Three bad thermostats? Or a bigger problem?

Tech topics for the TJ and LJ (Unlimited) models manufactured from 1997 to 2006.
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Fourthwolf
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Three bad thermostats? Or a bigger problem?

Postby Fourthwolf » Sun Nov 30, 2014 1:38 pm

Okay guys, I have a coolant leak that I am trying to track down. While trying to fix that, I realized that my thermostat might be the problem, so I replaced it. A little later, my engine started over cooling. The thermostat was locked open, so I replaced the thermostat and that fixed it. Temp was fine for a week or so, then it started over-cooling again. I pulled the thermostat today and it's again locked open. I'm replacing it now, but is there some larger problem causing all this, or am I just unlucky?


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Re: Three bad thermostats? Or a bigger problem?

Postby Shrek » Sun Nov 30, 2014 7:56 pm

That sounds weird, try one from a different place. Assuming you are installing correctly.
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Postby soonermatt » Sun Nov 30, 2014 8:02 pm

You might also check that you aren't getting air pockets in there. If I've done a full flush or water pump replacement. I sometimes have to fill into the heater core directly.

I've encountered situations where there is air in the top half so the thermostat is reading cold while there is boiling water down stream.
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Three bad thermostats? Or a bigger problem?

Postby emtgared » Sun Nov 30, 2014 8:07 pm

Seems strange. Where are you getting parts from? Hopefully the guy behind the counter is getting you right part. Maybe it's just that brand or something. I can't think of much that would cause that other than bad part or maybe installed backwards if you can with that particular style. I have had a few vehicles they could go either way.
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Three bad thermostats? Or a bigger problem?

Postby emtgared » Sun Nov 30, 2014 8:09 pm

Hmm that also could do it. Air pocket could cause the water to not circulate and water at thermostat to overheat and fry thermostat,
08 jk. Rebuild/Stretch/Cage in progress.

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Three bad thermostats? Or a bigger problem?

Postby Fourthwolf » Tue Dec 02, 2014 9:17 am

Update: I should probably mention that I am losing a LOT of coolant. I'm pouring in probably 2 quarts a week. Can't find any external leaks though, and nothing on the ground when it's parked/idling.

Also, autozone mechanic said to fill the radiator directly, start it up, then top it off, and if bubbles keep coming up the spout, it's a blown head gasket. I did this test and a spurt of bubbles kept coming up every 16 count or so...

Could a head gasket cause all of this?

Also, getting thermo's from autozone.


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Re: Three bad thermostats? Or a bigger problem?

Postby Fourthwolf » Tue Dec 02, 2014 5:54 pm

Further update:

Today I checked the oil for milkshake coloring. It looked like you'd expect, dark brown/black (i'm due for an oil change in the next hundred miles). Then I topped off the coolant again and let the jeep idle for a bit. I also throttled it up a few times. After a few minutes I noticed that the coolant level dropped a good chunk at once. It went from full to the top, to just over the radiator. I went looking for where it all went and it apparently dumped out my exhaust. So...any good suggestions as to what's going on and how to best isolate the problem and fix it?
Thanks for all the help so far!
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Re: Three bad thermostats? Or a bigger problem?

Postby Shrek » Tue Dec 02, 2014 7:34 pm

Sounds like a cracked head. :cry:
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Three bad thermostats? Or a bigger problem?

Postby Fourthwolf » Thu Dec 04, 2014 12:47 am

Something I could fix myself? Maybe with a more experienced hand guiding? YouTube videos + chilton's? Any cautionary tales I should heed?


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Re: Three bad thermostats? Or a bigger problem?

Postby dilleywhopper » Thu Dec 04, 2014 6:43 pm

A Hemi swap would be easier.
Look at that, a SILVER Jeep!

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