An I put a cooler tstat in my XJ? 210 just seems hot to me.

 

The thermostat does NOT control the maximum operating temperature of the engine.

And 210 is not too hot. It is considered by Jeep to be the "optimal" temperature of operation.

Use a 195 degree thermostat for the vast majority of stock 4.0 engine applications.

 

I pulled the 180 degree out of my 4.0 and put the correct 195 t-stat in and my engine temp is actually cooler according to the gauge. Guys on this forum state they removed the t-stat all together and never have a temp over 160 degrees. What they don't realize is that the temp they are seeing is the water temp, not the engine temp. The water is not staying in the engine long enough to absorb the heat from the engine, but the low gauge reading has them fooled.

 

i agree with the other two guys. you want the jeep to run at a the operating temp or just right below it. motor runs best when its at the right degrees. using a 190 will not hurt the jeep at all, im running a 185 and have no problems. it helps when its a hot freaking summer.

 

I've read on other XJ forums that Chrysler/Jeep part #5202 8446 is an available 180F t-stat. No where in the FSM does it say 210F is "optimal coolant temp" or "optimal operating temp". 210F is never mentioned or referenced anywhere in the FSM. The FSM says a heat cycle is counted when coolant temp passes 160F and it says the efan is turned on at 218F coolant temp. Those are the only 2 references to coolant temp. It does say do not operate without a t-stat.

Where do u buy 190 and 185 t-stats......I've never seen one?

 

I am going to order that 180 degree tstat for $7.21 and see