Heat management - coolant Temp fluctuation

[Surfwagon]

Hey all, not sure if these two items are related, but hoping to find out.

First issue: 2019, JLU, 58k on clock. No issues this far (knocks on wood). Randomly my coolant temps have been all over the place…from normal op temps, to 230+ in normal driving conditions. On two separate occasions, the temps soared into 3/4 gauge territory, while with the fan engaged. I immediately shut the engine down for a few moments and everything regulated again on both occasions. Both occasions were in restaurant drive thru’s.

second issue: the cabin temperature (at times) can’t seem to stay consistent when stopped. Basically internal heat is great until I come to a red light and then goes cool until I accelerate again. I notice this more within 10-20 minutes of the Jeep initially running.

Any thoughts or proposed remedies are welcome. TIA

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[Grayhound]

What does the oil look like on the dipstick?

 

[dstevens]

Low coolant level will present the same symptoms as the sensor reads steam at times. Also loss of pressure in the system will give normal running up to the point where the coolant boils and then temps skyrocket. And to throw in the most likely cause, a sticky thermostat will give the same symptoms.
Check coolant level when cold. Squeeze a radiator hose when hot and check it is firm. Then replace the thermostat.

 

[Surfwagon]

What does the oil look like on the dipstick?

Oil is clear….thankfully!!

 

[Surfwagon]

Low coolant level will present the same symptoms as the sensor reads steam at times. Also loss of pressure in the system will give normal running up to the point where the coolant boils and then temps skyrocket. And to throw in the most likely cause, a sticky thermostat will give the same symptoms.
Check coolant level when cold. Squeeze a radiator hose when hot and check it is firm. Then replace the thermostat.

I was thinking it was a thermostat issue.

Is a thermostat replacement a fairly straightforward DIY for a decently handy person?

I did look at my “cold” fluid level and it appears to be about .5” below the line….just top it off?

 

[Surfwagon]

BTW, there are no leaks whatsoever. Engine oil is clear, no foamy or milky….so at least it rules out head issues (I think). No drips on ground.

 

[NWJeepr]

Be sure to check both coolant reservoirs when cold. And yes, if they are low, it's time to top off, and then re-check after a couple engine cycles.

That's the first step.

 

[captainstabbins]

As far as the vehicle not heating when stopped do you have stop / start initiated??

 

[Willys41]

Hey all, not sure if these two items are related, but hoping to find out.

First issue: 2019, JLU, 58k on clock. No issues this far (knocks on wood). Randomly my coolant temps have been all over the place…from normal op temps, to 230+ in normal driving conditions. On two separate occasions, the temps soared into 3/4 gauge territory, while with the fan engaged. I immediately shut the engine down for a few moments and everything regulated again on both occasions. Both occasions were in restaurant drive thru’s.

second issue: the cabin temperature (at times) can’t seem to stay consistent when stopped. Basically internal heat is great until I come to a red light and then goes cool until I accelerate again. I notice this more within 10-20 minutes of the Jeep initially running.

Any thoughts or proposed remedies are welcome. TIA

I had the same high temps with my 3.6.
Your rad. fan comes on at 221 at 15% fan speed and 231 at 75% fan speed.
I solved this with the RPM Extreme JL fan controller.
Try this. Next time you see a high temp turn your a/c on high. That will turn your rad. fan on a high rate of speed and if it cools down you will know that more fan control is needed.

http://www.rpmextreme.com/Product/311/Jeep-JL-PWM-FAN-CONTROLLER.aspx

 

[Remorseless]

Check both coolant reservoirs and hoses for pink crust formations. When they leak sometimes it doesn't make it to the ground and will just evaporate at the spot of the leak leaving behind the pink crust.

 

[NPC 20883467]

Hey all, not sure if these two items are related, but hoping to find out.

second issue: the cabin temperature (at times) can’t seem to stay consistent when stopped.

When you say "stopped", is that a normal stop with the foot on the brake, or just when you are in park?

 

[RubiconJL392]

Besides what others have mentioned, you could have trapped air in your coolant system. Which can cause both of your issues.

 

[Surfwagon]

When you say "stopped", is that a normal stop with the foot on the brake, or just when you are in park?

Yes, normal stop with engine running

 

[Surfwagon]

As far as the vehicle not heating when stopped do you have stop / start initiated??

Star/stop turned off

 

[NPC 20883467]

Yes, normal stop with engine running

Sorry... I got nothin'.

If you had said the other, I'd have you check your AC system.

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