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running without thermostat?

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Old Nov 11, 2011 | 07:15 PM
  #1  
ol'DixieJeep's Avatar
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From: Warrenton MO
Year: 2000
Model: Cherokee
Engine: 4.7L I6
Default running without thermostat?

my buds run some of their trucks without a thermostat and it keeps theirs cooler... will this work with my 2000 XJ?
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Old Nov 11, 2011 | 07:30 PM
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From what I was told running without a thermoostat or some type of restriction for around town driving would be fine. If you are going to be going down highway with out the restriction, the coolant will be moving to fast to have the heat from the engine transferred to the coolant efficiently. So you could be going down the road and possibly over heat your engine with your gauge saying its running normal or cooler. I personally have never ran any of my cars without a thermostat but this is just what I was told.
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Old Nov 11, 2011 | 07:30 PM
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From: East TN
Year: 1997
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Engine: 4.0L HO
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it helped keep it a little bit cooler on my 97, but its gettin winter time so i put it back in because it takes forever to get the heat goin without the thermostat.
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Old Nov 11, 2011 | 07:47 PM
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From: Warrenton MO
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so its better while im wheelin of at slow speeds, but on highway im gonna overheat?
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Old Nov 11, 2011 | 07:52 PM
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Originally Posted by ol'DixieJeep
so its better while im wheelin of at slow speeds, but on highway im gonna overheat?
I dont want to say you will over heat since I personally have never come across a car that was running without a thermostat but this was what I was told by a mechanic that has been in the industry for decades.
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Old Nov 11, 2011 | 07:53 PM
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From: Warrenton MO
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ahh
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Old Nov 11, 2011 | 07:57 PM
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https://www.cherokeeforum.com/f2/eli...rmostat-15113/

I would just fix whatever is making it run hot. You have a 2000. Computer controlled. It makes major decisions about things based on engine and coolant temp. Without a t-stat it will never be able to close in on an ideal operating temp, most likely its going to be hot or cold, never just right. Probably gunna impact overall engine life in a negative way. Your motor is supposed to run at 210. Its engineered that way and runs best there.
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Old Nov 11, 2011 | 08:00 PM
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From: Warrenton MO
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its not running hot... its not running at all right now.

im getting my 4.7 stroker back from the shop this month and ive dropped $3,100 on it for all forge internals and a mean cam. i just wanna find the best and most optimum cooling set-up.
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Old Nov 11, 2011 | 08:15 PM
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From: The Republic of TEXAS
Year: 1998
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Plenty of myths/bad info in this thread. Only thing the FSM says is "don't run the motor WITHOUT a t-stat". Nowhere does it say 210 is normal operating temp or your motor is supposed to run at 210.
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Old Nov 11, 2011 | 08:54 PM
  #10  
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From: Williamsport, Pa
Year: 1997
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If you live in a warm climate and plan to drive in bumper to bumper traffic 90% of the time, or will be off roading in low gear alot you may want to do a 3-row CSF radiator and 180* thermostat. Running without a t-stat will adversly effect your gas mileage too. Just because it's a stroker doesn't mean it will run hot.
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Old Nov 11, 2011 | 09:28 PM
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Lols. How about we phrase it different then. 195 is the oem thermostat establishing a minimum. With the placement of the stock temp gauge 210 would be the "normal" displayed operating temp. That reading is probably the hot point and your engine is probably somewhat cooler than that, mine is. I don't know about your stroker. I want to do one of those myself. Here is a thread to check out: http://www.jeepstrokers.com/forum/vi...hp?f=24&t=2588 and http://www.jeepstrokers.com/forum/vi...hp?f=24&t=2588
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Old Nov 11, 2011 | 09:44 PM
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Whatever you do, DO NOT run your engine without a thermostat.......
Coolant will flow too fast through the engine to remove enough heat, and will flow too fast through the (already too small) radiator to transfer enough heat.........
I have seen a few cars, including one of my own years ago, overheat worse with the thermostat removed. The cooling system needs this restriction to operate efficiently.
Now keep in mind, the computer adjusts fuel, timing, and other events partly based on the operating temperature of the engine. IE: Cold-engine fuel enrichment, EGR, and canister purge functions, to name a few.
Running with a thermostat cooler than the manufacturer's recomendation with affect fuel milage at the very least. It will also affect some of the emissions related systems.
In some instances it could affect drivability.
The trade-off would be increasing the life of your engine/transmission by running it cooler. Heat, and Dirt are the biggest enemies here..
So, if you don't care about fuel mileage, or the environment, run a cooler thermostat. It will help your engine last longer.......
if you are searching for the most power, and efficiency from your engine, run the manufacturer specified thermostat.
There have been numerous studies by various companies, and performance engine builders regarding engine temperature, and performance. Most engines produce the most power, and the best efficiency in the 190-200 degree range.......I am sure there are exceptions. Some manufacturers(BMW comes to mind) are specifying a 205 degree thermostat. Most Nascar teams spend untold hours designing their cars to run 210-220 degrees during race conditions...They have found they make the most power in that range.....Their engines only have to last 1 event weekend though.
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Old Nov 11, 2011 | 10:10 PM
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From: The Republic of TEXAS
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Coolant flowing too fast is a myth.....the t-stat does one thing and one thing only and that's control MINIMUM coolant temp. When the t-stat is wide open, numerous other factors determine max coolant temps. Chrysler/Jeep also offered a "severe use" 180F t-stat part #5202 8446.

http://www.stewartcomponents.com/tec...ech_Tips_3.htm

http://www.arrowheadradiator.com/14_...utomobiles.htm

The FSM goes on to say a warm-up cycle is counted when coolant reaches 160F and also states the efan "on temp" is 218F......that's a 58 degree "range" for normal operating temp but the needle for the most part does stay in the middle.

Last edited by djb383; Nov 11, 2011 at 10:21 PM.
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Old Nov 11, 2011 | 10:45 PM
  #14  
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From: Warrenton MO
Year: 2000
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im getting a 3 fan conversion...

so i should maybe change to a 180 degree thermostat?
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Old Nov 11, 2011 | 11:11 PM
  #15  
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From: Orange County
Year: 88
Model: Cherokee
Engine: 4.0
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i was told by running no thermostat it allows the from cylinder to cool quicker than the others therefore making the shape of that number one cylinder a little bit different than the others and i had run with no thermostat for a good 2 years and i finally went and tore down that engine and i had noticed when spec'ing the engine out for rebuild it was .02 off and i had noticed the piston rings on the cylinder had been broken as well so i dont take my chances anymore
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