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Old 03-22-2012, 02:10 PM   #1
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Concerned about underhood temps

Anyone else concerned about this?

I went for a drive in the last week we had cool weather, 58 to 60 degrees.

My Jeep had to have been off for about 4 or 5 hours, before we got back in to run some errands, and it was still 1/4 way warmed up immediately on start up.

Anyone else seeing their engine staying warm for a very long time after use? I am thinking this could be cause for some concern, as our summers can approach 90-100 degree's all day long. I am wondering if I have something going on with mine alone.

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Old 03-22-2012, 02:30 PM   #2
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I just can't help myself...... Maybe a CAI ??

I haven't noticed this on mine but will check after my next drive.

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Old 03-22-2012, 02:42 PM   #3
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Wait until mid summer lol

And a black jeep.....

I will be using my Superchips to see what the temps read. Amazing... It seams the power is sucked out of the engine on real hot days.
Looked into a AEV hood last summer.
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Old 03-22-2012, 02:47 PM   #4
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No, its the actual engine temperature. Seems to stay hot and run hot for a very long time.
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Old 03-22-2012, 02:48 PM   #5
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How many miles do you have on it? I noticed the same thing, with heat radiating out of the wheel wells.

However, after about the first 500 miles or so, things seemed to cool off substantially. Also, it seemed like much of the heat was eminating from the transmission cooler rather than the engine. At 5k, I no longer find the Wrangler still hot after sitting in a cool gagrage for hours.

My understanding is that there is a "break in" cycle controlled by the computer, which, among other things, impacts fuel mileage until it's complete. I wonder if that has anything to do with it.
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Old 03-22-2012, 02:51 PM   #6
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The only thing I have noticed which has only happened with the Jeep is steam coming from the front. I'm in Texas so same lousy climate. Normally I would think condensation buring off but it happens while in my garage. I'll be curious next time what the temp gage says.
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Old 03-22-2012, 03:25 PM   #7
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I was surprised at how much heat radiates from the vents in my AEV Heat reduction Hood. But the Hood does help in letting it cool down.
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Old 03-22-2012, 03:32 PM   #8
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Quote:
Originally Posted by glowingghoul View Post
How many miles do you have on it? I noticed the same thing, with heat radiating out of the wheel wells.

However, after about the first 500 miles or so, things seemed to cool off substantially. Also, it seemed like much of the heat was eminating from the transmission cooler rather than the engine. At 5k, I no longer find the Wrangler still hot after sitting in a cool gagrage for hours.

My understanding is that there is a "break in" cycle controlled by the computer, which, among other things, impacts fuel mileage until it's complete. I wonder if that has anything to do with it.
I am about to cross 5000 miles on my 2012. I will continue to monitor.

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The only thing I have noticed which has only happened with the Jeep is steam coming from the front. I'm in Texas so same lousy climate. Normally I would think condensation buring off but it happens while in my garage. I'll be curious next time what the temp gage says.
Steam! Get that checked, haha!

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I was surprised at how much heat radiates from the vents in my AEV Heat reduction Hood. But the Hood does help in letting it cool down.
Grr, I wanted one of those. It is like you said, very surprising how hot it gets. Just wondering if it was something I should be on the lookout for.
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Old 03-22-2012, 03:36 PM   #9
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Quote:
Originally Posted by rics1997 View Post
I was surprised at how much heat radiates from the vents in my AEV Heat reduction Hood. But the Hood does help in letting it cool down.
Yep, when I stop in traffic, I can see the heat waves coming off mine.
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Old 03-22-2012, 03:45 PM   #10
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AEV mentioned something on their forums about how the Pentastar is highly inefficient when colder, and runs higher RPMs until "warm". They also mentioned the the engine likes running warm/hot?

I'm trying to dig up the post.
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Old 03-22-2012, 03:51 PM   #11
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Originally Posted by chris.george View Post
AEV mentioned something on their forums about how the Pentastar is highly inefficient when colder, and runs higher RPMs until "warm". They also mentioned the the engine likes running warm/hot?

