Need advice from 110 degree plus climate TJ owners

iamloganjames said:
Well yes, but the air is only directed to be blown through the core when the heat is selected, right?

In regards to your suggestion about the thermostat. Why is the hole at the 12 position important? There is already a bypass hole in the housing.
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That’s just how my original was,and how the new mopar one came.I think it lets air out,if your highest temps were on the highway you have a circulation problem,something is stopped up or compression is getting in and heating up the engine.
 
KingCarGuyZ said:
looks like I'm a little late to the party, but heres what I wind up doing to fight this ridiculous Texas heat (104*RN)

First step get yourself something to read the actual numerical output of the temp gauge, not the stupid idiot light excuse for a needle on the dash, but an actual gauge. I use an Ultragauge one of the best investments ever, plugs into the OBD2 and shows what the computer sees, super cheap and simple and waaay better than the wireless dongle and app I was using before

(you can see it in the top left of this photo - engine was cold at the time)
View attachment 336661

I then replaced the whole cooling system, using a HD fan clutch and all MOPAR parts. Make sure to replace your rad. cap and thermostat housing!!!!! my housing was cracked so slightly I hadn't noticed and led to VERY slight leak and overheating at idle.

if you are overheating going down the road, you have a different problem but for me I couldn't pull enough air through the rad at idle to keep her below 220* (whereI start to get nervous) so I wound up installing a AUX. electric cooling fan this was before I found the crack in my thermostat housing and may not have been ultimately necessary but has been absolutely dead nuts reliable thought the summer. I can not get this thing to go above 215 no matter how long I sit in traffic, fan comes on and cools her right back down to 200 if I leave the fan on she'll stay right on thermostat at 195.

View attachment 336659
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This displays MPG? Are the other gauge readings selectable?
 
Gollywomper said:
This displays MPG? Are the other gauge readings selectable?
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Yeah, I have like 8 pages of gauges, all customizable. Some of them are PCM gauges directly from the computer, and others (like the fuel MPG and distance to empty) are calculated by the ultraguage (it knows milage and fuel injector pulses. The milage is accurate over the long run. 13.5 is about what I get (vary's from 12.5-15 depending on what the jeep was doing) and that gauge has been sampling for probably 20,000 miles or more now with zero problems. it also has an oil change alarm that I can set and have it remind me to change the oil every 3K, one less thing to remember. It's a really great piece of kit, super simple LCD screen and 3 buttons, no tracking or linking with your phone or anything, just $100 a small annoyance to set it up the first time using the menues in the device and then it just turns on when I start the jeep and turns off when I turn the jeep off, it reads and clears codes and just sits there and is everything I need and nothing I don't for an excellent price.

You can read more on the website I linked, it looks scamy, but they are just trying to cut costs where they can to make the end product quality and affordable. I have ordered probably 5 for me and buddies and have had zero problems from any of them.
 
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KingCarGuyZ said:
Yeah, I have like 8 pages of gauges, all customizable. Some of them are PCM gauges directly from the computer, and others (like the fuel MPG and distance to empty) are calculated by the ultraguage (it knows milage and fuel injector pulses. The milage is accurate over the long run. 13.5 is about what I get (vary's from 12.5-15 depending on what the jeep was doing) and that gauge has been sampling for probably 20,000 miles or more now with zero problems. it also has an oil change alarm that I can set and have it remind me to change the oil every 3K, one less thing to remember. It's a really great piece of kit, super simple LCD screen and 3 buttons, no tracking or linking with your phone or anything, just $100 a small annoyance to set it up the first time using the menues in the device and then it just turns on when I start the jeep and turns off when I turn the jeep off, it reads and clears codes and just sits there and is everything I need and nothing I don't for an excellent price.

You can read more on the website I linked, it looks scamy, but they are just trying to cut costs where they can to make the end product quality and affordable. I have ordered probably 5 for me and buddies and have had zero problems from any of them.
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Can it show transmission fluid temp?
 
So I replaced the thermostat and the temp sensor. Burped the system afterwards. Just jacked the from end up and used a tall funnel filled above heater hose levels.

