Tech question..... - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today

Like Tree4Likes
  • 1 Post By NoWhiningX
  • 1 Post By Blort
  • 1 Post By tworley
  • 1 Post By jjvw
Thread Tools

Please support our sponsors and let them know you heard about them on
Old 08-15-2019, 05:05 PM
Thread Starter
HPD2000's Avatar
Join Date: Jul 2014
Location: Washington Court House, OH
Posts: 40
Tech question.....

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.

HPD2000 is offline   Quote
Old 08-15-2019, 05:12 PM   #2
No Whining now....

5-Year WF Supporting Member
NoWhiningX's Avatar
Join Date: Apr 2019
Location: North County San Diego Coast
Posts: 166
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...
HPD2000 likes this.

Roads?? Where we're going, we don't need roads!
NoWhiningX is offline   Quote
Old 08-15-2019, 05:16 PM
Thread Starter
HPD2000's Avatar
Join Date: Jul 2014
Location: Washington Court House, OH
Posts: 40
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.
HPD2000 is offline   Quote
Sponsored Links
Old 08-15-2019, 05:19 PM   #4
Join Date: Jul 2016
Posts: 1,078
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.
HPD2000 likes this.
Blort is offline   Quote
Old 08-15-2019, 05:20 PM
Thread Starter
HPD2000's Avatar
Join Date: Jul 2014
Location: Washington Court House, OH
Posts: 40
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.
HPD2000 is offline   Quote
Old 08-16-2019, 10:15 AM   #6
tworley's Avatar
Join Date: Jun 2014
Location: Morrison, CO
Posts: 4,523
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?
HPD2000 likes this.
97' 4.0L - AX-15 - 4.56 D30/Rubi44 - Currie 4" SL -1.25" BL - 1" MML - 35s - XRC Rear Bumper/Carrier - JB SSYE - MC F/R CAs - MC F/R TBs - Currie Currectlync - Currie AR - Savvy GTS - Savvy UA - Savvy Shift Cable - ARB RD100/116 - RG&A 4340 Axle Shafts - Currie Mini Skids - Superwinch LP8500 - Poison Spyder Rocker Knockers - Poison Spyder Defender XCs - BMB Brakes - Fox 12" Resi 2.0 Shocks -
Colorado Jeep
tworley is offline   Quote
Old 08-16-2019, 10:44 AM   #7
jjvw's Avatar
Join Date: Oct 2013
Location: Denver, CO
Posts: 4,589
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.
HPD2000 likes this.
2003 Rubicon
jjvw is offline   Quote
Old 08-16-2019, 06:15 PM   #8
Join Date: Mar 2010
Location: Warner Robins, GA
Posts: 998
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.
'92 Islander
'06 Rubicon
jkp is offline   Quote
Old 08-16-2019, 06:55 PM   #9
Knows a couple things...

WF Supporting Member
Jerry Bransford's Avatar
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 48,212
Being regeared to run those 35" tires at those rpms is a GOOD thing. That temperature it's running at is not a good thing.

When you have a choice, buy American.
Jerry Bransford is offline   Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 05:29 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC. is not in any way associated with the Chrysler Motors LLC