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Old 04-03-2019, 12:13 AM   #91
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Originally Posted by ScaldedDog View Post
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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Old 04-03-2019, 01:17 AM   #92
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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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Old 04-03-2019, 05:41 AM   #93
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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.

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Old 04-03-2019, 11:32 AM   #94
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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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Old 04-03-2019, 03:50 PM   #95
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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.

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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 Something in the Jeep production line is wonky and for some of us it truly sucks.
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Old 04-03-2019, 03:51 PM   #96
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Something I havenít 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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Old 04-03-2019, 04:14 PM   #97
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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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Old 04-04-2019, 11:40 AM   #98
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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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Old 04-04-2019, 11:48 AM   #99
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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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Old 04-04-2019, 11:54 AM   #100
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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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Old 04-04-2019, 12:00 PM   #101
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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.
It's interesting that several seem to report something like this while others have no issue at all. JK's are different than most other vehicles due to the amount of customization/modifications, particularly effective gear ratio (due to all the tire and wheel swapping) and I wonder if this is related to the on-road grade climbing issues. It might be helpful if people would indicate their tire size, gear ratio, and transmission type (or simply rpm in top gear at 60 mph if you know it) to see if there might be any correlation. When people upgrade tires it's almost always to a larger size, but probably only a relative minority do a matching gear change and being under-geared would increase engine load, and thus cooling load. Maybe not noticeable under most conditions but long, hot grades might be a tipping point.
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Old 04-04-2019, 12:08 PM   #102
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and also how many rpms your turning to reach these temps
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Old 04-04-2019, 12:27 PM   #103
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Maybe the easiest would be to use the chart below and indicate your 70 mph rpm. When entering your tire size you should use 1" smaller than your uninstalled diameter to account for weight loading.

Jeep Wrangler JK Gear Ratios


In my case:

2014 JK Rubicon, 3.6 auto, 4.10, 33" (loaded diameter on vehicle)

70 mph rpm is 2426

No on-road overheating problem that I've noticed.
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Old 04-04-2019, 02:08 PM   #104
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35s on 4.10s would have dropping to 2nd (WA580) at 60+mph is some places, and that'll heat 'em up quick. 4.88s helped, as I can now be in 3rd just about all the time, but it didn't "solve" the problem.

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Old 04-04-2019, 02:14 PM   #105
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It's not RPMs. I can rock crawl 5.13 all day in first gear with the 4:1 at 3000rpm+ and not overheat. And there is way less air movement crawling sub-1mph than on a highway.

I would suspect folks who are undergeared aka too low RPMs are getting more heat as the transmission hunts gears and the engine is working harder to compensate.

The 3.6 is intended to run warm.
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Old 04-04-2019, 02:16 PM   #106
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RPM's alone do not necessarily generate heat, engine load does. Usually the worst situation is low rpm/high load.
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Old 04-04-2019, 07:22 PM   #107
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Write 1000 VIN numbers on a wall. Throw a dart at it. Those Jeeps will have heating issues. No rhyme. No reason. No fix either.
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Old 04-07-2019, 08:34 PM   #108
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I was out again today crawling around offroad and since it was in the 90s I thought I'd do some more testing to confirm what we've found so far, and I saw pretty much the same thing as before... in 2WD temps were around 220-225 (slow going on rough roads) but as soon as I switched to 4WD the fan came on and kept temps reliably between 205-210. I then tried turning on the A/C but didn't really see any difference, temps stayed pretty much in that range.

I didn't see temps rise above the 220's when in 2WD offroad and I wasn't having any problems, but if you do want to keep them down 'just because' then it does seem that the fan becomes more aggressive in 4WD mode. Of course none of this helps for towing, but just FWIW.
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Old 04-08-2019, 12:48 AM   #109
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I was out again today crawling around offroad and since it was in the 90s I thought I'd do some more testing to confirm what we've found so far, and I saw pretty much the same thing as before... in 2WD temps were around 220-225 (slow going on rough roads) but as soon as I switched to 4WD the fan came on and kept temps reliably between 205-210. I then tried turning on the A/C but didn't really see any difference, temps stayed pretty much in that range.

I didn't see temps rise above the 220's when in 2WD offroad and I wasn't having any problems, but if you do want to keep them down 'just because' then it does seem that the fan becomes more aggressive in 4WD mode. Of course none of this helps for towing, but just FWIW.
How many mile do you have on you Jeep? What year also?
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Old 04-08-2019, 12:53 AM   #110
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There are definitely ones that run hot. 86F today, driving on level road at 50 MPH, 5th gear, AC on and she hit 231 on the EVIC.
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Old 04-08-2019, 01:14 AM   #111
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How many mile do you have on you Jeep? What year also?
Mentioned earlier, it's a 2014 2-dr Rubicon, auto, 4.10 gears. Mileage is about 51,000.
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Old 04-08-2019, 04:12 PM   #112
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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.
This is really good information. Thanks for sharing. I was always wondering if temperatures would be lower with the Mishimoto radiator and I too suspected the air dam for a long time. So far what you wrote seem to point at insufficient air flow, which the larger Mishimoto radiator won't be able to counter either.

