My 08 jku rubi has 159,000 on it. Lately when it is over 100 the temp gauge creeps up into the 3/4 mark sometimes a bit higher. It has never done that before ever. it has happened 2xs. I Have a trans cooler. I know this is not normal for my jeep. what have the rest of you seen? I have the lifetime power train warranty? but have also heard that jeep is not honoring the warranty the value of the Jeep is less than the cost of the motor or repairs?


Those of you where it is really f... hot like say phoenix. How hot does your motor run?
is the temp gauge always in the middle dead straight up?

so do I wait for the new JL buy a 2017 before they are all gone or gamble on the current state of my Jeep.

 

Well, drove around today in 110 degree heat and needle stayed where it always does. My jeep only has 56k miles though. 2010 so I have the 3.8 as well.

Can't say much about what might need replaced. Maybe a cheap sensor or radiator. New coolant? Flush?

 

My 2012 ran a bit hot a couple times. I noticed the coolant was a couple of cups low. Topped it off and filled reservoir. Problem was solved.

 

Like others commented, I'd check fluid levels. If the the system has never been flushed, I'd flush it and replace the thermostat. I had a thermostat go bad at 45,000 miles. Good luck

 

The temperature gauge on my 2007 was always unreliable. It would barely move when the temp would increase during runs across high temperature desert terrain. The Jeep does monitor the temperature, it's that gauge that's poor. Recommend that you use something like the Android app Torque Pro to monitor the actual temperature. That will also let you monitor other temperatures in the vehicle as well, including cats, intake, ambient, auto trans, etc.

FYI, when mine started having intermittent high temperature readings, it turned out to be the intake manifold gasket. I noticed the failure both on the coolant temp, and the intake manifold temp (which normally runs 10-15° above ambient temp). In my case, it didn't do it all of the time--just intermittently. Other problems included a vibration in the engine that was felt throughout the entire vehicle as it occurred. It wasn't a strong vibration, rather more like a vibrating bed in a cheap motel (please don't ask how I know this, LOL). It was obvious to more than just the me: While driving at Anza Borrego Desert State Park it occurred with another driver. He immediately asked me what was wrong with my Jeep. I figure since he was a two time winner of the 24 Hours of Daytona (2008 and 2010), he had the credentials to declare that something was amiss. This vibration might last for five to ten seconds before stopping and not recurring for a couple hours. After doing a lot of research and reading that lots of folks never figured out what was causing it, and that Jeep dealers were denying that anything was amiss, I learned that these symptoms can also be caused by a cracked head or intake manifold.

 

Had similar issues with my 07 recently and found out thermostat housing was cracked.

 

Is the Fan not always kicking on?

Mine just did this, and it was the fan switch shorting out... it sometimes ran, but then would randomly not turn the fan on.

Just pay attention when it starts running hot, pull over and pop the hood and listen to see if the fan is running. My would stop... and then it would get hot like you are saying. But after turning it off... and restarting it ... in normally got the fan going again. So I let it run in the garage and put a load on it... ( all lights on, AC running, etc...) and waited for it to heat up... it didn't. But on the second time of trying this the fan kicked out and stopped and let the temp climb to 3/4 on the temp gauge... I check relays- they were fine, fuse was fine, temp sending unit was replaced... it still did it! On your electric fan there is a harness going into a switch at the top passenger side. That switch had given out... tapped on it... it would start up... keep tapping it would turn off.

New switch (o-reilys and dealer both had them) ... and no problems again.

 

My needle is always straight up, so when I noticed erratic overheating I was concerned. Plus, the electric fan was running when I had never noticed it before. I found my waterpump was beginning to leak, so I kept it topped up unitl the repair could be made. Once I topped it up, no more overheating at all - and it only took a small amount. Also, I've had problems in the past with poor heat. I burper it by parking with the front uphill, opening the radiator cap and running the throttle up for awhile.

My electric fan seldom runs - and never when the engine is shut off.