the radiator than aftermarket or modified setups. I've played with mine some this winter (LoD bumper) but won't know till summer if what I did helped.

Mark

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Turning down the fan start temp - essentially matching what you found to be the 4wd behavior - absolutely does help in most driving situations.
Turning down the fan start temp to 205 will definitely help keep coolant temp closer to 205, and having a fan on temp of 225 will allow excursions up to 225, no doubt there. I would question whether it helps in most driving situations though since it really doesn't matter if the temp goes up to 225 during typical street operation as long as the cooling system can easily bring it back down as desired, and in my experience it can.

I'm not an FCA engineer so I can only speculate on why they system is set up as it is, but it probably isn't for something like emissions because a closed-loop catalyst-equipped system wouldn't really benefit from running a few degrees hotter. My guess would be that they simply don't want to run that power hungry fan when it isn't necessary, and it isn't necessary for the coolant temp to always track withing a few degrees of the thermostat setting. My KL Cherokee Trailhawk behaves pretty much the same way and I bet a lot of modern vehicles do.

Now for things like towing where the load is constantly high then lowering the set point probably would help, after all if not why would they do it off-road, but towing at the limit is not most driving situations. For heavy towing a 'tow mode' that changes transmission shift patterns and cooling system parameters (as is common in pickup trucks) would probably be valuable, but let's face it, a Wrangler is not really meant for towing and FCA probably saw no reason to equip it that way. That's why the aftermarket exists I guess.

But for most driving situations the system works fine as it is and I personally don't see any value in messing with it. And again anyone who is consistently overheating in common driving conditions probably needs to get their cooling system fixed, else I and most others have special immune vehicles. ;)
 

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I set my low temp fan to 210, and high temp to 215, which works well. It shuts off at 205, just above where the thermostat is fully open, and coolant temps stay in that range on all but the tallest passes, which was my goal. We'll see whether the modified airflow and larger radiator help enough there later this summer.

Mark

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I set my low temp fan to 210, and high temp to 215, which works well. It shuts off at 205, just above where the thermostat is fully open, and coolant temps stay in that range on all but the tallest passes, which was my goal. We'll see whether the modified airflow and larger radiator help enough there later this summer.
I've lost track of all the different tuner boxes :) What did you use to change the fan setpoint?
 

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Wow, a lot of good stuff here! A lot of opinions too! I did notice no one touched on engine timing affecting coolant temperature. I also believe the different ethanol levels in gasoline will affect the engine fueling which the computer will adjust continually on modern engines in the name of better emissions.

The proper air flow discussion jogged a memory of a particular engine overheating issue I worked on. Long story made short was undisturbed air flow decreases egr temp and coolant temp at highway speeds on a particular Diesel engine. Sounds like a good clean air flow through the radiator would help the op.

I don’t think any OEM engineer can correctly calibrate an engine for all situations. So they shot for the most common as a target. This could mean factors like speed, weight, baro, air temp, gas quality, emmisions output are all juggled to achieve a number the epa is satisfied with. The further away from that equation the varying amount of “ situations” can be expected.

Hope this makes sense.
 

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I've lost track of all the different tuner boxes :) What did you use to change the fan setpoint?
HPTuners. @rsmwrangler on here told me about it, and he's good with it. I don't see him on here anymore.

Mark

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Something I haven’t heard discussed yet is skid plates and skid plate systems such and Rock Hard and others that cover the bottom of the vehicle. Do they restrict air flow around the engine or through the radiator??
 

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IMHO, there's also something to the airflow issue, but I'm not referring to simple obstructions. Just from reading here and talking to friends with more stock bumper setups, it seems like the stock plate/dam/cover below the bumper does a better job of keeping air flowing through the radiator than aftermarket or modified setups. I've played with mine some this winter (LoD bumper) but won't know till summer if what I did helped.

Mark

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Many moons ago I added a Rock Hard or somebody's skid where the air dam sits. It sits at the exact same angle. Hasn't done anything for the overheating. Nor has removal of winch- I also happen to have a Warn Compact so it's small as they come. Stubby bumper vs. full did nothing. Vented inner fenders did nothing. (Most of this was for crawling purposes and not intended to correct it; but have been mentioned.) Mishimoto radiator helped for sure but I still have problems. I've gotten mixed results from people that have added vented hoods.
I am entirely convinced this is a programming issue. There have been hundreds of threads on this and not one single piece of aftermarket equipment can be pointed to. Not one solution. You can have two Jeeps with remarkably similar set ups and one person is blissfully unaware his buddy is sweating bullets behind him hoping his Jeep doesn't :atomic: Something in the Jeep production line is wonky and for some of us it truly sucks.
 

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Something I haven’t heard discussed yet is skid plates and skid plate systems such and Rock Hard and others that cover the bottom of the vehicle. Do they restrict air flow around the engine or through the radiator??

more heat soak on hot summer days with the ash-fault being 150F and causing metal black steal skid plates to act as a hot plates
 
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IMHO, there's also something to the airflow issue, but I'm not referring to simple obstructions. Just from reading here and talking to friends with more stock bumper setups, it seems like the stock plate/dam/cover below the bumper does a better job of keeping air flowing through the radiator than aftermarket or modified setups. I've played with mine some this winter (LoD bumper) but won't know till summer if what I did helped.
It's true that cooling systems today are highly engineered/optimized, and shrouds/air dam/covers etc. are often an integral part of the system. There's a good article on Jalopnik that describes the lengths FCA went though to get adequate cooling for the Gladiator given all the restrictions they had to work with.

Also remember that air passing through the radiator has to go somewhere or backpressure can build up and restrict efficiency, so covering the bottom front of the vehicle with skidplates probably doesn't help. Add to that skidplates that prevent airflow around the oil and transmission pans, etc. can contribute to decreased cooling efficiency. I would expect that well ventilated skidplates would be a better idea than solid ones.
 

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Take a trip up to the local rock crawling trails here and look under every Jeep- nearly all of them have skids. And only 1 or 2 might have overheating issues. If that were the case the trip up the mountain on a hot summer day would be littered with over-heating Jeeps. It's 100F at the base mid-summer and the rest is all climb that takes about 40 minutes. There are regularly Jeep Safari's and other events with hundreds of Jeeps- it would be pretty obvious if all the overheating Jeeps were the ones with armor. It's just not the case.
 

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Take a trip up to the local rock crawling trails here and look under every Jeep- nearly all of them have skids. And only 1 or 2 might have overheating issues. If that were the case the trip up the mountain on a hot summer day would be littered with over-heating Jeeps. It's 100F at the base mid-summer and the rest is all climb that takes about 40 minutes. There are regularly Jeep Safari's and other events with hundreds of Jeeps- it would be pretty obvious if all the overheating Jeeps were the ones with armor. It's just not the case.
FWIW I wasn't meaning to say that aftermarket armor causes overheating, in fact I agree that JK's seem to have perfectly adequate cooling systems and most experience no problems at all. I was only suggesting that aftermarket modifications could be a factor for those that seem to be on the edge for some reason.
 

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I've never had an overheating issue rock crawling, just on the highway. I still think the air dam and the rake help the air flow for cooling. Having replaced about everything in the cooling system I'm at a later as of what to do next. New radiator, thermostat, hoses, coolant, temp probe, rad cap, hood cents. Have tried the Misimoto radiator, 3 different ones, and no change. Haven't try Ed opening up the splash shield in the wells. With y MC last ft there is no rake and I don't have a front air dam. The them on the TD2 shows 200 to 230 around town. Normal highway about the same. Start going up long hills here out west and It'll climb to over 240. Steeper grades and I've gone into limp mode twice at 248 to 250.
 
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