When we bought our Wrangler I knew about the temperature stories already, so early on I did some temperature measurements for future repair reference.
2017 Wrangler JK Rubicon, Automatic, 3.73 gears, bone stock with 2300 miles. Temperatures as shown by the EVIC. Air Conditioning ON. Engine load unknown - sorry, I don't have a scanner for this vehicle YET.

Outside Temperature 90F; Freeway level
70mph in 5th:* 206F (208F brief max)

Outside Temperature 95F; Freeway 5% grade climb
70mph in 4th: 212-219F (221F brief max)
70mph in 3rd: 221-231F (235F brief max)

Outside Temperature 85F; Freeway 5% grade decent
70mph in 5th: 199-208F (203F most of the time)

Plus something weird:
I was waiting for my wife the other day, idling. I believe with the Air Conditioning ON. Outside temperatures were around 80F. I had temperature display selected in the EVIC. Car was running at 204-208F. The weird part was that I could hear the fan coming on @208F, while it should not come on before 215F. I was idling/waiting for at least 15minutes and this hapened several times. I kept switching between D and P to confirm it is not Transmission Temperature display.
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Old 04-08-2019, 04:20 PM   #113
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The above temps look perfectly normal to me, for just about any modern vehicle.

Re: fan operation at low speeds, as discussed earlier this seems to vary based on any number of parameters and having A/C on would probably be one of them.
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Old 04-08-2019, 04:32 PM   #114
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The above temps look perfectly normal to me, for just about any modern vehicle.
I 100% agree with that.

My intention of preparing (and sharing) the above info was for reference only (such reliable real world info with a new vehicle as reference is not always easy to obtain).

It might come handy for future maintenance and repairs of the cooling system, i.a. that way we don't to repair anything that is not broken.
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Old 04-08-2019, 07:10 PM   #115
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This is really good information. Thanks for sharing. I was always wondering if temperatures would be lower with the Mishimoto radiator and I too suspected the air dam for a long time. So far what you wrote seem to point at insufficient air flow, which the larger Mishimoto radiator won't be able to counter either.

When we bought our Wrangler I knew about the temperature stories already, so early on I did some temperature measurements for future repair reference.
2017 Wrangler JK Rubicon, Automatic, 3.73 gears, bone stock with 2300 miles. Temperatures as shown by the EVIC. Air Conditioning ON. Engine load unknown - sorry, I don't have a scanner for this vehicle YET.

Outside Temperature 90F; Freeway level
70mph in 5th:* 206F (208F brief max)

Outside Temperature 95F; Freeway 5% grade climb
70mph in 4th: 212-219F (221F brief max)
70mph in 3rd: 221-231F (235F brief max)

Outside Temperature 85F; Freeway 5% grade decent
70mph in 5th: 199-208F (203F most of the time)

Plus something weird:
I was waiting for my wife the other day, idling. I believe with the Air Conditioning ON. Outside temperatures were around 80F. I had temperature display selected in the EVIC. Car was running at 204-208F. The weird part was that I could hear the fan coming on @208F, while it should not come on before 215F. I was idling/waiting for at least 15minutes and this hapened several times. I kept switching between D and P to confirm it is not Transmission Temperature display.
The Mishimoto helped mine for sure. When the Mish. began to leak (replaced under warranty) I threw my stock back in. DEFINITE difference. I have that unicorn of JKs- bought mine without power. (literally LOL.) So I don't have digital temperature readings to provide. However it doesn't fully resolve it so I hesitate to recommend spending that much money on something that doesn't have a 100% fix. But clearly there is no 100% fix so I'll take what I can get.
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Old 04-08-2019, 10:02 PM   #116
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I noticed that on mine (18JKUS AT stock) the temp are pretty ok when moving 40+mph.
the temps goes up when slowly crawling or in stop&go traffic - i looked under and noticed that they deleted the cross-pipe heat-shield under the transmission pan, could it be that the radiant heat from the exhaust is transmitted to ATF at slow speeds (no airflow underneath) respectively all this extra heat ends up in trans radiator? Would it make sense to install (at list for the summer) some sort of insulation or heat-shield under transmission pan?.

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