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Old 11-18-2013, 07:25 AM   #1
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Wrangler running at 150 degrees

Got a 2000 Wrangler- 6cyc.

About 2-3 weeks ago the temp started running about 175. Then last week it dropped to 150. Was 23 degrees here in ATL last week.

I read up on the forum and the culprit seemed to be thermostat gone bad- stuck open. I bought a new fail-safe thermostat. Got it in after 3 tries- the thermostat kept falling out of place and causing a leak as I put it back together.

Jeep warms up- then goes to 220. I turned it off, fluid level is low. I let the Jeep cool off, then added water until I could drive for more coolant.

When I turned the Jeep back on, it only heated up to 150! Drove to store- still 150.

I got my old thermostat- dropped in boiling water- and it opens right up!

Now my brother pointed out that the old thermostat may have been sticking.

Cant understand why the new one is not working? I read other post that advised NOT to use the fail safe I got from Autozone. Why is that?

Is there any other thing that would cause the Jeep to run cold?

I guess next weekend Ill take the new one out- drop it in boiling water to see if it is broken.

Any other suggestions?

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Old 11-18-2013, 07:55 AM   #2
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Fail-safe thermostats won't work because the lock open at about 200 degrees. Jeep engines will run at about 210 degrees, this makes a fail-safe lock open and not regulate the engine temp properly. Get a regular 195 thermostat and install then you should be good to go. Also if you put a dab of rtv on the edge of the thermostat and put it in the engine block and let it set for a few mins then install the thermostat housing you will have less trouble with the thermostat falling out. Hope this helps.

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Old 11-18-2013, 08:16 AM   #3
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Quote:
Originally Posted by EagleQA View Post
Got a 2000 Wrangler- 6cyc.

About 2-3 weeks ago the temp started running about 175. Then last week it dropped to 150. Was 23 degrees here in ATL last week.

I read up on the forum and the culprit seemed to be thermostat gone bad- stuck open. I bought a new fail-safe thermostat.
Any other suggestions?
Search for fail-safe in this forum and you'll see suggestions to stay away from fail-safe thermostats:
http://www.wranglerforum.com/search....rchid=13793954
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Old 11-18-2013, 08:22 AM   #4
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Originally Posted by Redrider94 View Post
Fail-safe thermostats won't work because the lock open at about 200 degrees. Jeep engines will run at about 210 degrees, this makes a fail-safe lock open and not regulate the engine temp properly. Get a regular 195 thermostat and install then you should be good to go. Also if you put a dab of rtv on the edge of the thermostat and put it in the engine block and let it set for a few mins then install the thermostat housing you will have less trouble with the thermostat falling out. Hope this helps.

Thanks Red- now that makes sense! Did not think about it opening and staying open at 200. That explains why it seemed to work for a little bit....Ill try to find a OEM thermo....and no fail safe.

Only thing still fishy is why the old one stopped working- but seemed to open up when I dropped it in the boiling water. If it opened in the boiling water- it was not stuck in the open position- logically. My old one did not have a air hole it in- I wonder if the original factory thermo had an air hole? I had this used engine put in about 6 moths ago so I'm not sure if this is the original or not.
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Old 11-18-2013, 08:29 AM   #5
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Originally Posted by Tony T View Post
Search for fail-safe in this forum and you'll see suggestions to stay away from fail-safe thermostats:
http://www.wranglerforum.com/search....rchid=13793954
I'll try that search- but in my reading I saw people say stay away- but never mentioned why! I guess it should have been obvious- but I missed it...

My question is- why does the part store have those mapped to recommend as a replace part??? Newbies like me have no idea- and the whole not running hot part makes sense. I guess that is what the forum is for! I read here first but did not get all the details
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Old 11-18-2013, 08:45 AM   #6
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make sure your thermostat has a bleed hole in it and install with hole at top
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Old 11-18-2013, 09:02 AM   #7
Knows a couple things...

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Quote:
Originally Posted by Decoy_58 View Post
make sure your thermostat has a bleed hole in it and install with hole at top
That might be an exercise in frustration, thermostats with a vent hole are out there but they're not common.

That is a good idea however so for the OP, if you can't find one, you can use a 1/8" bit to drill your own. As Decoy said, rotate the thermostat so the vent hole is at the top so it will let any trapped air vent out.

And as said, make sure to install only a 195 degree thermostat and also, as also said, make sure to avoid a fail-safe thermostat.

The first thermostat below shows a factory vent, the second one shows one that was drilled...
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Old 11-18-2013, 09:36 AM   #8
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Thanks guys- I got it! Probably will just get the cheap one from Autozone and drill my own hole. Will report back in a few days when I can get the time to get this done.
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Old 11-22-2013, 05:28 PM   #9
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Went got the $3.99 thermostat from Advanced today. Drilled air hole in. Luckily gasket was still in good shape- they were out! Popped stat in place. Took a 4-5m min and pegged at 210! I let it run fro 10-15 min then drove it 10 miles down to lake and back. Still 210- and heater is blowing warm air again! It is not HOT like it used to be- ill try to flush the lines again soon- but fingers crossed this time it stays at 210!

My oil pressure is still running high- well over the 40 mark. That started happening when the jeep was running cold- at 150.

Maybe I just need to change the oil? It ran for 2 weeks at 150.

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