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Unread 10-19-2005, 06:57 AM   #1
TJ-Marine PA
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What is normal operating temp for a 4.0?

After running my Jeep at varying speeds for half an hour the temperature gauge reads just below the tick mark between 100 and 210. Is this normal or is this low? Is the thermostat bad?

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Unread 10-19-2005, 07:36 AM   #2
Mr. Joshua
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Mine runs about 210 as well.
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Unread 10-19-2005, 08:56 AM   #3
AjRagno
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It should warm up and reach 210, then stay there until the engine is shut off. If it drops to 100 while you're driving, the thermostat is stuck open.
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Unread 10-19-2005, 09:05 AM   #4
trailblaze
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mine runs just a hair under 210.....except when i go wheelin, if im goin slow or doin hill climbs it goes slightly over 210.
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Unread 10-19-2005, 09:37 AM   #5
TJ-Marine PA
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How long does it take for the engine to warm up? It was running for 30 mins today and may have hit 150 as a max temp. On the plus side when I got out I checked the radiator and it was still cool to the touch. so it does seem like the thermosat is open.
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Unread 10-19-2005, 10:15 AM   #6
JIMBOJAMES
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on average my 4.0 runs from 150-210. It depends on my driving conditions. If the thermostat was stuck then the Jeep would heat up.
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Unread 10-19-2005, 10:51 AM   #7
denverd0n
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Quote:
Originally Posted by TJ-Marine PA
It was running for 30 mins today and may have hit 150 as a max temp.
You have a bad thermostat. Replace it.
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Unread 10-19-2005, 11:30 AM   #8
TJ-Marine PA
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How long can I get away with the thermostat stuck open like this? I don't have time to fix it this week.
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Unread 10-19-2005, 11:57 AM   #9
Blake
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Quote:
Originally Posted by TJ-Marine PA
How long can I get away with the thermostat stuck open like this? I don't have time to fix it this week.
Terrible gas mileage is pretty much the only thing that will happen.
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Unread 10-22-2005, 09:10 AM   #10
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I think I've figured out the normal driving temps for these things.

200-205 - Temp while driving leisurely with no AC

210 - Temp while driving offroad with no AC; with AC and driving leisurely; or idling with no AC.

215 - Temp while driving offroad with AC, idling/stop n go traffic in hot weather with AC on

Anything below 200 is either an aftermarket, lower temp t-stat or a t-stat stuck open.
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Unread 10-24-2005, 06:09 AM   #11
TJ-Marine PA
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Quote:
Originally Posted by Achped
Anything below 200 is either an aftermarket, lower temp t-stat or a t-stat stuck open.
Or the previous owner removed the thermostat. I fixed it over the weekend the former owner or maybe the one before him removed the thermostat for some reason. The only reason I can think is it was stuck closed and they quick fixed it and for got it.
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Unread 10-25-2005, 09:39 AM   #12
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will the engine lift be affected (prolonged) with an aftermarket t-stat? or does that 30+/- degrees not effect longevity?
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Unread 10-26-2005, 02:54 PM   #13
limecolbyjack
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my 04 tj has a 195 degree t-stat from the factory the gauges are off a tad and they look to read 210. they put it on the computer and it read 195-198 and when they put the shield over the grill to heat it up it would only go 220. kinda interesting. but 210 on the gauge is really 195 they said. -chris
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