Overheating Part 2

[Electric Banana]

Afternoon once again. Here's the scoop. After replacing the thermostat, radiator cap, and multiple burping I thought the overheating was beat. I the last week I have found that the Electric Lemon has started to run a little warm. The temp will rise near 240 and then drop to normal (210) and the repeat. Still not a blown head gasket. Checked and did not find any air in the system. I have found that the cooling fan is now runnng at full speed. I've checked for codes and only finding a code for possible bad gas cap. Now my question is, Can a bad coolant temp sensor be causing the fan speed and the continuous fluctuation in the water temps? Heater is working fine.

 

[Mopar]

Maybe on the coolant temp sensor. Put a new one in it and see.

What outside temps are you now running in? It’s crazy but 240 is the upper end of where the 3.6 will run under normal conditions.

Turn on the AC on low (your AC works right?) and drive around. Does your temps run lower and more stable? Turning the AC on forces the fan to come on.


Get JScan and the proper adapter to work with your phone. Use JScan to turn the fan on. Does the temp fall and stay low?

Get a laser thermometer (as already recommended) and check the upper and lower portions of the radiator. Is there a big difference in temps? What is the difference? The JK radiator having the return to the engine where it is does encourage deposits to drop to the bottom of the radiator which eventually leads to clogging of the radiator if you neglect your cooling system. Good chance on the earlier models of the 3.6 but lower chance on later models unless someone has mixed coolants.

 

[Electric Banana]

Drove to work this morning with AC on, about 35 minute drive on interstate with cruise se at 64. The temp read out ran to 242 three times during trip an but didn't stay there. ran up and then dropped to lowest reading of 208 but climbed back to 214 to 222 for trip. At half way turned off AC and turned up heater and temp didn't climb but stay around 220. All readings are from digital temp readings from dash, I tried to keep track of a cycle going from normal to hot and then back to normal. It did cycle twice in the 33 minute trip. Ran up to 242 for 2 minutes and then back down for 10 minutes then back up for 2 then down again. Wgen I go home this afternoon I will use the JSCAN. Please give me a list of information that I can program the JSCAN for to get the best information to narrow down problem. Will be leaving work around 1200/1230 EDT.

 

[Mopar]

Drove to work this morning with AC on, about 35 minute drive on interstate with cruise se at 64. The temp read out ran to 242 three times during trip an but didn't stay there. ran up and then dropped to lowest reading of 208 but climbed back to 214 to 222 for trip. At half way turned off AC and turned up heater and temp didn't climb but stay around 220. All readings are from digital temp readings from dash, I tried to keep track of a cycle going from normal to hot and then back to normal. It did cycle twice in the 33 minute trip. Ran up to 242 for 2 minutes and then back down for 10 minutes then back up for 2 then down again. Wgen I go home this afternoon I will use the JSCAN. Please give me a list of information that I can program the JSCAN for to get the best information to narrow down problem. Will be leaving work around 1200/1230 EDT.

Again….what is your outside temp?

Again, have you checked the actual temps with a laser thermometer at different places….particularly the top and bottom of your radiator. You can also check the temp at the thermostat and anywhere else you want to know the actual temps.

On JScan there is a setting, I think it’s under “Trail View” or something like that. You can see your actual temps and RPM while running and can turn the fan on. The fan will only come on for a few minutes each time you turn it on but it will run full blast. It will also allow you to verify the fan is actually running.

Might be worth it to replace the temp sensor. Can’t hurt. I’d only use a Mopar sensor for it. If the Mopar sensor wasn’t available, then I’d use an aftermarket. But it is available to buy so use the Mopar one.

Run the AC with the inside fan on low. Open your windows if you are hot. The reason for that is turning the AC on makes your fan come on but with it on low, it doesn’t add a lot of heat load to the engine.

Technically, anything over 250 is overheating on the 3.6 so you aren’t actually overheating.