What is your normal coolant temperature on the 4.0?

Just a scosh to the left of 210. On a long, steep pass here in CO it may hit right at 210.
 
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You guys make me jealous with your temperature readings. Mine always sits right on 210 unless I turn the AC on or start driving fast in the heat. Then it creeps up to maybe 220. Been doing that for years and can't figure out why. Maybe I need to flush the system out again. It never sits under 210 like I wish it would, even in the winter. Woes of a 230,000 mile engine I guess.
 
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jodomcfrodo said:
You guys make me jealous with your temperature readings. Mine always sits right on 210 unless I turn the AC on or start driving fast in the heat. Then it creeps up to maybe 220. Been doing that for years and can't figure out why. Maybe I need to flush the system out again. It never sits under 210 like I wish it would, even in the winter. Woes of a 230,000 mile engine I guess.
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Mopar or aftermarket radiator?
 
jjvw said:
Fan clutch?
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Not sure what brand that is, but since it gets a bit hot on the highway I'd imagine that wouldn't be the problem. My fan is also loud as hell when it runs and I can feel a substantial power loss. Sometimes I think my fan is too loud but I don't know what would cause that.

I'm thinking the slight heat might just be due to the higher mileage. I also lose coolant extremely slowly (IE an inch or two in the overflow over the course of a few months). Pretty sure it might just be normal evaporation.
 
I just finished five days of offroading with 500 miles of Interstate to get there and back. Ambient temperatures were 80-100*F and the A/C was used frequently both on and offroad.

Once the engine warmed up each morning the needle of my temperature gauge pointed halfway between the "1" and "0" in 210 with very minor variation no matter what.

Bear in mind that the temperature gauge is a glorified idiot light that is designed not to vary much unless and until there is an overheating condition. If you want to know the true coolant temperature you will need to use a different gauge.
 
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I would be curious to see your ECT readings along with a IAT. My gauge stays a hair past 210 but sometimes I can hear the coolant bubble after turning off, especially off roading with the A/C on. My IAT seems really high and I believe that maybe an issue. I am testing some theories of how to reduce it.

EDIT* I am attaching some readings from last night. I was trying to mimic similar conditions to idling off road little/no air flow. I let the Jeep run in the garage, A/C on, garage door open. First pic shows hood closed and running after 15 min. second pic shows hood open. There is little to no change due to what I think is the fan clutch pushing hot air up and towards the sides. At the inlet of the air box with the hood up the air is still very hot.

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mattcogdell said:
sometimes I can hear the coolant bubble after turning off, especially off roading with the A/C on.
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This is often a sign of a leak in the system, it is probably not holding pressure. Most common offender is the radiator cap.

There is no value is watching your coolant temp closely. Left means cold, up means normal and right means hot, beyond that there is a light that will turn on.

Just find your leak and plug it, you'll be fine.
 
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Even considering the temp gauge is a dummy gauge, it can still be useful. Just to the right of 210 is hot but fine. There is a second position where the needle will go a little more right of 210 which means hot and probably not great. After that, it just pegs to the red at 260.

Watching for the gauge to move a little more than usual to the right of 210 is a good way to see if you're on your way to a problem.
 
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