JKU overheating

Aspen0429

Aspen0429

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Joined
Sep 9, 2020
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Location
Baton Rouge
I have a 2014 JKU that has begun to over heat. Like other on a long incline my Jeep over heats enough to throw a coolant code. Mechanics have been unsuccessful stopping it. So far we have replaced radiator cap, thermostat, water pump, the radiator itself and the coolant sensor. Have performed engine/,block test etc. Still I have seen it get up to 240 's. The coolant system has been replaced and still experience over heating. Any suggestions? I would greatly appreciate any wisdom this group would be willing to share. Thank you. I live in a national forest and my wings have been clipped not having confidence in my jku.
 
I know this sounds obvious and blatantly stupid, but have they burped the system and checked to make sure the proper amount of coolant is in it? I read so many stories like this, and more often than not, it boils down to such a simple thing, honestly.
 
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This may not solve, but it does a good job of laying out some tests.

1. When it overheats....is it repeatable? As in, only when at speed, only when sitting etc. (If it only does it at speed, then is your grill blocking airflow?)
2. Take a look, have you watched your overfill? This article walks how it works well.
3. Watch the fan, watch it work, does it come on at the correct times?

Personally, I would do a few of these tests, and try to isolate if it's repeatable per situation. I'd have it cold, on flat ground, and start it. Just watch, hold the top hose as it runs so you feel the thermostat open.

Put extra marks on the reservoir, and document what it does when. A huge rise is when it boils/creates vapor.

Are you 100% using the correct coolant, I believe OAT for your year, not HOAT.

There is a lot of information on burping/purging air, I would get as much detail and make 100% sure.

If it will overheat in the driveway, then start looking for the smallest leak ever. Losing pressure will elevate temp and cause it to boil, losing any pressure in the system at all makes a difference.

You can get exhaust tested for coolant leak, but if you did a block test, I'm assuming that's not an issue.

Is the heater core an issue, leak back in the cabin?
 
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I have no leaks. It does not over heat while running with ac on sitting in driveway. It does not over heat when driving on level terrain. It only over heats (per my observation) when climbing a long incline on the highway. Otherwise is fine. It appears whatever the problem is it seems to be worsening. I appreciate your reply and I will take the steps you suggest. Thus far no luck. Thank you once again.
 
cpwolf said:

This may not solve, but it does a good job of laying out some tests.

1. When it overheats....is it repeatable? As in, only when at speed, only when sitting etc. (If it only does it at speed, then is your grill blocking airflow?)
2. Take a look, have you watched your overfill? This article walks how it works well.
3. Watch the fan, watch it work, does it come on at the correct times?

Personally, I would do a few of these tests, and try to isolate if it's repeatable per situation. I'd have it cold, on flat ground, and start it. Just watch, hold the top hose as it runs so you feel the thermostat open.

Put extra marks on the reservoir, and document what it does when. A huge rise is when it boils/creates vapor.

Are you 100% using the correct coolant, I believe OAT for your year, not HOAT.

There is a lot of information on burping/purging air, I would get as much detail and make 100% sure.

If it will overheat in the driveway, then start looking for the smallest leak ever. Losing pressure will elevate temp and cause it to boil, losing any pressure in the system at all makes a difference.

You can get exhaust tested for coolant leak, but if you did a block test, I'm assuming that's not an issue.

Is the heater core an issue, leak back in the cabin?
Click to expand...
Thank ypu so much for the info. Just came in after printing out your info and started and observed my system.
What would it mean if my raduator is full...yet I do not see any change in my overflow. Looking for that inch rise and fall be see no change.
Next, I see that I may have the wrong type of antifreeze may have the wrong type of antifreeze. Had new radiator installed and tech may have put the hoat instead of oat. Could this be my problem?
Thanks in advance for your response.
 
I see from your profile that you have an automatic. Are you sure that it's the engine and not the transmission? Our trans overheated and the light said "hot oil". It doesn't state anything about what oil is hot.
Our engine temp gauge reads in the middle all the time, yet whenever I open the hood it seems really hot. I can barely touch the hood prop stick. I plan on installing a louvre kit soon to help.
Hopefully you figure this out soon. Good luck.
 
If you cannot find any issues, then yes, I would flush it, long process, drain radiator, fill with distilled water, run, do it again, run, do it again, until it’s clear, The. Drain and fill with 100% no 50/50 mix.
Or if you can disconnect and pull the plugs etc.

I’m not sure why there’s no change in overflow, that’s not acting the way I’ve seen them. Is the overflow hose hooked up to the radiator? Is it clogged?
 
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