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I've been looking at a 2006 Wrangler (advertised as a Rubicon) and I went and drove it a little while ago. The dealership replaced the thermostat in it yesterday, but it was still running around 235-240 degrees. It was also taching 2800-2900 RPMs on the freeway at 60 mph (it has 35 inch tires on it). These two things kinda scared me off. Should it have? The dealer says it has a 4.11 rear diff, but I'm suspicious.
 

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Double check the VIN against car fax (any reputable dealer should give this to you), this will let you know if it's really a Rubicon or not. I think there's also a way to check for the original build specs from FCA based on the VIN too.

It'd better have the same gears front and rear. Auto or manual transmission? Your RPM indicates maybe 4.88 gearing?? That wouldn't be a bad thing as it'd allow you to go to larger tires.

No whining now...
 

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Carfax does confirm Rubicon. Assuming that I don't go to larger tires immediately, is the RPMs and the temperature any concern at all? It is a six speed manual.
 

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I’d be concerned and would expect to replace the entire 15 year old cooling system. My rig runs right at 210 degrees while driving freeway speeds uphill in the desert. Definitely needs to be addressed.
 

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Discussion Starter #5
It's a six speed manual. It only has 49,700 miles on it. I have a 2000 TJ and it runs at 210 also.
 

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Sounds like it was regeared. 3k RPMs are not hurting anything. Its needed to turn 35" tires. The cooling system should not be that hot. Time for an overhaul in that dept. How is it running 35s? Suspension setup? It takes a lot to run 35s correctly. If it is a horrible hodge podge of parts then I would re think it. Do you have any pictures of the suspension?
 
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The temps are too high.

The rpms are not too high. Though I wonder if the speedo has been corrected. 4.88 is a nice gear for 35s/6 speed. 5.38 is right for the automatic. 75mph should be approaching 3k rpm.

To confirm that it is a Rubicon, the 6th digit of the VIN needs to be a 6. After that, the t case has a round tag on the rear upper left that clearly says 241(+a letter code) with 4-1 below that.

Make sure the lockers are there and actually work. Looking at the pinion, the rubber air hose is on the upper left of the diff housing. The pumps were originally on the rear of the center skid plate.

If you know what to look for, there isn't anything here to be too scared of.
 

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A bone stock Rubicon will turn about 3K at close to 80.

If you're turning that at 60 with 35s in 6th, that would def be regeared.

You also need to check the OPDA on 05 or 06s.
 
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