180* Thermostat

MichaelT

MichaelT

Well-Known Member
Joined
Sep 7, 2007
Location
Charlotte
I have a 99tj. Would I gain anything by putting a 180* thermostat in? Right now the engine runs about 210*. Thanks -Mike
 
I'm pretty sure 210 is the normal operating temperature for your engine. Why would you want to go to a lower temp thermostat. That should only make it take longer to warm up
 
cj777 said:
I'm pretty sure 210 is the normal operating temperature for your engine. Why would you want to go to a lower temp thermostat. That should only make it take longer to warm up
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The 4.0L is a warm-running engine. It was designed to run in the 200-210* range.
 
Another thing to keep in mind when thinking of putting a cooler than recommended t-stat in an OBDII engine. The engine and computer are designed to run at a constant temp, in the case of a 4.0LTJ, around 200 degrees. Now, if you think you're doing anything good with a cooler t-stat, think again. An OBDII controlled engine will intentionally run rich during warmup periods. This is called "open loop". In an open loop circumstance, the computer will intentionally run the engine rich to increase the temp to the optimum operating temp. If you try to put in a cooler stat, the engine will continually run rich, trying to reach a higher temp. Result? Lower MPG and poor performance. Under normal circumstances, with the proper stat, the engine will be in open loop (running rich) until the temp comes up to the ideal range. Then the computer will go into closed loop and return the fuel/air mix to a normal setting, resulting in the best possible MPG, performance and lowest emissions.
 
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