I'm trying to dig up the post.
Every modern car I have been in does this. When cold, the engine will idle higher to bring itself to proper operating temperature, then, the idle will drop.
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Old 03-22-2012, 03:55 PM   #12
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Average op temp for the JK/JKU is 218° F, thats why the temp indicator stays in the middle and it's notta guage--it indicates what the ECU tells it to !!

Best op temp for the 42rle auto is 180° F--

Ain't this Just like sunday school--

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Old 03-23-2012, 12:44 AM   #13
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Mine doesn't seem to run much over 200 degrees, and generally less just under 200. But it hasn't been much warmer here than about 70 to 75 degrees tops lately. I believe most of you above were referring to the pentastar engine. And with an auto, its an A580 transmission.

I've been monitoring the water temp, vacuum, hp, torque, and a few other interesting bits of data using the "Torque" app on my android, and a cheap (like $20) OBD II module. With this setup, you can easily get the real water temperature if you want to see what its doing. The temp guage, like most of them now days, is a joke. Google "ELM327 bluetooth OBDII module" and you'll find plenty of these fairly cheap. The Torque app is available in a free version, or you can pay a few bucks for the full version. Works great.

Best,
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Old 03-23-2012, 08:24 AM   #14
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Originally Posted by Second Wind View Post
Mine doesn't seem to run much over 200 degrees, and generally less just under 200. But it hasn't been much warmer here than about 70 to 75 degrees tops lately. I believe most of you above were referring to the pentastar engine. And with an auto, its an A580 transmission.

I've been monitoring the water temp, vacuum, hp, torque, and a few other interesting bits of data using the "Torque" app on my android, and a cheap (like $20) OBD II module. With this setup, you can easily get the real water temperature if you want to see what its doing. The temp guage, like most of them now days, is a joke. Google "ELM327 bluetooth OBDII module" and you'll find plenty of these fairly cheap. The Torque app is available in a free version, or you can pay a few bucks for the full version. Works great.

Best,
SW

I wasn't really using the temp gauge to measure anything, just for the still warm part.

I can actually feel heat radiating for hours after it has been off, just by walking around the front.
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Old 03-23-2012, 08:41 AM   #15
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Old 03-23-2012, 08:46 AM   #16
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Every modern car I have been in does this. When cold, the engine will idle higher to bring itself to proper operating temperature, then, the idle will drop.
IIRC, modern engines run warmer, due to emissions. Something about burning of more hippie(oops I mean harmful) gases.
Hopefully someone markets a lower T-stat for the 3.6L, like they do for the HEMI's. (if it helps performance)
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Old 03-23-2012, 09:04 AM   #17
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There's also a lotta plastic/insulation to retain heat in that modern aluminum engine--also the engine compt is usually pretty well insulated--

And Hitemp thermostats-I've switched them in a couple of my Corvettes, but that was a few years ago--shouldn't doit now !

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Old 03-23-2012, 10:49 AM   #18
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If your coolant temp gauge stays in the middle (normal), I honestly wouldn't worry about it at all. I'd actually consider it a good thing as your fluids tend to stay warmer longer, which helps when you restart the engine.

As for performance, a hotter engine runs better as long as you have the timing adjustment to deal with it.

As for the aluminum block. Aluminum conducts heat faster than cast iron, so it wouldn't be the cause. And the temperatures we see are no sweat for aluminum alloys.
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Old 03-25-2012, 10:13 PM   #19
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I wasn't really using the temp gauge to measure anything, just for the still warm part.

I can actually feel heat radiating for hours after it has been off, just by walking around the front.

And I understood this from reading your original post. What I am suggesting though, is that if you are concerned, is that (1) the temp guage in your dash sucks, and (2) that you can monitor the real operating temperature via other means if you are curious about operating temperature. That is the ONLY temperature that matters. As long as it is not running too hot when it is ...Running, then it doesn't much matter what it does after you shut it off. Without getting into thermodynamics - which I didn't much like studying anyway - All things being equal, from one '12 wrangler to the next, the rate at which the engine cools is a function of the original operating temperature, and the temperature of the surrounding environment when you shut it off. This is called "delta T" (not sure how to make a greek delta symbol here, and don't much care to learn). Transfer of heat from the heated mass to the cooler mass - surrounding air will vary depending upon the temperature difference between the two.