Things seem to be a little cooler. Running around 220-230 now. But that was at 95 degree ambient. So I'm not sure that anything is truly resolved.

Measuring temps on radiator the top tank by the hose was 207° and the bottom tank by the hose was 165°.

Both my Cats on the downpipe measure about 550° and there doesn't seem to be any deviation in temp across the side of the block. Not inclined to think it's running lean or anything. It actually runs pretty good, despite the temps. Haven't pulled the plugs yet. Not really inclined to at this point.

I'll get back with more info when I actually have some.
 
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I recently moved to AZ and wheeled this weekend. On the way @ 70 mph, my coolant temps hit 244. Definitely had power loss.

I've replaced the entire cooling system prior to this day, including a Mopar radiator.

Wheeling at 100 deg my temps were 215-230.

After the sun went down and temps were ~ 95 the coolant was down to it's normal 195-200.

Not sure what to do except for driving slower on the highway.
 
The normal temp is not 195, that's just the temperature rating of the correct thermostat. The engine's normal running temperature is at or close to 210 degrees. If your engine normally runs at 195-200 degrees it has the wrong temperature thermostat installed.
 
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Jerry Bransford said:
The normal temp is not 195, that's just the temperature rating of the correct thermostat. The engine's normal running temperature is at or close to 210 degrees. If your engine normally runs at 195-200 degrees it has the wrong temperature thermostat installed.
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When I say normal, I mean, normal for my jeep, as read by the scan tool, not the rating of the correct thermostat, which I have.
 
Jerry Bransford said:
Something's wrong if your TJ's coolant temperature is only 195-200 degrees, no matter how it was measured.
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🤔 My jeep runs hot on the highway, so I'm not sure I'd want it any warmer.

What's the harm here? No running with the correct fuel mixture when cold?
 
xXDavidCXx said:
🤔 My jeep runs hot on the highway, so I'm not sure I'd want it any warmer.

What's the harm here? No running with the correct fuel mixture when cold?
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What temperature is the temperature gauge on the instrument cluster indicating when you're on the highway? Yes the temperature it runs at affects when the PCM starts using the O2 sensors to set the air/fuel ratio.
 
These 4.0s aren't your carbed motors from the '60s, they're intended to run much hotter. They aren't even warmed up until 195. For reference, the factory XJ 4.0 aux electric fan doesn't turn on until 220. 230-240 isn't a problem. 250-260 is getting hot but shouldn't hurt anything.

Factory boil point is what, 280+ or something?
 
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Jerry Bransford said:
What temperature is the temperature gauge on the instrument cluster indicating when you're on the highway? Yes the temperature it runs at affects when the PCM starts using the O2 sensors to set the air/fuel ratio.
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@ 70 mph and 100 OAT, between the 210 mark and the next mark, 244 by the scan tool.

I pulled over and checked the coolant tank. No bubbling, but acceleration was very sluggish getting back on the highway. I slowed to 60 and the temps slowly reduced.

I'll add that I have a vented hood.
 
srimes said:
These 4.0s aren't your carbed motors from the '60s, they're intended to run much hotter. They aren't even warmed up until 195. For reference, the factory XJ 4.0 aux electric fan doesn't turn on until 220. 230-240 isn't a problem. 250-260 is getting hot but shouldn't hurt anything.

Factory boil point is what, 280+ or something?
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This is good to know, I was getting nervous at 220+.
 
xXDavidCXx said:
I recently moved to AZ and wheeled this weekend. On the way @ 70 mph, my coolant temps hit 244. Definitely had power loss.

I've replaced the entire cooling system prior to this day, including a Mopar radiator.

Wheeling at 100 deg my temps were 215-230.

After the sun went down and temps were ~ 95 the coolant was down to it's normal 195-200.

Not sure what to do except for driving slower on the highway.
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Your wheeling temps are fine. That's with a/c on I presume?

Highway temps are higher than expected, unless you're towing or blasting up a hill. Shouldn't damage anything and yes you can feel a power difference.

Pic of your hood? It's possible for hood vents to hurt cooling at speed. Maybe someone here has experience and can comment better. One way to test is to pull your hood and go for a drive and see if temps change.
 
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