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Discussion Starter · #1 ·
OK I've replaced my thermostat at least a half dozen times since I bought my '06 in 2013. I replaced it just 2 weeks ago, and a couple days ago I noticed it running warmer than it should. Then today I notice it is damn near pegged, even on the highway! I turned the heater on full blast and it came down to 3/4 on the gauge (220-230 degrees on my Trinity), and limped home. Took my other vehicle to Advance Auto and bought another MotorRad 180 (I swear no matter what "brand" all the thermostats for HEMIs are MotorRad). I pulled my old thermostat out and boiled both of them. Sure enough, the 2 week old one failed to open and the new one opened no problem. Runs at 192 consistently now.

I'm so good at replacing thermostats in this Jeep I can have a new one in in about 15 minutes, with only spilling SOME antifreeze!

Food Recipe Cookware and bakeware Ingredient Cuisine


Anyways, there doesn't seem to be much to these thermostats. WHY DO THEY KEEP FAILING ALL THE TIME!??
 

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BlaBlaBla
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Go to the dealership and buy a stock thermostat. I had two fail before I went back.


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2006 Jeep GC SRT8 with BWoody CAI and 93 Octane Tune
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My last failure I just took my out. Found the check engine light not that bad to live with. For the first 6 months I used my Dashawk to reset the light. Now I just enjoy the lower temps. I live in SFL so the coldest I usually drive in is about 50...
 

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2006 Jeep GC SRT8 with BWoody CAI and 93 Octane Tune
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At 193k miles, my truck isn't lasting much longer without an engine rebuild anyway. I have been sans thermostat for the last 3 years or so. Clogging the cats with that last thing I am worried about. My performance mechanic warns of weak valve springs being the Achilles heel of the 6.1L. Drop a valve buy a crate motor...
 

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Discussion Starter · #9 ·
So yesterday my Jeep was running hot again. 217, 219, 224, 226 degrees on the highway. It cooled down to 210 in town. So I bought another 180 degree thermostat from Advance Auto Parts and pulled my "old" one (less than 2 months old). I boiled them both and the old one didn't open, and the new one did at about 185. So I swapped it in and returned my old one again. Runs rock steady at 185 now. I hope this one lasts longer.

Does anyone besides MOTORAD make thermostats for these things? I might try something different next time.
 

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2006 Jeep GC SRT8 with BWoody CAI and 93 Octane Tune
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I just saw you are from the great white north, eh? You betcha you need one up there. I'm in south Florida and about 300 days a year my morning temp is over 75 F.

I use a local performance shop American Muscle Performance for my mechanical repairs. They hire Mopar trained mechanics and mainly do Hellcat and TrackHawk performance builds. They said as long as I stay in SFL, my engine will get to operating temp quicker than most hemis north of Orlando that have thermostats.

I was leery at first of running an open system, but after 3 years and 36k miles I'm now a believer that in our climate it's safe.
 

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Discussion Starter · #14 ·
drill 1/8" hole in a napa 191. thank you to Eric who turned me on to this solution!
From what I could tell with a quick Google search, a NAPA 191 is a MOTORAD.

Just ordered a MISHIMOTO MMTS-JED-06L off Amazon for $50+. Should arrive tomorrow. I'll post up if MOTORAD is stamped anywhere on it, or if it looks exactly like a crap MOTORAD.

I've literally replaced MOTORAD thermostats a dozen times on my '06 JGCSRT-8. They just fail for no apparent reason. Life expectancy is about a month.

The truck seems to run better at 185-195 degrees. I don't want a stock 203+ stat.
 

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Discussion Starter · #15 ·
do you run a tune? the 180's will fail or throw up constant error codes without. You probably know that but putting it out there just in case
What would cause the thermostat to fail without a tune? Like, what physically/mechanically/chemically is happening?

I've never gotten a code. What code?

I'm running an aftermarket Black Magic fan and Hayden fan controller, so not sure what the tune would do anyways. Thermostats seemed to fail just as often before and after my fan mods. HHP claims to have tuned it for the 180 stat; at least that is what I requested but who knows?
 

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Discussion Starter · #16 ·
I received my Mishimoto thermostat today. It IS physically different than a MOTORAD. Here are some pics for reference. MISHIMOTO on left; MOTORAD on right.

Wood Table Gas Hardwood Electric blue


Automotive tire Wood Coil spring Coil Household hardware


Automotive tire Wood Camera lens Rim Camera accessory


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I'll install it tomorrow. Worked too late today.
 

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Discussion Starter · #17 ·
Just wanted to update this thread: I've had this Mishimoto thermostat installed for 6 months without any issues. Runs solid 185 degrees all the time. Never had that happen with a crap MOTORAD thermostat.

I also got the new 3-core aluminum radiator from Wizard Cooling with SPAL fan/shroud. The Jeep runs TOO cold now that it is winter. I'm about to swap in a higher temp thermostat (Mishimoto or factory MOPAR).
 
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