So, the only variable to be concerned with - if concern is warranted - is the operating temperature. And like I said, the guage doesn't do a real good job of telling you this. I don't think you've anything to worry about though.

Best,

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Old 03-26-2012, 02:01 AM   #20
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Originally Posted by mxman122
The only thing I have noticed which has only happened with the Jeep is steam coming from the front. I'm in Texas so same lousy climate. Normally I would think condensation buring off but it happens while in my garage. I'll be curious next time what the temp gage says.
Your not alone I'll go wash my ride at the care was and when I start it up it starts right in front by ratiator all this smoke looks like its on fire i guess it's so hot that it's drying all the water on it. That's all I can figure. Guess its the same as your exhaust when it gets wet it will smoke. Idk. Any one else have this ?
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Old 03-26-2012, 02:01 AM   #21
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I think this high temp thing is caused by the big "S" bend in the exhaust pipe, that concentrates a lot of exhaust heat in one area and your not used to seeing this in the older models . So all of a sudden the NEW 3.6L Pentistar engine compartments are pushing out lots of heat not noticed before because of the "S" bend being used to equally scavenge both Cylinder Heads to produce all this extra Horse Power.
Besides the fact that the Higher Engine temps are needed to pass the exhaust requirements for SMOG.
I'm sure the engineers at MOPAR have it all under control....LOL. "BH"
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Old 03-26-2012, 02:08 AM   #22
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It seams the power is sucked out of the engine on real hot days.

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Old 03-26-2012, 07:54 AM   #23
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I hate the above hood temps here in the summer. Seriously, all vehicles have underhood temps. There is a lot of room under the JK's hood so heat is able to dissipate easily. The 3.8 and 3.6 engines do fine in a Caravan or Town and Country do just fine and they do not have the ventilation they have. If your cooling system is working fine, then there is nothing to worry about.
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Old 03-26-2012, 08:42 AM   #24
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My temp gauge is always half way mayb alittle hotter than cool side. Is this the norm?
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Old 03-26-2012, 06:17 PM   #25
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To those seeing steam from the front. We have electric fan. If they are off. Then any steam would rise in front of you instead of getting sucked into the engine if we had a mechanical fan.

Went though a car wash, steam was poring out the front. popped the hood. then the Dua moment, fan was off.
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Old 03-26-2012, 08:20 PM   #26
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Like I said, guages not bothering me. It was just the fact I feel the heat from the engine after it has been off for hours.

I guess normal, well see. Oh, and my engine ticks.
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Old 03-26-2012, 10:50 PM   #27
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Quote:
Originally Posted by n3qik
To those seeing steam from the front. We have electric fan. If they are off. Then any steam would rise in front of you instead of getting sucked into the engine if we had a mechanical fan.

Went though a car wash, steam was poring out the front. popped the hood. then the Dua moment, fan was off.
Cool thought it was just mine. Looks like its on fire when I get done washing it for about 10 sec or so.
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Old 03-26-2012, 11:28 PM   #28
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Anyone else concerned about this?

I went for a drive in the last week we had cool weather, 58 to 60 degrees.

My Jeep had to have been off for about 4 or 5 hours, before we got back in to run some errands, and it was still 1/4 way warmed up immediately on start up.

Anyone else seeing their engine staying warm for a very long time after use? I am thinking this could be cause for some concern, as our summers can approach 90-100 degree's all day long. I am wondering if I have something going on with mine alone.
I have an Ultra-Gauge hooked up to my OBD II thingy.
Water temp usually runs between 198 - 210.
I also monitor the air input temp which is a good indication of under hood temp.
When I start it up the temp is ambient, and never gets above 180 in stop-and-go traffic. Freeway it'll drop off to 160 or so.
Average temp here is 80 with humidity around 80 percent so I doubt your temp is any higher.
All normal, she just takes a long time to cool down when parked.

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